In the United States, direct energy use in buildings accounts for 39% of carbon dioxide emissions per yearmore than any other sector. Buildings contribute to a changing climate and warming of the earth in ways that will significantly affect future generations. Zero net energy (ZNE) buildings are a practical and cost-effective way to reduce our energy needs, employ clean solar and wind technologies, protect the environment, and improve our lives. Interest in ZNE buildings, which produce as much energy as they use over the course of a year, has been growing rapidly. In the Design Professional’s Guide to Zero Net Energy Buildings, Charles Eley draws from over 40 years of his own experience, and interviews with other industry experts, to lay out the principles for achieving ZNE buildings and the issues surrounding their development. Eley emphasizes the importance of building energy use in achieving a sustainable future; describes how building energy use can be minimized through smart design and energy efficiency technologies; and presents practical information on how to incorporate renewable energy technologies to meet the lowered energy needs. The book identifies the building types and climates where meeting the goal will be a challenge and offers solutions for these special cases. It shows the reader, through examples and explanations, that these solutions are viable and cost-effective. ZNE buildings are practical and cost-effective ways to address climate change without compromising our quality of life. ZNE buildings are an energizing concept and one that is broadly accepted yet, there is little information on what is required to actually meet these goals. This book shows that the goal is feasible and can be practically achieved in most buildings, that our construction industry is up to the challenge, and that we already have the necessary technologies and knowledge.
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About the Author
Charles Eley is an architect and mechanical engineer experienced in energy-efficient and sustainable design. He has advised in the design of many pioneering energy efficient buildings and has made significant contributions to the California energy standards, ASHRAE Standard 90.1, and other international standards and programs. Charles currently serves on non-profit boards, provides specialized consulting, and teaches classes on building energy efficiency and green technologies.
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Design Professional's Guide to Zero Net Energy Buildings
By Charles Eley
ISLAND PRESSCopyright © 2016 Charles Eley
All rights reserved.
Introduction: We Have But One Earth
Buckminster Fuller, the futurist and inventor, referred to Planet Earth as a spaceship, with the sun as its energy source. Our spaceship is far more advanced than the NASA shuttles, yet it is finite and delicate. It's our home and we need to take care of it. As Fuller said, "We are all astronauts."
The sun is responsible for all energy on Earth. Our reserves of oil and gas originate from plant materials grown from sun energy hundreds of millions of years ago. These fossil energy reserves are like wealth the Earth has saved for us. In the last 150 years, we have spent over half of this endowment. This is like working and saving for our entire career and then spending half of our lifetime savings in 15 minutes. This is clearly not sustainable; our savings will quickly (in geologic time) run out and we will have to start living within the limits of the energy income that is provided by the sun and quit gorging on the reserves built up over eons. But the more pressing problem is climate change. We have to leave most of the remaining reserves of coal, gas, and oil in the ground if we are to keep global warming within the 2°C (3.6°F) limit agreed to by most of the world's governments at Paris in December 2015. Climate change trumps peak oil.
The Threat of Climate Change
All of us share the Earth's atmosphere. Carbon dioxide (CO2) emissions in China show up in the readings atop Mauna Loa, and emissions from a coal-fired power plant in Ohio affect CO2 readings in China. If we are to address the problem of greenhouse-gas emissions and climate change, it must be done at the global scale. This does not mean that individual countries can't approach the problem differently and implement different solutions, but if we don't all work together, there will be little progress.
We have a special obligation in the United States to reduce CO2 emissions and address climate change, since we use much more energy per person than the rest of the world. With only 4.5 percent of the population, we consume about 19 percent of the world's energy.
Buildings are one of the largest energy users in the United States. Approximately 8.05 quads, or 28 percent of all natural gas consumption, is used directly in buildings and most of this is used for hot water and space heating. Approximately 75 percent of all electricity (9.4 quads) is used directly in buildings for a variety of purposes including air-conditioning, lights, and computers. The primary energy used to generate the electricity used in buildings is about three times greater that the energy that actually makes its way to the buildings, since so much is lost at the power plant and through the electricity distribution network.
In total, buildings used 39 percent of primary energy in 2015. This is mostly electricity and natural gas but also includes smaller contributions of petroleum and biomass. This is a lot of energy, and there are certainly many opportunities to reduce building energy use through smarter design, efficiency, on-site renewable energy, and operation, as discussed later in the book.
US energy consumption in 2014 resulted in 5.4 gigatonnes of CO2 being released to the atmosphere, about 15 percent of total global emissions. Generating electricity resulted in 2.04 gigatonnes of emissions, or 38 percent of the US total. Buildings in the United States accounted for 39 percent of all CO2 emissions in 2014. Transportation needs represent the second-largest share of CO2 emissions at 34 percent, and the location of our buildings within the urban fabric strongly influences this component of energy use (more on this in chapter 8). Industrial operations are next and represent about 18 percent. This includes emissions not only from energy consumption but from other industrial processes such as making cement.
Carbon emissions and energy use track each other very closely. Buildings directly use 39 percent of primary energy and are directly responsible for 39 percent of carbon emissions. In general, if you reduce energy use by 10 percent you thereby reduce carbon emissions by about the same amount. On the other hand, if you increase energy use you increase carbon emissions by the same percentage change.
Buildings represent enormous opportunities to save energy and reduce environmental impact. The green building movement has been under way for almost three decades, starting with the American Institute of Architects' Committee on the Environment in 1990 and the formation of the US Green Building Council in 1993. Energy efficiency is the single most important element of green buildings, but green buildings are about much more than energy efficiency. Green buildings also manage water movement and usage, are sited to avoid sensitive environmental areas like marshes and floodplains, and are efficiently constructed of materials that are sustainably produced or recycled. Green buildings also provide a healthy, comfortable, and productive interior environment that avoids the use of toxic material, meets high standards of air quality and thermal comfort, and provides occupants with abundant daylighting and views of the out-of-doors. Recognition programs such as LEED, Green Globes, and BREAM offer certificates for green buildings that meet their standards.
This book focuses on energy efficiency and renewable energy while respecting the broader goals of green buildings. It also raises the bar for energy efficiency and on-site renewable energy. A zero net energy (ZNE) building is one that uses no more energy on an annual basis than it produces. As can be seen in figure 1–4, the sum of all the energy delivered across the property line must be less than or equal to the sum of all the energy that is exported from the site. Energy transfers that happen inside the property line are not significant. The only thing that matters is what comes in and what goes out. The US Department of Energy (DOE) common definition of ZNE buildings allows the use of fossil fuels, but the production of electricity must be greater than the consumption of electricity by a margin adequate enough to make up for the use of gas, oil or any other non-electric energy that is delivered to the building. ZNE buildings go by other names as well: zero energy buildings (ZEB) and net-zero energy (NZE) buildings. Recognition programs for ZNE buildings are just beginning to emerge. The International Living Building Future and the New Buildings Institute have ZNE recognition programs.
We already have the knowledge and technology to design and construct our buildings to be zero net energy. Zero net energy buildings represent an excellent opportunity to reduce our energy use and help mitigate the impact of climate change. ZNE buildings are not a complete solution to climate change, but they are a good place to start: they represent something that is immediately achievable. This book is about how we can have an impact as we design, build, and use our buildings.
The Architecture 2030 Challenge calls for all new buildings to be ZNE by the year 2030. This policy has been adopted by the American Institute of Architects, the US Conference of Mayors, the American Society of Heating, Refrigeration, and Air-Conditioning Engineers (ASHRAE), the Congress for the New Urbanism, the American Solar Energy Society, the Society of Building Science Educators, and various other professional organizations. It has been adopted as policy in California with the goal that ZNE commercial buildings will be required by code by 2030 and residential buildings by 2020. The Energy Independence and Security Act requires that all federal buildings meet the challenge. More than three-fourths of the twenty largest architectural and engineering firms have adopted the challenge.
ZNE buildings are an energizing concept and one that is broadly accepted by professionals and laypersons alike, yet there is little information on what is required to actually design and construct a ZNE building. Is the goal feasible? Is our construction industry up to the challenge? Do we have the wherewithal and the technologies to meet the challenge? What will ZNE buildings look like? How much will they cost?
This book begins to answer these questions by laying out the principles for ZNE design and construction. The solutions offered are easy to implement. They do not require that we develop breakthrough technologies or new knowledge: the tools and technologies we need exist right now. Pioneering architects, engineers, and building owners have already achieved the goal of zero net energy in many of their buildings. We know how to do it. Leading designers, builders, and owners have shown us the way. However, we need the mainstream to take up the cause. It is not enough to have a few isolated examples; ZNE buildings must become the norm if we are to curb climate change and address other environmental problems.
While this book is written primarily for architects, engineers, energy consultants, green building advisors, and miscellaneous design and construction professionals, others will find the material useful. I have tried to present the information in simple terms with a minimum of technical jargon. Such technical information as is necessary is presented in graphic form or in sidebars.
Chapter 2 shows how we can design our buildings to be smarter, use far less energy, and improve environmental quality, all at the same time.
Chapter 3 recounts the remarkable development of renewable-energy systems in recent years; efficiency and reliability have improved and costs have declined.
Chapter 4 explains the principles of energy modeling and how it may be used to compare design options, assess the potential for achieving ZNE, and understand complex building interactions.
Chapter 5 details how to organize the building-project delivery system for success, to monitor energy performance, and to engage the building occupants.
Chapter 6 reviews the various metrics for ZNE accounting and evaluates offsite options when on-site ZNE is not possible.
Chapter 7 suggests some public policies and programs to extend ZNE from showcase examples to mainstream buildings.
The final chapter paints a vision of an energy future that goes beyond ZNE, minimizes the impact of climate change, and provides a livable world for our grandchildren.
An appendix has examples of low-energy and ZNE buildings that are referenced throughout the book.CHAPTER 2
Smart Building Design: Contextual Design, Energy Efficiency, and Curtailment
Our buildings use a lot more energy than they need to. Before making investments in renewable-energy systems, it is almost always more cost-effective to design our buildings to use as little energy as possible. This can be achieved in a number of ways. Through smart building design, we can harvest daylight, cool with outside air, heat with the sun, and take advantage of other natural processes that require very little additional energy. Better insulation reduces heat losses in the winter and gains in the summer. High-performance windows enable us to enjoy views and to harvest daylighting with minimal solar gain. By improving the energy efficiency of boilers, air conditioners, and fans, we can enjoy the same comfort conditions, but with less energy. We can also reduce energy use through curtailment, or what some call conservation. With curtailment, we find a way to get by with less. Maybe we don't really have to continually air-condition parts of the building that are rarely used. Contextual design, efficiency, and curtailment are closely related, and sometimes the lines between them become quite muddled.
In this chapter, I illustrate the fundamental principles of energy-efficient design through the stories and examples of architects, engineers, and owners who have found ways to design, build, and operate exceptional buildings. They share with us what has worked for them, ways of addressing common barriers, and techniques for achieving success.
Long Life, Loose Fit
The American Institute of Architects (AIA) Committee on the Environment (COTE) has been selecting its top ten green buildings every year for more than a decade, and the program has celebrated numerous exceptional buildings. As the program has developed, the committee has steadily refined the criteria for what constitutes a green building. One of the most important criteria is what the committee calls "Long Life, Loose Fit." If buildings are designed to last a long time and remain adaptable to different uses in the future, we will need to build fewer new buildings when we can more easily modify or adapt the old ones. This reduces embodied energy, which is the energy that is used to mine and process materials, manufacture building products, deliver them to the building site, and assembly them into the building.
Building structures, by their very nature, are permanent. Even temporary structures last much longer than intended. Building 20 on the MIT campus was built in 1943 by the military to house an emergency war effort to develop radar. It was never intended to be a permanent building, but it lasted for fifty-five years, providing space for innovations in radar, acoustics, linguistics, and computer science. When it was finally demolished in 1998, it was dubbed the "Magic Incubator" and was celebrated in commemoration of its former occupants and their achievements.
Building 20 was by all accounts an ugly building, clad with drab asbestos shingles, and was a poor example of energy efficiency: it was cold in the winter, hot in the summer. But its design and construction provide a great example of how a building can accommodate change. The three-story building stretched along Vassar Street, with four wings extending to the southeast. Circulation was provided by a central corridor that provided flexible space for building services. It was constructed of heavy wood timbers (because of the steel shortage during the war), which would support heavy equipment and a multitude of activities. A continuous band of operable windows around the perimeter provided daylight and natural ventilation. Because it was considered a temporary structure, the MIT building-management staff was less than vigilant, and tenants were free to knock down walls, build new ones, and basically modify the building to accommodate their needs. It was anything but a classy address, but it gave tenants the freedom to modify it as they saw fit. This freedom was an important factor in the multitude of innovations that had their birth there. Building 20 was the epitome of "loose fit." While it was never intended to have a "long life," it actually did.
Too often, we design our buildings to serve the needs of the first occupant, who may only use the building for five to ten years. Even worse, our buildings are sometimes so tightly tailored to that first use that it is very difficult for them to be adapted subsequently for other uses. Yogi Berra said, "It's tough to make predictions, especially about the future," but the construction of a building unavoidably represents a prediction of the future. In his wonderful book How Buildings Learn, Stewart Brand suggests that to achieve greater flexibility we should conduct scenario analysis at the programming phase, whereby we look not only at needs of the first occupant, but also the needs of possible future occupants as well as possible changes in technology, regulations, and economic competition that would affect future building use.
We can't possibly anticipate exactly how our buildings will be used in the future. Nevertheless, we should expect that the first uses will not be permanent and attempt to provide as much flexibility as we can for future adaptation. When the design team for the Rocky Mountain Institute was planning their new Innovation Center (see appendix), they kept office space flexible and adaptable to evolving work styles and technologies. They even installed some empty conduit to allow for inexpensive adaptation to future information technologies and DC wiring. Modular heating and cooling systems expand easily. Furthermore, durable finishes on both the interior and exterior will weather well and last for a century or more.
Urban warehouses and industrial space are also good examples of enduring buildings. We have seen how these heavy-timber structures with high ceilings, large floor plates, and generous windows have been remodeled to function as office space, residential lofts, schools, and retail space. Building services (heating, ventilation, and air-conditioning — "HVAC" — as well as lighting) have been replaced along with windows, but the basic structure and building envelopes have lasted and have proved to be adaptable.
High-rise office buildings also offer flexibility, but in a more limited way. Most often, office towers are designed with an inflexible core that houses restrooms, elevators, and service shafts, but the core is surrounded by a donut of flexible space. The size of the floor plate is determined by use but usually ranges between about 25,000 and 35,000 square feet. This provides an optimal mix of core services and surrounding tenant space.
Form and Configuration
An old maxim in architecture is that the most important decisions are made early in the design process, when the owner and design team decide where a new building will be located, how it will be positioned on the site, what the number of floors and the floor-to-floor height will be, how the major uses will be configured, and what the footprint will be. These decisions will have a century-long impact on future opportunities for daylighting, natural ventilation, lighting design, and HVAC, yet are often made with little forethought.
Excerpted from Design Professional's Guide to Zero Net Energy Buildings by Charles Eley. Copyright © 2016 Charles Eley. Excerpted by permission of ISLAND PRESS.
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Table of Contents
Preface Chapter 1 - We Have But One Earth Sources, Sinks and the Earth’s Limits Climate Change United States Energy Use ZNE Buildings Chapter 2 - Smart Building Design Long Life, Loose Fit Form and Configuration Building Envelope Lighting Systems and Visual Comfort Heating, Cooling, Ventilation and Thermal Comfort How Low Can We Go Chapter 3 - Here Comes the Sun The Potential Solar PV Technology Cost Effectiveness and Financing ZNE Feasibility Chapter 4 - Energy Modeling The Need for Energy Modeling Comparing Options Energy Performance Standards and Building Ratings Fixing the Baseline Scenario Analysis Chapter 5 - Making it all Work Project Delivery Methods Commissioning Building Management Systems Managing the Stuff Inside Chapter 6 - Metrics and Boundaries Operational vs. Asset Assessments Accounting for Energy Other Than Electricity Defining Renewable Energy Assessing ZNE for Multiple Buildings Expanding the Boundary Summary Chapter 7 - ZNE for the Mainstream Standards Making the Market Work ZNE and the Future Electric Utilities Chapter 8 -Beyond ZNE Indirect Building Energy Use New Urbanism A Vision for Our Grandchildren