Energy conservation, especially as applied to the built environment, can be simply defined as deliberately choosing to use less purchased energy, particularly electricity, natural gas, and fuel oil (Huelman 2012). Energy conservation in the built environment is generally accomplished through (1) modifications to, or management of, the equipment within a building (such as adjusting thermostat settings for heating and cooling), (2) improvements in the structure and envelope of the building (such as increasing insulation or installing more efficient lighting), and/or (3) lifestyle and building usage changes (such as dressing in layers of clothing to allow lower thermostat settings within the building or managing window treatments to allow control of sunlight during the changing seasons).
Energy conservation as an important tenet in building design and construction has increased in importance since the 1970s. The reduction of energy use in the built environment is critical due to the amount of energy used in this sector. For example, approximately 40% of energy use in the United States is in buildings (How much energy… 2017).
During the post-World War II era of the 1950s and 1960s, increasing energy consumption was generally equated with a growing and strong economy. Emphasis on increasing electrical energy use was particularly tied to developing technology and a rising standard of living. However, especially in the United States, growing tensions and conflict in, and with, the oil-producing regions of the Middle East became important factors in an increasing concern for energy conservation.
More recently, concern about increased concentrations of greenhouse gases in the atmosphere, from the burning of fossil fuels, and the impact on climate change and global warming has again put greater focus on energy conservation. Greenhouse gases in the earth’s atmosphere allow the transmission of sunlight but absorb outgoing infrared radiation. The gases function much like glass does in a greenhouse – thus the term greenhouse gases. Greenhouse gases raise the temperature of the earth and, in fact, contribute to the planet’s habitability. However, since the mid-nineteenth century, the concentration of carbon dioxide (CO2) in the earth’s atmosphere has been increasing and dramatically rising in the last 30–40 years. CO2 is a by-product of burning of fossil fuel and is considered the most influential greenhouse gas (Kutscher 2007). The result of increasing greenhouse gases in the earth’s atmosphere includes rising sea levels from thermal expansion of the water and melting glaciers, also contributing to higher sea levels. Changing climate patterns from rising atmospheric temperatures contribute to higher temperatures, drought, and increased storm severity (Kutscher 2007).
Energy conservation is deliberately using less energy. It is an important goal to especially limit the use of the finite supply of fossil fuels. Conservation is generally considered an economic advantage as the supply of energy tends toward rising and/or volatile costs. Energy conservation provides benefits of efficient use of energy sources, increased national security, environmental restoration, and the opportunity for sustainable prosperity (Krigger and Dorsi 2012). Nevertheless, energy conservation can also be seen to limit economic growth, especially in the development of energy-intensive products and technologies.
Energy conservation is generally the most direct and cost-effective policy to reduced energy use (Huelman 2012; Krigger and Dorsi 2012). Typically, conservation applications can be implemented with the lowest cost compared to other approaches to reducing total energy use, such as technological innovation. Energy conservation can be mandated. Examples of this approach include thermostat controls in public buildings and the phasing out of incandescent lighting in the US marketplace. However, change is not easy, and conservation policies can be politically unpopular. Energy conservation is often a personal choice that can affect comfort, cost, and convenience and require personal commitment. Energy conservation, particularly in buildings, requires changes in habits, lifestyle, and building operation (Huelman 2012).
Energy conservation can be accomplished through education which inspires voluntary reduction in energy use. Choices can be made to increase energy conservation by opting to function at minimum levels of energy intensity and specifically to cut back, or reduce, energy use patterns (Emmel 2003b). While voluntary conservation is admirable, it is not a consistent and dependable path toward a broad implementation of energy use reductions. Energy conservation can also be accomplished through various governmental policies and controls. However, political issues and conflicting priorities can interfere with the successful implementation of conservation policies and controls.
Alternative Terms and Ideas
There are alternatives to addressing energy issues other than to just use less. Concepts related to energy conservation include energy efficiency, energy management, and sustainability.
Energy efficiency goes beyond conservation through increased function and performance to more effectively use energy (Emmel 2003b). Energy efficiency in the built environment can be increased by energy-conserving design and construction and choosing the most efficient materials, construction methods, lighting, and equipment (Emmel 2003b). Energy efficiency can also provide greater comfort for the same energy input. Energy efficiency has been referred to as wise energy use as emphasizing efficiency emphasizes economic benefit (Krigger and Dorsi 2012). The net result of energy efficiency is less energy used (input) for the same functions (output) (Huelman 2012).
Energy efficiency tends to require a larger upfront investment as compared to conservation (Huelman 2012). However, an important concept to consider, related to energy efficiency, is life cycle cost (Emmel 2003b). Life cycle cost is considering the total cost to purchase, operate, and maintain a building or piece of equipment over its expected period of operation or usefulness. Energy efficiency, therefore, takes on a more critical role. An initial investment in a more expensive but energy-efficient choice may, in fact, be less expensive to own and operate over its intended lifespan. Thus, making energy-efficient choices can actually result in energy conservation.
Energy management is a corollary to both energy conservation and energy efficiency. Energy management involves developing strategies to maximize energy efficiency while minimizing (or conserving) energy use (Emmel 2003a). Typical strategies of energy management include practicing energy conservation. Energy management in the built environment is more proactive in that it includes design and construction of the built space to minimize energy use, plus equipment choices that will achieve energy efficiency.
Sustainability is a future-reaching concept related to energy use. There are multiple definitions of sustainability, but all encompass the concept of using resources (energy) today within appropriate limits that will not deplete these resources for future generations (Emmel 2003b). The increasing emphasis on sustainability, over the more direct approach of energy conservation, emerged in the 1980s, particularly as applied to the built environment (Kibert 1999).
Many discussions of sustainability reference the Seventh Generation Principle and credit it to the Great Law of the Haudenosaunee or the Iroquois Confederacy (Murphy 1997; Kayanerehkowa n.d.). There are numerous translations or wordings that say, in essence, in our every deliberation, we must consider the impact of our decisions on the next seven generations. Although the law of the Iroquois Confederacy was developed hundreds of years before the current concerns about energy conservation, its respect for future generations is a model for thinking about sustainability.
The concept of sustainability today has become much broader, especially with respect to the built environment. Among the ideas or issues that are frequently included in the goal to be sustainable are increased use of renewable energy, reductions in waste and pollution, limits on greenhouse gas emissions, protection of natural areas and biodiversity, and population stabilization (Kibert 1999). Today there is much emphasis on sustainable planning, design, and construction in the building industry. However, energy conservation, or energy management, remains a critical component (Davis and Fisher 2015; Orr 1999).
Energy Use Trends
Total energy use in the residential built environment has stayed about the same, while the total number of housing units has increased.
Proportionally, use of energy for space heating has decreased, while energy use for air conditioning has increased.
Energy use for appliances and electronics has increased dramatically as a proportion of total energy use (Huelman 2012).
However, in the typical American home, space heating is the largest energy use, followed by electrical technology (appliances, lighting, and electronics) and water heating (Huelman 2012).
The United States uses a variety of energy sources: petroleum (36%), natural gas (28%), coal (18%), renewable energy (10%), and nuclear electric power (8%) (Monthly Energy Review 2018). In the last 5–10 years, consumption of petroleum and natural gas has increased, whereas coal consumption has decreased. There has been a small increase in renewable energy use, while nuclear electric power use has been stable (as a percentage of the whole).
Many factors effect energy consumption trends, including political issues in the home country as well as internationally, population growth (or decline), technological developments, economic growth, and environmental concerns. For example, the trends discussed above are certainly influenced by the greater development of shale oil, especially through hydraulic fracturing (fracking), and oil sands.
Electricity is a secondary energy source that is generated from another energy source, such as coal, petroleum, or wind. In the United States, 63% of electricity is generated from fossil fuels (What is US electricity… 2018). The major sources of fuels for electricity generation are coal (43%), natural gas (22%), petroleum (less than 1%), and renewable energy, particularly hydropower and wind (13%) (What is US electricity… 2018). As with the total energy supply, the use of coal for electricity generation has decreased in recent years, while natural gas has increased. Renewable energy for electricity is slowly increasing.
Electricity as an energy source for the built environment needs to be considered differently than other fuel primary energy sources such as petroleum or coal. Electricity is a generated secondary energy source. The efficiency of this generation process is typically 30% or less, especially if transmission losses are included (Emmel 2003b; Huelman 2012; Krigger and Dorsi 2012). However, most electrical equipment and appliances used in the built environment are approximately 100% efficient. Electrical heating/cooling systems, such as heat pumps, can be upwards of 150% efficient (Emmel 2003b).
Renewable resources generally include solar, wind, hydropower (water), geothermal (heat sources underground or in the earth), and biofuels (biomass or fuels from plant matter). Many believe that increasing use of renewable energy sources is the most important energy policy and the future for energy security. Increasing use of renewable resources is highly compatible with energy conservation and efficiency. The more efficient we are in using energy and successful in reducing overall demand for energy, the more successful and sustainable we can be in using renewable energy sources. Therefore, energy conservation can be seen as a critical policy in bridging the gap between dependence on fossil fuels to primary use of renewable energy (Krigger and Dorsi 2012).
Technological developments that have improved renewable energy generation and lowered costs, thus increasing overall efficiency in the use and availability of renewable energy.
Concern for the impact of energy use on the environment has increased, especially as it relates to issues of the burning of fossil fuels or the development and placement of pipelines to transport oil and gas. However, renewable energy resources are not without environmental controversy. Examples include the destruction of natural habitat resulting from damming waterways to produce hydropower and the threat that wind turbines can bring to migratory birds.
Renewable resources are generally localized. For example, generating electricity from wind, water, or sunlight occurs where these sources are found. Therefore, greater use of renewable resources can increase a country’s national security and positively affect their international trade balance. If a country is more self-sufficient in their energy supply, they are less dependent on other countries for energy purchases. This is particularly important if the country selling the energy is unstable or hostile to the purchasing country. It also means that the energy-purchasing country is sending less money out of their country.
One advantage to using renewable energy is that there are multiple sources and opportunities to develop renewable sources. The successful implementation of renewable resources depends on using what is available in a location to full advantage. The Climate Reality Project identified 11 countries that are making and implementing a major, long-term commitment to renewable energy. These top countries were (in descending order) Sweden, Costa Rica, Nicaragua, Scotland, Germany, Uruguay, Denmark, China, Morocco, the United States, and Kenya (Follow the leader 2016). Located around the world, these countries capitalized on the various renewable resources in their locations, including solar, wind, geothermal, and hydropower.
Energy Conservation in the Built Environment
As previously discussed, voluntary energy conservation requires personal commitment and can be difficult to accomplish across society. As a result, various mandatory governmental policies have been put in place to increase energy conservation and efficiency (Huelman 2012). In tandem with government mandates, nonregulatory programs have also been developed with the goals of increasing energy efficiency and promoting energy conservation. These policies and programs include standards, codes, product labeling, certifications, and other similar strategies.
There are multiple reasons for the growth of these policies and programs since the 2000s, including cost savings as energy prices increased, growing concern about the environmental impacts related to energy use, and public health concerns (Turcotte 2012). Additionally, programs and policies for energy conservation became more proactive in approaching energy conservation by greater focus on building design and technological solutions to reduce energy use and the integration of renewable energy (Turcotte 2012). The policies and programs related to energy conservation are critical to establish safety and performance levels, to assist in consumer decision-making, and to specifically identify energy-conserving and energy-efficient products (Emmel 2003c).
A standard is prepared by a recognized standard setting organization (Emmel 2003c). Standards, such as those typical in the design and construction industries, are usually prepared by qualified and recognized professionals. A written standard would be extensively reviewed by experts knowledgeable on the topic as well as people from the public and businesses potentially affected by the standard. Standards developed by recognized organizations are often used as the basis for the development and updating of building codes.
Standard 62.1-2016 Ventilation for Acceptable Indoor Air Quality.
Standard 90.2-2007 Energy Efficient Design of Low-Rise Residential Buildings.
Standard 100-2018 Energy Efficiency in Existing Buildings.
Standard 189.1-2014 Standard for the Design of High Performance Green Buildings.
Another important standard related to energy conservation is the Residential Energy Services Network (RESNET). The Home Energy Rating System (HERS) of RESNET is used for rating home energy use with a standard numerical scale that evaluates factors in home energy use and is based on the International Code Council’s (ICC) energy code (About HERS 2018). A new home built to the code would be evaluated as 100. Ratings less than 100 are more energy efficient, exceeding the code requirements; greater than 100 signifies a less energy-efficient home. The HERS rating system has been recognized by the American National Standards Institute (ANSI) as a national standard for rating energy efficiency. The ICC’s International Energy Conservation Code (IECC) requires an energy rating index, and HERS is the primary index used in the residential building industry. The HERS index is also used extensively in the mortgage lending industry. Projected energy usage of a home, based on the HERS score, could influence availability of mortgage funds, with more efficient, lower energy-using homes possibly qualifying for a better mortgage rate or amount.
Codes are legal requirements adopted within a specific political jurisdiction (Emmel 2003c). Codes will define what is acceptable in structural design and construction of buildings within the jurisdiction. Codes may be written as specification codes that detail specific requirements. For example, a code might specify the minimum height of a ceiling, the width of a stairway tread, or the size of a window. Codes may also be written as performance codes which gives options in how to achieve the end results. Examples of performance codes include the R-value required in a wall structure (but not specify the type of insulation or design of the wall system to achieve the R-value) or the air exchange rate required for ventilation in the structure (but not specify the design, size, and type of ventilation equipment required).
Model codes represent the consensus of expert professionals and are similar to standards in their development and purpose. A model code developed by a qualified professional association is often adopted into a jurisdiction’s legal code. Model codes are generally considered minimum standards with the expectation that the municipality adopting the code will make additions or changes to reflect needs, goals, and issues related to the locality. For example, climate issues such as wind, storms, and snow loads are common reasons for adapting model codes.
The International Code Council (ICC) develops model codes for the design and building industry with the goal of construction of safe, sustainable, affordable, and resilient structures (About ICC 2018). Most jurisdictions in the United States now use one or more of the model ICC codes as the basis for their mandated codes. While the code development process is ongoing, major codes are typically revised and updated on a 3-year cycle. Two of the ICC model codes relate specifically to energy conservation: the International Energy Conservation Code (IECC) and the International Green Construction Code.
Labels are designed to assist with purchase decisions by providing standardized and impartial information about the product (Emmel 2003c). Labels provide a visible identification that can help consumers compare energy usage among types and models of products. As with standards and codes, the development of standardized labels involves professionals and industry experts in the design, writing, and review of the labels.
A well-known label that relates to energy conservation is the EnergyGuide label for appliances and similar equipment (Emmel 2003c). The EnergyGuide label was introduced by the US Federal Trade Commission in 1980. It is a mandatory program for designated appliances and equipment that are identified as having variation in energy use among models. The bright yellow EnergyGuide label on a specific piece of equipment provides comparisons to energy use of other similar models and gives a basis for choosing a product that is more energy efficient. Similar programs are found in other countries, such as Canada’s EnerGuide.
A certification involves an independent, third-party verification that a product (or building) meets specific standards or performance measures. Certification can provide documentation that a product contributes to energy conservation and efficiency and that claims made about the product are valid. Many certification programs use product labels to create visible and identifiable information about the product certification.
Energy Star is voluntary certification program for residential equipment and structures that provides a certified product with a recognizable logo and label (Emmel 2003c; About Energy Star 2018). This well-known and extensive program is a partnership of two agencies of the US government: Environmental Protection Agency (EPA) and Department of Energy. Energy Star requires third-party testing and certification of energy consumption and performance in a facility recognized by the EPA. To achieve Energy Star certification, there must be evidence of significant contribution to energy savings. Any increased cost for energy efficiency features of the tested product must be recoverable in a reasonable time from energy savings. Over 70 product categories are eligible for Energy Star certification.
There are numerous programs that certify buildings for energy use. Most of these certifications include environmental factors in addition to energy use in the certification program, such as water efficiency, waste management, indoor air quality, and site development. Taken as a group, these certifications are promoting the development of green buildings. There are many similar definitions of a green building, including using a set of design, construction, and maintenance techniques and practices that minimize a building’s total environmental impact (Kruger and Seville 2013). It is critical to note that a green building cannot be developed and certified without prime attention to energy conservation and efficiency. Increasingly, green building also encompasses the use of renewable energy (Turcotte 2012).
ICC/ASHRAE 700-2015 Green Building Standard™ of the National Association of Home Builders
Leadership in Energy and Environmental Design (LEED) of the US Green Building Council
Building Research Establishment Environmental Assessment Method (BREEAM) of the Building Research Establishment (founded in England)
Energy Star Certified Homes
Living Building Challenge of the International Living Future Institute
Earthcraft of the Southface Energy Institute
Strategies for Implementing Energy Conservation in the Built Environment
The policies and programs discussed suggest multiple choices and opportunities to increase energy conservation and efficiency. An overall strategy is needed to guide choices and implementation. Obviously, mandatory programs must be accomplished. Yet, what are the most efficient and cost-effective approaches?
Make thermal improvements in the building shell or envelope to address unwanted heat loss or gain and air leakage.
Where possible, replace older energy-using devices (such as heating/cooling systems, appliances, and lighting) with new and more efficient equipment.
Repair and adjust existing energy-using equipment and distribution systems, including furnaces, boilers, air conditioners, and water heaters.
Educate building occupants/users about energy-efficient behavior and practices (Krigger and Dorsi 2012).
For greatest success, implementing energy conservation measures should begin with an energy audit, such as might be provided by a utility company or an advocacy organization (Huelman 2012). The energy audit can help determine where there are specific opportunities for energy conservation and efficiency measures as well as helping to determine what might be the most cost-effective strategies.
Negative Consequences of Energy Conservation
One end result of the implementation of energy conservation changes in a building is to reduce uncontrolled ventilation and decrease air changes between inside the building and outside. This is desirable to control unwanted heat loss and to improve overall building energy efficiency. However, as buildings get “tighter” to conserve energy use, an unfortunate by-product is an increase in indoor air quality issues. Reduced building ventilation also results in increased concentration of moisture and toxins in indoor air (Emmel 2003a; Juzych 2003; Parrott 2003; Parrott and Atiles 2018). These toxins can include carbon dioxide from human breathing; off-gassing from cleaning products, chemicals, materials, and furnishings; incomplete venting of combustion by-products (backdrafting); and biological pollutants, including molds, animal dander, and insect residue (Parrott 2003).
Reduce the need for ventilation by greater control of indoor pollutants, including venting all combustion sources direct to the outside, selecting products and materials that minimize off-gassing of pollutants, controlling moisture production, and reconsidering behavioral choices and activities within the indoor environment that produce pollutants.
Use cost-effective heat recovery mechanical ventilation when appropriate to the building use, season, and climate.
Use controlled exhaust ventilation appropriate to locations and activities within the building, such as providing a ventilation fan over a gas range.
Increase natural ventilation in climates and seasons not requiring use of heating or cooling systems (Parrott 2003).
Energy conservation behavior is not always popular and can be considered as requiring a sacrifice. Following the energy shortages of the 1970s, many short-term changes in energy management resulted in buildings that were uncomfortable and had moisture and/or other indoor air quality problems. The result was a perception that energy conservation equated to being in buildings that were too hot or too cold, depending on the season. People’s clothing were not always appropriate to the building environment, and needed changes in clothing behavior were often resisted.
In the 1980s, when energy prices dropped in the United States and other countries, the short-term public perception was that the “crisis” was over because energy was now more affordable. People would no longer have to adapt to uncomfortable interior environments. Energy conservation behavior and choices were now less acceptable. This pattern has occurred over time as conservation and increased efficiency has reduced demand for energy sources and prices have dropped. Then a period of increasing energy demand and use follows, and increasing energy prices and energy conservation are once again more palatable (Swisher 2007).
What Is the Future of Energy Conservation?
Today, the talk is often more about sustainability and green buildings, then just conserving energy. Yet more than ever, there is a need for conserving and reducing the use of fossil fuels and for using all sources of energy as efficiently as possible.
Energy conservation, especially for the built environment, has moved beyond simply putting more insulation in the walls, caulking the windows, and turning down the thermostat. Today, the conversation about energy conservation and efficiency is including newer topics that reflect technological developments and greater public concern and awareness.
Life cycle costing for energy efficiency in the built environment includes the total cost to design, build, operate, maintain, and occupy a building over its expected useful life (Kellert 1999). Life cycle is a more complex but perhaps more realistic measure of the energy efficiency of a building. As more complex technological equipment and appliances are in buildings, hidden energy use also becomes important. Standby losses in equipment with instant-on features, remote controls, clock displays, and other features are not obvious, yet are constantly using energy and are part of total energy consumption in a building (Davis and Fisher 2015; Emmel 2003b; Kellert 1999; Krigger and Dorsi 2012; Kruger and Seville 2013).
In evaluation of the energy consumption, and potential for conservation, in the built environment, the concept of embodied energy in building materials is also of growing importance and concern (Davis and Fisher 2015; Kellert 1999; Krigger and Dorsi 2012; Kruger and Seville 2013). Embodied energy looks at the total energy involved “cradle to grave” of a building product. Embodied energy is a complex concept, but involves the idea that the energy used to develop (and transport) a product from the raw resource to its installation in a building through its useful life and disposal is part of the energy use attributed to a building. Therefore, building material and product choice to reduce embodied energy becomes part of the energy conservation equation for efficiency in the built environment. Embodied energy is typically measured in energy expenditure (MJs, megajoules, or BTUs, British thermal units) per weight or volume of the material.
Another concept that applies to the future of energy conservation is the idea of net-zero energy use buildings. A net-zero building is one that produces as least as much energy as it uses and has no carbon emissions from the use of fossil fuels (Laquatra 2018). A net-zero home would have a HERS score of 0. Net-zero buildings do still use some energy, such as for lighting, appliances, and ventilation. At the same time, they generate energy, such as from solar thermal, photovoltaic arrays, and/or wind turbines. Net zero is not necessarily the same as energy independent.
A final thought about energy conservation does not consider technology or policies and programs. Ethical consumption is a behavioral choice that can be applied to energy conservation (Newholm and Shaw 2003). People and households who practice ethical consumption typically espouse environmental priorities and practice socially responsible consumption of energy sources. More common in affluent countries, ethical consumers tend to make lifestyle choices, such as in housing, transportation, products, and eating habits, that seek to reduce their use of energy, particularly fossil fuels.
- About ASHRAE (2018) American Society of Heating, Refrigeration and Air-conditioning Engineers. Atlanta. www.ahsrae.org. Accessed 18 June 2018
- About Energy Star (2018) US Environmental Protection Agency and US Department of Energy, Washington, DC. www.energystar.gov. Accessed 18 June 2018
- About HERS (2018) Residential Energy Services Network. www.hersindex.com. Accessed 18 June 2018
- About ICC (2018) International Code Council, multiple locations. www.iccsafe.org. Accessed 18 June 2018
- Davis A, Fisher R (2015) Kitchen and bath sustainable design: conservation, materials, practices. Wiley, HobokenGoogle Scholar
- Emmel J (2003a) Energy and home usage. In: Miller J, Lerner R, Schiamberg L, Anderson P (eds) The encyclopedia of human ecology, vol 1. ABC-CLIO, Santa Barbara, pp 221–225Google Scholar
- Emmel J (2003b) Energy efficiency in the home. In: Miller J, Lerner R, Schiamberg L, Anderson P (eds) The encyclopedia of human ecology, vol 1. ABC-CLIO, Santa Barbara, pp 225–228Google Scholar
- Emmel J (2003c) Energy: standards, codes and labels. In: Miller J, Lerner R, Schiamberg L, Anderson P (eds) The encyclopedia of human ecology, vol 1. ABC-CLIO, Santa Barbara, pp 218–221Google Scholar
- Follow the leader (2016) The Climate Reality Project. Washington, DC. www.climaterealityproject.org. Accessed 18 June 2018
- How much energy is consumed in US residential and commercial buildings? (2017) US Energy Information Agency. Washington, DC. www.eia.gov/tools/faqs. Accessed 15 June 2018
- Huelman P (2012) Energy conservation. In: Carswell A (ed) The encyclopedia of housing, vol 1, 2nd edn. Sage, Thousand Oaks, pp 162–166Google Scholar
- Juzych N (2003) Air quality. In: Miller J, Lerner R, Schiamberg L, Anderson P (eds) The encyclopedia of human ecology, vol 1. ABC-CLIO, Santa Barbara, pp 46–50Google Scholar
- Kayanerehkowa. The Great Law of Peace (n.d.) www.ganienkeh.net/thelaw. Accessed 18 June 2018
- Kellert S (1999) Ecological challenge, human values of nature, and sustainability in the built environment. In: Kibert C (ed) Reshaping the built environment: ecology, ethics and economics. Island Press, Washington, DC, pp 39–53Google Scholar
- Kibert C (1999) The promises and limits of sustainability. In: Kibert C (ed) Reshaping the built environment: ecology, ethics and economics. Island Press, Washington, DC, pp 9–38Google Scholar
- Krigger J, Dorsi C (2012) Residential energy: cost savings and comfort for existing buildings. Saturn Resource Management, HelenaGoogle Scholar
- Kruger A, Seville C (2013) Green building: principles and practices in residential construction. Delmar, Cengage Learning, Clifton ParkGoogle Scholar
- Kutscher C (2007) The science and challenge of global warming. In: Kutscher C (ed) Tracking climate change in the US. American Solar Energy Society, Boulder, pp 165–172Google Scholar
- Laquatra J (2018) Sustainable housing. In: Anacker K, Carswell A, Kirby S, Tremblay K (eds) Introduction to housing, 2nd edn. University of Georgia Press, Athens, pp 341–355Google Scholar
- Monthly Energy Review (2018) Office of Energy Statistics, US Energy Information Agency. Washington, DC. www.eia.gov/totalenergy/data/monthly/pdf/mer.pdf. Accessed 15 June 2018
- Murphy G (1997) About the Iroquois Constitution. National Public Telecomputing Network. https://sourcebook.fordham.edu/mod/iroquois.asp. Accessed 18 June 2018
- Newholm A, Shaw D (2003) Consumption, ethical. In: Miller J, Lerner R, Schiamberg L, Anderson P (eds) The encyclopedia of human ecology, vol 1. ABC-CLIO, Santa Barbara, pp 148–151Google Scholar
- Orr D (1999) Architecture as pedagogy. In: Kibert C (ed) Reshaping the built environment: ecology, ethics and economics. Island Press, Washington, DC, pp 212–218Google Scholar
- Parrott K (2003) Healthy indoor air. In: Miller J, Lerner R, Schiamberg L, Anderson P (eds) The encyclopedia of human ecology, vol 1. ABC-CLIO, Santa Barbara, pp 350–353Google Scholar
- Parrott K, Atiles J (2018) Home environments and health. In: Anacker K, Carswell A, Kirby S, Tremblay K (eds) Introduction to housing, 2nd edn. University of Georgia Press, Athens, pp 316–340Google Scholar
- Swisher J (2007) Overall energy efficiency. In: Kutscher C (ed) Tracking climate change in the US. American Solar Energy Society, Boulder, pp 39–50Google Scholar
- Turcotte D (2012) Green building. In: Carswell A (ed) The encyclopedia of housing, vol 1, 2nd edn. Sage, Thousand Oaks, pp 250–255Google Scholar
- What is US electricity generation by energy source (2018) US Energy Information Agency. Washington, DC. www.eia.gov/tools/faqs. Accessed 18 June 2018