Internet: http://www.eren.doe.gov/femp/ Introduction Incorporating energy efficiency, renewable energy, and sustainable green design features into all Federal buildings has become a top priority in recent years for facilities managers, designers, contracting officers, and others in government buildings procurement. These progressive design strategies have been formalized through Executive Order 13123 (known as Greening the Government through Efficient Energy Management), which was issued on June 3, 1999. There are significant opportunities to accomplish the goals set forth in the executive order, whether in new building design or in the context of renovations. This guidebook addresses the first category—the design process for new Federal facilities. Because energy-efficient buildings reduce both resource depletion and the adverse environmental impacts of pollution generated by energy production, it is often considered to be the cornerstone of sustainable design. In this publication, we will be looking at what low-energy design means, specific strategies to be considered, when and where to apply these strategies, and how to evaluate their cost effectiveness. Low-energy building design is not just the result of applying one or more isolated technologies. Rather, it is an integrated whole-building process that requires advocacy and action on the part of the design team throughout the entire project development process. The whole-building approach is easily worth the time and effort, as it can save 30% or more in energy costs over a conventional building designed in accordance with Federal Standard 10 CFR 435. Moreover, low-energy design does not necessarily have to result in increased construction costs. Indeed, one of the key approaches to lowenergy design is to invest in the building’s form and enclosure (e.g., windows, walls) so that the heating, cooling, and lighting loads are reduced, and in turn, smaller, less costly heating, ventilating, and air conditioning systems are needed. In designing low-energy buildings, it is important to appreciate that the underlying purpose of the building is neither to save—nor use—energy. Rather, the building is there to serve the occupants and their activities. An understanding of building occupancy and activities can lead to building designs that not only save energy and reduce costs, but also improve occupant comfort and workplace performance. As such, low-energy building design is a vital component of sustainable, green design that also helps Federal property managers meet the requirements of the Energy Policy Act of 1992, Executive Order 13123, and other climate change goals. The low-energy design process begins when the occupants’ needs are assessed and a project budget is established. The proposed building is carefully sited and its programmed spaces are carefully arranged to reduce energy use for heating, cooling, and lighting. Its heating and cooling loads are minimized by designing standard building elements— windows, walls, and roofs—so that they control, collect, and store the sun’s energy to optimum advantage. These passive solar design strategies also require that particular attention be paid to building orientation and glazing. Taken together, they form the basis of integrated, whole-building design. Rounding out the whole-building picture is the efficient use of mechanical systems, equipment, and controls. Finally, by incorporating building- integrated photovoltaics into the facility, some conventional building envelope materials can be replaced by energy-producing technologies. For example, photovoltaics can be integrated into window, wall, or roof assemblies, and spandrel glass, skylights, and roof become both part of the building skin and a source of power generation. This guidebook has been prepared primarily for Federal energy managers to provide practical information for applying the principles of low-energy, whole-building design in new Federal buildings. An important objective of this guidebook is to teach energy managers how to be advocates for renewable energy and energy-efficient technologies, and how to apply specific strategies during each phase of a given project’s time line. These key action items are broken out by phase and appear in abbreviated form in this guidebook. Low-Energy Building Design Guidelines Energy-efficient design for new Federal facilities F E D E R A L E N E R G Y M A N A G E M E N T P R O G R A M A guidebook of practical information on designing energy-efficient Federal buildings. Prepared by the New Technology Demonstration Program No portion of this publication may be altered in any form without prior written consent from the U.S. Department of Energy and the authoring national laboratory. DOE/EE-0249 F E D E R A L E N E R G Y M A N A G E M E N T P R O G R A M Disclaimer This report was sponsored by the United States Department of Energy, Office of Federal Energy Management Programs. Neither the United States Government, nor any agency or contractor thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, mark, manufacturer, or otherwise, does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency or contractor thereof. The views and opinions of the authors expressed herein do not necessarily state or reflect those of the United States Government or any agency or contractor thereof. F E D E R A L E N E R G Y M A N A G E M E N T P R O G R A M Contents Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1 About the Technology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5 Application Domain . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6 Energy-Saving Mechanisms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6 Advantages of Low-Energy Building Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6 Application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7 Applications Screening . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7 Building Types: Characteristics and Profiles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9 Integrating Low-Energy Concepts into the Design Process . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12 What to Avoid . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .29 Design Considerations and Computer Modeling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .29 Strategy Interactions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .29 The Benefits of Multiple Use . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .30 Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .30 Costs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .30 Design and Analysis Tools . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .31 Energy Savings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .31 Other Impacts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .31 Case Studies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .31 The Technology in Perspective . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .35 Technology Development . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .35 Technology Outlook . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .36 Product Resources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .36 Who is Using the Technology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .36 For Further Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .37 Appendix A: Climate and Utility Data Sources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .42 Appendix B: Federal Life-Cycle Costing Procedures and the Building Life Cycle Cost (BLCC) Software . . . . . . . . . .42 3 F E D E R A L E N E R G Y M A N A G E M E N T P R O G R A M 4 This page left blank intentionally F E D E R A L E N E R G Y M A N A G E M E N T P R O G R A M About the Technology Buildings consume roughly 37% of the primary energy and 67% of the total electricity used each year in the United States. They also produce 35% of U.S. and 9% of global carbon dioxide (CO2) emissions. Preliminary figures indicate that in FY 1997, Federal government facilities used nearly 350.3 trillion British thermal units (Btus) of energy in approximately 500,000 buildings at a total cost of $3.6 billion. By following a careful design process, it is possible to produce buildings that use substantially less energy without compromising occupant comfort or the building’s functionality. Whole-building design considers the energy-related impacts and interactions of all building components, including the building site; its envelope (walls, windows, doors, and roof); its heating, ventilation, and air-conditioning (HVAC) system; and its lighting, controls, and equipment. This stands in marked contrast to the traditional design process, where there is generally no goal to minimize energy use and costs beyond what is required by codes and regulations. Executive Order 13123 calls for a 30% reduction in energy use per gross square foot by 2005. To achieve this goal, the agency and design team must establish minimized energy use as a high priority goal at the inception of the design process. Abalanced and appropriately funded team must be assembled that will work closely together, maintain open lines of communication, and remain responsive to key action items throughout the delivery of the project. Continuing advocacy of low-energy design strategies is essential to realizing the goal. Therefore, it is important that at least one technically astute member of the design team be designated as the energy advocate. This team member performs many useful functions, such as: • Introducing team members to design strategies that are appropriate to building type, size, and location. • Maintaining enthusiasm for the integration of low-energy design strategies as central components of the overall design solution. • Ensuring that these strategies are not abandoned or eliminated during the later phases. • Overseeing construction to ensure that the strategies are not thwarted or compromised by field changes. For most projects, it is also highly advisable to retain an experienced low-energy design consultant. Because low-energy design is not entirely intuitive, experience gained from a range of projects is vital. Indeed, the energy use and energy cost of a building depend on the complex interaction of many parameters and variables that require detailed analysis on a project-by-project basis. Some of the attributes that an energy consultant should bring to the project include: • Sufficient background to identify potential strategies based on experience. • Knowledge of Federal information sources (e.g., Federal Energy Management Program, national laboratories), Federal requirements (e.g., 10 CFR 435 and 436 Energy Star™ buildings and equipment, energy-savings performance contracting), the Energy Policy Act of 1992 (EPAct), and other relevant executive orders. • Technical expertise that generates enthusiasm, cooperation, and respect among team members. • The capacity to efficiently use detailed computerized energy simulation programs such as the latest version of Energy 10 or DOE 2. • The ability to make informed design recommendations based on computer results and life-cycle economic analyses. • Abreadth of experience sufficient to consider design options that not only save energy, but are also integrated with other project needs, including aesthetic considerations. In sum, the energy consultant should serve as a catalyst for eliciting innovative energy-conserving design ideas from the entire design team. In some cases, other members of the project team (such as the design architect and engineer) may, themselves, be quite pro- 5 Estimated Costs for Low-Energy Design Consulting Services Investment ($/ft2) Small buildings Medium buildings Large buildings Energy Use Type (0 to 20,000 ft2) (20,000 to 100,000 ft2) (100,000 ft2 and above) Moderate Energy Users Including single family residences, housing, and warehouses $0.35 to $0.25 $0.25 to $0.15 $0.15 to $0.05 High Energy Users Including offices, factories, and service centers $0.40 to $0.30 $0.30 to $0.20 $0.20 to $0.10 Very High Energy Users Including laboratories and hospitals $0.45 to $0.35 $0.35 to $0.25 $0.25 to $0.15 Note:This table adjusts the rule of thumb for building size and energy use characteristics and provides a more precise guideline. Note that as buildings get larger, there is an economy of scale, so it is not necessary to expend as much on a square-foot basis. U.S. Department of Energy (DOE) Federal Energy Management Program (FEMP), March 1999. Procuring Low-Energy Design and Consulting Services: A Guide for Federal Managers, Architects, and Engineers, available at www.nrel.gov or www.eren.doe.gov/femp. F E D E R A L E N E R G Y M A N A G E M E N T P R O G R A M ficient in low-energy building design and will respond well to the challenge. The only thing that may hold them back from advocating low-energy design on any particular project is the lack of a commitment and appropriate funding by the owner or agency. Estimated costs for this consulting service can be obtained from the table on the previous page. Application Domain The application domain for low-energy design is not so much a case of where the technology should be installed, but where it is integrated with the other elements of the project to produce an energy-efficient building that serves both the environmental and functional needs of its users. When thinking about whole buildings, it is important to consider not only the discrete components and materials but how the various parts can best work together to achieve the desired results. That is what is meant by the phrase “integrated, whole-building design.” Low-energy design strategies and renewable energy concepts can be applied to almost any type of new Federal building. Energy-Saving Mechanisms In Federal buildings, low-energy design mechanisms range from a few high-profile architectural features that are solar responsive to the application of more conventional, and often less conspicuous, energy conservation technologies. Many applications are reconfigurations of typical building components, such as a change from flat façades and roofs to those that are articulated and have surfaces designed to bounce or block direct solar rays. The low-energy design process described in this guidebook combines a broad range of practical systems, devices, materials, and design concepts that should be considered simultaneously whenever possible to achieve significant reductions in energy use. For most non-residential buildings, an energy-use reduction of 30% below what is required by codes and standards can usually be achieved with little, if any, increase in construction cost. The figure is closer to a 50% reduction in residences. Savings of 70% or more are possible for exemplary buildings, although achieving such significant reductions can be challenging in light of the demands occasioned by budgeting constraints and cost-effectiveness criteria. For example, daylighting, coupled with dimmable lighting and light-level controls, is increasingly commonplace. An effective and highly recommended energy conservation strategy, this technology cluster is an important component of low-energy building design. (See Applications Screening and How to Apply) Because energy-efficiency concepts and technologies must dovetail with all other building elements, one of the most important energy-saving tools is the use of computer modeling and design software. This strategy should be used early in the design process to analyze the efficiency and cost effectiveness of candidate strategies. Detailed computer simulation results are then referred to throughout the design process, and often through the value engineering (VE) phase, to ensure that the building will efficiently perform as intended, and that subsequent changes to the design in the interest of cost-cutting do not adversely affect performance. By using appropriate energy simulation tools in the context of a whole-building approach that emphasizes solar technologies and energy efficiency, design teams can achieve significant operating cost savings while still staying on budget. Alist of design and analysis tools is provided later. Advantages of Low-Energy Building Design While basic techniques and concepts are important, of greater relevance to a given building project are the specific lowenergy building design techniques themselves. One key element of lowenergy building design is the inventive use of the basic form and enclosure of a building to save energy while enhancing occupant comfort. The section titled How to Apply describes a wide range of lowenergy building design strategies that can be commonly applied to new Federal buildings. Low-energy building design combines energy-conservation strategies and energy-efficient technologies. Some of these are described in FEMP Federal Technology Alerts (FTAs), including high-efficiency lighting and lighting controls, spectrally selective glazing, and geothermal heat pumps. Low-energy design represents both a load-reduction strategy and the incorporation of renewable energy sources. Many low-energy building design strategies result in an absolute reduction in the use of power produced from fossil fuels. Together these innovations can save energy, reduce costs, and preserve natural resources while reducing environmental pollution. Low-energy building design strategies (including various daylighting techniques) can also provide a renewed sense of connection with the outdoors for occupants of Federal facilities. Low-energy design can also inspire planning concepts, such as interior private offices that borrow light from open office spaces at the building’s perimeter. 6 Basic energy-saving techniques should be used to reduce building energy use. • Siting and organizing the building configuration and massing to reduce loads. • Reducing cooling loads by eliminating undesirable solar heat gain. • Reducing heating loads by using desirable solar heat gain. • Using natural light as a substitute for (or complement to) electrical lighting. • Using natural ventilation whenever possible. • Using more efficient heating and cooling equipment to satisfy reduced loads. • Using computerized building control systems. F E D E R A L E N E R G Y M A N A G E M E N T P R O G R A M More difficult to measure are the increases in workplace performance and productivity that are often achieved through whole-building design and its resulting economic value. Nonetheless, organizations housed in low-energy buildings have reported that their indoor environments help retain employees, reduce tension, promote health, encourage communication, reduce absenteeism, and, in general, improve the work environment. Another potentially significant benefit is the public perception that, by its own example, the Federal government is helping to lead the construction industry toward a more responsible and sustainable future. Similarly, by using public funds for cost-effective measures that reduce operating costs, Federal agencies are performing these tasks in a responsible and frugal manner. Application Low-energy building design techniques are application specific. This section provides a practical method of determining the potential use of design techniques in different types of Federal buildings, in different climatic locations, and under various local energy cost scenarios. It also details the process and level of advocacy required to assure such strategies are considered and incorporated into the design process, beginning with the earliest project phases (see Needs Assessment and Site Selection) and continue through Construction and Building Occupancy. Refer to the time line on pages 22–23 for an illustration of the various phases and key action items to be addressed throughout the process. For a particular project, the specific energy- saving techniques, strategies, and mechanisms to be deployed will vary greatly, depending on building and space type. Their selection and configuration will also be influenced by: • Climate • Internal heat gains from occupants and their activities, lights, and electrical equipment • Building size and massing • Illumination (lighting) requirements • Hours of operation • Costs for electricity and other energy sources. In reviewing this list, one can quickly grasp that strategies specific to a particular building or space may not work nearly as well (or at all) in another application. Therefore, some general guidance about building and space types (provided in Applications Screening) will prove useful in understanding the factors that lead to significant energy use in buildings and in identifying the strategies that can yield optimum savings. It is essential that the team appreciate that a successful design solution under one set of circumstances may not be appropriate or cost effective for a different building type, size, or configuration; the same building type constructed in a different climate; or where variable energy costs apply. Applications Screening The use characteristics discussed below are representative of the majority of Federal building projects. The first step toward assuring low-energy building design for a particular project is to understand the energy implications of the structure’s basic form, organization, and internal operations. These criteria will dictate the relative importance of strategies to be deployed for heating, heat rejection, lighting, and, in some cases, hot water. The term heat rejection is used (as opposed to cooling) based on the idea that a fundamental goal of lowenergy building design is to greatly minimize the need for, and dependence on, mechanical cooling. It is important for those involved in Federal design projects to know how and why office buildings, courthouses, laboratories, hospitals, visitor centers, border stations, warehouses, and various residential building types use energy. Each of these will be summarized later, but first, some background information should prove useful in forming a basis of understanding. Perhaps the most basic division is that of houses and larger, non-residential buildings. Houses are the most common example of skin-load-dominated buildings, because their energy use is predicated by heat gain and loss through the building enclosure or skin (also known as the envelope, e.g., walls, windows, roof, floor). Houses and other skin-loaddominated buildings primarily require heat in cold climates, cooling in hot climates, and very little energy of any type (except hot water) in benign climates like San Diego. For low-energy performance, it is common for houses and other skin-load-dominated buildings to be well-insulated and to invite the low winter sun in while keeping it out (through shading and proper building orientation) during the summer. Simplistically, larger non-residential or commercial buildings are often referred to as internal-load-dominated buildings because a large portion of their energy use is in response to the heat gains from building occupants, lights, and electrical equipment (e.g., plug loads for computers, copiers). As a result of these internal heat sources, internal-load-dominated buildings are often designed to turn their backs on the sun, and further reduce solar gain through the use of tinted and reflective glass. There is some logic to this, but such an approach is too universal and precludes some of the most beneficial low-energy design strategies. Moreover, it often is too simplistic to think of a building with offices as simply an office building. The structure is also likely to have a lobby and circulation spaces, a cafeteria, a computer room, meeting rooms, and other spaces that have environmental needs and thermal characteristics that are very different from those of offices. Ideally, design strategies should first satisfy the needs of each individual space or zone. This requires careful attention during the programming phase of the project. Evaluating a specific project for selecting and integrating low-energy design strategies starts with an understanding of the following factors: 7 F E D E R A L E N E R G Y M A N A G E M E N T P R O G R A M Climate Not just is it hot or cold, but how humid is it? Is it predominantly clear or cloudy, and during what times of the year? Clear winter climates are well matched with spaces that incorporate passive solar heating strategies. In contrast, spaces (and buildings) in clear summer climates generally require a high degree of sun control. Clear climates also make the best use of light shelves—horizontal surfaces that bounce daylight deeper into buildings. Even the site-specific and seasonal nature of the wind needs to be understood if natural ventilation strategies are to be incorporated into a building design. Internal Heat Gains The heat gains from building occupants, lights, and electrical equipment can be thought of as the interior climate and should not be generalized. Instead, during the early programming of the project, the heat gains anticipated from these sources should be quantified for the various spaces where they apply. In some cases, such as in storage buildings and other areas with relatively few occupants and limited electrical equipment, these heat gains will be minor. In other instances, the presence of intensive and enduring internal heat gains may be a determining factor in HVAC system design. Examples of intensive and enduring influences include activitybased gains, such as those produced by cafeterias and laundry facilities (where increased humidity is also a factor), and technological or industrial gains, such as the heat produced by mainframe computers or heavy machinery. These factors should be identified early on, and appropriate design strategies investigated (such as heat recovery or using a closed-loop heat pump system). Building Size and Massing In a low-energy building, both the indoor and outdoor climates exert a powerful influence on all aspects of building design. Sometimes, they complement one another, such as the case of a building with a lot of internal heat gains sited in a very cold climate. At other times, however, the two climates are antagonistic, such as when there are a lot of internal heat gains in a very hot climate. Understanding the implications of these factors is fundamental to determining appropriate low-energy design strategies for a particular building project. Under hot/hot conditions, buildings with large footprints and a large amount of floor space far from the exterior of the building will require heat removal in the interior zones (generally by mechanical cooling) all or much of year. The other basic planning approach is to position all spaces that can benefit from connection to the outdoors in proximity to exterior walls. To achieve this, buildings become much narrower, with a maximum width of about 70 feet. Such an approach to building massing must, by necessity, be introduced very early in the design process. Also, recognize that not all spaces need or want to be exposed to the exterior, including many areas of complex building types like hospitals and courthouses. These spaces often function better as interior placements within a wider and more compact building form. Lighting Requirements The lighting needs of a building’s various spaces need to be identified, both quantitatively and qualitatively, as part of the environmental programming conducted early in the project. Many spaces, including lobbies and circulation areas, require general ambient lighting at relatively low foot-candle levels (10 foot-candles or less). Such spaces are ideal candidates for daylighting. In contrast, some spaces are used for demanding tasks that require high light levels (50 foot-candles or more) and a glare-free environment. Here the design team’s attention may shift from daylighting to a very efficient electrical lighting system with integrated occupancy sensors and other controls. Hours of Operation Typically, on a per-square-foot basis, the most energy-intensive Federal building types are those in continuous use, such as hospitals and border stations. In these buildings, the balance of heating and heat removal (cooling) may be altered dramatically from that of an office building with typical work hours. For example, the around-the-clock generation of heat by lights, people, and equipment will greatly reduce the amount of heating energy used and may even warrant a change in the heating system. Intensive building use also increases the need for well-controlled, high-efficiency lighting systems. Hours of use can also enhance the cost effectiveness of low-energy design strategies, such as daylighting in a border station or weather station. In contrast, buildings scheduled for operations during abbreviated hours (including seasonal occupancy facilities, like some visitor centers), should be designed with limited use clearly in mind. Energy Costs The cost for energy, particularly electrical energy, for most non-residential buildings is a critical factor in determining which design strategies will not only conserve energy, but will also be cost effective. In most locations in the United States, electricity is three to four times more expensive than natural gas per Btu. This disparity can, at times, be capitalized upon by introducing design strategies that effect a trade-off in energy use. For example, increasing the glass area and the commensurate daylight entry can save expensive electrical use but, at the same time, occasion the purchase of additional (but relatively lowcost) heating energy. However, such an example should not be misconstrued as indicating that daylighting requires an excessive amount of glass, as that is just not the case. Daylighting primarily requires placing the glass carefully and selecting the appropriate glazing. In many locations, utility deregulation imposes an uncertainty on future electrical and other energy prices. To the greatest extent possible, the life-cycle benefits of various design strategies should be investigated for the range of energy-cost scenarios deemed plausible. For some strategies—particularly those that affect the amount of heating energy used— 8 F E D E R A L E N E R G Y M A N A G E M E N T P R O G R A M deregulation may be of lesser importance. In other cases, however, rate structures, particularly those based on peak electrical demand, may significantly affect the economic impact of strategies such as daylighting. As part of a whole-building design strategy, purchasing bulk green power resources complements many buildingspecific design measures. Through a holistic approach to building design and operation, incorporating green power resources can further decrease the environmental impacts already minimized through the specification of energy efficiency and renewable energy measures in the design process. Minimizing electrical load requirements, and then meeting these requirements with clean electricity resources, is at the core of a whole-building design strategy. Green power refers to utility-scale electricity resources that are in some way environmentally preferable to conventional system power. The terms green and clean are often used interchangeably to describe this type of electricity. Green power supplied from the utility grid may be comprised of electricity from one or more types of renewable sources. The term renewable power refers to electricity generated from one or more of the following types of resources: •Wind—generated from wind-powered turbines, often grouped together into wind farms • Solar—typically generated from photovoltaic (solar cell) arrays, often placed on rooftops • Geothermal—generated from steam captured from below the earth’s surface when water contacts hot, underground rock • Biomass—burning of agricultural, forestry, and other byproducts (including landfill gas, digester gas, and municipal solid waste) • Small hydroelectric—generated from dams with a peak capacity of less than 30 megawatts (MW). Building Types: Characteristics and Profiles The following brief descriptions give broad categories of building types and some likely successful strategies for consideration. Residential Buildings In cold climates, the classic, skin-loaddominated building type really benefits from using high-performance, low emissivity (low-e) windows and high levels of insulation. In many cold climates, residential buildings can also significantly benefit from passive solar heating, so long as a reasonable amount of heat-absorbing thermal mass is incorporated into the design. In hot climates, solar control is paramount, based on the need to keep cooling loads and costs under control. It is also important to take advantage of the opportunity for passive or active solar water preheating. For remote structures that do not have easy access to the utility grid, photovoltaic systems should be considered as the primary, or sole, source of electricity. Small Non-Residential Buildings This profile describes buildings in which lighting and internal gains play a relatively small role in the building’s energy balance. Such buildings are the heart and soul of low-energy building design, as a multitude of low-energy building design strategies can be successfully applied to their construction. One common Federal building type that falls into this category is the visitor center. Visitor centers are among the most advanced energy-conserving structures. They generally have a robust budget, allowing the purchase of durable materials. They are normally located in severe 9 Natural Gas: Typical Cost for One Million Btu 1,000,000 Btu 100,000 Btu/Therm* x 0.75 (Heating System Eff.) Electricity: Typical Cost for One Million Btu 1,000,000 Btu 3413 Btu/kWh x 1.00 (Site Eff.) kWh = kilowatt-hour X $0.60/Therm = $8 per million Btu X $0.08/kWh = $23 per million Btu An example of an energy-efficient home in a cold climate using direct-gain passive solar heating. Steven Sargent/PIX08889 F E D E R A L E N E R G Y M A N A G E M E N T P R O G R A M (either hot or cold) climates inaccessible to utilities; they have a natural connection with the outdoors; and the structures present an opportunity to interpret the resource-conservation mission of the agency to the visiting public. These structures typically combine a need for window area, massive construction, and a tolerance for temperature swings—all of which are highly compatible with low-energy building design. Daylighting is another key strategy for deployment in these building types. Urban Office Buildings This building type evinces characteristics commonly found in major urban centers, where Federal office buildings are often located. Land is often expensive and must be used at a high density. The building is typically dominated by one repetitive use—office space—although it may also contain a number of other uses, such as support facilities. These buildings are often landmarks or showpieces. In highly controlled areas like Washington, D.C., this translates into height limits and tight controls over façade treatment. In most cities, however, there are few controls on the style or height of downtown office buildings. As a result, many of these buildings include or consist of towers that shade and are shaded by neighboring buildings, a factor that may significantly affect the design and sizing of the mechanical cooling system. Curtain walls are, by far, the most common enclosures for downtown office buildings, but most curtain walls are classic examples of a “building as a fortress against the environment” philosophy. The low-energy building design strategy for flat curtain walls is typically defensive in nature, limiting the boring and often unattractive result from the overuse of glass and by a lack of orientation-specific façades. Fortunately, there has been somewhat of a stylistic revolt against all-glass buildings, which has led to more articulated façades, variation in building façade treatments, and a resurgence in the use of masonry. All of these factors greatly enhance low-energy building design possibilities by creating opportunities to tune façades to suit their orientation and the activities taking place behind them. In most cases, thoughtful strategies will be needed to reduce solar gain. Exterior sunscreens or new glazing types (fritted, shaded) can both enliven the façade and provide substantial cooling load reduction. An excellent way to take advantage of low-energy building design is to move as many private offices away from the façade as possible. In this way, more light can be directed further into the building, and more of the building’s users can enjoy access to views and natural lighting. This scenario often yields increases in productivity and enables the adoption of more energyefficient HVAC strategies. If an atrium serves the program’s needs, it should be located and designed to substitute natural lighting for artificial lighting, to minimize cooling loads, and to take advantage of solar heating, if it is needed. The location and shape of the atrium will be highly building-specific. In general, taking full advantage of the unique opportunities of each urban site requires considerable expertise, particularly because of shading from surrounding buildings and the complex interactions among lighting, HVAC, façade design, orientation, and climate. 10 The Zion Visitor Center is designed to use 70% less energy than a typical building without costing more to build. Robb Williamson/PIX09249 Boston Edison joined Northwestern University to use solar electricity to power the Ell Student Center on the University’s Boston campus. The rooftop PV system incorporates 90 285-Wp modules installed on innovative ballasted mounting trays that require no roof penetration. Ascension Technology, Inc./PIX04478 F E D E R A L E N E R G Y M A N A G E M E N T P R O G R A M 11 Courthouses This building type typically entails highly complex and interrelated space programming. Many diverse functions must be accommodated, sites are often constricted, and the professional occupants are demanding. In addition, courthouses often serve a ceremonial function. In many cities, they are the most prestigious and conspicuous of Federal buildings. Their typically urban location often requires a sensitivity to surrounding buildings with historical styles and value and most certainly will require careful integration into the existing urban plan. Oftentimes, the functional needs of courthouses (i.e., security requirements) must be fully satisfied before energybased programming concerns can be addressed, and solar design strategies may not always apply to this building type. Still, low-energy design opportunities abound, especially in terms of efficient lighting, HVAC systems, equipment, and controls. It is also worthwhile to note that many of the design issues described for urban office buildings will also apply to courthouses. Hospitals These facilities tend to have a lot of small spaces, many of which need to be windowless. Offices and patient rooms can be thought of as small, mixed-use areas that incorporate both residential and commercial features. Cafeterias and public lobbies present special opportunities for daylighting. Overall, this building type has many spaces that require large quantities of outside ventilation air. Therefore, ventilation-air heat-recovery systems that are not prone to cross-contamination are particularly useful in these applications— especially in very cold climates. The around-the-clock nature of hospitals is a perfect opportunity to incorporate very efficient and well-controlled lighting and power systems. Laboratories Laboratories are an energy-intensive building type that often consumes more than 200,000 Btu per square foot, due to large ventilation requirements and in part to the long operating hours (two or three shifts) that are typical. The laboratory working environment normally requires enormous amounts of ventilation air to ensure good indoor-air quality, often making heat recovery systems cost effective. If there is a considerable demand for hot water, preheating the water using solar energy is recommended, particularly for facilities located in clear climates. This building type can often benefit from daylighting, but because the walls tend to be occupied with equipment, it is appropriate to consider either high windows or toplighting by roof monitors on the upper floor. Either way, avoiding glare is crucial. Circulation corridors along southern façades can function as solarheated sunspaces. Sunlight on south façades can be “bounced” through high glazing by way of light shelves. Depending on the regional climates, thermal mass walls for heat storage between labs and corridors may also make sense. The corridors can double as pleasant meeting and lounge spaces, while serving as a buffer to the south sun, thus permitting wider temperature swings than would be permissible in the main labs. On north-facing walls, small, well-spaced view windows can double as a source of diffuse daylight. Incorporating atriums into laboratory buildings also makes sense, both as a means of bringing natural light into the labs and providing casual meeting spaces adjacent to the labs. West façades may serve as good locations for windowless lecture halls. Cafeterias can use direct gain, or in some temperate climates, might even have a fabric roof. Warehousing/Shipping/Repairing These activities are typically carried out in one-story buildings with high ceilings. Offices, supervisory booths, employee services, restrooms, and loading docks often complement a main unpartitioned space. For roof and wall assemblies, steps must be taken to counteract heat A courthouse in St. Paul, Minnesota. The National Renewable Energy Laboratory’s Solar Energy Research Facility. Pamm McFadden/PIX02927 Warren Gretz/PIX01137 F E D E R A L E N E R G Y M A N A G E M E N T P R O G R A M loss due to continuous metal contacts throughout the construction. Though not limited to metal components, this process is known as thermal bridging, which can significantly compromise the resistance value of insulation. In climates with hot summers, a white or reflective roof is advisable. If lighting can be controlled electronically through light sensors and other devices, natural lighting strategies can be very useful. If the budget does not allow for proper roof monitors with vertical glass facing south or north, consider using high windows along the south and north walls with south-facing glass shaded by properly designed overhangs. Exercise care in using scattered skylights, as they can create glare and let in excessive amounts of solar heat. If the building is subject to around-theclock use, large high-intensity discharge (HID) lamps are appropriate when arranged in such a way as to light between inventory stacks when daylight is unavailable. Interior surfaces should be light-colored to reflect light. If the building is used intermittently, more and smaller HID or fluorescent lamps that easily switch on and off should be used. HVAC should be localized to work areas, with the overall building maintained at the maximum temperature range needed for its contents and the proper operation of machinery. Campus Layout This profile describes a wide variety of building types where space adjacency requirements are not crucial, and there is ample site area availability. Possible building types include rural or suburban office buildings, training and classroom facilities, some laboratories, barracks, and other multi-family housing. If the buildings can be spread out, more of the interior space will be close to an outside wall. Acampus plan makes the most sense in designing buildings for housing and classroom use, where deep interior spaces are inappropriate. Compared to a compact building form, the campus plan generally costs more at the outset, based on the need for a larger site, the cost of added building enclosures, and added lengths for service connections. When life-cycle economics are taken into account, these additional costs can be justified if the additional exposure is used to optimum advantage and daylighting and natural ventilation are brought into play. For spaces that can benefit from passive solar heating, it is essential that southfacing solar glazing be clear of any shade during the heating season, even deciduous trees. The bare branches of trees can change a sunspace from one that provides useful heat into one that does not. In very cold climates, it is worth considering a partially earthsheltered building, especially in the context of a sloping site. Renovations Renovating and reusing a building makes it low energy and sustainable in another very important way. Much less energy is needed to produce construction materials and deliver them to the site when the building’s basic shell is being reused. Older buildings, in particular, often make excellent candidates for low-energy design that utilizes their mass, higher ceilings, and narrower building form. Many aspects of low-energy building design are applicable to many largescale renovation projects. The only strategies that are clearly precluded are those based on siting, building form, or orientation. While these established features can limit a building’s low-energy performance potential, renovations can still reduce energy costs by 20% to 30%. Integrating Low-Energy Concepts into the Design Process Feasibility Phase The feasibility phase is normally when Federal building managers or other decision makers in the Federal sector determine that a project will be built to address a particular need. At this stage, the enabling premises of low-energy design and construction need to be defined and established. Think of this as the time when the seeds of the overall sustainable design and construction strategies are sown, and the framework is established for decisions to be made and actions to be taken throughout the design and construction process. Defining parameters; establishing general goals; and identifying policies, directives, and enabling legislation will guide and propel the process. During the feasibility phase, architects and engineers develop a capital project scope and planning document that provides a design program, an implementation strategy, and a budget assessment. Identifying these elements early is essential to establish project feasibility, support project selection, and coordinate project execution. Community plans for major cities and surrounding areas identify long-term space needs for Federal 12 An example of a multi-use building. Roch A. Ducey/PIX05184 F E D E R A L E N E R G Y M A N A G E M E N T P R O G R A M agencies and propose appropriate actions to address those needs. Major projects involving renovation or construction of Federal buildings must be developed in accordance with applicable community plans. Agencies often conduct studies to support project planning or assess building conditions, some of which may take into account coordination with state and local authorities, community groups, and others who may have a stake in the development process. Because Federal policy calls for cooperation with state and local authorities when planning Federal facilities, local government officials must be contacted to ensure that all documents impacting the project are discussed. These documents may include master plans, current and future land-use plans, zoning maps, traffic studies, and other documents that address the availability of essential support services (e.g., fire, police, utilities, telecommunications). Helpful information can also be obtained from your agency’s local office, including documentation of current building conditions, maintenance concerns, site access, communication with other agencies, and other potential impacts on project scope and implementation. Action Items • Conduct all required feasibility analyses (including, but not limited, to those described above). • Review all existing directives and policies to be sure of what your agency currently requires in the way of energy performance, materials usage (i.e., quality, durability, recycled content, energy saving features, impact on indoor environmental quality [IEQ]), daylighting, use of renewable energy sources, contracting issues, and other relevant concerns. • Select an energy champion and give them the authority to make decisions relating to low-energy design and construction practices. • Establish explicit energy-use targets that surpass those described in 10 CFR 435; specifically, reference Executive Order 13123. Factor in any additional criteria that may be specific to your agency or organization, facility location, or end use. • Identify and list your agency’s goals for other sustainable issues, such as site planning, materials use, water use, or IEQ. Budgeting Phase Some projects may be constructed using standard designs (those completed for similar projects or off-the-shelf, prefabricated structures). Be certain that your specific low-energy goals have been accounted for. Action Items • Program any special requirements into your budget submission. • Submit a budget that allows for an energy champion (as well as the meetings and other resources required to accommodate a team process), the additional studies, analyses, and verifications that will be needed, and slightly higher design fees (generally 2%–4%). • Include the requirement for an energy expert in your Request for Proposal/ Architectural & Engineering (RFP/A&E) solicitation. • Conduct a design charrette prior to concept development to ensure that low-energy building components and strategies will be adopted early in the planning and design stages, when these elements can be incorporated at the lowest possible cost. • Identify the certification and testing measures required to ensure compliance with energy targets and sustainability goals. Project Pre-Planning Phase At inception, and during the early phases of a low-energy project’s time line, a needs assessment is conducted (often with the assistance of a consultant). This process considers the long-term requirements of the building occupants and yields a program for the project that includes: • User group needs and square footage requirements • Location and site options • Estimated costs and schedule. For many Federal agencies, it is essential that the budget established at this time be based on all factors that will influence costs, including the incorporation of low-energy design strategies. Action Items • Select appropriate candidate low-energy design strategies. • Associate these strategies with the particular project phase during which they must be considered and evaluated. • Identify the team members who will be responsible for evaluating and incorporating the strategies at each phase. • Identify the appropriate evaluation tools to use at each phase and who will use them. • Identify the actions to be taken by various team members at each phase and carry them out. • Establish low-energy design as a core project goal. • Use case studies and passive solar performance maps to help determine appropriate strategies for the specific project type at hand. • Establish energy-use targets that surpass applicable codes and standards. In general, energy-use reductions in nonresidential buildings should be targeted at 30% or better in comparison to a standard, code-compliant building. • Ensure that the planned building configuration takes maximum advantage of the site and climate. • In selecting consultants, consider their level of experience and expertise in lowenergy design. Strategies to Consider During This Phase User Energy Needs Assessment Description: This is a direct assessment of the energy-related needs of facility users. Whether it is in the form of an Environmental Programming Matrix 13 F E D E R A L E N E R G Y M A N A G E M E N T P R O G R A M or other, less formal, documentation, it is a fairly rigorous and thorough evaluation that considers occupancy, operating hours, and all aspects of the interior and exterior climates. Goal: The needs assessment yields more precise energy use requirements, which, in turn, helps determine the applicability of low-energy building strategies. Best Applied: The needs assessment is appropriate for use on all projects. How to Do It: Classify users on the basis of specific needs that directly relate to specific low-energy building strategies. In addition to temperature, humidity, and general lighting standards, focus on other user needs such as the desire for exterior views and natural daylight; tolerance to moving air and temperature swings; and the type of automatic lighting control that is most appropriate for a given user. Related Strategies: The needs assessment is considered a prerequisite to almost all other strategies. Comments: This document may be seen as an expansion of the typical needs assessment procedure, and as such, may entail revision(s) to standard agency assessment protocols. Coming up with useful questions to ask in the needs assessment requires an understanding of the effects of various low-energy design strategies on user comfort. Building-Appropriate Site Selection Description: This process involves choosing a site that fully supports the energy reduction strategies contemplated for the project. Goal: Proper siting increases the likelihood that many other low-energy building strategies can be implemented. Best Applied: This strategy is appropriate for all new building projects. How to Do It: During site selection, locate buildings that do not require extensive exterior exposure on shaded or confined urban sites. Buildings that will benefit from a greater degree of exterior exposure should be located on open sites. Related Strategies: See Extended Plan. Comments: For many projects, the site may have been selected before the manager’s involvement. Complementary Building Uses Description: This process involves defining the nature of the facility and then matching the end use with complementary energy needs and minimizing the resulting wastes. Goal: The design team takes advantage of the natural symbioses and commonalties that exist between building uses that might otherwise be overlooked. Best Applied: When compatible projects are at similar points in their development; ideally, from the planning stages forward. How to Do It: At the earliest stages of project conception and site selection, consider co-locating any types of facilities where the waste products of one can be used to provide needed energy for another, or where constructionbased support services can be shared. Related Strategies: Building-Appropriate Site Selection; User Energy Needs Assessment Comments: Currently used in designing co-generation facilities, ecological industrial parks, district heating, and community- scale energy storage facilities; other applications may be identified on a caseby- case basis. Opportunities may also exist for co-locating non-polluting industrial and residential facilities. In all circumstances, action is required at the earliest stages of the project, before detailed plans for the various uses are fully developed. Project Planning Phase In close consultation with agency project personnel, the design consultants (e.g., architects and engineers) prepare initial and schematic design options. At this time, options for placing the proposed building(s) on the site and massing alternatives are evaluated. Fundamental low-energy design strategies (as detailed below) are also assessed for applicability to a specific project. Design consultants generally present their design options and analyses to agency project personnel for review and evaluation; this process is often repeated several times until the basic design is decided upon and approved. At the conclusion of this phase, the design should clearly indicate which low-energy design strategies have been incorporated in sufficient detail so that heating and cooling loads can be estimated and so HVAC system options can be examined. Action Items • Establish an interdisciplinary design team, including an energy professional, as early in the process as possible. • Develop a preliminary layout that maximizes or minimizes solar gain. Consider atrium spaces, direct or indirect passive solar heating, earthprotected spaces, and natural and constructed shading. • Develop landscape plans that contribute to the facility’s energy performance. Consider shading options, wind breaks, and using existing site features. • Develop a basic layout that maximizes the use of daylighting. Consider building orientation, the size and placement of windows, and toplighting. • Investigate using renewable power sources as part of the facility’s overall power supply. Consider using solar (domestic) hot water on building types with high hot water usage (such as laboratories) and building-integrated photovoltaics (BIPV) to reduce reliance on non-renewable power. • Conduct a preliminary energy analysis (analysis tools depend on scale of project). Use ENERGY-10 and other userfriendly tools for smaller, simpler projects (those with two or fewer zones, and roughly 50,000 square feet or less). Use DOE 2.2 and other applicable tools for larger and more complex projects. Strategies to Consider During This Phase The following strategies need to be assessed during the project planning phase of the time line. Their incorpora- 14 F E D E R A L E N E R G Y M A N A G E M E N T P R O G R A M 15 tion will influence the overall siting and massing of the building, as well as the basic organization of spaces. Perimeter Circulation Space Description: This passive solar strategy uses circulation (corridors) and casual meeting spaces as buffers between the façade and the interior conditioned spaces. Goal: To support several low-energy building strategies that are not compatible with certain uses (e.g., direct-gain sunspaces and office space). Best Applied: The strategy is appropriate in buildings needing large areas for circulation, waiting, and casual meetings, such as a visitors’ corridor in a hospital or casual meeting sunspaces outside laboratories or offices. How to Do It: Because perimeter circulation plans generally require slightly more total floor area, it is necessary to examine user needs and evaluate the strategy in light of the overall budget. If the strategy is acceptable, look for buffer spaces that can be located along the building’s exterior, particularly along the south façade. Related Strategies: Atrium Spaces; Open Office Space at Perimeter; Direct-Gain Passive Solar Heating; Daylighting through Windows; Light Shelves; Selective Glazing; Shading Devices; Window Geometry; Natural Ventilation through Windows. Comments: An accurate energy needs assessment is key to the effective integration of this strategy. Extended Plan Description: By extending the plan to produce a longer, narrower footprint, you can create more exterior wall surface. In most climates, elongating the building in an east-west direction makes the most sense from the standpoint of daylighting and passive solar heating. Goal: To increase the amount of usable space that is close to an outside wall. Best Applied: Building types that benefit most from exterior exposure include good candidates for daylighting and direct-gain passive solar heating. How to Do It: This is best accomplished early in the design process, as modifying the basic building form may occasion a slight increase in the construction budget. Related Strategies: Atrium Spaces; Open Office Space at Perimeter; Perimeter Circulation Space; Daylighting through Windows; all forms of Passive Solar Heating; Building-Appropriate Site Selection; Landscape Shading; Light Shelves; Shading Devices; Natural Ventilation through Windows. Direct-Gain Passive Solar Heating Description: Installing south-facing glazing in an occupied space enables the collection of solar energy, which is partially stored in the walls, floors, and/or ceiling of the space, and later released. Goals: With direct-gain passive solar heating, the savings achieved in heating energy is augmented by the aesthetic and productivity-enhancing benefits of daylighting, a valuable amenity for occupants. The functioning of the space should not be compromised by direct glare from glazed openings or by local overheating. Best Applied: This strategy works well in cold, clear climates. How to Do It: Glazing must face within 15 degrees of true (solar) south, and the affected areas must be compatible with daily temperature swings. Examples: Some appropriate contexts for direct-gain heating include corridor spaces, eating spaces, meeting spaces that can be scheduled for use during times when the temperature is most comfortable, sleeping spaces, and recreational sunspaces. Working with the energy consultant, the designer can fine tune the amount and type of glazing with glare and temperature controls, materials in the affected space, auxiliary heating, and cooling to address local climatic changes. Related Strategies: Atrium Spaces; Differentiated Façades; Extended Plan; Perimeter Circulation Space; Daylighting through Windows; Building-Appropriate Site Selection; Landscape Shading; Selective Glazing; Shading Devices; Window Geometry. Comments: Because true north and magnetic north are different, the design team will need to account for magnetic decli- An example of direct-gain passive solar used in a residential building. Warren Gretz/PIX03348 F E D E R A L E N E R G Y M A N A G E M E N T P R O G R A M nation. For optimum effect, floor and wall finish materials with high heatstorage capacity must be exposed to direct illumination by the low winter sun. Overall, this strategy is considered central to low-energy building design. Atrium Spaces Description: Atrium spaces are multifloor open areas appropriate for circulation, lobbies, dining, or other shared space. Atriums are typically covered by a glazed roof or one that incorporates roof monitors. Goal: Configure the atrium for minimum impact on the building’s energy load. Best Applied: Buildings with programmed spaces that can be well-served by one or more atrium spaces. How to Do It: Avoid configurations that produce heat losses or gains with no compensatory benefits. The atrium should bring daylight to the interior of the building while providing a “chimney” for natural ventilation during mild weather. In some cases, atriums can collect useful solar heat in cold climates— serving as a kind of transition zone, with larger temperature swings than would otherwise be appropriate in the rest of the building. The atrium’s configuration should be defined at the earliest possible stages of the design process, before an undesirable or arbitrary configuration is locked in. Related Strategies: Building-Appropriate Site Selection; Extended Plan; Perimeter Circulation Space; Roof Monitors; Glazed Roofs; Fabric Roofs; Direct-Gain Passive Solar Heating; Selective Glazing; Shading Devices; Induced (Stack-Effect) Ventilation. Comments: There is no hard and fast distinction between atriums and glazed roofs over large open spaces (such as gallerias). Induced (Stack-Effect) Ventilation Description: Heated air rises within a mid- or high-rise building to the top (often below a glazed roof in an atrium), where it exits through roof openings. This process induces ventilation of the adjoining spaces below. Goals: This strategy removes heat and reduces mechanical cooling and fan energy use requirements. Best Applied: Spaces that are not adversely affected by increased air motion are appropriate targets for natural wholebuilding ventilation, which effectively conditions the space during fair weather without using air conditioning. How to Do It: Incorporate air inlets, generally in the form of operable windows, at the building perimeter. For best results, use open-office space planning and avoid partitions that inhibit air movement. Consider complementing natural ventilation with controllable passive ventilators located in the upper portions of the building. Carefully coordinate the implementation of this strategy with building HVAC system and controls. Related Strategies: Atrium Spaces; Glazed Roofs; Roof Monitors; Natural Ventilation through Windows; Night-time Cooling Ventilation. Comments: Natural ventilation works best in low-humidity climates. An atrium often serves as an ideal chimney to exhaust hot air. Open Office Space at Perimeter Description: Locating private offices at interior positions leaves the perimeter open to general office space. Goal: Program open spaces at the perimeter to allow for more extensive use of daylighting deeper into interior sections. Best Applied: Use this strategy in buildings with large areas of office space. How to Do It: Private, interior-located offices need compensating amenities. At minimum, install glazing that lets onto the open office space or overlooks an atrium space. This strategy is especially appropriate for buildings with limited façade glazing, such as earth-protected buildings. Related Strategies: Atrium Spaces; Earth- Protected Space; Perimeter Circulation Space; Daylighting through Windows; Light Shelves; Selective Glazing; Shading Devices; Window Geometry; Natural Ventilation through Windows. Comments: This is an effective strategy that requires a strong commitment by the agency or organization to keep perimeter spaces open and not reserve them for high-ranking executives. (This is perhaps not as significant an issue in Federal buildings as compared to the private sector.) Landscape Shading Description: The use of existing or planned trees and major landscaping elements to provide beneficial shading. Goal: Locate trees and major landscape elements to provide useful shading and reduce cooling loads. Best Applied: Landscape shading works best when shading west and south façades. How to Do It: Study planting plans of existing site landscaping to determine whether existing trees can be retained and incorporated into the planning process. Perform shading analyses of plants in both immature and mature forms to estimate energy savings during plants’ anticipated life span. Whenever possible, avoid or remove plantings that would compromise useful solar gain. 16 An example of an atrium space. Warren Gretz/PIX02194 F E D E R A L E N E R G Y M A N A G E M E N T P R O G R A M Related Strategies: Atrium Spaces; Daylighting through Windows; all forms of Passive Solar Heating; Building-Appropriate Site Selection; Selective Glazing; Shading Devices; Natural Ventilation through Windows. Comments: Trees and landscaping can reduce peak cooling loads through shading and can cool the ventilation air entering a building. Even during the winter, most deciduous trees and plants cast substantial shade on solar collectors (e.g., south-facing windows). Earth-Protected Space Description: Bermed, or partially buried, construction can moderate building temperature, save energy, and preserve open space and views above the building. Goals: To minimize heating and cooling energy use by protecting more of the building from fluctuating outdoor air temperatures. Best Applied: Sites with a large natural slope in cold climates are ideal candidates for incorporating earth-protected spaces. How to Do It: Berm against walls or earthcover roofs (in severely hot or cold climates) or combine high horizontal windows with light shelves located above earth-sheltered walls. In some cases, using "invisible" earth-protected buildings can help counter community resistance to bulky new construction. Related Strategies: Open Office Space at Perimeter; Roof Monitors; Building- Appropriate Site Selection; Landscape Shading; Insulation. Comments: Similar low-energy performance can also be achieved by using additional insulation. Solar Water Heating Description: Solar water heating uses flat-plate solar collectors to preheat domestic hot water. Goal: To be considered effective, this strategy should yield a significant portion (50% or more) of the domestic hot water needed for day-to-day operations. Best Applied: Look to building types where hot water use is high year-round, such as hospitals and laboratories. Best performance will be achieved in hot climates with high solar radiation levels. How to Do It: Design an array of flat-plate solar collectors that include an absorber plate (usually metal), which heats when exposed to solar radiation. Most common among these are indirect systems that circulate a freeze-protected fluid through a closed loop and then transfer heat to potable water through a heat exchanger. Typically roof-mounted, solar collectors should face south and tilt at an angle above horizontal, approximately equal to the latitude of the project location. This configuration will provide optimum year-round performance. Provide a pipe chase to a mechanical room. The room needs to be large enough for storage tanks. Related Strategies: Roof Monitors; Non- Absorbing Roofing. Comments: Collectors should be mounted in a location that is unshaded by surrounding buildings or trees during the hours of 8 a.m. to 4 p.m. (at minimum) throughout the year. As is the case with many of the strategies described herein, an effective conservation program will help to minimize hot water demand and, in turn, reduce material and systemic requirements. Building-Integrated Photovoltaic Systems Description: Photovoltaic (PV) arrays are now available that take the place of ordinary building elements (such as shingles and other roofing components), converting sunlight into electrical energy without moving parts, noise, or harmful emissions. Goal: Reduce the first cost of the PV array by using it in place of high-cost building elements and take into account the energy cost reductions over time. Best Applied: Consider deployment in sunny climates with high electrical utility charges. 17 Landscaping and trees help minimize heat gain to the building and surrounding concrete. An example of an earth-sheltered building in Tempe, Arizona. Warren Gretz/PIX03779 Pamm McFadden/PIX02909 F E D E R A L E N E R G Y M A N A G E M E N T P R O G R A M How to Do It: Commercially available systems include thick, crystal, circular cells assembled in panels and thin-film products deposited on glass or metal substrates. At today’s prices, BIPV often provides a good payback if it replaces high-cost glazing, such as fritted glass (the arrays can even resemble fritted glass). To be cost effective, BIPV must intercept nearly a full day’s sun, so it is often most effective as a replacement for roof or atrium glazing. BIPV also works well as spandrels that are fully exposed to the sun. Related Strategies: Atrium Spaces; Differentiated Façades; Glazed Roofs; Roof Monitors; Building-Appropriate Site Selection; Shading Devices. Comments: One of the benefits of gridtied BIPV systems is that power production is typically greatest (on bright, sunny days) at or near the time of the building’s peak electrical and cooling loads. Schematic Design (or Preliminary Design) Phase During the previous phase of the time line, Project Planning, basic decisions were made regarding site placement, plan organization, and building massing. Those determinations will now influence the basic low-energy design strategies (e.g., daylighting) that will be evaluated in detail during this phase, especially those relating to the building enclosure (or envelope). Traditional building design has assigned a protective role to the walls, roofs, and floors of buildings—protection against cold, sun, rain, and unwanted intrusion. In low-energy building design, the protective role still exists, but the building envelope is also thought of as a membrane that manages or “mediates” interactions between the interior spaces and the outside environment. During schematic design, the Envelope-Related Strategies discussed below will be evaluated and integrated into the overall building design. Action Items • As the preliminary layout is refined, ensure that access to daylight continues to be optimized. Consider perimeter access to light and views, roof monitors, skylights and clerestory windows, and light shelves. • Develop material specifications and a building envelope configuration that maximizes energy performance. Consider window shape and placement, shading devices, differentiated façades, reflective roofing, fabric roofs, induced ventilation, nighttime cooling ventilation, and selective glazing. • Continue energy analyses, including multiple runs of similar products (e.g., various glazings and insulation levels) to determine best project-specific options. In addition to first cost, consider durability and long-term energy performance. Strategies to Consider During this Phase Selective Glazing for Walls Description: Glass products are now available with a wide range of performance attributes that allow designers to carefully select the amount of solar gain, visible light, and heat that they allow to pass through. Solar heat is measured by the properties of shading coefficient (SC) and solar heat gain factor (SHGF). An SC of 1.0 applies to clear 1/8-inchthick glass with other glasses that admit a lesser amount of solar heat having a lower SC (e.g., 0.50 for a tinted glass that admits 50% as much solar heat as 1/8- inch clear glass). The term SHGF, which is now widely used by the glazing (fenestration) industry because it takes into account a range of angles of solar incidence, is considered to be equal to a value of 0.86 times the SC. The degree of daylight, or visible light transmission, is expressed by the term “Tvis,” and the amount of heat loss is measured by the U-factor, which, expressed numerically, is the inverse of the total resistance of the glazing assembly. Single-glazing is about R-1 or 1/1 for a U-factor of about 1.0. Double-glazing is about R-2 for a U-factor of about 0.50. Commercially available low-e glass typically ranges in U-factor from about 0.35 down to 0.10, depending on the type and number of coatings and the fills (e.g., argon) used in the spaces between glazing layers. Goal: Specify glazings with the best combination of performance characteristics for the specific application at hand. Best Applied: The choice of glazing(s) is an essential consideration for all building types. How to Do It: Begin by incorporating glass performance characteristics (e.g., U-factor, shading coefficient) as required by the applicable codes or standards. Then, use computer analysis to investigate alternate glazings and narrow the field to those most beneficial to admitting daylight and saving energy, while still remaining within the project budget. Glazing technology has now advanced to the point that alternative glazings with very different performance characteristics can physically look very much alike. This increases the potential to use different glass types on different façades, although such an approach may be considered a maintenance headache. The best glazing selections are not merely those with the highest numerical performance levels in a given area. For example, daylighting a space with a large expanse of glass, using glazing with the highest daylight 18 An example of Building-Integrated PV is 4 Times Square in New York City. Andrew Gordon Photography and Fox & Fowle Architects/PIX09052 F E D E R A L E N E R G Y M A N A G E M E N T P R O G R A M transmission may result in excessive glare. Fritted glass should be considered when glare reduction through other means is difficult to achieve. Related Strategies: Atrium Spaces; Glazed Roofs; Roof Monitors; Scattered Skylights; Daylighting through Windows; Direct-Gain Passive Solar Heating; Landscape Shading; Light Shelves; Shading Devices; Window Geometry. Comments: Of the various building envelope components, glazing almost always has the most significant effect on heating, cooling, and lighting energy use. In the last 20 years, glazing technology has progressed more dramatically than perhaps any other building product or system. By using high R-factor glazing (indicating substantial resistance to heat inflow), it is often possible to eliminate perimeter baseboard heaters. Shading Devices Description: Fixed or movable (manual or motorized) devices located inside or outside the glazing are used to control direct or indirect solar gain. Goal: Shading should be used to provide cost-effective, aesthetically acceptable, functionally effective solar control. Best Applied: This strategy works well on south façades where overhangs provide effective shading for work space and can also serve as light shelves. Shading west façades is critical to reduce peak cooling loads. How to Do It: Awide range of shading devices are available, including overhangs (on south façades), fins (on east and west façades), interior blinds and shades, louvers, and special glazing (such as fritted glass). Reflective shading devices can further control solar heat gain and glare. Related Strategies: Atrium Spaces; BIPV; Differentiated Façades; Open Office Space at Perimeter; Perimeter Circulation Space; Glazed Roofs; Roof Monitors; Scattered Skylights; Daylighting through Windows; Direct-Gain Passive Solar Heating; Light Shelves; Selective Glazing; Window Geometry. Comments: Devices without moving parts are generally preferable. Movable devices on the exterior are typically difficult to maintain in corrosive environments or in climates with freezing temperatures. Other building elements, such as overhanging roofs, can also serve as shading devices. Daylighting through Windows Description: Using daylighting through building windows can displace artificial lighting, reduce energy costs, and is associated with improved occupant health, comfort, and productivity. Goal: Reduce lighting and cooling energy more than the increase in heating energy occasioned by reduced lighting loads. (In summer, cooling energy demand is less because the heat from artificial lighting sources is reduced. In winter, the heat that is not being produced by artificial lighting may need to be compensated for by the building’s heating system). Best Applied: Daylighting through windows is best accomplished on façades that have a generally clear view of the sky, particularly the sky at angles of 30 degrees or more above the horizon. How to Do It: Place much of the façade glazing high on the wall, so that daylight penetration is deeper. Consider the enhanced use of daylighting by installing light shelves on south façades. Recognize the interdependencies in glazing, light fixtures and controls, and HVAC systems. Whenever possible, electrical lighting should be considered a supplement to natural light. When the sun goes down on buildings with long hours of operation, however, efficient electrical lighting design takes on added importance. Related Strategies: Differentiated Façades; Extended Plan; Open Office Space at Perimeter; Perimeter Circulation Space; Direct-Gain Passive Solar Heating; Building-Appropriate Site Selection; Landscape Shading; Light Shelves; Selective Glazing; Shading Devices; Window Geometry. Comments: Daylighting is a central component of the vast majority of low-energy 19 Shade from trees is a simple but effective strategy to reduce costly cooling requirements. Warren Gretz/PIX00217 F E D E R A L E N E R G Y M A N A G E M E N T P R O G R A M buildings and, as such, merits significant time and attention. Extended Daylighting through Windows—Light Shelves Description: Ahorizontal device or “shelf” that bounces direct sunlight off the ceiling and deeper into the interior spaces. Light shelves are also used to provide shading and suppress glare. Light shelves are located above vision glazing (up to and slightly above eye level), but below high glazing above. They may be positioned inside or outside (where they also provide shading), or both (this is typical). Goal: Save lighting energy, reduce glare, and provide useful shading. Best Applied: In clear climates, light shelves are appropriate for integration on façades facing within about 30 degrees of true (solar) south. How to Do It: Integrate the light shelves with façade design, office layout, lighting design, lighting controls, glazing, and shading devices. They tend to work best with moderately high ceilings (about 10 feet, minimum) and open planning. Related Strategies: Differentiated Façades; Open Office Space at Perimeter; Daylighting through Windows; Selective Glazing; Window Geometry. Comments: Transom windows can be used to allow light from the shelves to enter interior office spaces located far from exterior walls. Maintenance may be an issue, and pigeons present a concern in some areas. Natural Ventilation through Windows Description: User-controlled operation of windows provides outdoor air for ventilation and cooling, and should improve indoor air quality. Goal: Abalanced approach involves taking advantage of users’ desire for environmental control without interfering with efficient HVAC operation. Best Applied: Particularly appropriate in building types and locations where security concerns and exterior noise or air quality is not an issue. Users must be tolerant of increased horizontal air motion. How to Do It: Locate windows that will serve as air inlets to face prevailing winds. During the cooling season, this strategy can be enhanced by landscaping features and projecting building features (such as fins). This strategy tends to work best in residential-type occupancies, where the user already has control over HVAC. Related Strategies: Atrium Spaces; Differentiated Façade; Perimeter Circulation Space; Window Daylighting; Landscape Shading; Window Geometry; Economizer Cycle Ventilation; Induced Ventilation; Nighttime Cooling Ventilation. Comments:Awell-considered control strategy (either mechanical or social) is required to prevent air conditioning from operating in a space with open windows. If such a control strategy cannot be devised or is not effective or realistic because of the building occupants, operable windows can increase building energy use. Window Geometry Description: Windows should be shaped and located in a manner that minimizes glare and unwanted solar gain and maximizes useful daylight and desirable solar heating. Goal: The design team should apply functional criteria to the size, proportion, and location of windows. It is important to avoid incorporating more window area than is beneficial to the building occupants or that is needed to enhance low-energy performance. Best Applied: Shape, size, and location of windows are important considerations in all projects. How to Do It: Make window decisions based on occupant activities and lowenergy performance rather than simply for aesthetic purposes. Having said this, reduce glass area whenever possible. To minimize glare and enhance daylighting benefits, substitute horizontal strips of high windows for “punched” windows, and scattered small windows in lieu of a few large ones. Related Strategies: Atrium Spaces; Differentiated Façades; Extended Plan; Perimeter Circulation Space; Light Shelves; Selective Glazing; Shading Devices; Natural Ventilation through Windows. Comments: The best way to evaluate the lighting effects of window geometry and configuration is through computer analysis, using programs such as RADIANCE. 20 Daylighting retrofits for U.S. Army warehouse in Hawaii. Scott Bly/PIX07626 F E D E R A L E N E R G Y M A N A G E M E N T P R O G R A M Differentiated Façades Description: In this strategy, the designer creates variations in the façade design in response to changes in orientation, the use of space behind the façade, and the low-energy design strategies being employed. Goal: Strive for seamless integration of energy-related design strategies with the overall aesthetic and functional design components of the project. Best Applied: If each façade is to be optimized, this strategy will work on almost all projects. How to Do It: Select a design consultant who can work with the concept that the appearance of a building’s various façades will likely differ in response to variations in their environmental loads. To that end, pursue a building style that is compatible with functionally varied façade elements. Related Strategies: Atrium Spaces; BIPV; Perimeter Circulation Space; Daylighting through Windows; all forms of Passive Solar Heating; Complementary Building Uses; Landscape Shading; Light Shelves; Selective Glazing; Shading Devices; Window Shape; Natural Ventilation through Windows. Comments: Considered as one of the most basic and effective low-energy building strategies, using different façades is really an approach to design and style that is driven by function. Different façades do not necessarily have to be radically unique; rather, they may simply be variations on a theme. For the sake of uniformity, designers sometimes put overhangs on all façades, even though they may only provide significant energy benefits on the south side. Such an approach can greatly compromise the basic cost-effectiveness of the strategy and should generally be avoided. Insulation Description: Awell-insulated building envelope reduces energy use, controls moisture, enhances comfort, and protects the energy-saving potential of passive solar design. Goal: Identify the optimum amount of building insulation to use in the walls, roof, and floor construction. Best Applied: Residential building types in cold climates benefit most from large amounts of insulation. How to Do It: Begin by incorporating insulation levels required by code or standard, then use computer analysis to investigate optimum insulation amounts. For buildings with mass walls, use computer analysis to determine the 21 This building has differentiated façades—broad overhangs for shading on the south side and no overhangs on the north side. This building uses a light shelf on the south side for daylighting. It also has small square windows on the east and west to minimize glare. Warren Gretz/PIX02191 Warren Gretz/PIX00132 OPERATIONS & MAINTENANCE WARRANTY PERIOD TURN OVER TO OCCUPANTS CONSTRUCTION PHASE (CM) BID SOLICITATION/CONTRACT AWARD MILESTONE (100%) CONSTRUCTION DOCUMENTS MILESTONE (95%) DESIGN DEVELOPMENT II VALUE ENGINEERING PHASE MILESTONE (50%–60%) DESIGN DEVELOPMENT I MILESTONE (35% DESIGN) SCHEMATIC DESIGN PHASE (OR PRELIMINARY DESIGN) MILESTONE (15% DESIGN) PROJECT PLANNING PHASE PROJECT PRE-PLANNING BUDGETING PHASE FEASIBILITY PHASE Action Items: · Program any special requirements into your budget submission; · Submit a budget that allows for an energy champion, the necessary meetings to accommodate a team process, the extra studies, analyses and verifications that will be needed, and slightly higher design fees (2%–4%); · Include the requirement for an energy expert in your RFP/A&E solicitation; · Conduct a design charrette BEFORE concept development; · Identify the certification and testing measures you will require. See page 13 for details on these Action Items and the strategies to consider during this phase. Action Items: · Conduct all required feasibility analyses; · Review all existing directives and policies to be sure what your agency currently requires; · Select an ‘energy champion and give them the necessary authority; · Establish explicit energy use targets that surpass 10 CFR 435; · Identify your agency’s goals for the other sustainable issues such as site planning, materials use, water use, and IEQ. See page 12 for details on Action Items and the strategies to consider during this phase. Action Items: · Establish low-energy as a core project goal; · Establish energy use targets; · In selecting consultants, consider their level of experience; · Classify the energy-related requirements of the users; · Identify the climate and utility costs at the project site; · Identify the characteristic space and building uses that apply to the project. See pages 13 for details on Action Items and the strategies to consider during this Phase. Action Items: · Establish interdisciplinary design team; · Develop a preliminary layout; · Develop landscape plans; · Develop a basic layout; · Investigate renewable power sources; · Conduct preliminary energy analysis. See page 14 for details on Action Items and the strategies to consider during this phase. Action Items: · Ensure optimization of daylighting; · Develop material specs and envelope configuration that maximizes performance; · Continue energy analyses; determine best project-specific options. See page 18 for details on Action Items and which strategies to consider during this phase. Action Items: · Continue energy analysis; ensure that performance objectives are maintained. See page 25 for details on these Action Items and the strategies to consider during this phase. Action Items: · Ensure that VE is based on life-cycle considerations; · Incorporate energy analysis directly into VE; · Ensure that energy targets are maintained. See page 28 for details on these Action Items and the strategies to consider during this phase. Action Items: · Ensure that construction details and specifications are consistent; · Ensure that mechanical equipment meets design targets; · Lighting system; · Conduct a final design review. See page 28 for details on Action Items and the strategies to consider at this phase. HOW TO USE THE TIME LINE: This time line is to be used by Federal project managers to remind them when they should be thinking about low-energy, sustainable design during the various phases of planning, design, construction, and turnover of a building. Without explicit actions throughout the process, the resulting buildings will often not meet the owner’s requirements and expectations. Because each agency has its own terms for these phases, the time line uses the traditional American Institute of Architects (AIA) terminology and notes the stages at which Federal agencies often demand milestone submissions (15%, 35%, 50%–60%, and 95%). During each of these stages, there are very different opportunities to ensure, or to lose, low-energy sustainable design. This guidebook is focused primarily on low-energy issues and recognizes that low-energy does not equal sustainability. Comprehensive sustainability includes many other issues such as water use, indoor environmental quality (IEQ), and green materials. It is assumed that whatever agency you are in already has specific directives for facility managers that provide guidance for procuring low-energy, sustainable buildings and facilities. These directives might range from general guiding principles to more specific energy and water use targets, foot-candle levels, requirements for using renewable energy sources, and even materials criteria for each building type. It is conceivable that there might be some existing policies that are contrary to your newly emerging low-energy, sustainable goals, and these should be recognized and eliminated if at all possible. You will need a unique perspective, one that relies on a whole-building approach to the problem. The time line suggests potential steps that will help you realize your goal of a low-energy (and a sustainable) facility. The time line will show you some new steps you will incorporate into your thinking, planning, and budgeting steps that are not needed in the traditional design process. For example, you will see the requirement for an energy champion and several stages where you have to conduct some evaluations to really understand the consequences of some very complex tradeoffs. You must be clear about the costs to have “extra” people (like the energy champion) on the job or additional costs to perform the necessary evaluations and include them in your budgets from Day One. There will be some new roles and responsibilities if you expect to deliver a low-energy, sustainable building: you will need to state your expectations clearly and give your team the resources and the authority they need to accomplish the goals on time and within budget. Refer to the section called “How to Apply,” which follows the time line. This section provides the details about which low-energy strategies should be considered during each phase. Each one notes Description, Goal, Best Applied, How to Do It, Related Strategies, and Comments for that strategy. Action Items: · Ensure energy features are constructed/ installed as designed. See page 28 for details on Action Items and the strategies to consider at this phase. Action Items: · Monitor energy performance; · Implement a full commissioning protocol. See page 28 for details on Action Items and the strategies to consider at this phase. Action Items: · Ensure that construction details and specifications are consistent; · Ensure that mechanical equipment meets design targets; · Conduct a final design review. See page 28 for details on Action Items and the strategies to consider at this phase. 22 23 F E D E R A L E N E R G Y M A N A G E M E N T P R O G R A M relative advantages of placing the insulation on the inside or on the outside of the mass. Detail assemblies containing insulation to avoid thermal bridges, where conductive elements (e.g., metal studs) penetrate the insulation and shortcircuit the system by conducting heat. In non-residential construction, there are many cases, particularly in hot climates, where using more insulation to enclose a sealed building will cause it to behave like a Thermos bottle—trapping heat and using even more energy. Related Strategies: High-Efficiency HVAC. Comments: The law of diminishing returns applies to additional levels of insulation, whereby the first increment of insulation reduces heat loss dramatically, and each additional increment provides less and less of an improvement. The quality of insulation—and how well it is installed— is very important, especially when it comes to batt insulation in walls. Air Leakage Control Description: Air retarder systems are used to reduce air leakage into or out of a building. Goal: To deploy a system that reduces energy use and serves to protect the building’s envelope, structure, and finishes. Best Applied: Air leakage control is considered to be standard low-energy procedure in cold climates. How to Do It: Install air-impermeable components that are sealed at the joints and penetrations to create a continuous, airtight membrane around the building. Note, however, that air retarders placed on the winter/cold side of the insulation must be vapor-permeable to avoid trapping moisture within the walls. Related Strategies: Insulation, High- Efficiency HVAC. Comments: Designers of many non-residential building types attempt to reduce air infiltration by maintaining the indoor space at a higher pressure than the outside ambient air. When an air retarder is installed, pressurization becomes easier to achieve, while at the same time, the need for pressurization becomes less critical. In masonry construction, bituminous membranes are sprayed or trowel-applied to serve as air retarders, with bitumen-based sheets typically used in curtain-wall construction. Evaluate the benefits of an air retarder not only for improved energy use, but also for reduced wall maintenance and repair costs. Also evaluate the air leakage characteristics of manufactured components such as windows, doors, and curtain walls. Roof Monitors Description: Roof monitors are windows installed at roof level, typically vertical or steeply sloped. Goal: To admit useful natural light and often desirable solar heat gain during the heating season. Best Applied: This approach works well on many building types, particularly low buildings with one or two stories. How to Do It: South-facing roof monitors should use vertical glass and be shaded by overhangs to provide daylight and useful solar heating (for many building types in many locations). By contrast, north-facing roof monitors need not be concerned with glare or the unwanted entry of direct solar rays. North-facing glazing can be inclined (tilted) somewhat to access the overhead sky better, which provides a much greater level of diffuse daylight than does the sky near the horizon. As a general rule of thumb, avoid east- and west-facing roof monitors. Also avoid horizontal glazing, which typically overheats the building, thereby dramatically increasing cooling loads. Minimize the amount of glass required to achieve desired illumination levels, and avoid narrow slots with glazing on opposite sides. Related Strategies: Direct-Gain Passive Solar Heating; Selective Shading; Shading Devices; Window Geometry; Induced Ventilation; Lighting and Lighting Controls. Comments: Design guidelines are available for various geometries of roof monitors and other toplighting strategies. To fine tune monitor locations, provide quality lighting environments, and quantify resulting energy benefits, computer analysis is advised. Scattered Skylights Description: Small, individual spot-located skylights. Goal: To obtain useful daylighting. Best Applied: Appropriate for use in onestory buildings, such as warehouses, and especially useful in buildings where sun control is of secondary importance. How to Do It: Generally achieved with prefabricated elements that have flat or domed glazing, spot-located skylights should be used with care, except in cases where potential glare and direct sun penetration is of little concern within the building. Use sparingly—large numbers of separate skylights are expensive in comparison to glazed roofs. Related Strategies: Extended Plan; Selective Glazing. Comments: Even when mounted above prefabricated or site-built wells, it is very difficult to entirely eliminate sun penetration when solar altitude angles are at their highest (around the summer solstice, June 21). Guidelines for spacing scattered skylights are available, and computer analysis to fine-tune sizing and spacing and quantify energy benefits is advised. Potential roof leaks are often a concern and should be addressed by proper detailing. Despite these drawbacks, scattered, spot-located skylights 24 Insulation. U.S. Department of Energy/Craig Miller/PIX02214 F E D E R A L E N E R G Y M A N A G E M E N T P R O G R A M are widely applicable to warehouses, low-rise residential, and many other smaller buildings. Glazed Roofs Description: Glazed roofs are large-area skylights typically found over atrium spaces. Goal: To provide daylighting in a manner that may increase the architectural impact of the space while providing a more direct connection between building occupants and the outside world. Best Applied: Glazed roofs work well above circulation areas and other highoccupancy spaces. How to Do It: Consider installing a clearspan glazed roof between buildings or building sections to create a covered “street.” Solar heat gain can be controlled through use of fritted glass or louvers. Related Strategies: Atrium Spaces; Extended Plan; Selective Glazing; Shading Devices; Induced Ventilation. Comments: Excessive cooling loads frequently accompany this design approach. When used over high spaces (such as atriums), incorporate induced ventilation strategies whenever possible. As a secondary option, mechanical cooling should be provided through a displacement ventilation approach, where only the air in the occupied zone of the space near the floor is conditioned. Non-Absorbing Roofing Description: Roofs covered by lightcolored or reflective membranes are a viable passive solar strategy, as they tend to absorb less heat. Goal: To reduce cooling loads. Best Applied: This is a common approach for use on low buildings in hot climates. How to Do It: Use roofing systems with light-colored or reflective top layers. Related Strategies: Extended Plan. Comments: Reflected light may complement other efforts aimed at daylighting “wedding cake”-type building forms. Early in the process, the designer needs to know the color of any roofing systems that will be visible to building occupants. Fabric Roofs Description: These are tension roofs constructed of stretched, light-transmitting fabric—an increasingly popular architectural element. Goals: Provides a buffer from direct exposure to solar heat gains occasioned by daylighting of space. Best Applied: Deploy fabric roofs over large, clear-span spaces. How to Do It: The overall approach must be decided early in the design process. Before committing to the design, carefully evaluate the balance between lighting, cooling, and heating loads for the specific building use and climate. Related Strategies: Extended Plan; Atrium. Comments: Fabric roofs are useful as temporary or permanent coverings over outdoor spaces (i.e., tents). They have been effectively used at the Denver International Airport and the San Diego Convention Center. Design Development I Phase During the earlier phases of the project, basic decisions are made that affect building massing and determine which low-energy design strategies will be implemented. During those phases, the overall thrust is to reduce the heating and cooling loads as much as possible. During design development, the design team’s attention should shift to identifying efficient lighting and HVAC systems. Action Item • Continue energy analysis and the “trade-off” process. 25 A skylighted entryway that also demonstrates the integration of photovoltaics at the Thoreau Center for Sustainability at Presidio National Park, California. Lawrence Berkeley Lab/PIX01053 Denver International Airport in Denver, Colorado, is an example of a fabriccovered roof. Warren Gretz/PIX07340 F E D E R A L E N E R G Y M A N A G E M E N T P R O G R A M Strategies to Consider During this Phase Energy-Efficient Lamps and Ballasts Description: Identifying and using application- specific, high-efficiency lamps and ballasts. Goal: Minimize the amount of electrical power required by lighting systems, while still meeting the task-specific needs of building occupants. Best Applied: The savings will be greatest in buildings with long hours of occupancy or in areas with high electrical utility rates. How to Do It: Use T-8 (tubular, 8/8th of one inch in diameter) lamps and compatible electronic ballasts for general ambient lighting. Compact fluorescent lamps should replace incandescent or halogen lamps in downlights, as they only use about one-third the electrical power. Determine what lamp/ballast combinations work best with other strategies (i.e., daylighting, shading, lighting controls). Use light-emitting diode (LED) exit lights with an estimated life of 30 years or more to enhance building safety and all but eliminate required maintenance. Related Strategies: All daylight-related strategies. Comments: The color rendition of all fluorescent lamps has improved dramatically in recent years, to the point where they are now deemed acceptable for most applications. Compact fluorescent lamps also provide maintenance savings, as the lamps last 10 to 20 times longer than the incandescents they replace. Lighting Controls Description: Lighting controls automatically adjust lighting levels in response to daylight availability. Other controls automatically turn lights off in response to unoccupied space. Goal: This strategy significantly reduces lighting-based electricity demand. Best Applied: Dimming controls are used in conjunction with building designs that encourage entry of natural daylight. Occupancy sensors are best used in spaces that have intermittent occupancy, such as conference rooms and storage areas. How to Do It: Automatic daylight dimming controls either provide light levels in discrete steps or through continuous dimming, based on light levels sensed. Dimming systems can also be used to dim newly installed lamps when their light output is greater than it will be once they “burn in”and achieve their rated output. Occupancy sensors are used to turn off lights and sometimes HVAC in unoccupied areas. They are made with multiple activation technologies, including those that sense body heat (infrared) as well as those that detect motion (ultrasound). Some sensors employ more than one technology as a means of eliminating false signals. Manual switching and timeclocks can also be used to control certain daylit spaces. Related Strategies: HVAC Controls Comments: Automatic lighting control functions are often included in a computerized energy management system that also controls the HVAC, fire safety, and security systems. High-Efficiency Heating, Ventilation, and Cooling Equipment Description: This category of equipment offers operating efficiencies far greater than those afforded by systems designed to simply meet applicable codes or standards. Goal: Integrate more efficient equipment whenever it can be shown to be cost effective. Best Applied: These systems are appropriate for use with large loads, long operating hours, and high energy prices (particularly for electricity). How to Do It: There are various types of efficient heating and cooling equipment that can readily address the specific needs and operating patterns of a given building. Many agencies require that alternate systems be subjected to a lifecycle cost analysis. If such an exercise is conducted, it should involve detailed computer analysis (such as DOE 2.2) rather than a process that simply confirms the selection of a preferred system. Ask the design team to prepare a list of performance criteria for equipment required by applicable codes and standards to be used as a basis for comparing more efficient equipment options. In some cases, the cost premium for more efficient equipment is small and can be justified by hand calculations. More often, DOE 2.2 computer analyses are required along with some form of rigorous life-cycle cost analysis. Consider using modular equipment (e.g., three small boilers instead of one 26 Some examples of energy-efficient lamps. D&R Int., LTD/PIX07737 F E D E R A L E N E R G Y M A N A G E M E N T P R O G R A M large one or a dual compressor chiller) and variable-speed equipment (modulating burner or variable-speed chiller) for greater flexibility in achieving targeted reductions in energy use. Related Strategies: All design decisions that affect heating and cooling loads. Comments: Specifying systems that are larger than necessary can be costly. The energy consultant should be careful throughout the design process to size the systems, components, and equipment appropriately. HVAC systems should also be designed to ensure healthful indoor air quality in a manner appropriate to individual spaces and the overall building type. Exhaust Air Heat Recovery Description: This process involves the recovery of useful heat from the air being dispelled from a building. Goal: Transfer 50% to 70% of the heat that would otherwise be lost to the incoming air stream. Best Applied: Apply this strategy in buildings with large populations or significant ventilation requirements, particularly those located in cold climates. How to Do It: Various types of heat exchangers are in use today, including heat wheels, plate and fin air-to-air heat exchangers, and heat pipes. Heat pipes are very simple devices that consist of a highly conductive tube filled with refrigerant which, when vaporized, transfers heat from the outgoing to the incoming air stream. Because heat exchangers obstruct the air passage of both intake and exhaust ducts, bypass dampers should be installed to facilitate operation during mild or warm weather. Related Strategies: HVAC controls Comments: Depending on the application, potential contamination of the incoming air stream may need to be monitored. For instance, recovery of heat from a combustion process is usually accompanied by a carbon monoxide sensor located in the intake. Economizer Cycle Ventilation Description: Contributing to both energy reduction and good indoor air quality, this strategy introduces a varying amount of ventilation air to cool the building in combination with normal air conditioning (AC). Goal: Avoid using the AC compressors or other mechanical cooling method when ambient air can provide some or all of the needed cooling. Best Applied: Look to buildings in cool climates where there is low relative humidity. How to Do It: Provide appropriate controls, along with 100% outside-air capability. Consider including enthalpy (total heat, sensible plus latent) controls to maximize benefits. Related Strategies: Induced Ventilation; Natural Ventilation through Windows; Nighttime Cooling Ventilation. Comments: This should be considered a standard low-energy HVAC procedure in all but the most humid climates. Nighttime Cooling Ventilation Description: High-volume, fan-powered ventilation of large areas during cool, dry nights. Goal: Cool the building (particularly exposed massive structural elements) with outside air as a means of saving more AC power than the sum of the power drawn by the ventilating fan, plus what is needed to overcome any excessive humidity the following day. Best Applied: This strategy is appropriate for hot, dry climates where the diurnal temperature difference (between day and night) often exceeds 30°F to 35°F. How to Do It: This strategy relies on moving large quantities of air in an economical manner and requires a secure source of intake ventilation that can be directed into spaces to be cooled. Related Strategies: Natural Ventilation through Windows; Economizer Cycle Ventilation Comments: Large amounts of interior mass enhance the cooling effect in dry climates that consistently experience significant temperature swings. In variable climates, lower mass is desirable. Relying on open windows for ventilation (in lieu of forced-air fan operation) may compromise security or lead to wind or water damage. HVAC Controls Description: Specify controls that maintain intended design conditions, including temperature, humidity, and airflow 27 The Louis Stokes Laboratory at the National Institute of Health in Bethesda, Maryland, is using desiccant heat wheels for exhaust air heat recovery. Frank Kutlak/PIX03683 F E D E R A L E N E R G Y M A N A G E M E N T P R O G R A M rate in terms of cubic feet per minute (cfm) throughout the building. Goal: The proper use of controls and building automation reduces energy consumption and electrical peak demand. Best Applied: In all circumstances, strive for a level of functional complexity that is compatible with the skills and capabilities of the building’s operating personnel. How to Do It: Keep control systems as simple as possible. Avoid controls that offer little in the way of improved operations or energy savings, especially if they complicate the system and add features that require frequent maintenance or are subject to malfunction. Evaluate the use of variable-speed drives (VSD) on all large pumps and fans serving loads that only occasionally function at peak capacity. In large spaces with varying occupancies (auditoriums, large meeting rooms, cafeterias), investigate control strategies (e.g., the use of carbon dioxide monitors) that regulate the amount of outside air in accordance with actual occupancy. Consider using setback thermostats in all building types. However, avoid setting temperatures back in spaces where a large amount of exposed thermal mass will make it difficult to reestablish comfortable temperatures. Related Strategies: Lighting Controls Comments: HVAC control systems can often be integrated into computerized systems that also control lighting, fire safety, and security. Value Engineering (VE) Phase Action Items • Ensure that VE analysis is based on life-cycle considerations rather than solely on cutting initial construction costs. • Incorporate energy analysis directly into the VE process. • Be certain that energy targets for the facility are maintained during VE. • Meet the needs of the building occupants and the intended use through design that is consistent with agency or organizational values and mission. Design Development II Phase Action Items • Continue energy analysis as design is finalized to ensure that desired energy performance objectives are maintained. • Review final working drawings, specs, and cost estimates. Construction Documents Phase Action Items • Ensure that construction details and specifications are consistent with energy use targets and strategies. • Be sure that mechanical system details and equipment sizing meet design targets. • Reaffirm that lighting system details and equipment specifications are consistent with energy design intent. • Before documents are sent out for bid, conduct a final energy design review. Bid Solicitation/Contract Award Phase Action Items • If cutting costs is required due to high bids, advocate preserving vital energysaving features in lieu of more easily replaceable or aesthetic components. • Conduct additional energy analyses as necessary to ensure that intended energy performance targets are still intact. Construction Phase Action Item • Ensure that energy features are constructed or installed as designed. Turn Over to Occupants Phase Action Item • Verify that occupants understand the building systems and the proper use of low-energy equipment and features of the building. Warranty Period/Commissioning Phase Action Items • Verify occupant comfort and understanding of building operation using a Post Occupancy Evaluation (POE). • Monitor the energy performance of the facility once per quarter during the warranty period and fine-tune the system as needed. • If feasible, develop and implement a full commissioning protocol. 28 This building incorporates many features that lessen its impact on the environment. Oberlin College/PIX09677 F E D E R A L E N E R G Y M A N A G E M E N T P R O G R A M What to Avoid Some low-energy buildings fail to meet the expected energy savings because the energy-efficient technologies incorporated into the design are not correctly integrated into the building. This may be due to a lack of understanding on the part of some team members as to the relationships between the specific energy technologies needed to reduce a given building’s energy use and the effective integration of these technologies into the design. Changing just one of the recommended building components changes the total environment and, thus, the effectiveness of the remaining technologies. To avoid this, it is crucial that all team members understand how each of the technologies interacts with all other building components in a given environment. When choosing energy-saving technologies, team members should be skeptical of claims for unrealistically high levels of performance and should avoid dependence on proprietary devices. It is not advisable to have a design that relies on a particular technology for which only one product is available. In those few cases where the use of such proprietary products can be defended in the context of competitive bidding requirements, a contingency design strategy should be in place. Claims of high-level performance should be supported by objective tests and case study results. Design Considerations and Computer Modeling The Base Case Abase-case design—a code-compliant building design without low-energy design features—is needed for comparison purposes in analyzing the cost and effectiveness of the low-energy design strategies identified for consideration. Considerations other than low-energy design often dictate the basic design of a building. In these instances, the basecase building is automatically created through the normal design process. To be effective, some low-energy building design technologies need to be applied during the early stages of the project, such as authorization, site selection, budgeting, and programming. In these instances, the base-case building may already include some low-energy design features. For example, an atrium is a desirable amenity that, if incorporated early in the project, should influence decisions about site selection, building orientation on the site, and the number of buildings required to satisfy the space needs of the facility. But if the atrium is introduced after the overall building configuration is set, the parallel use of the atrium as a low-energy design component will be compromised, and it may end up being an energy liability. Similarly, in climates where a campus plan yields energy benefits, these benefits can be included among the criteria used to define the basic site plan—especially if introduced in the early project stages. Anticipating low-energy design strategies early in the project can also influence the choice of a base case. One attraction of many low-energy building design strategies is that the occupants gain a closer connection with the outdoors environment. If this attraction is part of the design program, low-energy building design strategies may become more economical relative to the base-case design. For example, if the maximum allowable distance between any office worker and a source of natural light is lowered from the 60 feet typically accepted in a standard office buildings to 30 feet, a linear atrium between two 60-foot-wide building segments may result in a more attractive, compact, and, therefore, potentially more economical, design when compared to a 60-foot-wide base-case building. Strategy Interactions An important low-energy design approach involves rank-ordering a list of candidate technologies. At each step in a series of computer-driven energy simulations, candidate strategies are ranked in order of cost effectiveness relative to the base-case design. The top-ranked strategy would be the one that yields the largest energy savings for the smallest investment—the one with the shortest simple payback. [Note: according to the U.S. Department of Energy’s (DOE’s) A Guide to Making Energy-Smart Purchases, the simple payback period is the amount of time required for the investment to pay for itself in energy savings. You can obtain an estimate of the simple payback period by dividing the total cost of the product by the yearly energy savings. For example, an energy-efficient dryer that costs $500 and saves $100 per year in energy costs has a simple payback period of 5 years.] As each strategy is applied, the payback for all subsequent candidates may change. Because there is less energy to be saved, the savings potential is often reduced. If all the strategies were independent, the remaining ones would retain their order in the ranking as each is applied in succession. In practice, however, low-energy building design strategies do interact and change their relative order in the ranking as they are applied. Presuming that the initial ranking will remain constant can lead to misjudgments about which strategies to pursue. After applying each strategy in a simulation, re-rank the remaining candidate strategies. Designing Low- Energy Buildings with ENERGY-10 can perform this task automatically (see Design Tools). Another example of the interaction among building elements is in an office building where natural lighting displaces electrical energy by reducing the use of auxiliary lighting. In this case, the need for auxiliary heating increases in cold weather in response to the reduced heat contribution previously supplied by electrical lighting that is now dimmed or turned off. If this effect is not taken into account in the simulation, exaggerated estimates of energy savings will occur. Finally, it is important to remember that using one technology may preclude using certain others. For example, in buildings where heating or cooling loads have been significantly reduced, the benefits of using high-efficiency equipment to meet those loads may also be reduced and the resulting simple paybacks lengthened. 29 F E D E R A L E N E R G Y M A N A G E M E N T P R O G R A M The Benefits of Multiple Use As previously noted, BIPV—integrating PV into the building envelope—can replace conventional building envelope materials and their associated costs. PV is a solid-state, semiconductor-based technology that converts light energy directly into electricity. For example, spandrel glass, skylights, or roofing materials might be replaced with architecturally equivalent PV modules that serve the dual function of building skin and power generator. By avoiding the cost of conventional materials, the incremental cost of PV is reduced and its lifecycle cost is improved. BIPV systems can either be tied to the available utility grid or they may be designed as stand-alone, off-grid systems. One of the benefits of grid-tied BIPV systems is that on-site production of power is typically greatest at or near the time of a building’s peak loads. This provides energy cost savings through peak load shaving and demandside management capabilities. Maintenance Awell-designed, low-energy building requires less maintenance than one that relies on large mechanical systems. Unlike other technologies, well-integrated low-energy building design is much less dependent on hardware and equipment, so there is little to go wrong. The traditional building trades that use available construction materials are able to make repairs as needed. The reliability and performance record of other technologies (such as movable shading devices) should be investigated, and when deployed, moving parts should be regularly maintained. Cleaning and protecting the surface of shading devices and glazing is important and should be incorporated as part of ongoing, scheduled maintenance. When properly implemented, low-energy building design can reduce heating and cooling loads to allow for equipment downsizes and reductions in maintenance costs. Ideally, it also yields a building that can continue to function on a basic level and remain habitable even when systems experience unexpected downtime. Costs Cost effectiveness is typically the primary criterion for evaluating low-energy building technologies. 10 CFR 435 and Executive Order 13123 require that energyrelated design decisions be evaluated on a life-cycle basis, rather than simply on a first-cost basis (e.g., construction costs) alone. It should be noted that the higher first costs of low-energy design can often be avoided or greatly minimized by anticipating and incorporating these strategies at the outset of the planning process. Exceptions might include: • Demonstration projects with supplemental funds specifically earmarked for technology promotion. • High-profile projects where publicity value adds to the payback. • Cases where it is impractical to establish cost effectiveness. For example, relatively small investments that cannot justify a detailed simulation and seem practical based on prior experience. • The amenity value of the technology outweighs its energy performance. Care must be taken to ensure that the amenity does not increase energy demand. Typically, a building’s cost effectiveness should be measured using appropriate design and analysis tools, such as those described below. As previously noted, different forms of energy have different costs, with electricity costs approximately three times that of natural gas. Because the costs of various energy sources vary greatly by region, specific input is required in each case. Except for residences, utility cost data is not simply a matter of cents per kilowatt- hour of electricity, or dollars per therm of gas. Especially in larger buildings, the various fixed costs, variable costs, step rates, and demand charges must be accurately calculated. It is sometimes appropriate to run separate simulations, with and without demand rates, to see the extent to which the savings offered by a low-energy feature is dependent on demand rates. Small-scale co-generation may also be evaluated along with other energy sources appropriate for larger projects. To accurately model these costs, the more sophisticated design tools (such as DOE 2.2) accept all the details of utility rate structure, whereas simpler tools rely on a simplification of the rates. It is important to realize, however, that simplified rates may mask a large demand component and can be very misleading. It is also worth noting that when necessary energy-efficient technologies are well balanced and function in a complementary manner, they will significantly reduce energy consumption during peak load periods. This guidebook does not discuss utility rates, assuming that one of the final calculations made in evaluating a given technology involves using actual, project- specific utility rates to determine the anticipated savings. Team members with experience in using a given technology in a particular locality can often predict probable outcomes based on their knowledge of the interaction between the climate and utility costs. For example, measures affecting electrical consumption (such as fan energy or reduced lighting demand) will have a better payback in New England, where electricity costs are high, than in the Northwest, where lower-cost hydropower is available. Financing Options Energy savings performance contracting (ESPC) arrangements are a relatively new method of helping Federal agencies invest in energy-efficient building measures. ESPC is a contracting agreement that enables agencies to implement energy- saving projects without making costly up-front investments. The contractor or other partner, such as a utility, owns the energy system and incurs all costs— design, installation, testing, operations, and maintenance—in exchange for a share of any energy cost savings realized. FEMP provides ESPC and utility financing workshops, model solicitations, and a how-to manual. For more information, call FEMP at 703-243-8343. You may also wish to contact the Energy Efficiency and Renewable Energy Clearinghouse at 800-363-3732, or check their Web site at www.eren.doe.gov/femp. 30 F E D E R A L E N E R G Y M A N A G E M E N T P R O G R A M Design and Analysis Tools Typically, a building’s cost-effectiveness needs to be measured using an appropriate design and analysis tool, such as those described below. ADELINE (includes SUPERLITE and RADIANCE): Asoftware tool for daylighting design that links daylighting and thermal performance. Available from Lawrence Berkeley National Laboratory, 510-486-4000. BLAST:Adetailed, annual energy performance software tool capable of modeling the interactive effects of lowenergy building design strategies such as daylighting, passive solar heating, and thermal mass. Available from the BLAST Support Office, 217-333-3977. BLCC:Asoftware tool to calculate life cycle cost according to federal criteria. See http://www. eren.doe.gov/buildings/ tools_directory/software/blcc.htm CFD: An abbreviation for “computerized fluid dynamics,” this highly sophisticated type of program can track the flow of air within a space or building component and determine the temperature distribution within that space during system operation. It requires considerable experience to operate, but is invaluable for assessing the effectiveness of air diffusers. Available from several vendors under several names. See http://www. eren.doe.gov/buildings/tools_directory DOE 2/DOE 2.2: An energy analysis software program that calculates the hour-by-hour energy use of a building, given detailed information on the building’s location, construction, operation, and HVAC systems. Available from Lawrence Berkeley National Laboratory, 510-486-4000. Designing Low-Energy Buildings With ENERGY-10: An hour-by-hour, annual simulation program designed to analyze residential and commercial buildings of less than approximately 10,000 square feet (one or two zones). Specifically conceived for use during the earliest phases of design when low-energy building strategies can be incorporated at the lowest possible cost. Available from the Sustainable Buildings Industry Council (SBIC), 202-628-7400, ext. 209. FRAME:Apowerful thermal analysis program that accurately tracks the flow of heat through assemblies. Abasic tool for analyzing thermal bridging through façade elements, such as window frames. Requires some experience for optimum use. See http://www.eren. doe. gov/buildings/tools_directory/software/ framepls.htm POWERDOE:Windows-based version of DOE 2 with user-friendly interface. Available from Fred Winkleman, 510-486-4925. SERI-RES: (also SUNREL, which is an upgraded version of SERI-RES that features enhanced algorithms): Analyzes passive solar design and thermal performance in residential and small commercial buildings. Available from Ron Judkoff, National Renewable Energy Laboratory (NREL), 303-275-3000. TRNSYS: Modular FORTRAN-based transient simulation code that allows simulation of any thermal energy system, particularly solar thermal, building, and HVAC systems. Available from the Solar Energy Laboratory, University of Wisconsin, TRNSYS Coordinator, 608-263-1589 Energy Savings Energy savings will vary, depending on climate, building type, and strategies selected. In new office buildings, it is economically realistic to reduce energy costs by 30% or more below national averages if an optimum mix of lowenergy design strategies is applied. According to the Building Owners and Managers Association (BOMA), the average energy cost (taking into account indicative samples of both public and private buildings) is $1.85 per rentable square foot. As previously noted, the Federal government maintains approximately 2.9 billion square feet of rentable space. Thus, a 30% reduction in energy use would yield annual taxpayer savings of 55.5¢ per square foot, or a $1.6 billion reduction in the nation’s annual energy bill. This figure does not take into account the additional savings realized through pollution prevention, resource conservation, and related costreduction measures. Although a 30% reduction may seem ambitious, buildings monitored by NREL’s Low-Energy Building Program show energy consumption reductions as high as 75% in residential buildings and 70% in some non-residential buildings. Other Impacts Better design techniques and superior technologies have largely eliminated any negative impacts associated with low-energy building design, such as overheating due to uncontrolled solar gain. The environmental benefits of low-energy building design can be significant, depending on how many energy- efficient or sustainable products are used. For example, a building that incorporates green materials (such as paints with low or no volatile organic compounds [VOCs] and recycled building materials) has less of an impact on natural resources than does a conventional building. HVAC systems that use nonchlorofluorocarbon (CFC) refrigerants are less harmful to the earth’s ozone layer, and passive solar buildings that use significantly less energy from fossil fuels contribute less to the greenhouse gas effect than conventional buildings. Taken together, these low-energy, sustainable buildings not only reduce the burden on American taxpayers, but also contribute to the health, well-being, and productivity of their occupants. Case Studies The United States Courthouse Expansion, Denver, Colorado The United States Courthouse expansion in Denver, Colorado, consists of 17 new courtrooms and associated support spaces, totaling 383,000 square feet. The General Services Administration (GSA) designed this project to serve as a showcase for sustainable design and devoted considerable attention to the building’s energy and environmental design features. Sustainable design strategies integrated into the building include: • High-performance glazing system 31 F E D E R A L E N E R G Y M A N A G E M E N T P R O G R A M • Daylighting complemented by energyefficient electric lighting • Energy-efficient HVAC systems and controls (e.g., displacement ventilation and evaporative cooling) • Building-integrated photovoltaic system • Recycled and low-VOC materials used throughout • Integrated building automation system • Low-impact landscaping • Water-saving faucets and toilets. Based on computer analysis using DOE 2.2, the building is expected to consume approximately 50% less energy than a minimally compliant building designed in conformance with the Federal Energy Standard 10 CFR 435. As such, its annual energy costs will be reduced from just under $300,000 per year to just over $150,000. Much of the energy savings achieved in the Denver Courthouse expansion will be the result of reduced energy demand associated with lighting, heating, and cooling. Beyond its energy- and resource-efficient design features, the building will also provide an improved indoor environment that is expected to increase workplace performance while improving staff health, safety, and satisfaction. In keeping with its sustainable design approach, the Denver Courthouse expansion will also reduce operations and maintenance costs and will rely, in part, on non-polluting renewable energy sources. Descriptions of the facility’s specific low-energy, high-performance features follow. High-Performance Glazing Taking full advantage of Denver’s sunny, dry climate, a high-performance, tripleglazed curtain wall system is used on the court tower to minimize HVAC heating and cooling loads, while affording dramatic views and a source of natural light for adjacent courtroom and conference spaces. Aseries of PV cells are integrated into the curtain wall system, providing a clean, renewable source of power, as well as a visible representation of the government’s commitment to climate-responsive, sustainable architecture. Daylighting The daylighting design for the Denver Courthouse expansion is based on a conscious separation of view glass from daylighting-specific glass. The system provides for maximum daylight harvesting and usage to reduce electric lighting loads during the day, as well as occupant satisfaction based on a strong sense of connection with the outdoors. Perimeter light shelves are incorporated throughout the high-rise section of the building and are positioned at the junction between the view and the daylight glazing. The shelves diffuse daylight onto the ceiling plane and adjacent surfaces, thus minimizing contrast ratios between interior surfaces and elements viewed through the glazing. This, in turn, serves to increase visual comfort and improves the quality of the view to the outside. Energy-Efficient Electric Lighting The facility’s artificial lighting system is designed to supplement daylight and will use a combination of direct and indirect luminaries with T-5 fluorescent lamps and dimmable electronic ballasts, together with compact fluorescent and metal halide downlights and wall washers. Illumination levels are designed to work in tandem with daylighting and high-performance glazing systems to provide a balanced luminous environment with low energy consumption. Photocell controls will be used in conjunction with electronic fluorescent dimming ballasts to save energy in areas receiving daylight, while lowlevel ambient lighting enhanced by occupant-controlled task lighting will illuminate areas not served by daylighting. Occupancy sensors will control lighting in private offices. Displacement Ventilation The ventilation systems that serve the courtrooms, various offices, and public corridor spaces incorporate displacement ventilation air distribution. This system features low-velocity air introduced at floor level to efficiently condition the space and remove indoor air pollutants. Evaporative Cooling System Much of the building’s cooling and humidification loads are met using an indirect and direct evaporative cooling system, which provides a cooling effect through water evaporation. This process greatly reduces the need to run an electric- powered chiller. Denver’s dry climate makes this system ideal for much 32 The U.S. Courthouse Expansion in Denver, Colorado, will be a showcase for sustainable building design. 02527279 F E D E R A L E N E R G Y M A N A G E M E N T P R O G R A M of the cooling season; indeed, computer simulations show less than 100 full load hours of chiller operation per year. The system is also used to add humidity to the building during the winter to improve occupant comfort. Variable Air Volume Systems (VAV) Using Variable-Speed Drives (VSD) The heating and cooling needs are further addressed by a VAV air-handling system, which adjusts supply air volumes in response to the heating and cooling needs of the various zones. VSDs are installed on all fans and pumps to reduce the energy consumption of these devices during part-load operation. The main air handler incorporates four separate supply fans that can be individually staged, allowing for efficient operation of the system down to 5% of design air flow. The use of VSDs is especially important in courthouse facilities, due to their variable occupancy characteristics and occasional nighttime use. Building Automation System Afull direct-digital-control system is used to control the HVAC and lighting systems. The system is designed to shut down the HVAC and lighting systems in unoccupied spaces and, in tandem with the VAV air handling and pumping systems, provides efficient operation under partial occupancy. Building-Integrated Photovoltaics PV is integrated into the southeast curtain- wall system adjacent to the public corridor areas of the tower, and a skylight is located over the security drum element in the Special Proceedings pavilion. Translucent, thin-film cells are applied to the skylight and selected panels in the curtain wall system, and additional polycrystalline PV panels are used as spandrel panels in the curtain wall system. The PV panels provide electricity during sunlight hours, reducing peak electric demand. Battery storage is not necessary, because system output is greater than building demand. Landscaping Avariety of measures can be implemented to optimize the landscape surrounding a building. Among these, preservation of existing landscape features should be the designer’s first course of action. Mature trees and vegetation are valuable resources that take many years to replace. Preserving them not only allows for their use in natural shading (and in some climates, as a wind break or shelter belt), it also maintains existing wildlife habitats, existing drainage patterns, and soil conditions. Tree preservation reduces the need for excavation, transportation, and relocation of soil. In addition, it reduces the need for supply and transportation of fill and landscape materials. When adding new vegetation to a site, use regionally consistent landscaping strategies, composed of locally grown, native plants. Water Efficiency One of the most overlooked areas in developing a whole-building design strategy is the efficient use of water resources. To process and use water, the Federal government expends 59.2 billion Btu of energy on an annual basis; more than 98% of this energy is used to heat water. Thus, significant energy and dollar savings can be realized by implementing water-efficient measures. Water efficiency is the planned management of water to prevent waste, overuse, and exploitation of the resource. Effective water-efficiency planning seeks to “do more with less,” without sacrificing comfort or performance. Water-efficiency planning is a relatively new management practice that involves analyzing cost and water usage, specifying water-saving solutions, installing water-saving measures, and verifying the savings to quantify results. Avariety of water conservation technologies and techniques can be used to save water and associated energy costs, including: • Water-efficient plumbing fixtures (e.g., ultra-low-flow toilets and urinals, waterless urinals, low-flow and sensored sinks, low-flow showerheads, and water-efficient dishwashers and washing machines) • Reducing water use associated with irrigation and landscaping (water-efficient irrigation systems, irrigation-control systems, low-flow sprinkler heads, water-efficient scheduling practices, and xeriscaping) • Graywater and process recycling systems that recycle or reuse water • Reducing water use in HVAC systems. Demand-side management methods reduce the amount of water consumed on-site at a facility and include system optimization, water conservation measures, and water reuse and recycling systems. Other efficiency options include leak detection and repair, industrial process improvements, and changing the way fixtures and equipment are operated and maintained. National Renewable Energy Laboratory’s Thermal Testing Facility, Golden, Colorado NREL’s Thermal Testing Facility (TTF) is an open-space laboratory building comprised of high-bay laboratory areas, offices, and conference rooms. Design of the 10,000-square-foot building began early in 1994, and construction was completed in the summer of 1996. Performance monitoring has been underway since occupancy. Although the TTF was designed to serve as a laboratory, the technologies discussed in this case study are appropriate to a wide range of commercial buildings, offices, warehouses, and institutional facilities. Sustainable design strategies integrated into the building include: • Passive solar features • Efficient electric lighting • Daylighting features • Occupancy sensors • Efficient HVAC design • Energy management system with direct digital control (DDC). The TTF’s design team included an architect, mechanical engineer, electrical 33 F E D E R A L E N E R G Y M A N A G E M E N T P R O G R A M engineer, structural engineer, buildingowner facilities staff, and an energy consultant. From the outset, the team focused on optimizing the interactions among the building’s various systems, taking into account the influence of building occupants, their daily activities, and climatic conditions in the surrounding area. Energy-related design decisions were based in part on the results of computer simulations using DOE 2 (1994). The building’s owner (U.S. DOE) and eventual occupants (NREL staff) determined necessary building criteria at the outset of the design phase. The type of spaces required included flexible generic laboratory space, assorted openarea support offices, a conference room, washrooms, and a kitchenette area. Once the building’s use was established, the design team and NREL research engineers set a building energy cost reduction goal of 70%, and a strategic design and construction plan was developed to serve as a “road map” to guide the process. The plan included integrating passive solar features, low building load coefficient, efficient electric lighting, daylighting features, occupancy sensors, efficient HVAC design, and an energy management system with DDC. With a Congressional budget of $1.5 million to cover all design, construction, and commissioning costs, a code-compliant base case was created for the TTF’s design, using 10 CFR 435 (1995) as the reference. (The base-case design is a useful benchmark for gauging the relative cost effectiveness of both individual and collective performance improvements.) The base case was simulated using SERI-RES to study the thermal aspects of the building, and DOE 2.2 for HVAC and lighting studies. Initial base-case results showed that electrical lighting loads accounted for a large portion of the energy use—roughly 73%, not including plug loads. Cooling loads were next, at 15% of the building’s total energy consumption. Based on this information, the NREL research staff believed that internal heat gains could be minimized by reducing the electric lighting load and by minimizing unwanted solar gains. This was accomplished by integrating daylighting and efficient artificial lighting strategies, specifying high-performance windows, and by engineering the dimensions of overhangs. By minimizing the cooling load, the design team was also able to downsize the HVAC system in comparison to what would have been required in the base-case scenario. Computer modeling indicated that the largest energy savings could be achieved by reducing the electric lighting load. Reducing plug loads had a similar effect, but plug loads are not related to the building envelope design. Reducing infiltration, controlling ventilation and unwanted solar gains, and improving the building’s opaque envelope all produced similar energy-saving results. In addition, the facility’s interior was arranged to free up additional floor area. By moving the mechanical room from the exterior east wall to a location above the central core (where the restrooms, storage, and kitchen areas are located), an additional 800 square feet of laboratory floor space was created without a concomitant increase in energy use. The TTF’s final low-energy design achieved its energy reduction goal by applied energy-efficient design strategies as described below. Passive Solar Design To take advantage of Colorado’s sunny climate, the TTF integrates many passive solar features, including appropriate siting and building orientation. The design also incorporates a small amount of thermal mass in the slab floor and north wall of the building, and the north wall also acts as a retaining wall for a mesa, providing the thermal benefits of earth berming. Among the facility’s most important features, however, are the proper selection, orientation, and placement of windows and clerestories. The building was carefully engineered to provide passive solar gain in the winter months, while minimizing this gain during the summer. The final design incorporates 88% of its total fenestration as a single row of view glass and two rows of clerestories along the southern façade. An additional 8% of view glass is divided equally between the east and west façades, while the remaining 4% is positioned on the north wall. South-facing clerestory windows were designed with a high SC of 0.76 (SHGC of 0.68), 34 The National Renewable Energy Laboratory’s Thermal Testing Facility shows how sustainable design strategies can be integrated into a variety of commercial buildings, offices, warehouses, and institutional facilities. Warren Gretz/PIX04117 F E D E R A L E N E R G Y M A N A G E M E N T P R O G R A M while all others have a lower SC of 0.51 (SHGC of 0.45). The higher SCs allow more solar gain to enter the building. In addition, all windows have a low-e coating, which prevents the transmission of most non-visible spectrum light and unwanted solar gain. The careful design and placement of overhangs rounds out the picture by blocking direct solar radiation during the summer when sun angles are high, while allowing direct solar radiation in winter, when sun angles are much lower. Overall, the TTF’s envelope and its passive solar features were designed to heat the building during the day and into the evening hours, such that the only heat load on the building will take place during the morning hours. Bear in mind that the glazing configurations and other passive solar strategies described above are very much site- and applicationspecific and will not necessarily apply to different building types in other locales. Thermal Envelope The TTF’s floor is constructed of a 6-inch concrete slab with 4-foot perimeter insulation. The north wall is constructed of an 8-inch concrete slab with 2 inches of rigid polystyrene, while the east, west, and south walls use 6-inch steel studs with batt insulation positioned between the studs. Expanded polystyrene is placed over the entire exterior surface, which is finished with Exterior Insulation and Finish System (EIFS) stucco. The roof is constructed using metal decking atop steel supports with a 3-inch polyisocianurate covering. The thermal insulation positioned on the wall exterior creates an energy sink within the building, which dampens the building’s natural temperature swings. For example, during cold winter nights, when outdoor temperatures drop well below freezing, the TTF’s indoor temperature drops by only 10ºF. Lighting The TTF is illuminated by a dynamic combination of electric lighting and daylighting, depending on real-time occupancy status and daylight luminance values. Astair-stepped design is integral to the daylighting plan; daylight enters the building through a row of view glass and two additional rows of clerestories lining the south façades of the open office areas, mid-bays, and high-bays, respectively. Additional windows exist along the east, west, and north walls to balance incoming daylight. Again, all windows are engineered to take full advantage of daylighting opportunities. Asensor that measures illumination levels controls the building’s supplemental electric lighting system, and the building’s energy management system (EMS) uses this information to control electric lighting status, depending on the amount of natural light available in each lighting zone. In terms of lighting systems, the facility uses T-8 and compact fluorescent lighting, 72% of which provides supplemental lighting to daylit zones, while the remaining 28% provides primary lighting to the building’s central core. The EMS-integrated occupancy control protocol uses passive infrared and ultrasonic occupancy sensors to disengage lighting when not required. Together, these features have significantly reduced the building’s (lighting-based) electrical use as well as its cooling load, while heating loads increased only slightly during the winter months. Heating, Ventilation, and Air Conditioning Because the TTF minimizes HVAC requirements, a smaller, more efficient, and less expensive HVAC system was installed. Actually, the TTF uses two separate HVAC systems: a VAV air handling unit (AHU) to serve the main building, and a packaged single-zone AHU to serve the conference room. The VAV unit relies on direct and indirect evaporative cooling as its primary cooling source, supplemented by ceiling fans, which help reduce the temperature stratification that is common in spaces with large ceiling heights. The TTF’s efficient HVAC design limited the total amount of ductwork throughout the building, which, in turn, reduces material costs during construction, as well as maintenance thereafter. All ductwork is insulated and located indoors to reduce losses to the outside environment and bordering zones. Energy Management System The TTF uses a digital building control system for most mechanical building operations. This EMS allows for easy monitoring, tuning, and diagnosis, helping to keep the building operating as designed. The EMS operates each of the HVAC units and the electrical lighting system and also collects diagnostic and performance data. Two tankless heat-on-demand water heaters provide the facility with domestic hot water (DHW): one serving the kitchen and the other dedicated to the washrooms. Both units are natural gas-fired and provide 80% thermal efficiency. The Technology in Perspective Technology Development Since ancient times, people have designed buildings for the local climate, taking advantage of natural daylight and prevailing winds. Today, these same principles apply to low-energy building design but are combined with what we have learned about energy conservation; advanced materials, products, and mechanical systems; renewable energy; and energy performance design tools. When designed in tandem, technology clusters, such as energy-efficient lighting, occupancy sensors, and daylighting strategies, can reduce a building’s energy load and improve occupant comfort. Federal energy managers can be assured that sound, climate-responsive design will yield long-term energy savings regardless of fluctuations in energy prices and will serve as the basis for durable, comfortable, environmentally sound buildings. Advances in other key technologies will further transform the building industry. New design and analysis tools have greatly improved the designer’s ability to predict building energy performance, while giving energy managers better control over operations and maintenance costs. As these tools continue to be refined and their 35 F E D E R A L E N E R G Y M A N A G E M E N T P R O G R A M use becomes more commonplace, lowenergy building design will emerge as the only logical approach to new construction and renovation. Technology Outlook The technologies, systems, and design strategies discussed in this guidebook are helping to ensure a bright future for low-energy buildings. As consumers continue to demand more sustainable development and wise environmental stewardship from their elected leaders, the Federal government is uniquely positioned to take the lead in making its own buildings as energy efficient as possible, and at the same time making them more comfortable and attractive than their conventional counterparts. It is likely, however, that institutional barriers (e.g., restrictive codes, procedures, budget processes) will have to be revised or removed before the Federal sector can fully meet this challenge. This guidebook is a tangible step toward achieving more widespread use of wholebuilding energy design and analysis because it makes the process more comprehensible for all project team members. There is also an important role for those who develop new Federal guidelines and requirements that encourage the use of low energy and renewable energy strategies. Though often unsung, these individuals are laying the cornerstone for meaningful, enduring change. When starting your next project, remember that an accurate assessment of lowenergy design features and technologies comes from a clear understanding—not just of how the many components of a building work—but of how they work together. This often begins with an awareness that the current, highly fragmented building process is not producing the best results, and that a new view of the building as a system of interdependent components is required. Product Resources Avast array of products for low-energy buildings are available from suppliers of traditional building materials as well as from manufacturers of specialized technologies, such as PV systems. Because passive solar buildings are design intensive, it also is useful to know how to locate design professionals with special expertise in low-energy building design. For information on products and professional services, please refer to the following resources, as well as building product suppliers. Air-Conditioning and Refrigeration Institute Arlington, Virginia Phone: 703-524-8800, 800-AT-ARIES Web site: http://www.ari.com American Institute of Architects Committee on the Environment Washington, D.C. Phone: 202-626-7515 Web site: http://www.e-architect.com Architects’ First Source for Products Web site: http://www.afsonl.com APA—The Engineered Wood Association Tacoma, Washington Phone: 206-565-6600 Web site: http://www.apawood.org Association of Home Appliance Manufacturers Chicago, Illinois Phone: 312-984-5800 Building Design Assistance Center Florida Solar Energy Center E-mail: bdac@fsec.ucf.edu Web site: http://www.fsec.ucf.edu/~bdac/ Manufactures and supplies controls (i.e., dimming systems, motion/occupancy sensors, power reducers, switching systems), energy management systems, glazing (e.g., glass, windows, window films, skylights), insulation systems and radiant barriers, lighting (e.g., energy efficient ballasts, lamps, luminaries, exit lighting, specular reflectors), and roofing (e.g., energy-efficient reflective coatings, paints, tiles, shingles). Center for Renewable Energy and Sustainable Technology (CREST) Web site: http://www.crest.org Gas Appliance Manufacturers Association Arlington, Virginia Phone: 703-525-9565 Greening Federal Facilities: An Energy, Environmental, and Economic Resource Guide for Federal Facility Managers (1997). U.S. DOE/FEMP Phone: 800-DOE-EREC Web site: http://www.eren.doe.gov/ femp/ techassist/greening.html Primary Glass Manufacturers Council Topeka, Kansas Phone: 785-271-0208 Structural Insulated Panel Association Phone: 253-858-SIPA(7472) Web site: http://www.sips.org Sustainable Buildings Industry Council (formerly Passive Solar Industries Council) Washington, D.C. Phone: 202-628-7400 E-mail: SBIC@SBICouncil.org Web site: http://www.sbicouncil.org Sustainable Building Sourcebook Green Building Program Austin, Texas Web site: http://www.greenbuilder. com/ sourcebook Sustainable Building Technical Manual: Green Building Design, Construction and Operations (1996). Public Technology, Inc. U.S. Green Building Council U.S. DOE/U.S. EPA. U.S. Green Building Council San Francisco, California Phone: 415-543-3001 E-mail: info@usgbc.org Web site: http://www.usgbc.org Who is Using the Technology Thousands of low-energy buildings and homes have been constructed throughout the United States, many by the Federal government. The GSA has used low-energy approaches for some of its buildings. Several Federal facilities that feature low-energy design strategies are in the design phase, under construction, or recently completed, including an environmental learning center on the National Mall in Washington, D.C., and a 570,000-square-foot Federal courthouse in Phoenix, Arizona. The National Park Service (NPS) has integrated passive 36 F E D E R A L E N E R G Y M A N A G E M E N T P R O G R A M solar strategies into new employee housing units. NPS houses in Grand Canyon and Yosemite National Parks are included in the DOE Exemplary Buildings program. Projects have been completed or are in progress at Grand Teton National Park, Hovenweep National Monument, and Capitol Reef National Park. The Department of Defense is also using these low-energy strategies. Federal Sites Excellence in Facility Management, Five Federal Case Studies (1998). National Institute of Building Sciences Phone: 202-289-7800 E-mail: nibs@nibs.org Web site: http://www.nibs.org/ fmochome.htm The case studies included in this document are: (1) U.S. Department of Agriculture Headquarters, (2) Carbondale Federal Building, (3) Merritt Island Launch Annex, (4) Naval Station Everett, and (5) Defense Logistics Agency. National Park Service Employee Housing at Capitol Reef National Park National Renewable Energy Laboratory High-Performance Buildings Program Golden, Colorado Phone: 303-275-3000 Web site: http://www.nrel.gov/buildings/ highperformance Detailed case studies of state-of-the-art, low-energy buildings; pictures are available for download. The Naval Facilities Engineering Command has completed several projects that demonstrate low-energy design principles. Aphysical fitness center at Camp Pendleton, California; a $7.8 million project in Sugar Grove, West Virginia; and a restoration project at the Washington Navy Yard. Brown, Linda R. “SERF: ALandmark in Energy Efficiency.” (May/June 1994). Solar Today, American Solar Energy Society. U.S. Fish and Wildlife Service National Education and Training Center, Sheperdstown, West Virginia. AFEMP case study will soon be available. Among a host of energy-efficient features, the center incorporates passive solar design strategies. In winter, large southern windows capture solar gain, and brick floors behind windows store heat. Windows are made of high-performance glass. In summer, extended rooflines (overhangs) and landscaping provide optimum shading. Some windows are fitted with sunscreens, which also help reduce summer cooling loads. Non-Federal Sites Besser Company manufacturing facility, Alpena, Michigan. By Innovative Design. Energy conservation, daylighting. Blue Cross/Blue Shield building in New Haven, Connecticut. The 21,000-squarefoot building has deep overhangs on the south façade to protect it from direct solar radiation in summer and to reduce cooling loads. An atrium divides the building into two sectors. Light shelves on façades and in the atrium project natural light deep into the space. The project was completed in 1990; Ellenzweig Associates, Inc., were the architects. Brown Summit Youth Dormitory cabins, North Carolina. By Cooper-Lecky CUH2A, LLP. Natural ventilation. Buildings for a Sustainable America Case Studies, American Solar Energy Society, 303-443-3130, ases@ases.org, http://www. ases.org/solar and Sustainable Buildings Industry Council (formerly Passive Solar Industries Council), 202-628-7400, SBIC@SBICouncil.org, http://www. sbicouncil.org, with funding from U.S. Department of Energy. Acollection of 18 case studies, with easy-to-read summaries, thorough project details, and photographs. The Florida Solar Energy Center (FSEC) is building a state-of-the-art complex (office building, visitor’s center, and laboratories) for its new facility in Cocoa, Florida. The objective is to design and construct the most energyefficient facility possible within the limits of Florida’s hot and humid climate. For a detailed analysis of the low-energy design strategies used, check the FSEC Web site: http://www.fsec.ucf.edu/About/ TOUR/Tourhome.htm Illinois Department of Energy and Natural Resources Contact: R. Forrest Lupo Phone: 217-785-3484 Massachusetts State Transportation Building, Boston, Massachusetts Asolar water-heating system installed in 1982 cost $250,000 but saves $26,280 per year in avoided electricity costs. At this rate, the system will pay for itself in 9.5 years. Four thousand square feet of closed-loop propylene glycol solar collectors enable the solar water heaters to operate year-round, even though the outside temperature is below freezing for extended periods of time. The collectors supply 83% of the building’s annual domestic hot water needs, offsetting roughly 5,800 gallons of oil annually. Contact: Martha Goldsmith, Director, Office of Leasing Commonwealth of Massachusetts Phone: 617-727-8000 Sacramento Department of Transportation Building Uses nighttime flushing and passive solar cooling with atrium. Contact: Craig Hoellwarth Phone: 916-683-8378 Union of Concerned Scientists building Cambridge, Massachusetts Phone: 617-547-5552 E-mail: energy@ucsusa.org Web site: http://www.ucsusa.org Utah Department of Natural Resources (profiled in Solar Today, American Solar Energy Society, July/August 1997) For Further Information Trade/Professional Organizations American Council for an Energy Efficiency Economy (ACEEE) Alliance to Save Energy American Institute of Architects Committee on the Environment Washington, D.C. Phone: 202-626-7515 Web site: http://www.e-architect.com 37 F E D E R A L E N E R G Y M A N A G E M E N T P R O G R A M American Portland Cement Alliance Washington, D.C. Phone: 202-408-9494 Web site: http://www.portcement.org American Solar Energy Society Phone: 303-443-3130 E-mail: ases@ases.org Web site: http://www.ases.org American Society of Heating, Refrigeration, and Air-Conditioning Engineers (ASHRAE) Atlanta, Georgia Phone: 404-636-4800 Web site: http://www.ashrae.org American Society for Testing and Materials West Conshocken, Pennsylvania Phone: 610-832-9500 Web site: http://www.astm.org Association of Energy Engineers Atlanta, Georgia Phone: 770-447-5083 Web site: http://www.aeecenter.org Building Owners and Managers Association International Washington, D.C. Web site: http://www.boma.org Brick Institute of America, Mid East Region North Canton, Ohio Phone: 330-499-3001 Brick Industry Association Reston, Virginia Phone: 703-620-0010 Web site: http://www.bia.org Ceilings and Interior Systems Construction Association St. Charles, Illinois Phone: 630-584-1919 Electricity Consumers Resource Council Washington, D.C. Phone: 202-682-1390 Energy Efficient Building Association (EEBA) Minneapolis, Minnesota Phone: 612-851-9940 E-mail: EEBANews@aol.com Illuminating Engineering Society of North America New York, New York Phone: 212-248-5000 International Masonry Institute Ann Arbor, Michigan Phone: 313-769-1654 National Association of Energy Service Companies Washington, D.C. Phone: 202-822-0952 National Association of Home Builders Washington, D.C. Phone: 202-822-0200 (bookstore: extension 463) Web site: http://www.nahb.com National Concrete Masonry Association Herndon, Virginia Phone: 703-713-1900 Web site: http://www.ncma.org National Electrical Manufacturers Association Rosslyn, Virginia Phone: 703-841-3200 National Fenestration Rating Council Silver Spring, Maryland Phone: (301) 588-0854 Web site: http://www.nfrc.org National Institute of Building Sciences Phone: 202-289-7800 E-mail: nibs@nibs.org Web site: http://www.nibs.org/fmochome.htm National Society of Professional Engineers Alexandria, Virginia Phone: 703-684-2800 Web site: http://www.nspe.org National Wood Window and Door Association Des Plaines, Illinois Phone: 847-299-5200 Web site: http://www.nwwda.org North American Insulation Manufacturers Association Alexandria, Virginia Phone: 703-684-0084 Web site: http://www.naima.org North Carolina Solar Center Phone: (919) 515-3480 Northeast Sustainable Energy Association Phone: 413-774-6051 E-mail: buildings@nesea.org Web site: http://www.nesea.org Solar Energy Industries Association Washington, D.C. Web site: http://www.seia.org Southface Energy Institute Atlanta, Georgia Phone: 404-872-3549 E-mail: info@southface.org Web site: http://www.southface.org Sustainable Buildings Industry Council (SBIC) (formerly Passive Solar Industries Council) Washington, D.C. Phone: 202-628-7400 E-mail: SBIC@SBICouncil.org Web site: http://www.sbicouncil.org U.S. Green Building Council (USGBC) San Francisco, California Phone: 415-543-3001 E-mail: info@usgbc.org Web site: http://www.usgbc.org Design Guides Designing Low-Energy Buildings: Passive Solar Strategies and ENERGY-10 Software; Passive Solar Design Strategies: Guidelines for Home Building; Low-Energy, Sustainable Building Design for Federal Managers (Sustainable Buildings Industry Council [formerly Passive Solar Industries Council]) Phone: 202-628-7400 E-mail: SBIC@SBICouncil.org Web site: http://www.sbicouncil.org General Services Administration/Public Buildings Service—Proposed Comprehensive Building Commissioning LEED™ (Leadership in Energy and Environmental Design) Rating System, Version 2.0, available at http://www.usgbc.org Sustainable Building Technical Manual: Green Building Design, Construction and Operations, Public Technology, Inc. U.S. Green Building Council U.S. DOE, U.S. EPA, 1996. Whole Buildings Design Guide, a federally sponsored, vertical portal to a wide range of building specific criteria, technology, and product information. Web site: http://www.wbdg.org 38 F E D E R A L E N E R G Y M A N A G E M E N T P R O G R A M Utility, Information Service, or Government Agency Tech-Transfer Literature Utility Sources American Gas Association Arlington, Virginia Web site:http://www.aga.com Edison Electric Institute Washington, D.C. Phone: 202-508-5557 Web site: http://www.eei.org The Electricity Consumers Resource Council Washington, D.C. Phone: 202-682-1390 E-mail: elcon@elcon.org Web site: http://www.elcon.org Electric Power Research Institute Palo Alto, California Phone: 650-855-2000 Web site: http://www.epri.com National Association of Regulatory Utility Commissioners Washington, D.C. Phone: 202-898-2200 Web site: http://www.naruc.org National Association of State Utility Consumer Advocates Washington, D.C. Phone: 202-727-3908 Web site: http://www.nasuca.org Public Utilities Reports Vienna, Virginia Phone: 703-847-7720, 800-368-5001 E-mail: info@pur.com Web site: http://www.pur.com/ General Information Sources Energy Design Update Cutter Information Corp. 37 Broadway, Suite 1 Arlington, Massachusetts 02174-5552 Phone: 800-964-5118 Web site: http://www.cutter.com/energy/ Environmental Building News RR 1, Box 161 Brattleboro, Vermont 05301 Phone: 802-257-7300; Web site: http://www.ebuild.com E Source, Inc. Boulder, Colorado, Phone: 303-440-8500 Web site: http://www.esource.com Florida Solar Energy Center Phone: 407-638-1015 Web site: http://www.fsec.ucf.edu International Energy Agency Web site: http://www.iea.org Iris Catalog: Publications, Videos and Software for Green Construction Iris Communications, Inc. P.O. Box 5920 Eugene, Oregon 97405-9011 Phone: 800-346-0104 Web site: http://www.oikos.com ReInState, a guide to state-by-state renewable energy and sustainable development resources, including case studies, products and services, utility information, programs and policies, and energy usage and design data for each state. Web site: http://www.crest.org/gem.html American National Standards Institute Government Sources Energy Efficiency and Renewable Energy Clearinghouse Merrifield, Virginia, Phone: 800-363-3732 E-mail: erec@nciinc.com Web site: http://www.eren.doe.gov Energy Science and Technology Software Center Web site: http://www.osti.gov/estc Federal Laboratory Consortium 1850 M Street, NW, Suite 800 Washington, D.C. 20036 FLC Locator: 609-667-7727 Web site: http://www.Federallabs.org/ Guiding Principles of Sustainable Design U.S. Department of the Interior National Park Service Denver, Colorado: GPO, 1993. Lawrence Berkeley National Laboratory Berkeley, California Phone: 415-486-5771 Web site: http://www.lbl.gov/ National Energy Information Center Washington, D.C. Phone: 202-586-1181 E-mail: infoctr @eia.doe.gov National Institute of Standards and Technology Washington, D.C. Web site: http://www.nist.gov National Oceanic and Atmospheric Administration (NOAA) Phone: 704-271-4800 E-mail: orders@ncdc.noaa.gov Web site: http://www.ncdc.noaa.gov National Renewable Energy Laboratory Web site: http://www.nrel.gov/buildings/ highperformance National Technical Information Service Washington, D.C. Phone: 800-553-6847 Web site: http://www.fedworld.gov Oak Ridge National Laboratory Building Technology Center Web site: http://www.ornl.gov/ornl/btc Office of Scientific and Technical Information Oak Ridge, Tennessee Phone: 423-576-1188. Technical reports: 423-576-8401 Partnership for Advancing Technology in Housing (PATH) U.S. Department of Housing and Urban Development Phone: 202-708-1600 Web site: http://www.pathnet.org Procuring Low-Energy Design and Consulting Services: A Guide for Federal Building Managers, Architects, and Engineers, 1997 Phone: 800-DOE-FEMP Web site: http://www.eren.doe.gov/femp/ Sacramento Municipal Utility District Phone: 916-732-6679 Sandia National Laboratories Phone: 505-844-3077 Web site: http://www.sandia.gov/EE.htm U.S. Department of Energy Building Technology State and Community Programs Phone: 202-586-2998 U.S. Environmental Protection Agency Energy Star Program Web site: http://www.epa.gov Codes and Standards Executive Order 13123 mandates improvements in energy efficiency and water conservation in Federal buildings nationwide, including costeffective investments (payback of less 39 F E D E R A L E N E R G Y M A N A G E M E N T P R O G R A M than 10 years) in low-energy building design and active solar technologies. 10 CFR 435 establishes performance standards to be used in designing new Federal commercial and multifamily high-rise buildings. Some of the guidelines are relevant to retrofits. 10 CFR 436 establishes procedures for determining the life-cycle cost effectiveness of energy conservation measures and for prioritizing energy conservation measures in retrofits of existing Federal buildings. In general, building codes and standards address specific technologies and minimum requirements for building energy efficiency. They do not address whole building performance. Awell-designed, low-energy building can exceed existing Federal codes, as well as commercial code (ASHRAE 90.1—Energy Efficient Design of New Buildings Except Low- Rise Residential Buildings), by as much as 50%. Documents and Other References American Institute of Architects, Com - mittee on the Environment, Energy, Environment and Architecture, Washington, D.C., 1991. Ander, Gregg, Daylighting Performance and Design, New York, New York, Van Nostrand Reinhold, 1998. Balcomb, J. Douglas, editor. Passive Solar Buildings. Cambridge, Massachusetts, MIT Press, 1992. Bobenhausen, William, Simplified Design of HVAC Systems. New York, John Wiley and Sons, Inc., 1994. Idea exchange among facility managers Web site: www.fmdata.com Interstate Renewable Energy Council 15 Haydn Street Roslindale P.O. Boston, Massachusetts 01131-4013 Phone: 617-323-7377 International Energy Agency Solar Heating and Cooling Programme. Passive Solar Commercial and Institutional Buildings: A Sourcebook of Examples and Design Insights. West Sussex, United Kingdom, John Wiley and Sons, Ltd., 1994. National Institute of Building Sciences www.nibs.org Productivity Studies • www.workplaceforum.com • Miller, Burke, Buildings for a Sustainable America Case Studies; Daylighting and Productivity at Lockheed, Boulder, Colorado, American Solar Energy Society. • Joseph Romm and William Browning, Greening the Building and the Bottom Line: Increasing Productivity through Energy- Efficient Design, Snowmass, Colorado, Rocky Mountain Institute, 1994. Steven Winter Associates, Inc., The Passive Solar Design and Construction Handbook, New York, John Wiley and Sons, Inc., 1998. Tuluca, Adrian; Steven Winter Associates, Inc., Energy-Efficient Design and Construction for Commercial Buildings. New York, McGraw-Hill, 1997. 40 F E D E R A L E N E R G Y M A N A G E M E N T P R O G R A M 41 Appendixes Appendix A: Climate and Utility Data Sources Appendix B: Federal Life-Cycle Costing Procedures and the Building Life Cycle Cost (BLCC) Software F E D E R A L E N E R G Y M A N A G E M E N T P R O G R A M 42 Appendix A: Climate and Utility Data Sources Energy User News includes a ranking of electricity and gas utility prices by state in each of its monthly issues. Available at http://www.energyusernews.com. NOAAprovides detailed available climate data and summaries for sites in or near a locality. Call 704-271-4800, e-mail requests to orders@ncdc.noaa.gov, or available on the World Wide Web at http://www.ncdc.noaa.gov. Opportunities for Renewable Energy Supply in New Buildings (Solar Potential Maps). ABuildings for a Sustainable America Education Campaign Resource from the Sustainable Buildings Industry Council, Washington, D.C. Funded by the U.S. DOE, researched and produced by Mark Kelley and Henry Amistadi of Building Science Engineering in Harvard, Massachusetts. For more information, call 202-628-7400, send e-mail to SBICouncil@aol.com, or access the SBIC Web site at http://www.sbicouncil.org. Putting Energy into Profits. U.S. Environmental Protection Agency, #430-B-97-040, December 1997. Five U.S. climate zones are mapped, showing average annual energy use and average annual energy costs for specific building types. Available from Government Printing Office, Superintendent of Documents, Washington, DC 20402, or call 202-512-1800. Appendix B: Federal Life-Cycle Costing Procedures and the Building Life Cycle Cost (BLCC) Software Federal agencies are required to evaluate energy-related investments on the basis of life-cycle costs (10 CFR 436). Life-cycle cost analysis (or life-cycle costing [LCC]) is a means of predicting the overall cost of building ownership, including initial costs, operating costs for energy, water and other utilities; personnel costs; and maintenance, repair, and replacement costs. LCC analyzes changes to the building, including all significant costs over the predicted life of the building. It can be used to refine the design to ensure the facility will provide the lowest overall cost of ownership consistent with its desired quality and function. Analysis tools such as the National Institute of Standards and Technology’s (NIST) BLCC computer program performs calculations to predict life-cycle costs, providing an economic analysis of proposed capital investments that are expected to reduce longterm operating costs of buildings. BLCC is designed to comply with 10 CFR 436. ERATES (electricity rates) is another computer program from NIST that calculates monthly and annual electricity costs for a facility under a variety of electric rate schedules. ERATES block-rate and demand-rate schedules can be imported by BLCC. BLCC is available from the FEMP Help Desk at 800-566-2877. F E D E R A L E N E R G Y M A N A G E M E N T P R O G R A M Federal Energy Management Program The Federal Government is the largest energy consumer in the nation. Annually, in its 500,000 buildings and 8,000 locations worldwide, it uses nearly two quadrillion Btu (quads) of energy, costing over $8 billion. This represents 2.5% of all primary energy consumption in the United States. The Federal Energy Management Program was established in 1974 to provide direction, guidance, and assistance to Federal agencies in planning and implementing energy management programs that will improve the energy efficiency and fuel flexibility of the Federal infrastructure. Over the years, several Federal laws and Executive Orders have shaped FEMP’s mission. These include the Energy Policy and Conservation Act of 1975; the National Energy Conservation and Policy Act of 1978; the Federal Energy Management Improvement Act of 1988; and, most recently, Executive Order 12759 in 1991, the National Energy Policy Act of 1992 (EPACT), Executive Order 12902 in 1994, and Executive Order 13123 in 1999. FEMP is currently involved in a wide range of energy-assessment activities, including conducting New Technology Demonstrations, to hasten the penetration of energy-efficient technologies into the Federal marketplace. The Energy Policy Act of 1992, and subsequent Executive Orders, mandate that energy consumption in Federal buildings be reduced by 35% from 1985 levels by the year 2010. To achieve this goal, the U.S. Department of Energy’s Federal Energy Management Program (FEMP) is sponsoring a series of programs to reduce energy consumption at Federal installations nationwide. One of these programs, the New Technology Demonstration Program (NTDP), is tasked to accelerate the introduction of energyefficient and renewable technologies into the Federal sector and to improve the rate of technology transfer. As part of this effort, FEMP is sponsoring a series of publications that are designed to disseminate information on new and emerging technologies. New Technology Demonstration Program publications comprise three separate series: Federal Technology Alerts—longer summary reports that provide details on energy-efficient, water-conserving, and renewable-energy technologies that have been selected for further study for possible implementation in the Federal sector. Technology Installation Reviews— concise reports describing a new technology and providing case study results, typically from another demonstration program or pilot project. Technology Focuses—brief information on new, energy-efficient, environmentally friendly technologies of potential interest to the Federal sector. About FEMP’s New Technology Demonstration Program For More Information FEMP Help Desk (800) 363-3732 International callers please use (703) 287-8391 Web site: www.eren.doe.gov/femp General Contacts Ted Collins New Technology Demonstration Program Manager Federal Energy Management Program U.S. Department of Energy 1000 Independence Ave., SW, EE-92 Washington, D.C. 20585 Phone: (202) 586-8017 Fax: (202) 586-3000 theodore.collins@ee.doe.gov Steven A. Parker Pacific Northwest National Laboratory P.O. Box 999, MSIN: K5-08 Richland, WA 99352 Phone: (509) 375-6366 Fax: (509) 375-3614 steven.parker@pnl.gov Technical Contact Nancy Carlisle National Renewable Energy Laboratory 1617 Cole Boulevard, M.S. 2723 Golden, CO 80401 Phone: (303) 384-7509 Fax: (303) 384-7411 Nancy_Carlisle@nrel.gov Prepared for the U.S. Department of Energy by the National Renewable Energy Laboratory, a DOE national laboratory DOE/EE-0249 July 2001 F E D E R A L E N E R G Y M A N A G E M E N T P R O G R A M Printed with a renewable-source ink on paper containing at least 50% wastepaper, including 20% post consumer waste Log on to FEMP’s New Technology Demonstration Program Web site http://www.eren.doe.gov/femp/prodtech/newtechdemo.html You will find links to: • An overview of the New Technology Demonstration Program • Information on the program’s technology demonstrations • Downloadable versions of program publications in Adobe Portable Document Format (PDF) • A list of new technology projects underway • Electronic access to the program’s regular mailing list for new products when they become available • How Federal agencies may submit requests for the program to assess new and emerging technologies.

Low-Energy Building Design Guidelines
Energy-efficient design for new Federal facilities
F E D E R A L E N E R G Y M A N A G E M E N T P R O G R A M
A guidebook of practical
information on designing
energy-efficient
Federal buildings.
Prepared by the
New Technology
Demonstration
Program
No portion of this publication
may be altered in
any form without prior
written consent from
the U.S. Department of
Energy and the authoring
national laboratory.
DOE/EE-0249
F E D E R A L E N E R G Y M A N A G E M E N T P R O G R A M
Disclaimer
This report was sponsored by the United States Department of Energy, Office of Federal Energy Management
Programs. Neither the United States Government, nor any agency or contractor thereof, nor any of their employees,
makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness,
or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would
not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade
name, mark, manufacturer, or otherwise, does not necessarily constitute or imply its endorsement, recommendation,
or favoring by the United States Government or any agency or contractor thereof. The views and opinions of the
authors expressed herein do not necessarily state or reflect those of the United States Government or any agency or
contractor thereof.
F E D E R A L E N E R G Y M A N A G E M E N T P R O G R A M
Contents
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1
About the Technology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5
Application Domain . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6
Energy-Saving Mechanisms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6
Advantages of Low-Energy Building Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6
Application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7
Applications Screening . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7
Building Types: Characteristics and Profiles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9
Integrating Low-Energy Concepts into the Design Process . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12
What to Avoid . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .29
Design Considerations and Computer Modeling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .29
Strategy Interactions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .29
The Benefits of Multiple Use . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .30
Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .30
Costs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .30
Design and Analysis Tools . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .31
Energy Savings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .31
Other Impacts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .31
Case Studies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .31
The Technology in Perspective . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .35
Technology Development . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .35
Technology Outlook . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .36
Product Resources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .36
Who is Using the Technology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .36
For Further Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .37
Appendix A: Climate and Utility Data Sources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .42
Appendix B: Federal Life-Cycle Costing Procedures and the Building Life Cycle Cost (BLCC) Software . . . . . . . . . .42
3
F E D E R A L E N E R G Y M A N A G E M E N T P R O G R A M
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F E D E R A L E N E R G Y M A N A G E M E N T P R O G R A M
About the Technology
Buildings consume roughly 37% of the
primary energy and 67% of the total
electricity used each year in the United
States. They also produce 35% of U.S.
and 9% of global carbon dioxide (CO2)
emissions. Preliminary figures indicate
that in FY 1997, Federal government
facilities used nearly 350.3 trillion
British thermal units (Btus) of energy
in approximately 500,000 buildings
at a total cost of $3.6 billion.
By following a careful design process, it
is possible to produce buildings that use
substantially less energy without compromising
occupant comfort or the
building’s functionality. Whole-building
design considers the energy-related
impacts and interactions of all building
components, including the building
site; its envelope (walls, windows,
doors, and roof); its heating, ventilation,
and air-conditioning (HVAC) system;
and its lighting, controls, and equipment.
This stands in marked contrast
to the traditional design process, where
there is generally no goal to minimize
energy use and costs beyond what is
required by codes and regulations.
Executive Order 13123 calls for a 30%
reduction in energy use per gross square
foot by 2005. To achieve this goal, the
agency and design team must establish
minimized energy use as a high priority
goal at the inception of the design process.
Abalanced and appropriately funded
team must be assembled that will work
closely together, maintain open lines of
communication, and remain responsive
to key action items throughout the
delivery of the project.
Continuing advocacy of low-energy
design strategies is essential to realizing
the goal. Therefore, it is important that
at least one technically astute member
of the design team be designated as the
energy advocate. This team member
performs many useful functions, such as:
• Introducing team members to design
strategies that are appropriate to building
type, size, and location.
• Maintaining enthusiasm for the integration
of low-energy design strategies
as central components of the overall
design solution.
• Ensuring that these strategies are not
abandoned or eliminated during the
later phases.
• Overseeing construction to ensure that
the strategies are not thwarted or compromised
by field changes.
For most projects, it is also highly advisable
to retain an experienced low-energy
design consultant. Because low-energy
design is not entirely intuitive, experience
gained from a range of projects is
vital. Indeed, the energy use and energy
cost of a building depend on the complex
interaction of many parameters
and variables that require detailed
analysis on a project-by-project basis.
Some of the attributes that an energy
consultant should bring to the project
include:
• Sufficient background to identify
potential strategies based on experience.
• Knowledge of Federal information
sources (e.g., Federal Energy Management
Program, national laboratories),
Federal requirements (e.g., 10 CFR 435
and 436 Energy Star™ buildings and
equipment, energy-savings performance
contracting), the Energy Policy
Act of 1992 (EPAct), and other relevant
executive orders.
• Technical expertise that generates
enthusiasm, cooperation, and respect
among team members.
• The capacity to efficiently use detailed
computerized energy simulation programs
such as the latest version of
Energy 10 or DOE 2.
• The ability to make informed design
recommendations based on computer
results and life-cycle economic analyses.
• Abreadth of experience sufficient to
consider design options that not only
save energy, but are also integrated with
other project needs, including aesthetic
considerations.
In sum, the energy consultant should
serve as a catalyst for eliciting innovative
energy-conserving design ideas
from the entire design team. In some
cases, other members of the project
team (such as the design architect and
engineer) may, themselves, be quite pro-
5
Estimated Costs for Low-Energy Design Consulting Services
Investment ($/ft2)
Small buildings Medium buildings Large buildings
Energy Use Type (0 to 20,000 ft2) (20,000 to 100,000 ft2) (100,000 ft2 and above)
Moderate Energy Users
Including single family
residences, housing,
and warehouses $0.35 to $0.25 $0.25 to $0.15 $0.15 to $0.05
High Energy Users
Including offices,
factories, and service
centers $0.40 to $0.30 $0.30 to $0.20 $0.20 to $0.10
Very High Energy Users
Including laboratories
and hospitals $0.45 to $0.35 $0.35 to $0.25 $0.25 to $0.15
Note:This table adjusts the rule of thumb for building size and energy use characteristics and
provides a more precise guideline. Note that as buildings get larger, there is an economy of
scale, so it is not necessary to expend as much on a square-foot basis.
U.S. Department of Energy (DOE) Federal Energy Management Program (FEMP), March 1999.
Procuring Low-Energy Design and Consulting Services: A Guide for Federal Managers, Architects, and
Engineers, available at www.nrel.gov or www.eren.doe.gov/femp.
F E D E R A L E N E R G Y M A N A G E M E N T P R O G R A M
ficient in low-energy building design
and will respond well to the challenge.
The only thing that may hold them back
from advocating low-energy design on
any particular project is the lack of a commitment
and appropriate funding by the
owner or agency. Estimated costs for this
consulting service can be obtained from
the table on the previous page.
Application Domain
The application domain for low-energy
design is not so much a case of where
the technology should be installed, but
where it is integrated with the other
elements of the project to produce an
energy-efficient building that serves
both the environmental and functional
needs of its users. When thinking about
whole buildings, it is important to consider
not only the discrete components
and materials but how the various parts
can best work together to achieve the
desired results. That is what is meant by
the phrase “integrated, whole-building
design.” Low-energy design strategies
and renewable energy concepts can be
applied to almost any type of new
Federal building.
Energy-Saving Mechanisms
In Federal buildings, low-energy design
mechanisms range from a few high-profile
architectural features that are solar
responsive to the application of more
conventional, and often less conspicuous,
energy conservation technologies.
Many applications are reconfigurations
of typical building components, such as
a change from flat façades and roofs to
those that are articulated and have surfaces
designed to bounce or block direct
solar rays.
The low-energy design process described
in this guidebook combines a broad range
of practical systems, devices, materials,
and design concepts that should be considered
simultaneously whenever possible
to achieve significant reductions in
energy use. For most non-residential
buildings, an energy-use reduction of
30% below what is required by codes
and standards can usually be achieved
with little, if any, increase in construction
cost. The figure is closer to a 50%
reduction in residences. Savings of 70%
or more are possible for exemplary buildings,
although achieving such significant
reductions can be challenging in light of
the demands occasioned by budgeting
constraints and cost-effectiveness criteria.
For example, daylighting, coupled
with dimmable lighting and light-level
controls, is increasingly commonplace.
An effective and highly recommended
energy conservation strategy, this technology
cluster is an important component
of low-energy building design.
(See Applications Screening and How
to Apply)
Because energy-efficiency concepts and
technologies must dovetail with all other
building elements, one of the most
important energy-saving tools is the
use of computer modeling and design
software. This strategy should be used
early in the design process to analyze
the efficiency and cost effectiveness of
candidate strategies. Detailed computer
simulation results are then referred to
throughout the design process, and
often through the value engineering
(VE) phase, to ensure that the building
will efficiently perform as intended, and
that subsequent changes to the design
in the interest of cost-cutting do not
adversely affect performance. By using
appropriate energy simulation tools in
the context of a whole-building
approach that emphasizes solar technologies
and energy efficiency, design
teams can achieve significant operating
cost savings while still staying on budget.
Alist of design and analysis tools is
provided later.
Advantages of Low-Energy Building
Design
While basic techniques and concepts are
important, of greater relevance to a given
building project are the specific lowenergy
building design techniques
themselves. One key element of lowenergy
building design is the inventive
use of the basic form and enclosure of a
building to save energy while enhancing
occupant comfort. The section titled How
to Apply describes a wide range of lowenergy
building design strategies that
can be commonly applied to new Federal
buildings. Low-energy building design
combines energy-conservation strategies
and energy-efficient technologies. Some
of these are described in FEMP Federal
Technology Alerts (FTAs), including
high-efficiency lighting and lighting
controls, spectrally selective glazing,
and geothermal heat pumps.
Low-energy design represents both a
load-reduction strategy and the incorporation
of renewable energy sources.
Many low-energy building design strategies
result in an absolute reduction in
the use of power produced from fossil
fuels. Together these innovations can
save energy, reduce costs, and preserve
natural resources while reducing environmental
pollution. Low-energy building
design strategies (including various
daylighting techniques) can also provide
a renewed sense of connection with the
outdoors for occupants of Federal facilities.
Low-energy design can also inspire
planning concepts, such as interior private
offices that borrow light from open
office spaces at the building’s perimeter.
6
Basic energy-saving techniques should be used to reduce building energy use.
• Siting and organizing the building configuration and massing to reduce loads.
• Reducing cooling loads by eliminating undesirable solar heat gain.
• Reducing heating loads by using desirable solar heat gain.
• Using natural light as a substitute for (or complement to) electrical lighting.
• Using natural ventilation whenever possible.
• Using more efficient heating and cooling equipment to satisfy reduced loads.
• Using computerized building control systems.
F E D E R A L E N E R G Y M A N A G E M E N T P R O G R A M
More difficult to measure are the increases
in workplace performance and productivity
that are often achieved through
whole-building design and its resulting
economic value. Nonetheless, organizations
housed in low-energy buildings
have reported that their indoor environments
help retain employees, reduce
tension, promote health, encourage
communication, reduce absenteeism,
and, in general, improve the work environment.
Another potentially significant
benefit is the public perception that, by
its own example, the Federal government
is helping to lead the construction
industry toward a more responsible and
sustainable future. Similarly, by using
public funds for cost-effective measures
that reduce operating costs, Federal
agencies are performing these tasks in
a responsible and frugal manner.
Application
Low-energy building design techniques
are application specific. This section
provides a practical method of determining
the potential use of design techniques
in different types of Federal
buildings, in different climatic locations,
and under various local energy cost
scenarios. It also details the process
and level of advocacy required to assure
such strategies are considered and incorporated
into the design process, beginning
with the earliest project phases
(see Needs Assessment and Site Selection)
and continue through Construction
and Building Occupancy. Refer to
the time line on pages 22–23 for an
illustration of the various phases and
key action items to be addressed
throughout the process.
For a particular project, the specific energy-
saving techniques, strategies, and
mechanisms to be deployed will vary
greatly, depending on building and
space type. Their selection and configuration
will also be influenced by:
• Climate
• Internal heat gains from occupants and
their activities, lights, and electrical
equipment
• Building size and massing
• Illumination (lighting) requirements
• Hours of operation
• Costs for electricity and other energy
sources.
In reviewing this list, one can quickly
grasp that strategies specific to a particular
building or space may not work
nearly as well (or at all) in another application.
Therefore, some general guidance
about building and space types
(provided in Applications Screening)
will prove useful in understanding the
factors that lead to significant energy use
in buildings and in identifying the strategies
that can yield optimum savings.
It is essential that the team appreciate that
a successful design solution under one
set of circumstances may not be appropriate
or cost effective for a different
building type, size, or configuration; the
same building type constructed in a different
climate; or where variable energy
costs apply.
Applications Screening
The use characteristics discussed below
are representative of the majority of
Federal building projects. The first step
toward assuring low-energy building
design for a particular project is to
understand the energy implications of
the structure’s basic form, organization,
and internal operations. These criteria
will dictate the relative importance of
strategies to be deployed for heating,
heat rejection, lighting, and, in some
cases, hot water. The term heat rejection
is used (as opposed to cooling) based on
the idea that a fundamental goal of lowenergy
building design is to greatly minimize
the need for, and dependence on,
mechanical cooling.
It is important for those involved in Federal
design projects to know how and
why office buildings, courthouses, laboratories,
hospitals, visitor centers, border
stations, warehouses, and various residential
building types use energy. Each
of these will be summarized later, but
first, some background information
should prove useful in forming a basis
of understanding.
Perhaps the most basic division is that of
houses and larger, non-residential buildings.
Houses are the most common
example of skin-load-dominated buildings,
because their energy use is predicated
by heat gain and loss through the
building enclosure or skin (also known
as the envelope, e.g., walls, windows,
roof, floor). Houses and other skin-loaddominated
buildings primarily require
heat in cold climates, cooling in hot climates,
and very little energy of any type
(except hot water) in benign climates
like San Diego. For low-energy performance,
it is common for houses and other
skin-load-dominated buildings to be
well-insulated and to invite the low winter
sun in while keeping it out (through
shading and proper building orientation)
during the summer.
Simplistically, larger non-residential or
commercial buildings are often referred
to as internal-load-dominated buildings
because a large portion of their energy
use is in response to the heat gains from
building occupants, lights, and electrical
equipment (e.g., plug loads for computers,
copiers). As a result of these internal heat
sources, internal-load-dominated buildings
are often designed to turn their
backs on the sun, and further reduce
solar gain through the use of tinted and
reflective glass. There is some logic to
this, but such an approach is too universal
and precludes some of the most beneficial
low-energy design strategies.
Moreover, it often is too simplistic to
think of a building with offices as simply
an office building. The structure is also
likely to have a lobby and circulation
spaces, a cafeteria, a computer room,
meeting rooms, and other spaces that
have environmental needs and thermal
characteristics that are very different
from those of offices. Ideally, design
strategies should first satisfy the needs
of each individual space or zone. This
requires careful attention during the
programming phase of the project.
Evaluating a specific project for selecting
and integrating low-energy design
strategies starts with an understanding
of the following factors:
7
F E D E R A L E N E R G Y M A N A G E M E N T P R O G R A M
Climate
Not just is it hot or cold, but how humid
is it? Is it predominantly clear or cloudy,
and during what times of the year? Clear
winter climates are well matched with
spaces that incorporate passive solar
heating strategies. In contrast, spaces
(and buildings) in clear summer climates
generally require a high degree of sun
control. Clear climates also make the
best use of light shelves—horizontal
surfaces that bounce daylight deeper
into buildings. Even the site-specific
and seasonal nature of the wind needs
to be understood if natural ventilation
strategies are to be incorporated into a
building design.
Internal Heat Gains
The heat gains from building occupants,
lights, and electrical equipment can be
thought of as the interior climate and
should not be generalized. Instead, during
the early programming of the project,
the heat gains anticipated from these
sources should be quantified for the various
spaces where they apply. In some
cases, such as in storage buildings and
other areas with relatively few occupants
and limited electrical equipment,
these heat gains will be minor. In other
instances, the presence of intensive and
enduring internal heat gains may be a
determining factor in HVAC system
design. Examples of intensive and
enduring influences include activitybased
gains, such as those produced by
cafeterias and laundry facilities (where
increased humidity is also a factor), and
technological or industrial gains, such
as the heat produced by mainframe
computers or heavy machinery. These
factors should be identified early on,
and appropriate design strategies investigated
(such as heat recovery or using
a closed-loop heat pump system).
Building Size and Massing
In a low-energy building, both the
indoor and outdoor climates exert a
powerful influence on all aspects of
building design. Sometimes, they complement
one another, such as the case
of a building with a lot of internal heat
gains sited in a very cold climate. At
other times, however, the two climates
are antagonistic, such as when there are
a lot of internal heat gains in a very hot
climate. Understanding the implications
of these factors is fundamental to determining
appropriate low-energy design
strategies for a particular building project.
Under hot/hot conditions, buildings
with large footprints and a large amount
of floor space far from the exterior of the
building will require heat removal in the
interior zones (generally by mechanical
cooling) all or much of year.
The other basic planning approach is to
position all spaces that can benefit from
connection to the outdoors in proximity
to exterior walls. To achieve this, buildings
become much narrower, with a
maximum width of about 70 feet. Such
an approach to building massing must,
by necessity, be introduced very early
in the design process. Also, recognize
that not all spaces need or want to be
exposed to the exterior, including many
areas of complex building types like
hospitals and courthouses. These spaces
often function better as interior placements
within a wider and more compact
building form.
Lighting Requirements
The lighting needs of a building’s various
spaces need to be identified, both quantitatively
and qualitatively, as part of the
environmental programming conducted
early in the project. Many spaces, including
lobbies and circulation areas, require
general ambient lighting at relatively
low foot-candle levels (10 foot-candles
or less). Such spaces are ideal candidates
for daylighting. In contrast, some spaces
are used for demanding tasks that require
high light levels (50 foot-candles or more)
and a glare-free environment. Here the
design team’s attention may shift from
daylighting to a very efficient electrical
lighting system with integrated occupancy
sensors and other controls.
Hours of Operation
Typically, on a per-square-foot basis, the
most energy-intensive Federal building
types are those in continuous use, such
as hospitals and border stations. In these
buildings, the balance of heating and
heat removal (cooling) may be altered
dramatically from that of an office building
with typical work hours. For example,
the around-the-clock generation of
heat by lights, people, and equipment
will greatly reduce the amount of heating
energy used and may even warrant
a change in the heating system. Intensive
building use also increases the need for
well-controlled, high-efficiency lighting
systems. Hours of use can also enhance
the cost effectiveness of low-energy
design strategies, such as daylighting
in a border station or weather station.
In contrast, buildings scheduled for
operations during abbreviated hours
(including seasonal occupancy facilities,
like some visitor centers), should be
designed with limited use clearly in
mind.
Energy Costs
The cost for energy, particularly electrical
energy, for most non-residential buildings
is a critical factor in determining
which design strategies will not only
conserve energy, but will also be cost
effective. In most locations in the United
States, electricity is three to four times
more expensive than natural gas per
Btu. This disparity can, at times, be capitalized
upon by introducing design
strategies that effect a trade-off in energy
use. For example, increasing the glass
area and the commensurate daylight
entry can save expensive electrical use
but, at the same time, occasion the purchase
of additional (but relatively lowcost)
heating energy. However, such an
example should not be misconstrued as
indicating that daylighting requires an
excessive amount of glass, as that is just
not the case. Daylighting primarily
requires placing the glass carefully
and selecting the appropriate glazing.
In many locations, utility deregulation
imposes an uncertainty on future electrical
and other energy prices. To the greatest
extent possible, the life-cycle benefits
of various design strategies should be
investigated for the range of energy-cost
scenarios deemed plausible. For some
strategies—particularly those that affect
the amount of heating energy used—
8
F E D E R A L E N E R G Y M A N A G E M E N T P R O G R A M
deregulation may be of lesser importance.
In other cases, however, rate structures,
particularly those based on peak electrical
demand, may significantly affect the
economic impact of strategies such as
daylighting.
As part of a whole-building design strategy,
purchasing bulk green power
resources complements many buildingspecific
design measures. Through a
holistic approach to building design and
operation, incorporating green power
resources can further decrease the environmental
impacts already minimized
through the specification of energy efficiency
and renewable energy measures
in the design process. Minimizing electrical
load requirements, and then meeting
these requirements with clean electricity
resources, is at the core of a
whole-building design strategy.
Green power refers to utility-scale electricity
resources that are in some way
environmentally preferable to conventional
system power. The terms green
and clean are often used interchangeably
to describe this type of electricity. Green
power supplied from the utility grid
may be comprised of electricity from
one or more types of renewable sources.
The term renewable power refers to electricity
generated from one or more of
the following types of resources:
•Wind—generated from wind-powered
turbines, often grouped together into
wind farms
• Solar—typically generated from photovoltaic
(solar cell) arrays, often placed
on rooftops
• Geothermal—generated from steam
captured from below the earth’s surface
when water contacts hot, underground
rock
• Biomass—burning of agricultural,
forestry, and other byproducts (including
landfill gas, digester gas, and municipal
solid waste)
• Small hydroelectric—generated from
dams with a peak capacity of less than
30 megawatts (MW).
Building Types: Characteristics and
Profiles
The following brief descriptions give
broad categories of building types and
some likely successful strategies for
consideration.
Residential Buildings
In cold climates, the classic, skin-loaddominated
building type really benefits
from using high-performance, low emissivity
(low-e) windows and high levels
of insulation. In many cold climates,
residential buildings can also significantly
benefit from passive solar heating,
so long as a reasonable amount of
heat-absorbing thermal mass is incorporated
into the design. In hot climates,
solar control is paramount, based on the
need to keep cooling loads and costs
under control. It is also important to
take advantage of the opportunity for
passive or active solar water preheating.
For remote structures that do not have
easy access to the utility grid, photovoltaic
systems should be considered as
the primary, or sole, source of electricity.
Small Non-Residential Buildings
This profile describes buildings in which
lighting and internal gains play a relatively
small role in the building’s energy
balance. Such buildings are the heart
and soul of low-energy building design,
as a multitude of low-energy building
design strategies can be successfully
applied to their construction. One common
Federal building type that falls
into this category is the visitor center.
Visitor centers are among the most
advanced energy-conserving structures.
They generally have a robust budget,
allowing the purchase of durable materials.
They are normally located in severe
9
Natural Gas:
Typical Cost for One Million Btu
1,000,000 Btu
100,000 Btu/Therm* x 0.75 (Heating System Eff.)
Electricity:
Typical Cost for One Million Btu
1,000,000 Btu
3413 Btu/kWh x 1.00 (Site Eff.)
kWh = kilowatt-hour
X $0.60/Therm = $8 per million Btu
X $0.08/kWh = $23 per million Btu
An example of an energy-efficient home in a cold climate using direct-gain passive solar
heating.
Steven Sargent/PIX08889
F E D E R A L E N E R G Y M A N A G E M E N T P R O G R A M
(either hot or cold) climates inaccessible
to utilities; they have a natural connection
with the outdoors; and the structures
present an opportunity to interpret
the resource-conservation mission of
the agency to the visiting public. These
structures typically combine a need for
window area, massive construction, and
a tolerance for temperature swings—all
of which are highly compatible with
low-energy building design. Daylighting
is another key strategy for deployment
in these building types.
Urban Office Buildings
This building type evinces characteristics
commonly found in major urban centers,
where Federal office buildings are often
located. Land is often expensive and
must be used at a high density. The
building is typically dominated by one
repetitive use—office space—although
it may also contain a number of other
uses, such as support facilities. These
buildings are often landmarks or showpieces.
In highly controlled areas like
Washington, D.C., this translates into
height limits and tight controls over
façade treatment. In most cities, however,
there are few controls on the style
or height of downtown office buildings.
As a result, many of these buildings
include or consist of towers that shade
and are shaded by neighboring buildings,
a factor that may significantly
affect the design and sizing of the
mechanical cooling system.
Curtain walls are, by far, the most common
enclosures for downtown office
buildings, but most curtain walls are
classic examples of a “building as a
fortress against the environment”
philosophy. The low-energy building
design strategy for flat curtain walls is
typically defensive in nature, limiting
the boring and often unattractive result
from the overuse of glass and by a lack
of orientation-specific façades. Fortunately,
there has been somewhat of a
stylistic revolt against all-glass buildings,
which has led to more articulated
façades, variation in building façade
treatments, and a resurgence in the use
of masonry. All of these factors greatly
enhance low-energy building design
possibilities by creating opportunities
to tune façades to suit their orientation
and the activities taking place behind
them. In most cases, thoughtful strategies
will be needed to reduce solar gain.
Exterior sunscreens or new glazing
types (fritted, shaded) can both enliven
the façade and provide substantial cooling
load reduction.
An excellent way to take advantage of
low-energy building design is to move
as many private offices away from the
façade as possible. In this way, more
light can be directed further into the
building, and more of the building’s
users can enjoy access to views and
natural lighting. This scenario often
yields increases in productivity and
enables the adoption of more energyefficient
HVAC strategies.
If an atrium serves the program’s needs,
it should be located and designed to
substitute natural lighting for artificial
lighting, to minimize cooling loads, and
to take advantage of solar heating, if it
is needed. The location and shape of the
atrium will be highly building-specific.
In general, taking full advantage of the
unique opportunities of each urban site
requires considerable expertise, particularly
because of shading from surrounding
buildings and the complex interactions
among lighting, HVAC, façade
design, orientation, and climate.
10
The Zion Visitor Center is designed to use 70% less energy than a typical building without
costing more to build.
Robb Williamson/PIX09249
Boston Edison joined Northwestern University
to use solar electricity to power the Ell
Student Center on the University’s Boston
campus. The rooftop PV system incorporates
90 285-Wp modules installed on innovative
ballasted mounting trays that require
no roof penetration.
Ascension Technology, Inc./PIX04478
F E D E R A L E N E R G Y M A N A G E M E N T P R O G R A M
11
Courthouses
This building type typically entails highly
complex and interrelated space programming.
Many diverse functions must
be accommodated, sites are often constricted,
and the professional occupants
are demanding. In addition, courthouses
often serve a ceremonial function. In
many cities, they are the most prestigious
and conspicuous of Federal buildings.
Their typically urban location often
requires a sensitivity to surrounding
buildings with historical styles and value
and most certainly will require careful
integration into the existing urban plan.
Oftentimes, the functional needs of
courthouses (i.e., security requirements)
must be fully satisfied before energybased
programming concerns can be
addressed, and solar design strategies
may not always apply to this building
type. Still, low-energy design opportunities
abound, especially in terms of efficient
lighting, HVAC systems, equipment,
and controls. It is also worthwhile
to note that many of the design issues
described for urban office buildings
will also apply to courthouses.
Hospitals
These facilities tend to have a lot of small
spaces, many of which need to be windowless.
Offices and patient rooms can
be thought of as small, mixed-use areas
that incorporate both residential and
commercial features. Cafeterias and public
lobbies present special opportunities
for daylighting. Overall, this building
type has many spaces that require large
quantities of outside ventilation air. Therefore,
ventilation-air heat-recovery systems
that are not prone to cross-contamination
are particularly useful in these applications—
especially in very cold climates.
The around-the-clock nature of hospitals
is a perfect opportunity to incorporate
very efficient and well-controlled lighting
and power systems.
Laboratories
Laboratories are an energy-intensive
building type that often consumes more
than 200,000 Btu per square foot, due to
large ventilation requirements and in
part to the long operating hours (two or
three shifts) that are typical. The laboratory
working environment normally
requires enormous amounts of ventilation
air to ensure good indoor-air quality,
often making heat recovery systems
cost effective.
If there is a considerable demand for hot
water, preheating the water using solar
energy is recommended, particularly for
facilities located in clear climates. This
building type can often benefit from daylighting,
but because the walls tend to be
occupied with equipment, it is appropriate
to consider either high windows or
toplighting by roof monitors on the
upper floor. Either way, avoiding glare
is crucial. Circulation corridors along
southern façades can function as solarheated
sunspaces. Sunlight on south
façades can be “bounced” through high
glazing by way of light shelves. Depending
on the regional climates, thermal
mass walls for heat storage between labs
and corridors may also make sense. The
corridors can double as pleasant meeting
and lounge spaces, while serving as a
buffer to the south sun, thus permitting
wider temperature swings than would
be permissible in the main labs. On
north-facing walls, small, well-spaced
view windows can double as a source
of diffuse daylight.
Incorporating atriums into laboratory
buildings also makes sense, both as a
means of bringing natural light into
the labs and providing casual meeting
spaces adjacent to the labs. West façades
may serve as good locations for windowless
lecture halls. Cafeterias can use
direct gain, or in some temperate climates,
might even have a fabric roof.
Warehousing/Shipping/Repairing
These activities are typically carried out
in one-story buildings with high ceilings.
Offices, supervisory booths, employee
services, restrooms, and loading docks
often complement a main unpartitioned
space. For roof and wall assemblies,
steps must be taken to counteract heat
A courthouse in St. Paul, Minnesota.
The National Renewable Energy Laboratory’s Solar Energy Research Facility.
Pamm McFadden/PIX02927
Warren Gretz/PIX01137
F E D E R A L E N E R G Y M A N A G E M E N T P R O G R A M
loss due to continuous metal contacts
throughout the construction. Though
not limited to metal components, this
process is known as thermal bridging,
which can significantly compromise
the resistance value of insulation. In
climates with hot summers, a white
or reflective roof is advisable.
If lighting can be controlled electronically
through light sensors and other devices,
natural lighting strategies can be very
useful. If the budget does not allow for
proper roof monitors with vertical glass
facing south or north, consider using
high windows along the south and north
walls with south-facing glass shaded by
properly designed overhangs. Exercise
care in using scattered skylights, as they
can create glare and let in excessive
amounts of solar heat.
If the building is subject to around-theclock
use, large high-intensity discharge
(HID) lamps are appropriate when
arranged in such a way as to light
between inventory stacks when daylight
is unavailable. Interior surfaces should
be light-colored to reflect light. If the
building is used intermittently, more
and smaller HID or fluorescent lamps
that easily switch on and off should be
used. HVAC should be localized to
work areas, with the overall building
maintained at the maximum temperature
range needed for its contents and
the proper operation of machinery.
Campus Layout
This profile describes a wide variety of
building types where space adjacency
requirements are not crucial, and there
is ample site area availability. Possible
building types include rural or suburban
office buildings, training and classroom
facilities, some laboratories, barracks,
and other multi-family housing.
If the buildings can be spread out, more
of the interior space will be close to an
outside wall. Acampus plan makes the
most sense in designing buildings for
housing and classroom use, where
deep interior spaces are inappropriate.
Compared to a compact building form,
the campus plan generally costs more
at the outset, based on the need for a
larger site, the cost of added building
enclosures, and added lengths for service
connections. When life-cycle economics
are taken into account, these additional
costs can be justified if the additional
exposure is used to optimum advantage
and daylighting and natural ventilation
are brought into play.
For spaces that can benefit from passive
solar heating, it is essential that southfacing
solar glazing be clear of any
shade during the heating season, even
deciduous trees. The bare branches of
trees can change a sunspace from one
that provides useful heat into one that
does not. In very cold climates, it is
worth considering a partially earthsheltered
building, especially in the
context of a sloping site.
Renovations
Renovating and reusing a building makes
it low energy and sustainable in another
very important way. Much less energy is
needed to produce construction materials
and deliver them to the site when the
building’s basic shell is being reused.
Older buildings, in particular, often
make excellent candidates for low-energy
design that utilizes their mass, higher
ceilings, and narrower building form.
Many aspects of low-energy building
design are applicable to many largescale
renovation projects. The only
strategies that are clearly precluded are
those based on siting, building form, or
orientation. While these established features
can limit a building’s low-energy
performance potential, renovations can
still reduce energy costs by 20% to 30%.
Integrating Low-Energy Concepts
into the Design Process
Feasibility Phase
The feasibility phase is normally when
Federal building managers or other decision
makers in the Federal sector determine
that a project will be built to address
a particular need. At this stage, the
enabling premises of low-energy design
and construction need to be defined and
established. Think of this as the time
when the seeds of the overall sustainable
design and construction strategies are
sown, and the framework is established
for decisions to be made and actions to
be taken throughout the design and
construction process. Defining parameters;
establishing general goals; and
identifying policies, directives, and
enabling legislation will guide and
propel the process.
During the feasibility phase, architects
and engineers develop a capital project
scope and planning document that provides
a design program, an implementation
strategy, and a budget assessment.
Identifying these elements early is essential
to establish project feasibility, support
project selection, and coordinate
project execution. Community plans for
major cities and surrounding areas identify
long-term space needs for Federal
12
An example of a multi-use building.
Roch A. Ducey/PIX05184
F E D E R A L E N E R G Y M A N A G E M E N T P R O G R A M
agencies and propose appropriate actions
to address those needs. Major projects
involving renovation or construction of
Federal buildings must be developed in
accordance with applicable community
plans. Agencies often conduct studies to
support project planning or assess building
conditions, some of which may take
into account coordination with state and
local authorities, community groups,
and others who may have a stake in the
development process.
Because Federal policy calls for cooperation
with state and local authorities
when planning Federal facilities, local
government officials must be contacted
to ensure that all documents impacting
the project are discussed. These documents
may include master plans, current
and future land-use plans, zoning maps,
traffic studies, and other documents that
address the availability of essential support
services (e.g., fire, police, utilities,
telecommunications). Helpful information
can also be obtained from your
agency’s local office, including documentation
of current building conditions,
maintenance concerns, site access,
communication with other agencies, and
other potential impacts on project scope
and implementation.
Action Items
• Conduct all required feasibility analyses
(including, but not limited, to those
described above).
• Review all existing directives and policies
to be sure of what your agency currently
requires in the way of energy
performance, materials usage (i.e., quality,
durability, recycled content, energy saving
features, impact on indoor environmental
quality [IEQ]), daylighting, use
of renewable energy sources, contracting
issues, and other relevant concerns.
• Select an energy champion and give
them the authority to make decisions
relating to low-energy design and construction
practices.
• Establish explicit energy-use targets
that surpass those described in 10 CFR
435; specifically, reference Executive
Order 13123. Factor in any additional
criteria that may be specific to your
agency or organization, facility location,
or end use.
• Identify and list your agency’s goals
for other sustainable issues, such as site
planning, materials use, water use, or
IEQ.
Budgeting Phase
Some projects may be constructed using
standard designs (those completed for
similar projects or off-the-shelf, prefabricated
structures). Be certain that your
specific low-energy goals have been
accounted for.
Action Items
• Program any special requirements into
your budget submission.
• Submit a budget that allows for an
energy champion (as well as the meetings
and other resources required to
accommodate a team process), the additional
studies, analyses, and verifications
that will be needed, and slightly
higher design fees (generally 2%–4%).
• Include the requirement for an energy
expert in your Request for Proposal/
Architectural & Engineering (RFP/A&E)
solicitation.
• Conduct a design charrette prior to
concept development to ensure that
low-energy building components and
strategies will be adopted early in the
planning and design stages, when these
elements can be incorporated at the lowest
possible cost.
• Identify the certification and testing
measures required to ensure compliance
with energy targets and sustainability
goals.
Project Pre-Planning Phase
At inception, and during the early phases
of a low-energy project’s time line, a needs
assessment is conducted (often with the
assistance of a consultant). This process
considers the long-term requirements of
the building occupants and yields a program
for the project that includes:
• User group needs and square footage
requirements
• Location and site options
• Estimated costs and schedule.
For many Federal agencies, it is essential
that the budget established at this time
be based on all factors that will influence
costs, including the incorporation of
low-energy design strategies.
Action Items
• Select appropriate candidate low-energy
design strategies.
• Associate these strategies with the particular
project phase during which they
must be considered and evaluated.
• Identify the team members who will
be responsible for evaluating and incorporating
the strategies at each phase.
• Identify the appropriate evaluation
tools to use at each phase and who will
use them.
• Identify the actions to be taken by various
team members at each phase and
carry them out.
• Establish low-energy design as a core
project goal.
• Use case studies and passive solar performance
maps to help determine
appropriate strategies for the specific
project type at hand.
• Establish energy-use targets that surpass
applicable codes and standards. In
general, energy-use reductions in nonresidential
buildings should be targeted
at 30% or better in comparison to a standard,
code-compliant building.
• Ensure that the planned building configuration
takes maximum advantage
of the site and climate.
• In selecting consultants, consider their
level of experience and expertise in lowenergy
design.
Strategies to Consider During This
Phase
User Energy Needs Assessment
Description: This is a direct assessment
of the energy-related needs of facility
users. Whether it is in the form of an
Environmental Programming Matrix
13
F E D E R A L E N E R G Y M A N A G E M E N T P R O G R A M
or other, less formal, documentation, it is
a fairly rigorous and thorough evaluation
that considers occupancy, operating
hours, and all aspects of the interior
and exterior climates.
Goal: The needs assessment yields more
precise energy use requirements, which,
in turn, helps determine the applicability
of low-energy building strategies.
Best Applied: The needs assessment is
appropriate for use on all projects.
How to Do It: Classify users on the basis
of specific needs that directly relate to
specific low-energy building strategies.
In addition to temperature, humidity,
and general lighting standards, focus
on other user needs such as the desire
for exterior views and natural daylight;
tolerance to moving air and temperature
swings; and the type of automatic lighting
control that is most appropriate for
a given user.
Related Strategies: The needs assessment
is considered a prerequisite to almost all
other strategies.
Comments: This document may be seen
as an expansion of the typical needs
assessment procedure, and as such, may
entail revision(s) to standard agency
assessment protocols. Coming up with
useful questions to ask in the needs
assessment requires an understanding
of the effects of various low-energy
design strategies on user comfort.
Building-Appropriate Site Selection
Description: This process involves choosing
a site that fully supports the energy
reduction strategies contemplated for
the project.
Goal: Proper siting increases the likelihood
that many other low-energy building
strategies can be implemented.
Best Applied: This strategy is appropriate
for all new building projects.
How to Do It: During site selection, locate
buildings that do not require extensive
exterior exposure on shaded or confined
urban sites. Buildings that will benefit
from a greater degree of exterior exposure
should be located on open sites.
Related Strategies: See Extended Plan.
Comments: For many projects, the site
may have been selected before the manager’s
involvement.
Complementary Building Uses
Description: This process involves defining
the nature of the facility and then
matching the end use with complementary
energy needs and minimizing the
resulting wastes.
Goal: The design team takes advantage
of the natural symbioses and commonalties
that exist between building uses that
might otherwise be overlooked.
Best Applied: When compatible projects
are at similar points in their development;
ideally, from the planning stages forward.
How to Do It: At the earliest stages of
project conception and site selection,
consider co-locating any types of facilities
where the waste products of one
can be used to provide needed energy
for another, or where constructionbased
support services can be shared.
Related Strategies: Building-Appropriate
Site Selection; User Energy Needs
Assessment
Comments: Currently used in designing
co-generation facilities, ecological industrial
parks, district heating, and community-
scale energy storage facilities; other
applications may be identified on a caseby-
case basis. Opportunities may also
exist for co-locating non-polluting
industrial and residential facilities. In
all circumstances, action is required at
the earliest stages of the project, before
detailed plans for the various uses are
fully developed.
Project Planning Phase
In close consultation with agency project
personnel, the design consultants (e.g.,
architects and engineers) prepare initial
and schematic design options. At this
time, options for placing the proposed
building(s) on the site and massing alternatives
are evaluated. Fundamental
low-energy design strategies (as detailed
below) are also assessed for applicability
to a specific project. Design consultants
generally present their design options and
analyses to agency project personnel for
review and evaluation; this process is
often repeated several times until the
basic design is decided upon and
approved. At the conclusion of this
phase, the design should clearly indicate
which low-energy design strategies
have been incorporated in sufficient
detail so that heating and cooling loads
can be estimated and so HVAC system
options can be examined.
Action Items
• Establish an interdisciplinary design
team, including an energy professional,
as early in the process as possible.
• Develop a preliminary layout that
maximizes or minimizes solar gain.
Consider atrium spaces, direct or indirect
passive solar heating, earthprotected
spaces, and natural and
constructed shading.
• Develop landscape plans that contribute
to the facility’s energy performance.
Consider shading options, wind
breaks, and using existing site features.
• Develop a basic layout that maximizes
the use of daylighting. Consider building
orientation, the size and placement of
windows, and toplighting.
• Investigate using renewable power
sources as part of the facility’s overall
power supply. Consider using solar
(domestic) hot water on building types
with high hot water usage (such as laboratories)
and building-integrated photovoltaics
(BIPV) to reduce reliance on
non-renewable power.
• Conduct a preliminary energy analysis
(analysis tools depend on scale of project).
Use ENERGY-10 and other userfriendly
tools for smaller, simpler projects
(those with two or fewer zones, and
roughly 50,000 square feet or less). Use
DOE 2.2 and other applicable tools for
larger and more complex projects.
Strategies to Consider During This
Phase
The following strategies need to be
assessed during the project planning
phase of the time line. Their incorpora-
14
F E D E R A L E N E R G Y M A N A G E M E N T P R O G R A M
15
tion will influence the overall siting and
massing of the building, as well as the
basic organization of spaces.
Perimeter Circulation Space
Description: This passive solar strategy
uses circulation (corridors) and casual
meeting spaces as buffers between the
façade and the interior conditioned
spaces.
Goal: To support several low-energy
building strategies that are not compatible
with certain uses (e.g., direct-gain
sunspaces and office space).
Best Applied: The strategy is appropriate
in buildings needing large areas for circulation,
waiting, and casual meetings,
such as a visitors’ corridor in a hospital
or casual meeting sunspaces outside
laboratories or offices.
How to Do It: Because perimeter circulation
plans generally require slightly
more total floor area, it is necessary to
examine user needs and evaluate the
strategy in light of the overall budget.
If the strategy is acceptable, look for
buffer spaces that can be located along
the building’s exterior, particularly
along the south façade.
Related Strategies: Atrium Spaces; Open
Office Space at Perimeter; Direct-Gain
Passive Solar Heating; Daylighting
through Windows; Light Shelves;
Selective Glazing; Shading Devices;
Window Geometry; Natural Ventilation
through Windows.
Comments: An accurate energy needs
assessment is key to the effective integration
of this strategy.
Extended Plan
Description: By extending the plan to produce
a longer, narrower footprint, you
can create more exterior wall surface. In
most climates, elongating the building
in an east-west direction makes the most
sense from the standpoint of daylighting
and passive solar heating.
Goal: To increase the amount of usable
space that is close to an outside wall.
Best Applied: Building types that benefit
most from exterior exposure include
good candidates for daylighting and
direct-gain passive solar heating.
How to Do It: This is best accomplished
early in the design process, as modifying
the basic building form may occasion a
slight increase in the construction budget.
Related Strategies: Atrium Spaces; Open
Office Space at Perimeter; Perimeter
Circulation Space; Daylighting through
Windows; all forms of Passive Solar
Heating; Building-Appropriate Site
Selection; Landscape Shading; Light
Shelves; Shading Devices; Natural
Ventilation through Windows.
Direct-Gain Passive Solar Heating
Description: Installing south-facing glazing
in an occupied space enables the collection
of solar energy, which is partially
stored in the walls, floors, and/or ceiling
of the space, and later released.
Goals: With direct-gain passive solar
heating, the savings achieved in heating
energy is augmented by the aesthetic
and productivity-enhancing benefits
of daylighting, a valuable amenity for
occupants. The functioning of the space
should not be compromised by direct
glare from glazed openings or by local
overheating.
Best Applied: This strategy works well in
cold, clear climates.
How to Do It: Glazing must face within
15 degrees of true (solar) south, and the
affected areas must be compatible with
daily temperature swings.
Examples: Some appropriate contexts for
direct-gain heating include corridor
spaces, eating spaces, meeting spaces
that can be scheduled for use during
times when the temperature is most
comfortable, sleeping spaces, and recreational
sunspaces. Working with the
energy consultant, the designer can fine
tune the amount and type of glazing
with glare and temperature controls,
materials in the affected space, auxiliary
heating, and cooling to address local
climatic changes.
Related Strategies: Atrium Spaces; Differentiated
Façades; Extended Plan; Perimeter
Circulation Space; Daylighting
through Windows; Building-Appropriate
Site Selection; Landscape Shading;
Selective Glazing; Shading Devices;
Window Geometry.
Comments: Because true north and magnetic
north are different, the design team
will need to account for magnetic decli-
An example of direct-gain passive solar used in a residential building.
Warren Gretz/PIX03348
F E D E R A L E N E R G Y M A N A G E M E N T P R O G R A M
nation. For optimum effect, floor and
wall finish materials with high heatstorage
capacity must be exposed to
direct illumination by the low winter
sun. Overall, this strategy is considered
central to low-energy building design.
Atrium Spaces
Description: Atrium spaces are multifloor
open areas appropriate for circulation,
lobbies, dining, or other shared
space. Atriums are typically covered
by a glazed roof or one that incorporates
roof monitors.
Goal: Configure the atrium for minimum
impact on the building’s energy load.
Best Applied: Buildings with programmed
spaces that can be well-served by one or
more atrium spaces.
How to Do It: Avoid configurations that
produce heat losses or gains with no
compensatory benefits. The atrium
should bring daylight to the interior of
the building while providing a “chimney”
for natural ventilation during mild
weather. In some cases, atriums can collect
useful solar heat in cold climates—
serving as a kind of transition zone, with
larger temperature swings than would
otherwise be appropriate in the rest of
the building. The atrium’s configuration
should be defined at the earliest possible
stages of the design process, before an
undesirable or arbitrary configuration
is locked in.
Related Strategies: Building-Appropriate
Site Selection; Extended Plan; Perimeter
Circulation Space; Roof Monitors; Glazed
Roofs; Fabric Roofs; Direct-Gain Passive
Solar Heating; Selective Glazing; Shading
Devices; Induced (Stack-Effect)
Ventilation.
Comments: There is no hard and fast distinction
between atriums and glazed
roofs over large open spaces (such as
gallerias).
Induced (Stack-Effect) Ventilation
Description: Heated air rises within a
mid- or high-rise building to the top
(often below a glazed roof in an atrium),
where it exits through roof openings.
This process induces ventilation of the
adjoining spaces below.
Goals: This strategy removes heat and
reduces mechanical cooling and fan
energy use requirements.
Best Applied: Spaces that are not adversely
affected by increased air motion are
appropriate targets for natural wholebuilding
ventilation, which effectively
conditions the space during fair weather
without using air conditioning.
How to Do It: Incorporate air inlets, generally
in the form of operable windows,
at the building perimeter. For best results,
use open-office space planning and
avoid partitions that inhibit air movement.
Consider complementing natural
ventilation with controllable passive
ventilators located in the upper portions
of the building. Carefully coordinate the
implementation of this strategy with
building HVAC system and controls.
Related Strategies: Atrium Spaces; Glazed
Roofs; Roof Monitors; Natural Ventilation
through Windows; Night-time
Cooling Ventilation.
Comments: Natural ventilation works
best in low-humidity climates. An atrium
often serves as an ideal chimney to
exhaust hot air.
Open Office Space at Perimeter
Description: Locating private offices at
interior positions leaves the perimeter
open to general office space.
Goal: Program open spaces at the perimeter
to allow for more extensive use of
daylighting deeper into interior sections.
Best Applied: Use this strategy in buildings
with large areas of office space.
How to Do It: Private, interior-located
offices need compensating amenities. At
minimum, install glazing that lets onto
the open office space or overlooks an
atrium space. This strategy is especially
appropriate for buildings with limited
façade glazing, such as earth-protected
buildings.
Related Strategies: Atrium Spaces; Earth-
Protected Space; Perimeter Circulation
Space; Daylighting through Windows;
Light Shelves; Selective Glazing; Shading
Devices; Window Geometry; Natural
Ventilation through Windows.
Comments: This is an effective strategy
that requires a strong commitment by
the agency or organization to keep
perimeter spaces open and not reserve
them for high-ranking executives. (This
is perhaps not as significant an issue in
Federal buildings as compared to the
private sector.)
Landscape Shading
Description: The use of existing or
planned trees and major landscaping
elements to provide beneficial shading.
Goal: Locate trees and major landscape
elements to provide useful shading and
reduce cooling loads.
Best Applied: Landscape shading works
best when shading west and south
façades.
How to Do It: Study planting plans of
existing site landscaping to determine
whether existing trees can be retained
and incorporated into the planning
process. Perform shading analyses of
plants in both immature and mature
forms to estimate energy savings during
plants’ anticipated life span. Whenever
possible, avoid or remove plantings that
would compromise useful solar gain.
16
An example of an atrium space.
Warren Gretz/PIX02194
F E D E R A L E N E R G Y M A N A G E M E N T P R O G R A M
Related Strategies: Atrium Spaces; Daylighting
through Windows; all forms of
Passive Solar Heating; Building-Appropriate
Site Selection; Selective Glazing;
Shading Devices; Natural Ventilation
through Windows.
Comments: Trees and landscaping can
reduce peak cooling loads through shading
and can cool the ventilation air
entering a building. Even during the
winter, most deciduous trees and plants
cast substantial shade on solar collectors
(e.g., south-facing windows).
Earth-Protected Space
Description: Bermed, or partially buried,
construction can moderate building
temperature, save energy, and preserve
open space and views above the building.
Goals: To minimize heating and cooling
energy use by protecting more of the
building from fluctuating outdoor air
temperatures.
Best Applied: Sites with a large natural
slope in cold climates are ideal candidates
for incorporating earth-protected
spaces.
How to Do It: Berm against walls or earthcover
roofs (in severely hot or cold climates)
or combine high horizontal windows
with light shelves located above
earth-sheltered walls. In some cases,
using "invisible" earth-protected buildings
can help counter community resistance
to bulky new construction.
Related Strategies: Open Office Space at
Perimeter; Roof Monitors; Building-
Appropriate Site Selection; Landscape
Shading; Insulation.
Comments: Similar low-energy performance
can also be achieved by using additional
insulation.
Solar Water Heating
Description: Solar water heating uses
flat-plate solar collectors to preheat
domestic hot water.
Goal: To be considered effective, this
strategy should yield a significant portion
(50% or more) of the domestic hot
water needed for day-to-day operations.
Best Applied: Look to building types
where hot water use is high year-round,
such as hospitals and laboratories. Best
performance will be achieved in hot climates
with high solar radiation levels.
How to Do It: Design an array of flat-plate
solar collectors that include an absorber
plate (usually metal), which heats when
exposed to solar radiation. Most common
among these are indirect systems that
circulate a freeze-protected fluid through
a closed loop and then transfer heat to
potable water through a heat exchanger.
Typically roof-mounted, solar collectors
should face south and tilt at an angle
above horizontal, approximately equal
to the latitude of the project location. This
configuration will provide optimum
year-round performance. Provide a pipe
chase to a mechanical room. The room
needs to be large enough for storage
tanks.
Related Strategies: Roof Monitors; Non-
Absorbing Roofing.
Comments: Collectors should be mounted
in a location that is unshaded by surrounding
buildings or trees during the
hours of 8 a.m. to 4 p.m. (at minimum)
throughout the year. As is the case with
many of the strategies described herein,
an effective conservation program will
help to minimize hot water demand
and, in turn, reduce material and systemic
requirements.
Building-Integrated Photovoltaic
Systems
Description: Photovoltaic (PV) arrays are
now available that take the place of ordinary
building elements (such as shingles
and other roofing components), converting
sunlight into electrical energy without
moving parts, noise, or harmful
emissions.
Goal: Reduce the first cost of the PV
array by using it in place of high-cost
building elements and take into account
the energy cost reductions over time.
Best Applied: Consider deployment in
sunny climates with high electrical utility
charges.
17
Landscaping and trees help minimize heat
gain to the building and surrounding
concrete.
An example of an earth-sheltered building in Tempe, Arizona.
Warren Gretz/PIX03779
Pamm McFadden/PIX02909
F E D E R A L E N E R G Y M A N A G E M E N T P R O G R A M
How to Do It: Commercially available
systems include thick, crystal, circular
cells assembled in panels and thin-film
products deposited on glass or metal
substrates. At today’s prices, BIPV often
provides a good payback if it replaces
high-cost glazing, such as fritted glass
(the arrays can even resemble fritted
glass). To be cost effective, BIPV must
intercept nearly a full day’s sun, so it is
often most effective as a replacement for
roof or atrium glazing. BIPV also works
well as spandrels that are fully exposed
to the sun.
Related Strategies: Atrium Spaces;
Differentiated Façades; Glazed Roofs;
Roof Monitors; Building-Appropriate
Site Selection; Shading Devices.
Comments: One of the benefits of gridtied
BIPV systems is that power production
is typically greatest (on bright, sunny
days) at or near the time of the building’s
peak electrical and cooling loads.
Schematic Design (or Preliminary
Design) Phase
During the previous phase of the time
line, Project Planning, basic decisions
were made regarding site placement,
plan organization, and building massing.
Those determinations will now
influence the basic low-energy design
strategies (e.g., daylighting) that will
be evaluated in detail during this phase,
especially those relating to the building
enclosure (or envelope).
Traditional building design has assigned
a protective role to the walls, roofs, and
floors of buildings—protection against
cold, sun, rain, and unwanted intrusion.
In low-energy building design, the protective
role still exists, but the building
envelope is also thought of as a membrane
that manages or “mediates” interactions
between the interior spaces and
the outside environment. During schematic
design, the Envelope-Related
Strategies discussed below will be
evaluated and integrated into the
overall building design.
Action Items
• As the preliminary layout is refined,
ensure that access to daylight continues
to be optimized. Consider perimeter
access to light and views, roof monitors,
skylights and clerestory windows, and
light shelves.
• Develop material specifications and a
building envelope configuration that
maximizes energy performance. Consider
window shape and placement, shading
devices, differentiated façades, reflective
roofing, fabric roofs, induced ventilation,
nighttime cooling ventilation, and
selective glazing.
• Continue energy analyses, including
multiple runs of similar products (e.g.,
various glazings and insulation levels)
to determine best project-specific options.
In addition to first cost, consider durability
and long-term energy performance.
Strategies to Consider During this Phase
Selective Glazing for Walls
Description: Glass products are now
available with a wide range of performance
attributes that allow designers to
carefully select the amount of solar gain,
visible light, and heat that they allow to
pass through. Solar heat is measured by
the properties of shading coefficient
(SC) and solar heat gain factor (SHGF).
An SC of 1.0 applies to clear 1/8-inchthick
glass with other glasses that admit
a lesser amount of solar heat having a
lower SC (e.g., 0.50 for a tinted glass that
admits 50% as much solar heat as 1/8-
inch clear glass). The term SHGF, which
is now widely used by the glazing (fenestration)
industry because it takes into
account a range of angles of solar incidence,
is considered to be equal to a
value of 0.86 times the SC. The degree
of daylight, or visible light transmission,
is expressed by the term “Tvis,” and the
amount of heat loss is measured by the
U-factor, which, expressed numerically,
is the inverse of the total resistance of
the glazing assembly.
Single-glazing is about R-1 or 1/1 for a
U-factor of about 1.0. Double-glazing is
about R-2 for a U-factor of about 0.50.
Commercially available low-e glass
typically ranges in U-factor from about
0.35 down to 0.10, depending on the
type and number of coatings and the
fills (e.g., argon) used in the spaces
between glazing layers.
Goal: Specify glazings with the best combination
of performance characteristics
for the specific application at hand.
Best Applied: The choice of glazing(s) is
an essential consideration for all building
types.
How to Do It: Begin by incorporating
glass performance characteristics (e.g.,
U-factor, shading coefficient) as required
by the applicable codes or standards.
Then, use computer analysis to investigate
alternate glazings and narrow the
field to those most beneficial to admitting
daylight and saving energy, while
still remaining within the project budget.
Glazing technology has now
advanced to the point that alternative
glazings with very different performance
characteristics can physically look
very much alike. This increases the
potential to use different glass types
on different façades, although such an
approach may be considered a maintenance
headache. The best glazing selections
are not merely those with the
highest numerical performance levels
in a given area. For example, daylighting
a space with a large expanse of glass,
using glazing with the highest daylight
18
An example of Building-Integrated PV is
4 Times Square in New York City.
Andrew Gordon Photography and Fox & Fowle Architects/PIX09052
F E D E R A L E N E R G Y M A N A G E M E N T P R O G R A M
transmission may result in excessive
glare. Fritted glass should be considered
when glare reduction through other
means is difficult to achieve.
Related Strategies: Atrium Spaces; Glazed
Roofs; Roof Monitors; Scattered Skylights;
Daylighting through Windows;
Direct-Gain Passive Solar Heating;
Landscape Shading; Light Shelves;
Shading Devices; Window Geometry.
Comments: Of the various building envelope
components, glazing almost always
has the most significant effect on heating,
cooling, and lighting energy use. In
the last 20 years, glazing technology has
progressed more dramatically than perhaps
any other building product or system.
By using high R-factor glazing
(indicating substantial resistance to heat
inflow), it is often possible to eliminate
perimeter baseboard heaters.
Shading Devices
Description: Fixed or movable (manual
or motorized) devices located inside or
outside the glazing are used to control
direct or indirect solar gain.
Goal: Shading should be used to provide
cost-effective, aesthetically acceptable,
functionally effective solar control.
Best Applied: This strategy works well on
south façades where overhangs provide
effective shading for work space and can
also serve as light shelves. Shading west
façades is critical to reduce peak cooling
loads.
How to Do It: Awide range of shading
devices are available, including overhangs
(on south façades), fins (on east
and west façades), interior blinds and
shades, louvers, and special glazing
(such as fritted glass). Reflective shading
devices can further control solar heat
gain and glare.
Related Strategies: Atrium Spaces; BIPV;
Differentiated Façades; Open Office
Space at Perimeter; Perimeter Circulation
Space; Glazed Roofs; Roof Monitors;
Scattered Skylights; Daylighting
through Windows; Direct-Gain Passive
Solar Heating; Light Shelves; Selective
Glazing; Window Geometry.
Comments: Devices without moving parts
are generally preferable. Movable devices
on the exterior are typically difficult to
maintain in corrosive environments or
in climates with freezing temperatures.
Other building elements, such as overhanging
roofs, can also serve as shading
devices.
Daylighting through Windows
Description: Using daylighting through
building windows can displace artificial
lighting, reduce energy costs, and is
associated with improved occupant
health, comfort, and productivity.
Goal: Reduce lighting and cooling energy
more than the increase in heating energy
occasioned by reduced lighting loads.
(In summer, cooling energy demand
is less because the heat from artificial
lighting sources is reduced. In winter,
the heat that is not being produced by
artificial lighting may need to be compensated
for by the building’s heating
system).
Best Applied: Daylighting through windows
is best accomplished on façades
that have a generally clear view of the
sky, particularly the sky at angles of 30
degrees or more above the horizon.
How to Do It: Place much of the façade
glazing high on the wall, so that daylight
penetration is deeper. Consider
the enhanced use of daylighting by
installing light shelves on south
façades. Recognize the interdependencies
in glazing, light fixtures and controls,
and HVAC systems. Whenever
possible, electrical lighting should be
considered a supplement to natural light.
When the sun goes down on buildings
with long hours of operation, however,
efficient electrical lighting design takes
on added importance.
Related Strategies: Differentiated Façades;
Extended Plan; Open Office Space at
Perimeter; Perimeter Circulation Space;
Direct-Gain Passive Solar Heating;
Building-Appropriate Site Selection;
Landscape Shading; Light Shelves;
Selective Glazing; Shading Devices;
Window Geometry.
Comments: Daylighting is a central component
of the vast majority of low-energy
19
Shade from trees is a simple but effective strategy to reduce costly cooling requirements.
Warren Gretz/PIX00217
F E D E R A L E N E R G Y M A N A G E M E N T P R O G R A M
buildings and, as such, merits significant
time and attention.
Extended Daylighting through
Windows—Light Shelves
Description: Ahorizontal device or “shelf”
that bounces direct sunlight off the ceiling
and deeper into the interior spaces.
Light shelves are also used to provide
shading and suppress glare. Light
shelves are located above vision glazing
(up to and slightly above eye level), but
below high glazing above. They may be
positioned inside or outside (where they
also provide shading), or both (this is
typical).
Goal: Save lighting energy, reduce glare,
and provide useful shading.
Best Applied: In clear climates, light
shelves are appropriate for integration
on façades facing within about 30 degrees
of true (solar) south.
How to Do It: Integrate the light shelves
with façade design, office layout, lighting
design, lighting controls, glazing,
and shading devices. They tend to work
best with moderately high ceilings
(about 10 feet, minimum) and open
planning.
Related Strategies: Differentiated Façades;
Open Office Space at Perimeter; Daylighting
through Windows; Selective
Glazing; Window Geometry.
Comments: Transom windows can be
used to allow light from the shelves to
enter interior office spaces located far
from exterior walls. Maintenance may
be an issue, and pigeons present a concern
in some areas.
Natural Ventilation through Windows
Description: User-controlled operation of
windows provides outdoor air for ventilation
and cooling, and should improve
indoor air quality.
Goal: Abalanced approach involves taking
advantage of users’ desire for environmental
control without interfering
with efficient HVAC operation.
Best Applied: Particularly appropriate in
building types and locations where
security concerns and exterior noise or
air quality is not an issue. Users must
be tolerant of increased horizontal air
motion.
How to Do It: Locate windows that will
serve as air inlets to face prevailing
winds. During the cooling season, this
strategy can be enhanced by landscaping
features and projecting building features
(such as fins). This strategy tends
to work best in residential-type occupancies,
where the user already has
control over HVAC.
Related Strategies: Atrium Spaces; Differentiated
Façade; Perimeter Circulation
Space; Window Daylighting; Landscape
Shading; Window Geometry; Economizer
Cycle Ventilation; Induced Ventilation;
Nighttime Cooling Ventilation.
Comments:Awell-considered control
strategy (either mechanical or social)
is required to prevent air conditioning
from operating in a space with open
windows. If such a control strategy cannot
be devised or is not effective or realistic
because of the building occupants,
operable windows can increase building
energy use.
Window Geometry
Description: Windows should be shaped
and located in a manner that minimizes
glare and unwanted solar gain and maximizes
useful daylight and desirable
solar heating.
Goal: The design team should apply
functional criteria to the size, proportion,
and location of windows. It is
important to avoid incorporating more
window area than is beneficial to the
building occupants or that is needed
to enhance low-energy performance.
Best Applied: Shape, size, and location of
windows are important considerations
in all projects.
How to Do It: Make window decisions
based on occupant activities and lowenergy
performance rather than simply
for aesthetic purposes. Having said this,
reduce glass area whenever possible. To
minimize glare and enhance daylighting
benefits, substitute horizontal strips of
high windows for “punched” windows,
and scattered small windows in lieu of
a few large ones.
Related Strategies: Atrium Spaces; Differentiated
Façades; Extended Plan; Perimeter
Circulation Space; Light Shelves;
Selective Glazing; Shading Devices;
Natural Ventilation through Windows.
Comments: The best way to evaluate the
lighting effects of window geometry
and configuration is through computer
analysis, using programs such as
RADIANCE.
20
Daylighting retrofits for U.S. Army warehouse in Hawaii.
Scott Bly/PIX07626
F E D E R A L E N E R G Y M A N A G E M E N T P R O G R A M
Differentiated Façades
Description: In this strategy, the designer
creates variations in the façade design
in response to changes in orientation,
the use of space behind the façade, and
the low-energy design strategies being
employed.
Goal: Strive for seamless integration of
energy-related design strategies with the
overall aesthetic and functional design
components of the project.
Best Applied: If each façade is to be optimized,
this strategy will work on almost
all projects.
How to Do It: Select a design consultant
who can work with the concept that the
appearance of a building’s various
façades will likely differ in response to
variations in their environmental loads.
To that end, pursue a building style that
is compatible with functionally varied
façade elements.
Related Strategies: Atrium Spaces; BIPV;
Perimeter Circulation Space; Daylighting
through Windows; all forms of Passive
Solar Heating; Complementary Building
Uses; Landscape Shading; Light Shelves;
Selective Glazing; Shading Devices;
Window Shape; Natural Ventilation
through Windows.
Comments: Considered as one of the most
basic and effective low-energy building
strategies, using different façades is really
an approach to design and style that is
driven by function. Different façades
do not necessarily have to be radically
unique; rather, they may simply be variations
on a theme. For the sake of uniformity,
designers sometimes put overhangs
on all façades, even though they
may only provide significant energy
benefits on the south side. Such an
approach can greatly compromise the
basic cost-effectiveness of the strategy
and should generally be avoided.
Insulation
Description: Awell-insulated building
envelope reduces energy use, controls
moisture, enhances comfort, and protects
the energy-saving potential of passive
solar design.
Goal: Identify the optimum amount of
building insulation to use in the walls,
roof, and floor construction.
Best Applied: Residential building types
in cold climates benefit most from large
amounts of insulation.
How to Do It: Begin by incorporating
insulation levels required by code or
standard, then use computer analysis
to investigate optimum insulation
amounts. For buildings with mass walls,
use computer analysis to determine the
21
This building has differentiated façades—broad overhangs for shading on the south side and
no overhangs on the north side.
This building uses a light shelf on the south side for daylighting. It also has small square
windows on the east and west to minimize glare.
Warren Gretz/PIX02191
Warren Gretz/PIX00132
OPERATIONS & MAINTENANCE
WARRANTY PERIOD
TURN OVER TO OCCUPANTS
CONSTRUCTION PHASE (CM)
BID SOLICITATION/CONTRACT AWARD
MILESTONE (100%)
CONSTRUCTION DOCUMENTS
MILESTONE (95%)
DESIGN DEVELOPMENT II
VALUE ENGINEERING PHASE
MILESTONE (50%–60%)
DESIGN DEVELOPMENT I
MILESTONE (35% DESIGN)
SCHEMATIC DESIGN PHASE
(OR PRELIMINARY DESIGN)
MILESTONE (15% DESIGN)
PROJECT PLANNING PHASE
PROJECT PRE-PLANNING
BUDGETING PHASE
FEASIBILITY PHASE
Action Items:
· Program any special requirements into your budget submission;
· Submit a budget that allows for an energy champion, the necessary meetings to
accommodate a team process, the extra studies, analyses and verifications that
will be needed, and slightly higher design fees (2%–4%);
· Include the requirement for an energy expert in your RFP/A&E solicitation;
· Conduct a design charrette BEFORE concept development;
· Identify the certification and testing measures you will require.
See page 13 for details on these Action Items and the strategies to consider during this
phase.
Action Items:
· Conduct all required feasibility analyses;
· Review all existing directives and policies to be sure what your agency currently requires;
· Select an ‘energy champion and give them the necessary authority;
· Establish explicit energy use targets that surpass 10 CFR 435;
· Identify your agency’s goals for the other sustainable issues such as site planning, materials use, water
use, and IEQ.
See page 12 for details on Action Items and the strategies to consider during this phase.
Action Items:
· Establish low-energy as a core project goal;
· Establish energy use targets;
· In selecting consultants, consider their level of experience;
· Classify the energy-related requirements of the users;
· Identify the climate and utility costs at the project site;
· Identify the characteristic space and building uses that apply to the
project.
See pages 13 for details on Action Items and the strategies to consider
during this Phase.
Action Items:
· Establish interdisciplinary design team;
· Develop a preliminary layout;
· Develop landscape plans;
· Develop a basic layout;
· Investigate renewable power sources;
· Conduct preliminary energy analysis.
See page 14 for details on Action Items and the strategies to
consider during this phase.
Action Items:
· Ensure optimization of daylighting;
· Develop material specs and envelope configuration that maximizes
performance;
· Continue energy analyses; determine best project-specific options.
See page 18 for details on Action Items and which strategies to
consider during this phase.
Action Items:
· Continue energy analysis; ensure that performance objectives
are maintained.
See page 25 for details on these Action Items and the strategies
to consider during this phase.
Action Items:
· Ensure that VE is based on life-cycle considerations;
· Incorporate energy analysis directly into VE;
· Ensure that energy targets are maintained.
See page 28 for details on these Action Items and the strategies
to consider during this phase.
Action Items:
· Ensure that construction details and specifications are consistent;
· Ensure that mechanical equipment meets design targets;
· Lighting system;
· Conduct a final design review.
See page 28 for details on Action Items and the strategies to
consider at this phase.
HOW TO USE THE TIME LINE:
This time line is to be used by Federal project managers to remind them when they should be thinking about low-energy, sustainable design during the various phases
of planning, design, construction, and turnover of a building. Without explicit actions throughout the process, the resulting buildings will often not meet the owner’s
requirements and expectations. Because each agency has its own terms for these phases, the time line uses the traditional American Institute of Architects (AIA)
terminology and notes the stages at which Federal agencies often demand milestone submissions (15%, 35%, 50%–60%, and 95%). During each of these stages,
there are very different opportunities to ensure, or to lose, low-energy sustainable design. This guidebook is focused primarily on low-energy issues and recognizes
that low-energy does not equal sustainability. Comprehensive sustainability includes many other issues such as water use, indoor environmental quality (IEQ), and
green materials.
It is assumed that whatever agency you are in already has specific directives for facility managers that provide guidance for procuring low-energy, sustainable buildings
and facilities. These directives might range from general guiding principles to more specific energy and water use targets, foot-candle levels, requirements for using
renewable energy sources, and even materials criteria for each building type. It is conceivable that there might be some existing policies that are contrary to your newly
emerging low-energy, sustainable goals, and these should be recognized and eliminated if at all possible.
You will need a unique perspective, one that relies on a whole-building approach to the problem. The time line suggests potential steps that will help you realize your
goal of a low-energy (and a sustainable) facility. The time line will show you some new steps you will incorporate into your thinking, planning, and budgeting steps
that are not needed in the traditional design process. For example, you will see the requirement for an energy champion and several stages where you have to conduct
some evaluations to really understand the consequences of some very complex tradeoffs. You must be clear about the costs to have “extra” people (like the energy
champion) on the job or additional costs to perform the necessary evaluations and include them in your budgets from Day One.
There will be some new roles and responsibilities if you expect to deliver a low-energy, sustainable building: you will need to state your expectations clearly and give
your team the resources and the authority they need to accomplish the goals on time and within budget.
Refer to the section called “How to Apply,” which follows the time line. This section provides the details about which low-energy strategies should be considered during
each phase. Each one notes Description, Goal, Best Applied, How to Do It, Related Strategies, and Comments for that strategy.
Action Items:
· Ensure energy features are constructed/
installed as designed.
See page 28 for details on Action Items and
the strategies to consider at this phase.
Action Items:
· Monitor energy performance;
· Implement a full commissioning protocol.
See page 28 for details on Action Items and the strategies to
consider at this phase.
Action Items:
· Ensure that construction details and specifications are consistent;
· Ensure that mechanical equipment meets design targets;
· Conduct a final design review.
See page 28 for details on Action Items and the strategies to consider
at this phase.
22 23
F E D E R A L E N E R G Y M A N A G E M E N T P R O G R A M
relative advantages of placing the insulation
on the inside or on the outside of
the mass. Detail assemblies containing
insulation to avoid thermal bridges,
where conductive elements (e.g., metal
studs) penetrate the insulation and shortcircuit
the system by conducting heat. In
non-residential construction, there are
many cases, particularly in hot climates,
where using more insulation to enclose
a sealed building will cause it to behave
like a Thermos bottle—trapping heat
and using even more energy.
Related Strategies: High-Efficiency HVAC.
Comments: The law of diminishing returns
applies to additional levels of insulation,
whereby the first increment of insulation
reduces heat loss dramatically, and each
additional increment provides less and
less of an improvement. The quality of
insulation—and how well it is installed—
is very important, especially when it
comes to batt insulation in walls.
Air Leakage Control
Description: Air retarder systems are
used to reduce air leakage into or out
of a building.
Goal: To deploy a system that reduces
energy use and serves to protect the
building’s envelope, structure, and
finishes.
Best Applied: Air leakage control is
considered to be standard low-energy
procedure in cold climates.
How to Do It: Install air-impermeable
components that are sealed at the joints
and penetrations to create a continuous,
airtight membrane around the building.
Note, however, that air retarders placed
on the winter/cold side of the insulation
must be vapor-permeable to avoid trapping
moisture within the walls.
Related Strategies: Insulation, High-
Efficiency HVAC.
Comments: Designers of many non-residential
building types attempt to reduce
air infiltration by maintaining the indoor
space at a higher pressure than the outside
ambient air. When an air retarder is
installed, pressurization becomes easier
to achieve, while at the same time, the
need for pressurization becomes less
critical. In masonry construction, bituminous
membranes are sprayed or
trowel-applied to serve as air retarders,
with bitumen-based sheets typically
used in curtain-wall construction.
Evaluate the benefits of an air retarder
not only for improved energy use, but
also for reduced wall maintenance and
repair costs. Also evaluate the air leakage
characteristics of manufactured
components such as windows, doors,
and curtain walls.
Roof Monitors
Description: Roof monitors are windows
installed at roof level, typically vertical
or steeply sloped.
Goal: To admit useful natural light and
often desirable solar heat gain during
the heating season.
Best Applied: This approach works well
on many building types, particularly
low buildings with one or two stories.
How to Do It: South-facing roof monitors
should use vertical glass and be shaded
by overhangs to provide daylight and
useful solar heating (for many building
types in many locations). By contrast,
north-facing roof monitors need not be
concerned with glare or the unwanted
entry of direct solar rays. North-facing
glazing can be inclined (tilted) somewhat
to access the overhead sky better,
which provides a much greater level of
diffuse daylight than does the sky near
the horizon. As a general rule of thumb,
avoid east- and west-facing roof monitors.
Also avoid horizontal glazing, which
typically overheats the building, thereby
dramatically increasing cooling loads.
Minimize the amount of glass required
to achieve desired illumination levels,
and avoid narrow slots with glazing on
opposite sides.
Related Strategies: Direct-Gain Passive
Solar Heating; Selective Shading;
Shading Devices; Window Geometry;
Induced Ventilation; Lighting and
Lighting Controls.
Comments: Design guidelines are available
for various geometries of roof monitors
and other toplighting strategies.
To fine tune monitor locations, provide
quality lighting environments, and
quantify resulting energy benefits,
computer analysis is advised.
Scattered Skylights
Description: Small, individual spot-located
skylights.
Goal: To obtain useful daylighting.
Best Applied: Appropriate for use in onestory
buildings, such as warehouses, and
especially useful in buildings where sun
control is of secondary importance.
How to Do It: Generally achieved with
prefabricated elements that have flat or
domed glazing, spot-located skylights
should be used with care, except in cases
where potential glare and direct sun
penetration is of little concern within
the building. Use sparingly—large numbers
of separate skylights are expensive
in comparison to glazed roofs.
Related Strategies: Extended Plan;
Selective Glazing.
Comments: Even when mounted above
prefabricated or site-built wells, it is
very difficult to entirely eliminate sun
penetration when solar altitude angles
are at their highest (around the summer
solstice, June 21). Guidelines for spacing
scattered skylights are available, and
computer analysis to fine-tune sizing
and spacing and quantify energy benefits
is advised. Potential roof leaks are
often a concern and should be addressed
by proper detailing. Despite these drawbacks,
scattered, spot-located skylights
24
Insulation.
U.S. Department of Energy/Craig Miller/PIX02214
F E D E R A L E N E R G Y M A N A G E M E N T P R O G R A M
are widely applicable to warehouses,
low-rise residential, and many other
smaller buildings.
Glazed Roofs
Description: Glazed roofs are large-area
skylights typically found over atrium
spaces.
Goal: To provide daylighting in a manner
that may increase the architectural
impact of the space while providing a
more direct connection between building
occupants and the outside world.
Best Applied: Glazed roofs work well
above circulation areas and other highoccupancy
spaces.
How to Do It: Consider installing a clearspan
glazed roof between buildings or
building sections to create a covered
“street.” Solar heat gain can be controlled
through use of fritted glass or louvers.
Related Strategies: Atrium Spaces;
Extended Plan; Selective Glazing;
Shading Devices; Induced Ventilation.
Comments: Excessive cooling loads
frequently accompany this design
approach. When used over high spaces
(such as atriums), incorporate induced
ventilation strategies whenever possible.
As a secondary option, mechanical cooling
should be provided through a displacement
ventilation approach, where
only the air in the occupied zone of the
space near the floor is conditioned.
Non-Absorbing Roofing
Description: Roofs covered by lightcolored
or reflective membranes are a
viable passive solar strategy, as they
tend to absorb less heat.
Goal: To reduce cooling loads.
Best Applied: This is a common approach
for use on low buildings in hot climates.
How to Do It: Use roofing systems with
light-colored or reflective top layers.
Related Strategies: Extended Plan.
Comments: Reflected light may complement
other efforts aimed at daylighting
“wedding cake”-type building forms.
Early in the process, the designer needs
to know the color of any roofing systems
that will be visible to building occupants.
Fabric Roofs
Description: These are tension roofs constructed
of stretched, light-transmitting
fabric—an increasingly popular architectural
element.
Goals: Provides a buffer from direct
exposure to solar heat gains occasioned
by daylighting of space.
Best Applied: Deploy fabric roofs over
large, clear-span spaces.
How to Do It: The overall approach must
be decided early in the design process.
Before committing to the design, carefully
evaluate the balance between lighting,
cooling, and heating loads for the
specific building use and climate.
Related Strategies: Extended Plan; Atrium.
Comments: Fabric roofs are useful as
temporary or permanent coverings
over outdoor spaces (i.e., tents). They
have been effectively used at the Denver
International Airport and the San Diego
Convention Center.
Design Development I Phase
During the earlier phases of the project,
basic decisions are made that affect
building massing and determine which
low-energy design strategies will be
implemented. During those phases, the
overall thrust is to reduce the heating
and cooling loads as much as possible.
During design development, the design
team’s attention should shift to identifying
efficient lighting and HVAC systems.
Action Item
• Continue energy analysis and the
“trade-off” process.
25
A skylighted entryway that also demonstrates the integration of photovoltaics at the Thoreau
Center for Sustainability at Presidio National Park, California.
Lawrence Berkeley Lab/PIX01053
Denver International Airport in Denver,
Colorado, is an example of a fabriccovered
roof.
Warren Gretz/PIX07340
F E D E R A L E N E R G Y M A N A G E M E N T P R O G R A M
Strategies to Consider During this Phase
Energy-Efficient Lamps and Ballasts
Description: Identifying and using application-
specific, high-efficiency lamps
and ballasts.
Goal: Minimize the amount of electrical
power required by lighting systems,
while still meeting the task-specific
needs of building occupants.
Best Applied: The savings will be greatest
in buildings with long hours of occupancy
or in areas with high electrical utility rates.
How to Do It: Use T-8 (tubular, 8/8th of
one inch in diameter) lamps and compatible
electronic ballasts for general
ambient lighting. Compact fluorescent
lamps should replace incandescent or
halogen lamps in downlights, as they
only use about one-third the electrical
power. Determine what lamp/ballast
combinations work best with other
strategies (i.e., daylighting, shading,
lighting controls). Use light-emitting
diode (LED) exit lights with an estimated
life of 30 years or more to enhance building
safety and all but eliminate required
maintenance.
Related Strategies: All daylight-related
strategies.
Comments: The color rendition of all fluorescent
lamps has improved dramatically
in recent years, to the point where they
are now deemed acceptable for most
applications. Compact fluorescent lamps
also provide maintenance savings, as the
lamps last 10 to 20 times longer than the
incandescents they replace.
Lighting Controls
Description: Lighting controls automatically
adjust lighting levels in response
to daylight availability. Other controls
automatically turn lights off in response
to unoccupied space.
Goal: This strategy significantly reduces
lighting-based electricity demand.
Best Applied: Dimming controls are used
in conjunction with building designs
that encourage entry of natural daylight.
Occupancy sensors are best used in
spaces that have intermittent occupancy,
such as conference rooms and storage
areas.
How to Do It: Automatic daylight dimming
controls either provide light levels
in discrete steps or through continuous
dimming, based on light levels sensed.
Dimming systems can also be used to dim
newly installed lamps when their light
output is greater than it will be once they
“burn in”and achieve their rated output.
Occupancy sensors are used to turn off
lights and sometimes HVAC in unoccupied
areas. They are made with multiple
activation technologies, including those
that sense body heat (infrared) as well as
those that detect motion (ultrasound).
Some sensors employ more than one
technology as a means of eliminating
false signals. Manual switching and
timeclocks can also be used to control
certain daylit spaces.
Related Strategies: HVAC Controls
Comments: Automatic lighting control
functions are often included in a computerized
energy management system
that also controls the HVAC, fire safety,
and security systems.
High-Efficiency Heating, Ventilation,
and Cooling Equipment
Description: This category of equipment
offers operating efficiencies far greater
than those afforded by systems designed
to simply meet applicable codes or
standards.
Goal: Integrate more efficient equipment
whenever it can be shown to be cost
effective.
Best Applied: These systems are appropriate
for use with large loads, long
operating hours, and high energy prices
(particularly for electricity).
How to Do It: There are various types of
efficient heating and cooling equipment
that can readily address the specific
needs and operating patterns of a given
building. Many agencies require that
alternate systems be subjected to a lifecycle
cost analysis. If such an exercise is
conducted, it should involve detailed
computer analysis (such as DOE 2.2)
rather than a process that simply confirms
the selection of a preferred system.
Ask the design team to prepare a list
of performance criteria for equipment
required by applicable codes and standards
to be used as a basis for comparing
more efficient equipment options.
In some cases, the cost premium for
more efficient equipment is small and
can be justified by hand calculations.
More often, DOE 2.2 computer analyses
are required along with some form
of rigorous life-cycle cost analysis.
Consider using modular equipment
(e.g., three small boilers instead of one
26
Some examples of energy-efficient lamps.
D&R Int., LTD/PIX07737
F E D E R A L E N E R G Y M A N A G E M E N T P R O G R A M
large one or a dual compressor chiller)
and variable-speed equipment (modulating
burner or variable-speed chiller)
for greater flexibility in achieving targeted
reductions in energy use.
Related Strategies: All design decisions
that affect heating and cooling loads.
Comments: Specifying systems that are
larger than necessary can be costly. The
energy consultant should be careful
throughout the design process to size
the systems, components, and equipment
appropriately. HVAC systems
should also be designed to ensure
healthful indoor air quality in a manner
appropriate to individual spaces and
the overall building type.
Exhaust Air Heat Recovery
Description: This process involves the
recovery of useful heat from the air
being dispelled from a building.
Goal: Transfer 50% to 70% of the heat
that would otherwise be lost to the
incoming air stream.
Best Applied: Apply this strategy in
buildings with large populations or significant
ventilation requirements, particularly
those located in cold climates.
How to Do It: Various types of heat
exchangers are in use today, including
heat wheels, plate and fin air-to-air heat
exchangers, and heat pipes. Heat pipes
are very simple devices that consist of a
highly conductive tube filled with refrigerant
which, when vaporized, transfers
heat from the outgoing to the incoming
air stream. Because heat exchangers
obstruct the air passage of both intake
and exhaust ducts, bypass dampers
should be installed to facilitate operation
during mild or warm weather.
Related Strategies: HVAC controls
Comments: Depending on the application,
potential contamination of the incoming
air stream may need to be monitored.
For instance, recovery of heat from a
combustion process is usually accompanied
by a carbon monoxide sensor
located in the intake.
Economizer Cycle Ventilation
Description: Contributing to both energy
reduction and good indoor air quality,
this strategy introduces a varying
amount of ventilation air to cool the
building in combination with normal
air conditioning (AC).
Goal: Avoid using the AC compressors
or other mechanical cooling method
when ambient air can provide some
or all of the needed cooling.
Best Applied: Look to buildings in cool
climates where there is low relative
humidity.
How to Do It: Provide appropriate controls,
along with 100% outside-air capability.
Consider including enthalpy
(total heat, sensible plus latent)
controls to maximize benefits.
Related Strategies: Induced Ventilation;
Natural Ventilation through Windows;
Nighttime Cooling Ventilation.
Comments: This should be considered a
standard low-energy HVAC procedure
in all but the most humid climates.
Nighttime Cooling Ventilation
Description: High-volume, fan-powered
ventilation of large areas during cool,
dry nights.
Goal: Cool the building (particularly
exposed massive structural elements)
with outside air as a means of saving
more AC power than the sum of the
power drawn by the ventilating fan,
plus what is needed to overcome any
excessive humidity the following day.
Best Applied: This strategy is appropriate
for hot, dry climates where the diurnal
temperature difference (between day
and night) often exceeds 30°F to 35°F.
How to Do It: This strategy relies on moving
large quantities of air in an economical
manner and requires a secure source
of intake ventilation that can be directed
into spaces to be cooled.
Related Strategies: Natural Ventilation
through Windows; Economizer Cycle
Ventilation
Comments: Large amounts of interior
mass enhance the cooling effect in dry
climates that consistently experience
significant temperature swings. In variable
climates, lower mass is desirable.
Relying on open windows for ventilation
(in lieu of forced-air fan operation)
may compromise security or lead to
wind or water damage.
HVAC Controls
Description: Specify controls that maintain
intended design conditions, including
temperature, humidity, and airflow
27
The Louis Stokes Laboratory at the National Institute of Health in Bethesda, Maryland, is
using desiccant heat wheels for exhaust air heat recovery.
Frank Kutlak/PIX03683
F E D E R A L E N E R G Y M A N A G E M E N T P R O G R A M
rate in terms of cubic feet per minute
(cfm) throughout the building.
Goal: The proper use of controls and
building automation reduces energy
consumption and electrical peak
demand.
Best Applied: In all circumstances, strive
for a level of functional complexity that
is compatible with the skills and capabilities
of the building’s operating personnel.
How to Do It: Keep control systems as
simple as possible. Avoid controls that
offer little in the way of improved operations
or energy savings, especially if
they complicate the system and add
features that require frequent maintenance
or are subject to malfunction.
Evaluate the use of variable-speed
drives (VSD) on all large pumps and
fans serving loads that only occasionally
function at peak capacity. In large
spaces with varying occupancies
(auditoriums, large meeting rooms,
cafeterias), investigate control strategies
(e.g., the use of carbon dioxide monitors)
that regulate the amount of outside air
in accordance with actual occupancy.
Consider using setback thermostats in
all building types. However, avoid setting
temperatures back in spaces where
a large amount of exposed thermal mass
will make it difficult to reestablish comfortable
temperatures.
Related Strategies: Lighting Controls
Comments: HVAC control systems can
often be integrated into computerized
systems that also control lighting, fire
safety, and security.
Value Engineering (VE) Phase
Action Items
• Ensure that VE analysis is based on
life-cycle considerations rather than
solely on cutting initial construction
costs.
• Incorporate energy analysis directly
into the VE process.
• Be certain that energy targets for the
facility are maintained during VE.
• Meet the needs of the building occupants
and the intended use through
design that is consistent with agency
or organizational values and mission.
Design Development II Phase
Action Items
• Continue energy analysis as design is
finalized to ensure that desired energy
performance objectives are maintained.
• Review final working drawings, specs,
and cost estimates.
Construction Documents Phase
Action Items
• Ensure that construction details and
specifications are consistent with energy
use targets and strategies.
• Be sure that mechanical system details
and equipment sizing meet design
targets.
• Reaffirm that lighting system details
and equipment specifications are
consistent with energy design intent.
• Before documents are sent out for bid,
conduct a final energy design review.
Bid Solicitation/Contract Award Phase
Action Items
• If cutting costs is required due to high
bids, advocate preserving vital energysaving
features in lieu of more easily
replaceable or aesthetic components.
• Conduct additional energy analyses as
necessary to ensure that intended energy
performance targets are still intact.
Construction Phase
Action Item
• Ensure that energy features are constructed
or installed as designed.
Turn Over to Occupants Phase
Action Item
• Verify that occupants understand the
building systems and the proper use of
low-energy equipment and features of
the building.
Warranty Period/Commissioning Phase
Action Items
• Verify occupant comfort and understanding
of building operation using a
Post Occupancy Evaluation (POE).
• Monitor the energy performance of the
facility once per quarter during the warranty
period and fine-tune the system as
needed.
• If feasible, develop and implement a
full commissioning protocol.
28
This building incorporates many features that lessen its impact on the environment.
Oberlin College/PIX09677
F E D E R A L E N E R G Y M A N A G E M E N T P R O G R A M
What to Avoid
Some low-energy buildings fail to meet
the expected energy savings because the
energy-efficient technologies incorporated
into the design are not correctly
integrated into the building. This may
be due to a lack of understanding on
the part of some team members as to
the relationships between the specific
energy technologies needed to reduce
a given building’s energy use and the
effective integration of these technologies
into the design. Changing just one
of the recommended building components
changes the total environment
and, thus, the effectiveness of the remaining
technologies. To avoid this, it is crucial
that all team members understand
how each of the technologies interacts
with all other building components in
a given environment.
When choosing energy-saving technologies,
team members should be skeptical
of claims for unrealistically high levels
of performance and should avoid dependence
on proprietary devices. It is not
advisable to have a design that relies on
a particular technology for which only
one product is available. In those few
cases where the use of such proprietary
products can be defended in the context
of competitive bidding requirements, a
contingency design strategy should be
in place. Claims of high-level performance
should be supported by objective
tests and case study results.
Design Considerations and
Computer Modeling
The Base Case
Abase-case design—a code-compliant
building design without low-energy
design features—is needed for comparison
purposes in analyzing the cost and
effectiveness of the low-energy design
strategies identified for consideration.
Considerations other than low-energy
design often dictate the basic design of
a building. In these instances, the basecase
building is automatically created
through the normal design process. To
be effective, some low-energy building
design technologies need to be applied
during the early stages of the project,
such as authorization, site selection,
budgeting, and programming. In these
instances, the base-case building may
already include some low-energy
design features.
For example, an atrium is a desirable
amenity that, if incorporated early in
the project, should influence decisions
about site selection, building orientation
on the site, and the number of buildings
required to satisfy the space needs of the
facility. But if the atrium is introduced
after the overall building configuration
is set, the parallel use of the atrium as a
low-energy design component will be
compromised, and it may end up being
an energy liability. Similarly, in climates
where a campus plan yields energy benefits,
these benefits can be included
among the criteria used to define the
basic site plan—especially if introduced
in the early project stages.
Anticipating low-energy design strategies
early in the project can also influence the
choice of a base case. One attraction of
many low-energy building design strategies
is that the occupants gain a closer
connection with the outdoors environment.
If this attraction is part of the
design program, low-energy building
design strategies may become more economical
relative to the base-case design.
For example, if the maximum allowable
distance between any office worker and
a source of natural light is lowered from
the 60 feet typically accepted in a standard
office buildings to 30 feet, a linear
atrium between two 60-foot-wide building
segments may result in a more
attractive, compact, and, therefore,
potentially more economical, design
when compared to a 60-foot-wide
base-case building.
Strategy Interactions
An important low-energy design
approach involves rank-ordering a list
of candidate technologies. At each step
in a series of computer-driven energy
simulations, candidate strategies are
ranked in order of cost effectiveness
relative to the base-case design. The
top-ranked strategy would be the one
that yields the largest energy savings
for the smallest investment—the one
with the shortest simple payback.
[Note: according to the U.S. Department
of Energy’s (DOE’s) A Guide to Making
Energy-Smart Purchases, the simple
payback period is the amount of time
required for the investment to pay for
itself in energy savings. You can obtain
an estimate of the simple payback period
by dividing the total cost of the product
by the yearly energy savings. For example,
an energy-efficient dryer that costs
$500 and saves $100 per year in energy
costs has a simple payback period of
5 years.]
As each strategy is applied, the payback
for all subsequent candidates may
change. Because there is less energy to
be saved, the savings potential is often
reduced. If all the strategies were independent,
the remaining ones would
retain their order in the ranking as each
is applied in succession. In practice,
however, low-energy building design
strategies do interact and change their
relative order in the ranking as they are
applied. Presuming that the initial ranking
will remain constant can lead to misjudgments
about which strategies to
pursue. After applying each strategy in
a simulation, re-rank the remaining
candidate strategies. Designing Low-
Energy Buildings with ENERGY-10
can perform this task automatically
(see Design Tools).
Another example of the interaction among
building elements is in an office building
where natural lighting displaces electrical
energy by reducing the use of auxiliary
lighting. In this case, the need for auxiliary
heating increases in cold weather in
response to the reduced heat contribution
previously supplied by electrical
lighting that is now dimmed or turned
off. If this effect is not taken into account
in the simulation, exaggerated estimates
of energy savings will occur. Finally, it is
important to remember that using one
technology may preclude using certain
others. For example, in buildings where
heating or cooling loads have been significantly
reduced, the benefits of using
high-efficiency equipment to meet those
loads may also be reduced and the
resulting simple paybacks lengthened.
29
F E D E R A L E N E R G Y M A N A G E M E N T P R O G R A M
The Benefits of Multiple Use
As previously noted, BIPV—integrating
PV into the building envelope—can
replace conventional building envelope
materials and their associated costs. PV
is a solid-state, semiconductor-based
technology that converts light energy
directly into electricity. For example,
spandrel glass, skylights, or roofing
materials might be replaced with architecturally
equivalent PV modules that
serve the dual function of building skin
and power generator. By avoiding the
cost of conventional materials, the incremental
cost of PV is reduced and its lifecycle
cost is improved. BIPV systems can
either be tied to the available utility grid
or they may be designed as stand-alone,
off-grid systems. One of the benefits of
grid-tied BIPV systems is that on-site
production of power is typically greatest
at or near the time of a building’s peak
loads. This provides energy cost savings
through peak load shaving and demandside
management capabilities.
Maintenance
Awell-designed, low-energy building
requires less maintenance than one that
relies on large mechanical systems.
Unlike other technologies, well-integrated
low-energy building design is
much less dependent on hardware and
equipment, so there is little to go wrong.
The traditional building trades that use
available construction materials are able
to make repairs as needed. The reliability
and performance record of other technologies
(such as movable shading devices)
should be investigated, and when
deployed, moving parts should be regularly
maintained. Cleaning and protecting
the surface of shading devices and
glazing is important and should be
incorporated as part of ongoing,
scheduled maintenance.
When properly implemented, low-energy
building design can reduce heating and
cooling loads to allow for equipment
downsizes and reductions in maintenance
costs. Ideally, it also yields a
building that can continue to function
on a basic level and remain habitable
even when systems experience unexpected
downtime.
Costs
Cost effectiveness is typically the primary
criterion for evaluating low-energy building
technologies. 10 CFR 435 and Executive
Order 13123 require that energyrelated
design decisions be evaluated on
a life-cycle basis, rather than simply on
a first-cost basis (e.g., construction costs)
alone. It should be noted that the higher
first costs of low-energy design can often
be avoided or greatly minimized by
anticipating and incorporating these
strategies at the outset of the planning
process. Exceptions might include:
• Demonstration projects with supplemental
funds specifically earmarked
for technology promotion.
• High-profile projects where publicity
value adds to the payback.
• Cases where it is impractical to establish
cost effectiveness. For example, relatively
small investments that cannot
justify a detailed simulation and seem
practical based on prior experience.
• The amenity value of the technology
outweighs its energy performance. Care
must be taken to ensure that the amenity
does not increase energy demand.
Typically, a building’s cost effectiveness
should be measured using appropriate
design and analysis tools, such as those
described below. As previously noted,
different forms of energy have different
costs, with electricity costs approximately
three times that of natural gas. Because
the costs of various energy sources vary
greatly by region, specific input is
required in each case.
Except for residences, utility cost data is
not simply a matter of cents per kilowatt-
hour of electricity, or dollars per
therm of gas. Especially in larger buildings,
the various fixed costs, variable
costs, step rates, and demand charges
must be accurately calculated. It is
sometimes appropriate to run separate
simulations, with and without demand
rates, to see the extent to which the savings
offered by a low-energy feature is
dependent on demand rates. Small-scale
co-generation may also be evaluated
along with other energy sources appropriate
for larger projects.
To accurately model these costs, the more
sophisticated design tools (such as
DOE 2.2) accept all the details of utility
rate structure, whereas simpler tools
rely on a simplification of the rates. It is
important to realize, however, that simplified
rates may mask a large demand
component and can be very misleading.
It is also worth noting that when necessary
energy-efficient technologies are
well balanced and function in a complementary
manner, they will significantly
reduce energy consumption during
peak load periods.
This guidebook does not discuss utility
rates, assuming that one of the final calculations
made in evaluating a given
technology involves using actual, project-
specific utility rates to determine
the anticipated savings. Team members
with experience in using a given technology
in a particular locality can often
predict probable outcomes based on
their knowledge of the interaction
between the climate and utility costs.
For example, measures affecting electrical
consumption (such as fan energy
or reduced lighting demand) will have
a better payback in New England,
where electricity costs are high, than
in the Northwest, where lower-cost
hydropower is available.
Financing Options
Energy savings performance contracting
(ESPC) arrangements are a relatively
new method of helping Federal agencies
invest in energy-efficient building measures.
ESPC is a contracting agreement
that enables agencies to implement energy-
saving projects without making costly
up-front investments. The contractor
or other partner, such as a utility, owns
the energy system and incurs all costs—
design, installation, testing, operations,
and maintenance—in exchange for a
share of any energy cost savings realized.
FEMP provides ESPC and utility financing
workshops, model solicitations, and
a how-to manual. For more information,
call FEMP at 703-243-8343. You may also
wish to contact the Energy Efficiency
and Renewable Energy Clearinghouse
at 800-363-3732, or check their Web
site at www.eren.doe.gov/femp.
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F E D E R A L E N E R G Y M A N A G E M E N T P R O G R A M
Design and Analysis Tools
Typically, a building’s cost-effectiveness
needs to be measured using an appropriate
design and analysis tool, such
as those described below.
ADELINE (includes SUPERLITE and
RADIANCE): Asoftware tool for daylighting
design that links daylighting
and thermal performance. Available
from Lawrence Berkeley National
Laboratory, 510-486-4000.
BLAST:Adetailed, annual energy performance
software tool capable of modeling
the interactive effects of lowenergy
building design strategies such
as daylighting, passive solar heating,
and thermal mass. Available from the
BLAST Support Office, 217-333-3977.
BLCC:Asoftware tool to calculate life
cycle cost according to federal criteria.
See http://www. eren.doe.gov/buildings/
tools_directory/software/blcc.htm
CFD: An abbreviation for “computerized
fluid dynamics,” this highly sophisticated
type of program can track the flow of air
within a space or building component
and determine the temperature distribution
within that space during system
operation. It requires considerable experience
to operate, but is invaluable for
assessing the effectiveness of air diffusers.
Available from several vendors
under several names. See http://www.
eren.doe.gov/buildings/tools_directory
DOE 2/DOE 2.2: An energy analysis
software program that calculates the
hour-by-hour energy use of a building,
given detailed information on the building’s
location, construction, operation,
and HVAC systems. Available from
Lawrence Berkeley National Laboratory,
510-486-4000.
Designing Low-Energy Buildings With
ENERGY-10: An hour-by-hour, annual
simulation program designed to analyze
residential and commercial buildings of
less than approximately 10,000 square
feet (one or two zones). Specifically conceived
for use during the earliest phases
of design when low-energy building
strategies can be incorporated at the
lowest possible cost. Available from the
Sustainable Buildings Industry Council
(SBIC), 202-628-7400, ext. 209.
FRAME:Apowerful thermal analysis
program that accurately tracks the flow
of heat through assemblies. Abasic tool
for analyzing thermal bridging through
façade elements, such as window
frames. Requires some experience for
optimum use. See http://www.eren. doe.
gov/buildings/tools_directory/software/
framepls.htm
POWERDOE:Windows-based version
of DOE 2 with user-friendly interface.
Available from Fred Winkleman,
510-486-4925.
SERI-RES: (also SUNREL, which is an
upgraded version of SERI-RES that features
enhanced algorithms): Analyzes
passive solar design and thermal performance
in residential and small commercial
buildings. Available from Ron
Judkoff, National Renewable Energy
Laboratory (NREL), 303-275-3000.
TRNSYS: Modular FORTRAN-based
transient simulation code that allows
simulation of any thermal energy system,
particularly solar thermal, building,
and HVAC systems. Available from the
Solar Energy Laboratory, University of
Wisconsin, TRNSYS Coordinator,
608-263-1589
Energy Savings
Energy savings will vary, depending on
climate, building type, and strategies
selected. In new office buildings, it is
economically realistic to reduce energy
costs by 30% or more below national
averages if an optimum mix of lowenergy
design strategies is applied.
According to the Building Owners and
Managers Association (BOMA), the
average energy cost (taking into account
indicative samples of both public and
private buildings) is $1.85 per rentable
square foot. As previously noted, the
Federal government maintains approximately
2.9 billion square feet of rentable
space. Thus, a 30% reduction in energy
use would yield annual taxpayer savings
of 55.5¢ per square foot, or a $1.6
billion reduction in the nation’s annual
energy bill. This figure does not take
into account the additional savings
realized through pollution prevention,
resource conservation, and related costreduction
measures. Although a 30%
reduction may seem ambitious, buildings
monitored by NREL’s Low-Energy
Building Program show energy consumption
reductions as high as 75% in
residential buildings and 70% in some
non-residential buildings.
Other Impacts
Better design techniques and superior
technologies have largely eliminated
any negative impacts associated with
low-energy building design, such as
overheating due to uncontrolled solar
gain. The environmental benefits of
low-energy building design can be significant,
depending on how many energy-
efficient or sustainable products are
used. For example, a building that incorporates
green materials (such as paints
with low or no volatile organic compounds
[VOCs] and recycled building
materials) has less of an impact on natural
resources than does a conventional
building. HVAC systems that use nonchlorofluorocarbon
(CFC) refrigerants
are less harmful to the earth’s ozone
layer, and passive solar buildings that
use significantly less energy from fossil
fuels contribute less to the greenhouse
gas effect than conventional buildings.
Taken together, these low-energy, sustainable
buildings not only reduce the
burden on American taxpayers, but also
contribute to the health, well-being, and
productivity of their occupants.
Case Studies
The United States Courthouse Expansion,
Denver, Colorado
The United States Courthouse expansion
in Denver, Colorado, consists of 17 new
courtrooms and associated support
spaces, totaling 383,000 square feet. The
General Services Administration (GSA)
designed this project to serve as a showcase
for sustainable design and devoted
considerable attention to the building’s
energy and environmental design features.
Sustainable design strategies
integrated into the building include:
• High-performance glazing system
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• Daylighting complemented by energyefficient
electric lighting
• Energy-efficient HVAC systems and
controls (e.g., displacement ventilation
and evaporative cooling)
• Building-integrated photovoltaic
system
• Recycled and low-VOC materials used
throughout
• Integrated building automation system
• Low-impact landscaping
• Water-saving faucets and toilets.
Based on computer analysis using
DOE 2.2, the building is expected
to consume approximately 50% less
energy than a minimally compliant
building designed in conformance with
the Federal Energy Standard 10 CFR 435.
As such, its annual energy costs will be
reduced from just under $300,000 per
year to just over $150,000. Much of the
energy savings achieved in the Denver
Courthouse expansion will be the result
of reduced energy demand associated
with lighting, heating, and cooling.
Beyond its energy- and resource-efficient
design features, the building will also
provide an improved indoor environment
that is expected to increase workplace
performance while improving
staff health, safety, and satisfaction.
In keeping with its sustainable design
approach, the Denver Courthouse
expansion will also reduce operations
and maintenance costs and will rely, in
part, on non-polluting renewable energy
sources. Descriptions of the facility’s
specific low-energy, high-performance
features follow.
High-Performance Glazing
Taking full advantage of Denver’s sunny,
dry climate, a high-performance, tripleglazed
curtain wall system is used on
the court tower to minimize HVAC heating
and cooling loads, while affording
dramatic views and a source of natural
light for adjacent courtroom and conference
spaces. Aseries of PV cells are integrated
into the curtain wall system, providing
a clean, renewable source of
power, as well as a visible representation
of the government’s commitment
to climate-responsive, sustainable
architecture.
Daylighting
The daylighting design for the Denver
Courthouse expansion is based on a
conscious separation of view glass from
daylighting-specific glass. The system
provides for maximum daylight harvesting
and usage to reduce electric
lighting loads during the day, as well as
occupant satisfaction based on a strong
sense of connection with the outdoors.
Perimeter light shelves are incorporated
throughout the high-rise section of the
building and are positioned at the junction
between the view and the daylight
glazing. The shelves diffuse daylight
onto the ceiling plane and adjacent surfaces,
thus minimizing contrast ratios
between interior surfaces and elements
viewed through the glazing. This, in
turn, serves to increase visual comfort
and improves the quality of the view
to the outside.
Energy-Efficient Electric Lighting
The facility’s artificial lighting system is
designed to supplement daylight and
will use a combination of direct and
indirect luminaries with T-5 fluorescent
lamps and dimmable electronic ballasts,
together with compact fluorescent and
metal halide downlights and wall
washers. Illumination levels are
designed to work in tandem with daylighting
and high-performance glazing
systems to provide a balanced luminous
environment with low energy consumption.
Photocell controls will be used in
conjunction with electronic fluorescent
dimming ballasts to save energy in
areas receiving daylight, while lowlevel
ambient lighting enhanced by
occupant-controlled task lighting will
illuminate areas not served by daylighting.
Occupancy sensors will control
lighting in private offices.
Displacement Ventilation
The ventilation systems that serve the
courtrooms, various offices, and public
corridor spaces incorporate displacement
ventilation air distribution. This
system features low-velocity air introduced
at floor level to efficiently condition
the space and remove indoor air
pollutants.
Evaporative Cooling System
Much of the building’s cooling and
humidification loads are met using an
indirect and direct evaporative cooling
system, which provides a cooling effect
through water evaporation. This process
greatly reduces the need to run an electric-
powered chiller. Denver’s dry climate
makes this system ideal for much
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The U.S. Courthouse Expansion in Denver, Colorado, will be a showcase for sustainable
building design.
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F E D E R A L E N E R G Y M A N A G E M E N T P R O G R A M
of the cooling season; indeed, computer
simulations show less than 100 full load
hours of chiller operation per year. The
system is also used to add humidity to
the building during the winter to
improve occupant comfort.
Variable Air Volume Systems (VAV)
Using Variable-Speed Drives (VSD)
The heating and cooling needs are further
addressed by a VAV air-handling
system, which adjusts supply air volumes
in response to the heating and
cooling needs of the various zones.
VSDs are installed on all fans and
pumps to reduce the energy consumption
of these devices during part-load
operation. The main air handler incorporates
four separate supply fans that
can be individually staged, allowing
for efficient operation of the system
down to 5% of design air flow. The
use of VSDs is especially important in
courthouse facilities, due to their variable
occupancy characteristics and
occasional nighttime use.
Building Automation System
Afull direct-digital-control system is
used to control the HVAC and lighting
systems. The system is designed to shut
down the HVAC and lighting systems in
unoccupied spaces and, in tandem with
the VAV air handling and pumping systems,
provides efficient operation under
partial occupancy.
Building-Integrated Photovoltaics
PV is integrated into the southeast curtain-
wall system adjacent to the public
corridor areas of the tower, and a skylight
is located over the security drum
element in the Special Proceedings
pavilion. Translucent, thin-film cells
are applied to the skylight and selected
panels in the curtain wall system, and
additional polycrystalline PV panels are
used as spandrel panels in the curtain
wall system. The PV panels provide
electricity during sunlight hours, reducing
peak electric demand. Battery storage
is not necessary, because system
output is greater than building demand.
Landscaping
Avariety of measures can be implemented
to optimize the landscape surrounding a
building. Among these, preservation of
existing landscape features should be
the designer’s first course of action.
Mature trees and vegetation are valuable
resources that take many years to
replace. Preserving them not only
allows for their use in natural shading
(and in some climates, as a wind break
or shelter belt), it also maintains existing
wildlife habitats, existing drainage patterns,
and soil conditions. Tree preservation
reduces the need for excavation,
transportation, and relocation of soil.
In addition, it reduces the need for supply
and transportation of fill and landscape
materials. When adding new
vegetation to a site, use regionally consistent
landscaping strategies, composed
of locally grown, native plants.
Water Efficiency
One of the most overlooked areas in
developing a whole-building design
strategy is the efficient use of water
resources. To process and use water,
the Federal government expends
59.2 billion Btu of energy on an annual
basis; more than 98% of this energy is
used to heat water. Thus, significant
energy and dollar savings can be realized
by implementing water-efficient
measures. Water efficiency is the
planned management of water to prevent
waste, overuse, and exploitation
of the resource. Effective water-efficiency
planning seeks to “do more with
less,” without sacrificing comfort or
performance. Water-efficiency planning
is a relatively new management practice
that involves analyzing cost and water
usage, specifying water-saving solutions,
installing water-saving measures,
and verifying the savings to quantify
results.
Avariety of water conservation technologies
and techniques can be used to save
water and associated energy costs,
including:
• Water-efficient plumbing fixtures
(e.g., ultra-low-flow toilets and urinals,
waterless urinals, low-flow and sensored
sinks, low-flow showerheads, and
water-efficient dishwashers and washing
machines)
• Reducing water use associated with
irrigation and landscaping (water-efficient
irrigation systems, irrigation-control
systems, low-flow sprinkler heads,
water-efficient scheduling practices,
and xeriscaping)
• Graywater and process recycling systems
that recycle or reuse water
• Reducing water use in HVAC systems.
Demand-side management methods
reduce the amount of water consumed
on-site at a facility and include system
optimization, water conservation measures,
and water reuse and recycling systems.
Other efficiency options include
leak detection and repair, industrial
process improvements, and changing
the way fixtures and equipment are
operated and maintained.
National Renewable Energy Laboratory’s
Thermal Testing Facility, Golden, Colorado
NREL’s Thermal Testing Facility (TTF) is
an open-space laboratory building comprised
of high-bay laboratory areas,
offices, and conference rooms. Design
of the 10,000-square-foot building
began early in 1994, and construction
was completed in the summer of 1996.
Performance monitoring has been
underway since occupancy. Although
the TTF was designed to serve as a
laboratory, the technologies discussed
in this case study are appropriate to a
wide range of commercial buildings,
offices, warehouses, and institutional
facilities. Sustainable design strategies
integrated into the building include:
• Passive solar features
• Efficient electric lighting
• Daylighting features
• Occupancy sensors
• Efficient HVAC design
• Energy management system with
direct digital control (DDC).
The TTF’s design team included an architect,
mechanical engineer, electrical
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engineer, structural engineer, buildingowner
facilities staff, and an energy
consultant. From the outset, the team
focused on optimizing the interactions
among the building’s various systems,
taking into account the influence of
building occupants, their daily activities,
and climatic conditions in the surrounding
area. Energy-related design decisions
were based in part on the results
of computer simulations using DOE 2
(1994). The building’s owner (U.S. DOE)
and eventual occupants (NREL staff)
determined necessary building criteria
at the outset of the design phase. The
type of spaces required included flexible
generic laboratory space, assorted openarea
support offices, a conference room,
washrooms, and a kitchenette area.
Once the building’s use was established,
the design team and NREL research
engineers set a building energy cost
reduction goal of 70%, and a strategic
design and construction plan was developed
to serve as a “road map” to guide
the process. The plan included integrating
passive solar features, low building
load coefficient, efficient electric lighting,
daylighting features, occupancy sensors,
efficient HVAC design, and an energy
management system with DDC.
With a Congressional budget of $1.5 million
to cover all design, construction, and
commissioning costs, a code-compliant
base case was created for the TTF’s
design, using 10 CFR 435 (1995) as the
reference. (The base-case design is a
useful benchmark for gauging the relative
cost effectiveness of both individual
and collective performance improvements.)
The base case was simulated
using SERI-RES to study the thermal
aspects of the building, and DOE 2.2
for HVAC and lighting studies.
Initial base-case results showed that electrical
lighting loads accounted for a large
portion of the energy use—roughly 73%,
not including plug loads. Cooling loads
were next, at 15% of the building’s total
energy consumption. Based on this
information, the NREL research staff
believed that internal heat gains could
be minimized by reducing the electric
lighting load and by minimizing
unwanted solar gains. This was accomplished
by integrating daylighting and
efficient artificial lighting strategies,
specifying high-performance windows,
and by engineering the dimensions of
overhangs. By minimizing the cooling
load, the design team was also able to
downsize the HVAC system in comparison
to what would have been required
in the base-case scenario.
Computer modeling indicated that the
largest energy savings could be achieved
by reducing the electric lighting load.
Reducing plug loads had a similar effect,
but plug loads are not related to the
building envelope design. Reducing
infiltration, controlling ventilation and
unwanted solar gains, and improving
the building’s opaque envelope all produced
similar energy-saving results.
In addition, the facility’s interior was
arranged to free up additional floor area.
By moving the mechanical room from
the exterior east wall to a location above
the central core (where the restrooms,
storage, and kitchen areas are located),
an additional 800 square feet of laboratory
floor space was created without a
concomitant increase in energy use. The
TTF’s final low-energy design achieved
its energy reduction goal by applied
energy-efficient design strategies as
described below.
Passive Solar Design
To take advantage of Colorado’s sunny
climate, the TTF integrates many passive
solar features, including appropriate
siting and building orientation. The
design also incorporates a small amount
of thermal mass in the slab floor and
north wall of the building, and the
north wall also acts as a retaining wall
for a mesa, providing the thermal benefits
of earth berming. Among the facility’s
most important features, however,
are the proper selection, orientation,
and placement of windows and
clerestories.
The building was carefully engineered
to provide passive solar gain in the winter
months, while minimizing this gain
during the summer. The final design
incorporates 88% of its total fenestration
as a single row of view glass and two
rows of clerestories along the southern
façade. An additional 8% of view glass
is divided equally between the east and
west façades, while the remaining 4% is
positioned on the north wall. South-facing
clerestory windows were designed
with a high SC of 0.76 (SHGC of 0.68),
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The National Renewable Energy Laboratory’s Thermal Testing Facility shows how sustainable
design strategies can be integrated into a variety of commercial buildings, offices, warehouses,
and institutional facilities.
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F E D E R A L E N E R G Y M A N A G E M E N T P R O G R A M
while all others have a lower SC of 0.51
(SHGC of 0.45). The higher SCs allow
more solar gain to enter the building.
In addition, all windows have a low-e
coating, which prevents the transmission
of most non-visible spectrum light
and unwanted solar gain. The careful
design and placement of overhangs
rounds out the picture by blocking
direct solar radiation during the summer
when sun angles are high, while
allowing direct solar radiation in winter,
when sun angles are much lower.
Overall, the TTF’s envelope and its passive
solar features were designed to heat
the building during the day and into the
evening hours, such that the only heat
load on the building will take place
during the morning hours. Bear in mind
that the glazing configurations and other
passive solar strategies described above
are very much site- and applicationspecific
and will not necessarily apply
to different building types in other locales.
Thermal Envelope
The TTF’s floor is constructed of a 6-inch
concrete slab with 4-foot perimeter insulation.
The north wall is constructed of
an 8-inch concrete slab with 2 inches of
rigid polystyrene, while the east, west,
and south walls use 6-inch steel studs
with batt insulation positioned between
the studs. Expanded polystyrene is
placed over the entire exterior surface,
which is finished with Exterior Insulation
and Finish System (EIFS) stucco.
The roof is constructed using metal
decking atop steel supports with a
3-inch polyisocianurate covering. The
thermal insulation positioned on the
wall exterior creates an energy sink
within the building, which dampens the
building’s natural temperature swings.
For example, during cold winter nights,
when outdoor temperatures drop well
below freezing, the TTF’s indoor temperature
drops by only 10ºF.
Lighting
The TTF is illuminated by a dynamic
combination of electric lighting and
daylighting, depending on real-time
occupancy status and daylight luminance
values. Astair-stepped design
is integral to the daylighting plan; daylight
enters the building through a row
of view glass and two additional rows
of clerestories lining the south façades
of the open office areas, mid-bays, and
high-bays, respectively. Additional
windows exist along the east, west,
and north walls to balance incoming
daylight. Again, all windows are engineered
to take full advantage of daylighting
opportunities.
Asensor that measures illumination levels
controls the building’s supplemental
electric lighting system, and the building’s
energy management system (EMS)
uses this information to control electric
lighting status, depending on the amount
of natural light available in each lighting
zone. In terms of lighting systems, the
facility uses T-8 and compact fluorescent
lighting, 72% of which provides supplemental
lighting to daylit zones, while
the remaining 28% provides primary
lighting to the building’s central core.
The EMS-integrated occupancy control
protocol uses passive infrared and ultrasonic
occupancy sensors to disengage
lighting when not required. Together,
these features have significantly reduced
the building’s (lighting-based) electrical
use as well as its cooling load, while
heating loads increased only slightly
during the winter months.
Heating, Ventilation, and Air
Conditioning
Because the TTF minimizes HVAC
requirements, a smaller, more efficient,
and less expensive HVAC system was
installed. Actually, the TTF uses two
separate HVAC systems: a VAV air
handling unit (AHU) to serve the main
building, and a packaged single-zone
AHU to serve the conference room.
The VAV unit relies on direct and indirect
evaporative cooling as its primary
cooling source, supplemented by ceiling
fans, which help reduce the temperature
stratification that is common in spaces
with large ceiling heights.
The TTF’s efficient HVAC design limited
the total amount of ductwork throughout
the building, which, in turn, reduces
material costs during construction, as
well as maintenance thereafter. All ductwork
is insulated and located indoors
to reduce losses to the outside environment
and bordering zones.
Energy Management System
The TTF uses a digital building control
system for most mechanical building
operations. This EMS allows for easy
monitoring, tuning, and diagnosis,
helping to keep the building operating
as designed. The EMS operates each of
the HVAC units and the electrical lighting
system and also collects diagnostic
and performance data. Two tankless
heat-on-demand water heaters provide
the facility with domestic hot water
(DHW): one serving the kitchen and the
other dedicated to the washrooms. Both
units are natural gas-fired and provide
80% thermal efficiency.
The Technology in
Perspective
Technology Development
Since ancient times, people have designed
buildings for the local climate, taking
advantage of natural daylight and prevailing
winds. Today, these same principles
apply to low-energy building
design but are combined with what we
have learned about energy conservation;
advanced materials, products, and
mechanical systems; renewable energy;
and energy performance design tools.
When designed in tandem, technology
clusters, such as energy-efficient lighting,
occupancy sensors, and daylighting
strategies, can reduce a building’s energy
load and improve occupant comfort.
Federal energy managers can be assured
that sound, climate-responsive design
will yield long-term energy savings
regardless of fluctuations in energy
prices and will serve as the basis for
durable, comfortable, environmentally
sound buildings. Advances in other key
technologies will further transform the
building industry. New design and
analysis tools have greatly improved
the designer’s ability to predict building
energy performance, while giving energy
managers better control over operations
and maintenance costs. As these
tools continue to be refined and their
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F E D E R A L E N E R G Y M A N A G E M E N T P R O G R A M
use becomes more commonplace, lowenergy
building design will emerge as
the only logical approach to new construction
and renovation.
Technology Outlook
The technologies, systems, and design
strategies discussed in this guidebook
are helping to ensure a bright future for
low-energy buildings. As consumers
continue to demand more sustainable
development and wise environmental
stewardship from their elected leaders,
the Federal government is uniquely
positioned to take the lead in making
its own buildings as energy efficient
as possible, and at the same time
making them more comfortable and
attractive than their conventional counterparts.
It is likely, however, that institutional
barriers (e.g., restrictive codes,
procedures, budget processes) will have
to be revised or removed before the Federal
sector can fully meet this challenge.
This guidebook is a tangible step toward
achieving more widespread use of wholebuilding
energy design and analysis
because it makes the process more comprehensible
for all project team members.
There is also an important role for
those who develop new Federal guidelines
and requirements that encourage
the use of low energy and renewable
energy strategies. Though often unsung,
these individuals are laying the cornerstone
for meaningful, enduring change.
When starting your next project, remember
that an accurate assessment of lowenergy
design features and technologies
comes from a clear understanding—not
just of how the many components of a
building work—but of how they work
together. This often begins with an
awareness that the current, highly fragmented
building process is not producing
the best results, and that a new view
of the building as a system of interdependent
components is required.
Product Resources
Avast array of products for low-energy
buildings are available from suppliers
of traditional building materials as well
as from manufacturers of specialized
technologies, such as PV systems.
Because passive solar buildings are
design intensive, it also is useful to
know how to locate design professionals
with special expertise in low-energy
building design. For information on
products and professional services,
please refer to the following resources,
as well as building product suppliers.
Air-Conditioning and Refrigeration
Institute
Arlington, Virginia
Phone: 703-524-8800, 800-AT-ARIES
Web site: http://www.ari.com
American Institute of Architects
Committee on the Environment
Washington, D.C.
Phone: 202-626-7515
Web site: http://www.e-architect.com
Architects’ First Source for Products
Web site: http://www.afsonl.com
APA—The Engineered Wood
Association
Tacoma, Washington
Phone: 206-565-6600
Web site: http://www.apawood.org
Association of Home Appliance
Manufacturers
Chicago, Illinois
Phone: 312-984-5800
Building Design Assistance Center
Florida Solar Energy Center
E-mail: bdac@fsec.ucf.edu
Web site: http://www.fsec.ucf.edu/~bdac/
Manufactures and supplies controls (i.e.,
dimming systems, motion/occupancy
sensors, power reducers, switching systems),
energy management systems,
glazing (e.g., glass, windows, window
films, skylights), insulation systems and
radiant barriers, lighting (e.g., energy
efficient ballasts, lamps, luminaries, exit
lighting, specular reflectors), and roofing
(e.g., energy-efficient reflective coatings,
paints, tiles, shingles).
Center for Renewable Energy and
Sustainable Technology (CREST)
Web site: http://www.crest.org
Gas Appliance Manufacturers Association
Arlington, Virginia
Phone: 703-525-9565
Greening Federal Facilities: An Energy,
Environmental, and Economic Resource
Guide for Federal Facility Managers
(1997). U.S. DOE/FEMP
Phone: 800-DOE-EREC
Web site: http://www.eren.doe.gov/ femp/
techassist/greening.html
Primary Glass Manufacturers Council
Topeka, Kansas
Phone: 785-271-0208
Structural Insulated Panel Association
Phone: 253-858-SIPA(7472)
Web site: http://www.sips.org
Sustainable Buildings Industry Council
(formerly Passive Solar Industries
Council)
Washington, D.C.
Phone: 202-628-7400
E-mail: SBIC@SBICouncil.org
Web site: http://www.sbicouncil.org
Sustainable Building Sourcebook
Green Building Program
Austin, Texas
Web site: http://www.greenbuilder. com/
sourcebook
Sustainable Building Technical Manual:
Green Building Design, Construction and
Operations (1996).
Public Technology, Inc.
U.S. Green Building Council
U.S. DOE/U.S. EPA.
U.S. Green Building Council
San Francisco, California
Phone: 415-543-3001
E-mail: info@usgbc.org
Web site: http://www.usgbc.org
Who is Using the Technology
Thousands of low-energy buildings and
homes have been constructed throughout
the United States, many by the
Federal government. The GSA has used
low-energy approaches for some of its
buildings. Several Federal facilities that
feature low-energy design strategies are
in the design phase, under construction,
or recently completed, including an
environmental learning center on the
National Mall in Washington, D.C., and
a 570,000-square-foot Federal courthouse
in Phoenix, Arizona. The National Park
Service (NPS) has integrated passive
36
F E D E R A L E N E R G Y M A N A G E M E N T P R O G R A M
solar strategies into new employee housing
units. NPS houses in Grand Canyon
and Yosemite National Parks are included
in the DOE Exemplary Buildings program.
Projects have been completed or
are in progress at Grand Teton National
Park, Hovenweep National Monument,
and Capitol Reef National Park. The
Department of Defense is also using
these low-energy strategies.
Federal Sites
Excellence in Facility Management, Five
Federal Case Studies (1998).
National Institute of Building Sciences
Phone: 202-289-7800
E-mail: nibs@nibs.org
Web site: http://www.nibs.org/
fmochome.htm
The case studies included in this document
are: (1) U.S. Department of Agriculture
Headquarters, (2) Carbondale
Federal Building, (3) Merritt Island
Launch Annex, (4) Naval Station
Everett, and (5) Defense Logistics
Agency.
National Park Service Employee
Housing at Capitol Reef National Park
National Renewable Energy Laboratory
High-Performance Buildings Program
Golden, Colorado
Phone: 303-275-3000
Web site: http://www.nrel.gov/buildings/
highperformance
Detailed case studies of state-of-the-art,
low-energy buildings; pictures are available
for download.
The Naval Facilities Engineering Command
has completed several projects
that demonstrate low-energy design
principles. Aphysical fitness center at
Camp Pendleton, California; a $7.8 million
project in Sugar Grove, West
Virginia; and a restoration project at
the Washington Navy Yard.
Brown, Linda R. “SERF: ALandmark in
Energy Efficiency.” (May/June 1994).
Solar Today, American Solar Energy
Society.
U.S. Fish and Wildlife Service National
Education and Training Center, Sheperdstown,
West Virginia. AFEMP case
study will soon be available. Among a
host of energy-efficient features, the
center incorporates passive solar design
strategies. In winter, large southern windows
capture solar gain, and brick floors
behind windows store heat. Windows
are made of high-performance glass.
In summer, extended rooflines (overhangs)
and landscaping provide optimum
shading. Some windows are fitted
with sunscreens, which also help reduce
summer cooling loads.
Non-Federal Sites
Besser Company manufacturing facility,
Alpena, Michigan. By Innovative Design.
Energy conservation, daylighting.
Blue Cross/Blue Shield building in New
Haven, Connecticut. The 21,000-squarefoot
building has deep overhangs on
the south façade to protect it from direct
solar radiation in summer and to reduce
cooling loads. An atrium divides the
building into two sectors. Light shelves
on façades and in the atrium project natural
light deep into the space. The project
was completed in 1990; Ellenzweig
Associates, Inc., were the architects.
Brown Summit Youth Dormitory cabins,
North Carolina. By Cooper-Lecky
CUH2A, LLP. Natural ventilation.
Buildings for a Sustainable America Case
Studies, American Solar Energy Society,
303-443-3130, ases@ases.org, http://www.
ases.org/solar and Sustainable Buildings
Industry Council (formerly Passive
Solar Industries Council), 202-628-7400,
SBIC@SBICouncil.org, http://www.
sbicouncil.org, with funding from U.S.
Department of Energy. Acollection of
18 case studies, with easy-to-read summaries,
thorough project details, and
photographs.
The Florida Solar Energy Center (FSEC)
is building a state-of-the-art complex
(office building, visitor’s center, and
laboratories) for its new facility in
Cocoa, Florida. The objective is to
design and construct the most energyefficient
facility possible within the limits
of Florida’s hot and humid climate. For
a detailed analysis of the low-energy
design strategies used, check the FSEC
Web site: http://www.fsec.ucf.edu/About/
TOUR/Tourhome.htm
Illinois Department of Energy and
Natural Resources
Contact: R. Forrest Lupo
Phone: 217-785-3484
Massachusetts State Transportation
Building, Boston, Massachusetts
Asolar water-heating system installed in
1982 cost $250,000 but saves $26,280 per
year in avoided electricity costs. At this
rate, the system will pay for itself in 9.5
years. Four thousand square feet of
closed-loop propylene glycol solar collectors
enable the solar water heaters
to operate year-round, even though the
outside temperature is below freezing
for extended periods of time. The collectors
supply 83% of the building’s annual
domestic hot water needs, offsetting
roughly 5,800 gallons of oil annually.
Contact: Martha Goldsmith, Director,
Office of Leasing
Commonwealth of Massachusetts
Phone: 617-727-8000
Sacramento Department of Transportation
Building
Uses nighttime flushing and passive
solar cooling with atrium.
Contact: Craig Hoellwarth
Phone: 916-683-8378
Union of Concerned Scientists building
Cambridge, Massachusetts
Phone: 617-547-5552
E-mail: energy@ucsusa.org
Web site: http://www.ucsusa.org
Utah Department of Natural Resources
(profiled in Solar Today, American Solar
Energy Society, July/August 1997)
For Further Information
Trade/Professional Organizations
American Council for an Energy
Efficiency Economy (ACEEE)
Alliance to Save Energy
American Institute of Architects
Committee on the Environment
Washington, D.C.
Phone: 202-626-7515
Web site: http://www.e-architect.com
37
F E D E R A L E N E R G Y M A N A G E M E N T P R O G R A M
American Portland Cement Alliance
Washington, D.C.
Phone: 202-408-9494
Web site: http://www.portcement.org
American Solar Energy Society
Phone: 303-443-3130
E-mail: ases@ases.org
Web site: http://www.ases.org
American Society of Heating,
Refrigeration, and Air-Conditioning
Engineers (ASHRAE)
Atlanta, Georgia
Phone: 404-636-4800
Web site: http://www.ashrae.org
American Society for Testing and
Materials
West Conshocken, Pennsylvania
Phone: 610-832-9500
Web site: http://www.astm.org
Association of Energy Engineers
Atlanta, Georgia
Phone: 770-447-5083
Web site: http://www.aeecenter.org
Building Owners and Managers
Association International
Washington, D.C.
Web site: http://www.boma.org
Brick Institute of America,
Mid East Region
North Canton, Ohio
Phone: 330-499-3001
Brick Industry Association
Reston, Virginia
Phone: 703-620-0010
Web site: http://www.bia.org
Ceilings and Interior Systems Construction
Association
St. Charles, Illinois
Phone: 630-584-1919
Electricity Consumers Resource Council
Washington, D.C.
Phone: 202-682-1390
Energy Efficient Building Association
(EEBA)
Minneapolis, Minnesota
Phone: 612-851-9940
E-mail: EEBANews@aol.com
Illuminating Engineering Society of
North America
New York, New York
Phone: 212-248-5000
International Masonry Institute
Ann Arbor, Michigan
Phone: 313-769-1654
National Association of Energy Service
Companies
Washington, D.C.
Phone: 202-822-0952
National Association of Home Builders
Washington, D.C.
Phone: 202-822-0200 (bookstore: extension
463)
Web site: http://www.nahb.com
National Concrete Masonry Association
Herndon, Virginia
Phone: 703-713-1900
Web site: http://www.ncma.org
National Electrical Manufacturers
Association
Rosslyn, Virginia
Phone: 703-841-3200
National Fenestration Rating Council
Silver Spring, Maryland
Phone: (301) 588-0854
Web site: http://www.nfrc.org
National Institute of Building Sciences
Phone: 202-289-7800
E-mail: nibs@nibs.org
Web site: http://www.nibs.org/fmochome.htm
National Society of Professional
Engineers
Alexandria, Virginia
Phone: 703-684-2800
Web site: http://www.nspe.org
National Wood Window and Door
Association
Des Plaines, Illinois
Phone: 847-299-5200
Web site: http://www.nwwda.org
North American Insulation Manufacturers
Association
Alexandria, Virginia
Phone: 703-684-0084
Web site: http://www.naima.org
North Carolina Solar Center
Phone: (919) 515-3480
Northeast Sustainable Energy
Association
Phone: 413-774-6051
E-mail: buildings@nesea.org
Web site: http://www.nesea.org
Solar Energy Industries Association
Washington, D.C.
Web site: http://www.seia.org
Southface Energy Institute
Atlanta, Georgia
Phone: 404-872-3549
E-mail: info@southface.org
Web site: http://www.southface.org
Sustainable Buildings Industry Council
(SBIC) (formerly Passive Solar
Industries Council)
Washington, D.C.
Phone: 202-628-7400
E-mail: SBIC@SBICouncil.org
Web site: http://www.sbicouncil.org
U.S. Green Building Council (USGBC)
San Francisco, California
Phone: 415-543-3001
E-mail: info@usgbc.org
Web site: http://www.usgbc.org
Design Guides
Designing Low-Energy Buildings: Passive
Solar Strategies and ENERGY-10 Software;
Passive Solar Design Strategies: Guidelines
for Home Building; Low-Energy, Sustainable
Building Design for Federal Managers (Sustainable
Buildings Industry Council [formerly
Passive Solar Industries Council])
Phone: 202-628-7400
E-mail: SBIC@SBICouncil.org
Web site: http://www.sbicouncil.org
General Services Administration/Public
Buildings Service—Proposed Comprehensive
Building Commissioning
LEED™ (Leadership in Energy and Environmental
Design) Rating System,
Version 2.0, available at
http://www.usgbc.org
Sustainable Building Technical Manual:
Green Building Design, Construction and
Operations, Public Technology, Inc.
U.S. Green Building Council
U.S. DOE, U.S. EPA, 1996.
Whole Buildings Design Guide, a federally
sponsored, vertical portal to a wide
range of building specific criteria, technology,
and product information.
Web site: http://www.wbdg.org
38
F E D E R A L E N E R G Y M A N A G E M E N T P R O G R A M
Utility, Information Service, or Government
Agency Tech-Transfer Literature
Utility Sources
American Gas Association
Arlington, Virginia
Web site:http://www.aga.com
Edison Electric Institute
Washington, D.C.
Phone: 202-508-5557
Web site: http://www.eei.org
The Electricity Consumers Resource
Council
Washington, D.C.
Phone: 202-682-1390
E-mail: elcon@elcon.org
Web site: http://www.elcon.org
Electric Power Research Institute
Palo Alto, California
Phone: 650-855-2000
Web site: http://www.epri.com
National Association of Regulatory
Utility Commissioners
Washington, D.C.
Phone: 202-898-2200
Web site: http://www.naruc.org
National Association of State Utility
Consumer Advocates
Washington, D.C.
Phone: 202-727-3908
Web site: http://www.nasuca.org
Public Utilities Reports
Vienna, Virginia
Phone: 703-847-7720, 800-368-5001
E-mail: info@pur.com
Web site: http://www.pur.com/
General Information Sources
Energy Design Update
Cutter Information Corp.
37 Broadway, Suite 1
Arlington, Massachusetts 02174-5552
Phone: 800-964-5118
Web site: http://www.cutter.com/energy/
Environmental Building News
RR 1, Box 161
Brattleboro, Vermont 05301
Phone: 802-257-7300;
Web site: http://www.ebuild.com
E Source, Inc.
Boulder, Colorado,
Phone: 303-440-8500
Web site: http://www.esource.com
Florida Solar Energy Center
Phone: 407-638-1015
Web site: http://www.fsec.ucf.edu
International Energy Agency
Web site: http://www.iea.org
Iris Catalog: Publications, Videos and Software
for Green Construction
Iris Communications, Inc.
P.O. Box 5920
Eugene, Oregon 97405-9011
Phone: 800-346-0104
Web site: http://www.oikos.com
ReInState, a guide to state-by-state renewable
energy and sustainable development
resources, including case studies,
products and services, utility information,
programs and policies, and energy
usage and design data for each state.
Web site: http://www.crest.org/gem.html
American National Standards Institute
Government Sources
Energy Efficiency and Renewable
Energy Clearinghouse
Merrifield, Virginia,
Phone: 800-363-3732
E-mail: erec@nciinc.com
Web site: http://www.eren.doe.gov
Energy Science and Technology
Software Center
Web site: http://www.osti.gov/estc
Federal Laboratory Consortium
1850 M Street, NW, Suite 800
Washington, D.C. 20036
FLC Locator: 609-667-7727
Web site: http://www.Federallabs.org/
Guiding Principles of Sustainable Design
U.S. Department of the Interior
National Park Service
Denver, Colorado: GPO, 1993.
Lawrence Berkeley National Laboratory
Berkeley, California
Phone: 415-486-5771
Web site: http://www.lbl.gov/
National Energy Information Center
Washington, D.C.
Phone: 202-586-1181
E-mail: infoctr @eia.doe.gov
National Institute of Standards and
Technology
Washington, D.C.
Web site: http://www.nist.gov
National Oceanic and Atmospheric
Administration (NOAA)
Phone: 704-271-4800
E-mail: orders@ncdc.noaa.gov
Web site: http://www.ncdc.noaa.gov
National Renewable Energy Laboratory
Web site: http://www.nrel.gov/buildings/
highperformance
National Technical Information Service
Washington, D.C.
Phone: 800-553-6847
Web site: http://www.fedworld.gov
Oak Ridge National Laboratory
Building Technology Center
Web site: http://www.ornl.gov/ornl/btc
Office of Scientific and Technical
Information
Oak Ridge, Tennessee
Phone: 423-576-1188. Technical reports:
423-576-8401
Partnership for Advancing Technology
in Housing (PATH)
U.S. Department of Housing and Urban
Development
Phone: 202-708-1600
Web site: http://www.pathnet.org
Procuring Low-Energy Design and
Consulting Services: A Guide for Federal
Building Managers, Architects, and
Engineers, 1997
Phone: 800-DOE-FEMP
Web site: http://www.eren.doe.gov/femp/
Sacramento Municipal Utility District
Phone: 916-732-6679
Sandia National Laboratories
Phone: 505-844-3077
Web site: http://www.sandia.gov/EE.htm
U.S. Department of Energy
Building Technology
State and Community Programs
Phone: 202-586-2998
U.S. Environmental Protection Agency
Energy Star Program
Web site: http://www.epa.gov
Codes and Standards
Executive Order 13123 mandates
improvements in energy efficiency
and water conservation in Federal
buildings nationwide, including costeffective
investments (payback of less
39
F E D E R A L E N E R G Y M A N A G E M E N T P R O G R A M
than 10 years) in low-energy building
design and active solar technologies.
10 CFR 435 establishes performance standards
to be used in designing new
Federal commercial and multifamily
high-rise buildings. Some of the guidelines
are relevant to retrofits.
10 CFR 436 establishes procedures for
determining the life-cycle cost effectiveness
of energy conservation measures
and for prioritizing energy conservation
measures in retrofits of existing Federal
buildings.
In general, building codes and standards
address specific technologies and minimum
requirements for building energy
efficiency. They do not address whole
building performance. Awell-designed,
low-energy building can exceed existing
Federal codes, as well as commercial
code (ASHRAE 90.1—Energy Efficient
Design of New Buildings Except Low-
Rise Residential Buildings), by as much
as 50%.
Documents and Other References
American Institute of Architects, Com -
mittee on the Environment, Energy,
Environment and Architecture, Washington,
D.C., 1991.
Ander, Gregg, Daylighting Performance
and Design, New York, New York, Van
Nostrand Reinhold, 1998.
Balcomb, J. Douglas, editor. Passive Solar
Buildings. Cambridge, Massachusetts,
MIT Press, 1992.
Bobenhausen, William, Simplified Design
of HVAC Systems. New York, John Wiley
and Sons, Inc., 1994.
Idea exchange among facility managers
Web site: www.fmdata.com
Interstate Renewable Energy Council
15 Haydn Street
Roslindale P.O.
Boston, Massachusetts 01131-4013
Phone: 617-323-7377
International Energy Agency Solar
Heating and Cooling Programme.
Passive Solar Commercial and Institutional
Buildings: A Sourcebook of Examples and
Design Insights. West Sussex, United
Kingdom, John Wiley and Sons, Ltd.,
1994.
National Institute of Building Sciences
www.nibs.org
Productivity Studies
• www.workplaceforum.com
• Miller, Burke, Buildings for a Sustainable
America Case Studies; Daylighting
and Productivity at Lockheed, Boulder,
Colorado, American Solar Energy
Society.
• Joseph Romm and William Browning,
Greening the Building and the Bottom Line:
Increasing Productivity through Energy-
Efficient Design, Snowmass, Colorado,
Rocky Mountain Institute, 1994.
Steven Winter Associates, Inc., The
Passive Solar Design and Construction
Handbook, New York, John Wiley and
Sons, Inc., 1998.
Tuluca, Adrian; Steven Winter Associates,
Inc., Energy-Efficient Design and
Construction for Commercial Buildings.
New York, McGraw-Hill, 1997.
40
F E D E R A L E N E R G Y M A N A G E M E N T P R O G R A M
41
Appendixes
Appendix A: Climate and Utility Data Sources
Appendix B: Federal Life-Cycle Costing Procedures and the Building Life Cycle Cost (BLCC) Software
F E D E R A L E N E R G Y M A N A G E M E N T P R O G R A M
42
Appendix A: Climate and Utility Data Sources
Energy User News includes a ranking of electricity and gas utility prices by state in each of its monthly issues. Available at
http://www.energyusernews.com.
NOAAprovides detailed available climate data and summaries for sites in or near a locality. Call 704-271-4800, e-mail requests
to orders@ncdc.noaa.gov, or available on the World Wide Web at http://www.ncdc.noaa.gov.
Opportunities for Renewable Energy Supply in New Buildings (Solar Potential Maps). ABuildings for a Sustainable America Education
Campaign Resource from the Sustainable Buildings Industry Council, Washington, D.C. Funded by the U.S. DOE, researched
and produced by Mark Kelley and Henry Amistadi of Building Science Engineering in Harvard, Massachusetts. For more information,
call 202-628-7400, send e-mail to SBICouncil@aol.com, or access the SBIC Web site at http://www.sbicouncil.org.
Putting Energy into Profits. U.S. Environmental Protection Agency, #430-B-97-040, December 1997. Five U.S. climate zones are
mapped, showing average annual energy use and average annual energy costs for specific building types. Available from
Government Printing Office, Superintendent of Documents, Washington, DC 20402, or call 202-512-1800.
Appendix B: Federal Life-Cycle Costing Procedures and the Building Life Cycle Cost (BLCC)
Software
Federal agencies are required to evaluate energy-related investments on the basis of life-cycle costs (10 CFR 436). Life-cycle cost
analysis (or life-cycle costing [LCC]) is a means of predicting the overall cost of building ownership, including initial costs, operating
costs for energy, water and other utilities; personnel costs; and maintenance, repair, and replacement costs. LCC analyzes
changes to the building, including all significant costs over the predicted life of the building. It can be used to refine the design
to ensure the facility will provide the lowest overall cost of ownership consistent with its desired quality and function.
Analysis tools such as the National Institute of Standards and Technology’s (NIST) BLCC computer program performs calculations
to predict life-cycle costs, providing an economic analysis of proposed capital investments that are expected to reduce longterm
operating costs of buildings. BLCC is designed to comply with 10 CFR 436. ERATES (electricity rates) is another computer
program from NIST that calculates monthly and annual electricity costs for a facility under a variety of electric rate schedules.
ERATES block-rate and demand-rate schedules can be imported by BLCC. BLCC is available from the FEMP Help Desk at
800-566-2877.
F E D E R A L E N E R G Y M A N A G E M E N T P R O G R A M
Federal Energy Management Program
The Federal Government is the largest energy consumer in the nation. Annually, in its 500,000 buildings and 8,000 locations
worldwide, it uses nearly two quadrillion Btu (quads) of energy, costing over $8 billion. This represents 2.5% of all primary
energy consumption in the United States. The Federal Energy Management Program was established in 1974 to provide
direction, guidance, and assistance to Federal agencies in planning and implementing energy management programs that
will improve the energy efficiency and fuel flexibility of the Federal infrastructure.
Over the years, several Federal laws and Executive Orders have shaped FEMP’s mission. These include the Energy Policy
and Conservation Act of 1975; the National Energy Conservation and Policy Act of 1978; the Federal Energy Management
Improvement Act of 1988; and, most recently, Executive Order 12759 in 1991, the National Energy Policy Act of 1992
(EPACT), Executive Order 12902 in 1994, and Executive Order 13123 in 1999.
FEMP is currently involved in a wide range of energy-assessment activities, including conducting New Technology
Demonstrations, to hasten the penetration of energy-efficient technologies into the Federal marketplace.
The Energy Policy Act of 1992, and subsequent
Executive Orders, mandate that
energy consumption in Federal buildings
be reduced by 35% from 1985 levels
by the year 2010. To achieve this goal, the
U.S. Department of Energy’s Federal
Energy Management Program (FEMP)
is sponsoring a series of programs to
reduce energy consumption at Federal
installations nationwide. One of these
programs, the New Technology Demonstration
Program (NTDP), is tasked to
accelerate the introduction of energyefficient
and renewable technologies
into the Federal sector and to improve
the rate of technology transfer.
As part of this effort, FEMP is sponsoring
a series of publications that are designed
to disseminate information on new and
emerging technologies. New Technology
Demonstration Program publications
comprise three separate series:
Federal Technology Alerts—longer
summary reports that provide details
on energy-efficient, water-conserving,
and renewable-energy technologies
that have been selected for further
study for possible implementation in
the Federal sector.
Technology Installation Reviews—
concise reports describing a new technology
and providing case study results,
typically from another demonstration
program or pilot project.
Technology Focuses—brief information
on new, energy-efficient, environmentally
friendly technologies of potential
interest to the Federal sector.
About FEMP’s New Technology Demonstration Program
For More Information
FEMP Help Desk
(800) 363-3732
International callers please use
(703) 287-8391
Web site: www.eren.doe.gov/femp
General Contacts
Ted Collins
New Technology Demonstration
Program Manager
Federal Energy Management
Program
U.S. Department of Energy
1000 Independence Ave., SW, EE-92
Washington, D.C. 20585
Phone: (202) 586-8017
Fax: (202) 586-3000
theodore.collins@ee.doe.gov
Steven A. Parker
Pacific Northwest National
Laboratory
P.O. Box 999, MSIN: K5-08
Richland, WA 99352
Phone: (509) 375-6366
Fax: (509) 375-3614
steven.parker@pnl.gov
Technical Contact
Nancy Carlisle
National Renewable Energy
Laboratory
1617 Cole Boulevard, M.S. 2723
Golden, CO 80401
Phone: (303) 384-7509
Fax: (303) 384-7411
Nancy_Carlisle@nrel.gov
Prepared for the U.S. Department of
Energy by the National Renewable
Energy Laboratory, a DOE national
laboratory
DOE/EE-0249
July 2001
F E D E R A L E N E R G Y M A N A G E M E N T P R O G R A M
Printed with a renewable-source ink on paper containing at least 50% wastepaper, including 20% post consumer waste
Log on to FEMP’s New Technology Demonstration Program
Web site
http://www.eren.doe.gov/femp/prodtech/newtechdemo.html
You will find links to:
• An overview of the New Technology Demonstration Program
• Information on the program’s technology demonstrations
• Downloadable versions of program publications in Adobe Portable
Document Format (PDF)
• A list of new technology projects underway
• Electronic access to the program’s regular mailing list for new products
when they become available
• How Federal agencies may submit requests for the program to assess
new and emerging technologies.