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Real Prospects for Energy Efficiency in the United States (2010)

Chapter: 2 Energy Efficiency in Residential and Commercial Buildings

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Suggested Citation:"2 Energy Efficiency in Residential and Commercial Buildings." National Academy of Sciences, National Academy of Engineering, and National Research Council. 2010. Real Prospects for Energy Efficiency in the United States. Washington, DC: The National Academies Press. doi: 10.17226/12621.
×

2
Energy Efficiency in Residential and Commercial Buildings

The efficiency of the appliances and equipment used in homes and businesses has increased greatly over the past three decades. However, there is still much that can be done to reduce the amount and slow the growth of energy consumption in residential and commercial buildings.

This chapter describes how energy is used in buildings today and discusses the factors that have driven the growth of energy use. It then identifies opportunities for improving energy efficiency in the near term (through 2020) as well as the medium term (through 2030–2035). The chapter presents conservation supply curves that show the amount of energy that could be saved as a function of the cost of the saved energy and describes how whole-building approaches can produce new buildings with very low energy consumption. It reviews the market barriers to improving energy efficiency in buildings and presents some factors that are helping to overcome the barriers. Finally, the chapter presents the findings of the Panel on Energy Efficiency Technologies with regard to the potential for greater efficiency in residential and commercial buildings.

2.1
ENERGY USE IN BUILDINGS

In 2006, residential and commercial buildings accounted for 39 percent of the total primary energy used and 72 percent of the electricity used in the United States to supply power and fuel for heating, cooling, lighting, computing, and other needs. As Figures 2.1 (residential buildings) and 2.2 (commercial buildings) show, heating, ventilation, and air-conditioning (HVAC) consumed the most energy, followed by lighting.

Suggested Citation:"2 Energy Efficiency in Residential and Commercial Buildings." National Academy of Sciences, National Academy of Engineering, and National Research Council. 2010. Real Prospects for Energy Efficiency in the United States. Washington, DC: The National Academies Press. doi: 10.17226/12621.
×
FIGURE 2.1 Energy use in U.S. residential buildings by end-use, 2006.

FIGURE 2.1 Energy use in U.S. residential buildings by end-use, 2006.

Note: *, Energy Information Administration (EIA) adjustment factor that accounts for incomplete data in EIA’s sampling and survey methodology.

Source: Pew Center on Climate Change, based on data in DOE/EERE (2008), available at http://www.pewclimate.org/technology/overview/buildings.

FIGURE 2.2 Energy use in U.S. commercial buildings by end-use, 2006.

FIGURE 2.2 Energy use in U.S. commercial buildings by end-use, 2006.

Note: *, Energy Information Administration (EIA) adjustment factor that accounts for incomplete data in EIA’s sampling and survey methodology.

Source: Pew Center on Climate Change, based on data in DOE/EERE (2008), available at http://www.pewclimate.org/technology/overview/buildings.

Suggested Citation:"2 Energy Efficiency in Residential and Commercial Buildings." National Academy of Sciences, National Academy of Engineering, and National Research Council. 2010. Real Prospects for Energy Efficiency in the United States. Washington, DC: The National Academies Press. doi: 10.17226/12621.
×

On the residential side, this energy was used in approximately 80.8 million single-family homes, 24.8 million multifamily housing units, and nearly 6.9 million mobile homes in the United States as of 2006 (EIA, 2008b). On the commercial side, there were approximately 75 billion square feet (7 billion square meters) of floor space in 5 million commercial buildings as of 2006 (EIA, 2008b). The building stock is long-lived: homes can last 100 years or more, commercial buildings often last 50 years or more, and appliances and equipment used in buildings can last 10–20 years (IWG, 1997). Nonetheless, there have been significant changes in energy use and energy efficiency in buildings over the past 30 years.

Energy use in buildings has increased over the past 30 years, but at a rate slower than the rate of increases in gross domestic product (GDP). As shown in Figure 2.3, in the residential sector over the period 1975–2005, delivered-energy

FIGURE 2.3 U.S. residential energy use trends. Primary energy use (accounting for losses in electricity generation and transmission and distribution, and for fuels, such as natural gas, used on-site) has increased faster than delivered energy use (which does not account for such losses, but does include fuels used on-site) because use of electricity has increased faster than use of other fuels.

FIGURE 2.3 U.S. residential energy use trends. Primary energy use (accounting for losses in electricity generation and transmission and distribution, and for fuels, such as natural gas, used on-site) has increased faster than delivered energy use (which does not account for such losses, but does include fuels used on-site) because use of electricity has increased faster than use of other fuels.

Source: Data from EIA, 2007b.

Suggested Citation:"2 Energy Efficiency in Residential and Commercial Buildings." National Academy of Sciences, National Academy of Engineering, and National Research Council. 2010. Real Prospects for Energy Efficiency in the United States. Washington, DC: The National Academies Press. doi: 10.17226/12621.
×

use1 increased about 15 percent whereas primary energy use increased 46 percent. This difference is due to the growing electrification of energy use in homes. In 1975, direct fuel use in homes was four times that of electricity use in terms of end-use energy content, but by 2005 this ratio had fallen to about 1.4 to 1.

Understanding the potential for improvements in building energy efficiency requires detailed energy-use data beyond those presented in Figures 2.1 and 2.2, because the sector potential is composed of a long list of appliance-specific and building-specific measures. Unfortunately, much of the available data on energy use in buildings is based on self-reporting or inferences rather than on direct measurement, and estimates of uncertainties around the data are seldom available. Expanded data gathering, particularly through direct measurement, would facilitate more rigorous evaluation of energy efficiency measures and would contribute to the accuracy and completeness of future studies.

Growth in the use of a variety of electrical appliances is one factor contributing to the growth of energy use in buildings in recent decades. Figure 2.4 shows the penetration (the percentage of U.S. households having an appliance) of selected appliances in U.S. households between 1980 and 2005. During this period the percentage of households having central air-conditioning more than doubled, and the penetration of microwave ovens increased by more than a factor of six and that of dishwashers by 57 percent. Personal computer use was essentially nonexistent in 1980, yet by 2005, 68 percent of all U.S. households had a personal computer. In addition, 56 percent of households had cable television service, nearly 22 percent had a satellite dish antenna, and more than 27 percent of households had at least one large-screen television as of 2005 (DOE, 2009).

Compared with the residential sector, the commercial sector experienced much faster growth in energy use over the period 1975–2005: delivered-energy use in the commercial sector increased approximately 50 percent, and primary energy use increased 90 percent (Figure 2.5). As in the residential sector, the growing electrification of energy use in the commercial sector led to a faster rise in primary energy use than in delivered-energy use (DOE, 2008a).

Residential energy intensity, defined as energy use per square foot of living space, declined over the past 30 years in spite of the growing penetration of

1

“Delivered” energy refers to the electricity delivered to a site plus the fuels used directly onsite (e.g., natural gas for heating water). This measure does not account for the losses incurred in generating and transmitting and distributing the electricity. Delivered energy plus these losses is referred to as “primary” energy. See Box 1.4 in Chapter 1.

Suggested Citation:"2 Energy Efficiency in Residential and Commercial Buildings." National Academy of Sciences, National Academy of Engineering, and National Research Council. 2010. Real Prospects for Energy Efficiency in the United States. Washington, DC: The National Academies Press. doi: 10.17226/12621.
×
FIGURE 2.4 Household appliance penetration trends. “Penetration” is the percentage of U.S. households having the appliance specified. Data for personal computers are unavailable before 1990.

FIGURE 2.4 Household appliance penetration trends. “Penetration” is the percentage of U.S. households having the appliance specified. Data for personal computers are unavailable before 1990.

Source: U.S. Department of Energy, Energy Information Administration. Data through 2001 are from Regional Energy Profiles, Appliance Reports, Table 1: Appliances in U.S. Households, Selected Years, 1980–2001, available at http://www.eia.doe.gov/emeu/reps/appli/all_tables.html. Data for 2005 are from 2005 Residential Energy Consumption Survey—Detailed Tables, available at http://www.eia.doe.gov/emeu/recs/recs2005/hc2005_tables/detailed_tables2005.html.

appliances (see discussion below). However, the rate of decline depends on how energy intensity is measured. Total delivered-energy use per household fell 31 percent over the period 1978–2005, while primary energy use per household fell 16 percent (Table 2.1). Although household size in terms of square feet of floor area has been increasing, leading to a steeper decline in primary energy use per square foot of floor area (DOE, 2008a), the number of people living in a typical household declined from 2.8 in 1980 to 2.6 in 2001 (Battles and Hojjati, 2005). Thus primary energy use per household member remained relatively constant over the period 1980–2005. Smaller households use less absolute energy than larger households do, but more energy is used per person in the former. The 2005 residential

Suggested Citation:"2 Energy Efficiency in Residential and Commercial Buildings." National Academy of Sciences, National Academy of Engineering, and National Research Council. 2010. Real Prospects for Energy Efficiency in the United States. Washington, DC: The National Academies Press. doi: 10.17226/12621.
×
FIGURE 2.5 U.S. commercial energy-use trends. Primary energy use (accounting for losses in electricity generation and transmission and distribution and for fuels, such as natural gas, used on-site) has increased faster than delivered energy use (which does not account for such losses but does include fuels used on-site) because use of electricity has increased faster than use of other fuels.

FIGURE 2.5 U.S. commercial energy-use trends. Primary energy use (accounting for losses in electricity generation and transmission and distribution and for fuels, such as natural gas, used on-site) has increased faster than delivered energy use (which does not account for such losses but does include fuels used on-site) because use of electricity has increased faster than use of other fuels.

Source: EIA, 2007b.

energy consumption survey showed that, on average, one-person households annually consumed 71 million Btu per capita; two-person households, 48 million Btu per capita; and three-person households, 35 million Btu per capita (DOE, 2009).

A geographic shift in population (e.g., that from the northeastern and midwestern regions of the United States to the more temperate southern and western regions of the country) was one of the factors leading to the decline in residential energy intensity. Energy intensity tends to be lower in the latter regions, especially on a delivered-energy basis. Improvements in energy efficiency resulting from the adoption of efficiency standards for appliances and the offering of utility-sponsored and government-sponsored demand-side management (DSM) programs also helped reduce residential energy intensity (Battles and Hojjati, 2005).

Suggested Citation:"2 Energy Efficiency in Residential and Commercial Buildings." National Academy of Sciences, National Academy of Engineering, and National Research Council. 2010. Real Prospects for Energy Efficiency in the United States. Washington, DC: The National Academies Press. doi: 10.17226/12621.
×

TABLE 2.1 Residential Sector Energy Intensity Trends

Year

Delivered (million Btu/household)

Primary (million Btu/household)

Primary (1000 Btu/ft2)

Primary (million Btu/household member)

1978

138

204

 

72

1980

114

176

101

63

1984

105

164

98

61

1987

101

163

94

63

1990

98

164

91

63

1993

104

172

92

66

1997

101

172

 

66

2001

92

164

79

64

2005

95

171

79

66

Note: Trend may look different depending on the metric used.

Source: DOE, 2009, available at www.eia.doe.gov/emeu/recs/recs2005/hc2005_tables/detailed_tables2005.html.

TABLE 2.2 Household Energy Expenditures by Income Level in 2001

Household Incomea

Percentage of Households

Energy Expenditures (dollars)a

Percentage of Income Spent on Energy

Less than $9,999

10

1,039

16

$10,000 to $14,999

7

1,124

9

$15,000 to $19,999

8

1,290

7

$20,000 to $29,999

13

1,315

5

$30,000 to $39,999

13

1,398

4

$40,000 to $49,999

12

1,518

3

$50,000 to $74,999

20

1,683

3

$75,000 to $99,999

8

1,825

2

$100,000 or more

8

2,231

2

a2001 dollars.

Source: DOE/EERE, 2007.

Residential energy use varies by household income, as shown in Table 2.2. Upper-income households earning more than $100,000 annually in 2001 used about twice the energy used by lower-income households earning under $15,000 annually. But the energy burden (the fraction of income spent on energy) is much

Suggested Citation:"2 Energy Efficiency in Residential and Commercial Buildings." National Academy of Sciences, National Academy of Engineering, and National Research Council. 2010. Real Prospects for Energy Efficiency in the United States. Washington, DC: The National Academies Press. doi: 10.17226/12621.
×

higher for lower-income households compared with middle- or upper-income households.

Commercial energy intensity measured in energy use per square foot of floor area declined over the 1979–1986 period but has fluctuated since 1986, as shown in Table 2.3. Commercial energy intensity has increased in particular types of buildings, such as health care and educational facilities. Efficiency improvements in lighting and air-conditioning have tended to reduce overall energy intensity, whereas greater use of amenities and devices such as computers and other plug loads have tended to increase it. Overall energy intensity in commercial buildings has declined in spite of a 45 percent increase in electricity use per square foot between 1983 and 2005 (Belzer, 2007). Energy use per square foot declined more on a delivered-energy basis than on a primary-energy basis during 1979–2003 owing to the increasing electrification of energy use.

There is great diversity in energy intensity in different commercial building types, as shown in Table 2.4. On the basis of delivered-energy and primary-energy use, food sales and food services facilities use more than two times as much energy per square foot of floor area as is used by office, retail, education, and lodging facilities. Likewise, health care facilities tend to have high energy use per square foot of floor area.

Table 2.5 presents a breakdown of energy end-use in residential and commercial buildings in 2005, as estimated by the Energy Information Administration (EIA). In housing, space heating represented about 48 percent of total energy

TABLE 2.3 Commercial Sector Energy Intensity Trends

Year

Delivered (1000 Btu/ft2)

Primary (1000 Btu/ft2)

1979

114.0

203.2

1983

97.5

187.1

1986

85.5

170.2

1989

91.6

180.4

1992

80.0

158.5

1995

90.5

180.1

1999

85.1

178.0

2003

91.0

191.0

Source: Energy Information Administration. Data through 1999 from http://www.eia.doe.gov/emeu/consumptionbriefs/cbecs/cbecs_trends/intensity.html. Data for 2003 from http://www.eia.doe.gov/emeu/cbecs/cbecs2003/detailed_tables_2003/detailed_tables_2003.html#consumexpen03.

Suggested Citation:"2 Energy Efficiency in Residential and Commercial Buildings." National Academy of Sciences, National Academy of Engineering, and National Research Council. 2010. Real Prospects for Energy Efficiency in the United States. Washington, DC: The National Academies Press. doi: 10.17226/12621.
×

TABLE 2.4 Commercial Sector Energy Intensity by Principal Building Activity, 2003

Principal Activity

Delivered (1000 Btu/ft2)

Primary (1000 Btu/ft2)

Education

83

159

Food sales

200

535

Food service

258

523

Health care

188

346

Lodging

100

193

Mercantile and service

87

204

Office

93

212

Public assembly

94

180

Public order and safety

116

221

Religious worship

43

77

Warehouse

45

94

Other

164

319

Source: Energy Information Administration. Data from http://www.eia.doe.gov/emeu/cbecs/cbecs2003/detailed_tables_2003/detailed_tables_2003.html#consumexpen03.

use on a delivered basis and 31 percent on a primary basis. Water heating, space cooling, and lighting each represented 11–12 percent of total residential primary energy use. Electronic devices such as televisions, computers, and other types of office equipment represented about 8.5 percent of residential primary energy use in 2005, and this fraction increases as households acquire more and bigger electronic products.

Space heating in commercial buildings in 2005 accounted for 24 percent of delivered-energy use and 14 percent of primary energy use, on average. Lighting accounted for about 17 percent of delivered-energy use and more than 25 percent of primary energy use, on average. Likewise, the end-use of space cooling and ventilation accounted for nearly 13 percent of delivered-energy use and 19 percent of primary energy use, on average. The end-use data should be viewed as approximate owing to the lack of metered data by end-use. “Other” energy use in Table 2.5 includes laboratory, medical, and telecommunications equipment; pumps; and fuel use for combined heat and power production.

Suggested Citation:"2 Energy Efficiency in Residential and Commercial Buildings." National Academy of Sciences, National Academy of Engineering, and National Research Council. 2010. Real Prospects for Energy Efficiency in the United States. Washington, DC: The National Academies Press. doi: 10.17226/12621.
×

TABLE 2.5 Energy End-Uses in Buildings, 2005

End-Use

Residential Sector

Commercial Sector

Primary (quads)

(%)

Delivered (quads)

(%)

Primary (quads)

(%)

Delivered (quads)

(%)

Space heating

6.69

(30.7)

5.61

(48.2)

(2.55)

(14.2)

2.04

(24.0)

Space cooling and ventilation

2.67

(12.3)

0.84

(7.2)

3.42

(19.1)

1.09

(12.8)

Water heating

2.66

(12.2)

1.75

(15.0)

1.23

(6.8)

0.84

(9.9)

Lighting

2.40

(11.0)

0.75

(6.5)

4.57

(25.5)

1.44

(16.9)

Refrigeration

1.64

(7.5)

0.52

(4.4)

0.74

(4.1)

0.23

(2.7)

Electronicsa

1.86

(8.5)

0.58

(5.0)

1.70

(9.5)

0.53

(6.2)

Laundry and dishwashers

1.05

(4.8)

0.38

(3.2)

NAb

 

NAb

 

Cooking

0.98

(4.5)

0.48

(4.1)

0.35

(2.0)

0.27

(3.2)

Other

0.83

(3.8)

0.41

(3.5)

2.37

(18.2)

1.12

(13.2)

Adjustmentc

1.02

(4.7)

0.32

(2.8)

0.98

(5.5)

0.92

(10.9)

Total

21.78

(100)

11.63

(100)

17.91

(100)

8.49

(100)

aElectronics include TVs, computers, and other office equipment.

bNA, not available.

cAdjustment to reconcile discrepancies between sources.

Source: DOE/EERE, 2007.

2.2
ENERGY EFFICIENCY TRENDS

Improvements in energy efficiency are a key factor in the decline in energy intensity in buildings over the past 30 years. Driven largely by research, development, and demonstration (RD&D), building energy codes, ENERGY STAR® labeling, and state and federal efficiency standards (see Chapter 5), the efficiency of new appliances has improved dramatically since the 1970s. For example, the average electricity use of new refrigerators sold in 2007 was about 498 kWh per year, 71 percent less than the average electricity use of new refrigerators sold 30 years earlier (AHAM, 2008). This is in spite of the fact that refrigerators have become larger and offer more features, such as automatic defrosting, ice makers, and through-the-door water and ice dispensers. Likewise, the average efficiency of other products, including air conditioners, gas furnaces, clothes washers, and dishwashers, has improved significantly over the past 30 years. Yet progress has been minimal for other products, such as water heaters. Less policy attention has been paid to the energy use of these other appliances and equipment, accounting in part for this divergence of trends in energy efficiency improvements.

Suggested Citation:"2 Energy Efficiency in Residential and Commercial Buildings." National Academy of Sciences, National Academy of Engineering, and National Research Council. 2010. Real Prospects for Energy Efficiency in the United States. Washington, DC: The National Academies Press. doi: 10.17226/12621.
×

Significant energy efficiency gains have also been made in lighting. The sales and use of compact fluorescent lamps (CFLs), which use about 75 percent less electricity per unit of light output relative to incandescent lamps, have increased greatly in the past decade. As shown in Figure 2.6, CFL shipments (based on data on imports, since all CFLs are imported into the United States) increased from about 21 million units in 2000 to 185 million units by 2006. But as a result of various factors—growing state, regional, and utility energy efficiency programs, along with a federal procurement program aimed at reducing the size and improving the quality of CFLs; stepped-up marketing efforts by some large retailers; and national promotion campaigns led by the federal ENERGY STAR® program—CFL shipments jumped to about 400 million units in 2007. This means that CFLs represented about 20–25 percent of all screw-in lightbulbs (incandescent and fluorescent) sold in 2007. Given that CFLs last 5 to 10 times longer than incandescent lamps, CFLs actually accounted for the majority of the total “light service” (i.e., lumen-hours) sold in 2007. CFLs do have some drawbacks, such as their use of mercury and difficulty with dimming. However, the small amount of mercury released to the environment if a CFL is disposed of in a landfill is much less than

FIGURE 2.6 Shipments of compact fluorescent lamps.

FIGURE 2.6 Shipments of compact fluorescent lamps.

Source: U.S. Department of Commerce data obtained from USA Trade Online, available at https://orders.stat-usa.gov/on_sam.nsf/fsetOrder/UTO.

Suggested Citation:"2 Energy Efficiency in Residential and Commercial Buildings." National Academy of Sciences, National Academy of Engineering, and National Research Council. 2010. Real Prospects for Energy Efficiency in the United States. Washington, DC: The National Academies Press. doi: 10.17226/12621.
×

the mercury avoided through the reduction in electricity generation, given average mercury emissions associated with electricity generation in the United States (ENERGY STAR®, 2008). Solid-state lighting, which addresses these shortcomings of CFLs, is now emerging in the marketplace (see Section 2.6.1).

Energy-efficient fluorescent lighting fixtures containing T8 fluorescent lamps (these have a diameter of 1 inch) and high-frequency electronic lamp ballasts used in commercial buildings use 30–40 percent less power per unit of light output compared with older fixtures containing T12 lamps (which have a diameter of 1.5 inches) and electromagnetic ballasts (Suozzo et al., 2000). The U.S. Department of Energy (DOE) played a major role in the development of electronic ballasts during the early 1980s (NRC, 2001; Geller and McGaraghan, 1998). Utility and state DSM programs and the Environmental Protection Agency’s (EPA’s) “Green Lights” program (which developed into the ENERGY STAR® program), helped move the product from the laboratory into the marketplace. As shown in Table 2.6, the market share for electronic ballasts increased from about 1 percent in the late 1980s to 47 percent by 2000 and then to 73 percent in 2005 (DOE/EERE, 2007). Minimum efficiency standards promulgated by the U.S. DOE in 2000 that took effect in 2005 are facilitating the transition from magnetic to more efficient electronic ballasts.

Periodic EIA surveys of commercial buildings show growth in the use of energy efficiency and conservation measures from 1992 to 2003, as indicated in Table 2.7. The increase in the use of energy-efficient lighting devices such as CFLs, electronic ballasts, and specular light reflectors is most noteworthy. At the same time, a significant fraction, and in some cases a majority of commercial buildings, still do not use common energy efficiency measures such as energy management and control systems or HVAC economizer cycles (which make use of outdoor air for cooling when temperature and humidity levels permit).

The adoption of ENERGY STAR®-labeled products and new homes has also increased substantially in recent years. For example, the construction and certification of ENERGY STAR® new homes—which must be at least 15 percent more efficient for heating, cooling, and water heating than homes built to meet the International Energy Conservation Code (IECC) or 15 percent more efficient than the prevailing state energy code, whichever is more rigorous—grew from about 57,000 new homes in 2001 to 189,000 new homes in 2006. That is, 11.4 percent of all new homes built in 2006 were certified as ENERGY STAR®-compliant. The market share for ENERGY STAR® new homes exceeded 25 percent in 10 states and 50 percent in 2 states—Nevada and Iowa, in 2006 (EPA, 2007a).

Suggested Citation:"2 Energy Efficiency in Residential and Commercial Buildings." National Academy of Sciences, National Academy of Engineering, and National Research Council. 2010. Real Prospects for Energy Efficiency in the United States. Washington, DC: The National Academies Press. doi: 10.17226/12621.
×

TABLE 2.6 Shipments of Fluorescent Lamp Ballasts

Year

Number of Magnetic Type Shipped (million)

Number of Electronic Type Shipped (million)

Electronic Market Share (%)

1986

69.4

0.4

1

1988

74.6

1.1

1

1990

78.4

3

4

1992

83.7

13.3

14

1994

83.5

24.6

23

1996

67

30.3

31

1998

63.9

39.8

38

2000

55.4

49.3

47

2001

46.9

52.5

53

2002

40.7

53.8

57

2003

35.2

54.4

61

2004

30.5

59.2

66

2005

22.2

61.3

73

Source: DOE/EERE, 2007.

TABLE 2.7 Growth in the Use of Energy Efficiency Measures in Commercial Buildings

Efficiency Measure

Percentage of Floorspace with Measure

1992

2003

HVAC economizer cycle

27

33

HVAC variable air volume system

21

30

Energy management and control system

21

24

Compact fluorescent lamps

12

43

Electronic lamp ballasts

NAa

72

Specular light reflectors

22

40

Multipaned windows

44

60

Tinted or reflective window glass

37

59

Daylighting sensors

NAa

4

aNA, not available.

Source: Energy Information Administration, 2003 Commercial Buildings Energy Consumption Survey: Building Characteristics Tables and Commercial Buildings Characteristics 1992, both available on the EIA website.

Suggested Citation:"2 Energy Efficiency in Residential and Commercial Buildings." National Academy of Sciences, National Academy of Engineering, and National Research Council. 2010. Real Prospects for Energy Efficiency in the United States. Washington, DC: The National Academies Press. doi: 10.17226/12621.
×

2.3
THE POTENTIAL FOR ENERGY EFFICIENCY IN BUILDINGS

2.3.1
Review of Studies

Energy use in buildings embraces dozens of end-uses, and for each there are a variety of efficiency-improvement technologies (and levels of intensity of application—e.g., insulation thickness) available. The more rigorous and analytically valid studies of efficiency potential2 aggregate similar measures—often hundreds or thousands of them (especially if the research disaggregates the measures by building type, climate, and so on)—into supply curves of energy efficiency potential. The supply curves depict graphically the energy savings available from a given measure (or aggregation of measures) as a function of the cost of saved energy. Section 2.5 presents conservation supply curves for both residential and commercial buildings.

This section presents a review of what the Panel on Energy Efficiency Technologies believes is a representative sample of the most credible such studies. Most of these studies concentrate only on the United States, but the one study reviewed by the panel that looked at worldwide savings potential (IEA, 2006) comes to conclusions very similar to those of the U.S. studies regarding percentage savings.

All of these studies rely on similar methodologies. They look at end-use data on a level of disaggregation and detail far higher than that available in most energy-demand forecasts. Efficiency measures are compared to the efficiency inherent in one or several average base cases. Capital stock turnover is explicitly considered: new appliances and buildings are added to the stock while old buildings and products are slowly retired, and retrofits are considered for items such as building envelopes. None of the studies assumes early retirement as an efficiency measure. Because some degree of “natural” improvement in energy efficiency is assumed in the “business as usual” case, some of the initially projected savings are in the end subtracted.

The panel reviewed and synthesized several of the most important (though not all) relevant studies carried out at the national, regional, state, and utility levels. Some of the major national or regional energy-savings potential studies performed over the past 12 years include those by Optimal Energy, Inc. (2003); IWG

2

Analysts of building energy use often use the term “potentials” studies to refer to studies of the potential for energy savings. This report uses the latter terminology.

Suggested Citation:"2 Energy Efficiency in Residential and Commercial Buildings." National Academy of Sciences, National Academy of Engineering, and National Research Council. 2010. Real Prospects for Energy Efficiency in the United States. Washington, DC: The National Academies Press. doi: 10.17226/12621.
×

(1997, 2000); Energy Innovations (1997); Nadel and Geller (2001); NPCC (2005); EETF (2006); and Creyts et al. (2007).

Studies of the potential for energy efficiency improvement in buildings typically assess this potential in terms of three categories: technical potential, which is the broadest and includes technologies with improved performance but not necessarily lower costs; economic potential, which includes those technologies that are judged to be economically attractive; and achievable potential, which is a subset of economic potential that takes account of various market failures and barriers. This section looks most closely at the economic potential: that is, how much potential there is for energy savings at prices of energy up to or moderately above current or projected electricity market prices.

The economic potential as assessed in any study depends on the following: how many end-uses are examined in detail (since it is hard to posit a supply curve for saved energy from the “miscellaneous” or “other” categories of energy use); the timeframe of the study; the policy authority of the agency that commissioned the study (e.g., a typical utility-sponsored study will not look at the technical and economic potential of codes and standards, and a state-funded study might not consider measures that require federal action); and how the study will be used (studies that lead to mandatory goals typically show less potential than studies with broader and more flexible uses).

The results of the studies also depend in part on the policies that the authors assume will be used to achieve the potential. If the authors assume that the use of a technology can be boosted through standards or through generous financial incentives that cause close to 100 percent adoption, they will have a larger efficiency resource potential than the studies that do not make this assumption. For example, a study carried out by five national laboratories (IWG, 1997) postulates penetration rates of 35 percent and 65 percent in its two scenarios; an assumption that cost-effective technologies could be implemented at near-100 percent levels would have produced substantially different results. The subsequent study Scenarios for a Clean Energy Future included explicit assumptions about policies, programs, and their impacts (IWG, 2000).

If a study assumes that the adoption of strong standards or incentives that achieve near-100 percent market acceptance induces manufacturers or designers to invest in new product development to introduce a next-generation product (which studies generally do not assume), then the results will show more potential savings than if next-generation products are not included. Thus, for the limited number of products for which these policies were adopted, most studies understate the effi-

Suggested Citation:"2 Energy Efficiency in Residential and Commercial Buildings." National Academy of Sciences, National Academy of Engineering, and National Research Council. 2010. Real Prospects for Energy Efficiency in the United States. Washington, DC: The National Academies Press. doi: 10.17226/12621.
×

ciency advances that actually occurred (Goldstein and Hoffman, 2004). This issue is discussed further in the succeeding paragraphs.

Nadel et al. (2004) reviewed 11 studies of energy savings potential in buildings, covering the period 2000 through 2004. This meta-analysis indicated a potential in the United States for substantial technical, economic, and achievable energy savings (Table 2.8). Across all sectors (residential, commercial, and industrial), the studies reviewed by Nadel et al. (2004) showed a median technical savings potential of 33 percent for electricity and 41 percent for natural gas (see Table 2.8). The median achievable savings potential was 24 percent for electricity (an average of 1.2 percent per year) and 9 percent for natural gas (an average of 0.5 percent per year). The review compared the findings on achievable potential to recent-year actual savings from portfolios of electricity and natural gas efficiency programs in leading states and found substantial consistency. (Note that the natural-gas savings potential suggested by these studies is less than that indicated

TABLE 2.8 Summary of Results from the ACEEE Meta-Analysis: Studies of the Potential for Energy Savings in Buildings, 2000–2004

Region

Year

No. of Years

Potential (%)

Technical

Economic

Achievable

Electricity

 

 

 

 

 

California

2003

10

18

13

10

Massachusetts

2001

5

 

24

 

New York

2003

20

36

27

 

Oregon

2003

10

31

 

 

Puget

2003

20

35

19

11

Southwest

2002

17

 

 

33

Vermont

2003

10

 

 

31

United States

2000

20

 

 

24

Median

 

 

33

21.5

24

Natural Gas

 

 

 

 

 

California

2003

10

 

21

10

Oregon

2003

10

47

35

 

Puget

2003

20

40

13

9

Utah

2004

10

41

22

 

United States

2000

20

 

 

8

Median

 

 

41

22

9

Source: Nadel et al., 2004.

Suggested Citation:"2 Energy Efficiency in Residential and Commercial Buildings." National Academy of Sciences, National Academy of Engineering, and National Research Council. 2010. Real Prospects for Energy Efficiency in the United States. Washington, DC: The National Academies Press. doi: 10.17226/12621.
×

in the conservation supply curves presented in Section 2.5, because the studies assumed only limited policy and program interventions for the purpose of estimating achievable natural-gas savings potential.)

Nadel et al. (2004) also reported on savings potential by sector. The median technical potential for saving electricity across the studies was 32 percent for the residential sector, 36 percent for the commercial sector, and only 21 percent for the industrial sector. The median achievable potentials were 26 percent, 22 percent, and 14 percent, respectively. For natural gas, savings potentials appear to be higher in the residential sector than in the commercial sector. The median technical potential for gas savings across the studies is 48 percent in the residential sector and 20 percent in the commercial sector. The median achievable gas-savings potential drops to 9 percent in the residential sector and 8 percent in the commercial sector.

These savings percentages are based on the business-as-usual cases specific to each study. But because constructing a business-as-usual forecast is problematic, there is some uncertainty about what is the appropriate basis for calculating savings. However, such calculations are still useful for the purpose of rough estimates; they would have to be refined for use in program planning.3

The overall median achievable electricity savings potential across the studies is 1.2 percent per year, with similar medians for each of the sectors. However, the annual achievable potential is often lower for studies extending further in time (e.g., 20 years) than for shorter-term studies. Nadel et al. (2004) suggest that this is primarily because existing technologies can be heavily adopted over the first decade, and the new technologies and practices that would emerge during the second decade are not included in most studies.

A detailed comparison of the results of various studies is desirable, but it is problematic because many studies examine hundreds or even thousands of discrete efficiency measures, making such a comparison difficult and costly to perform.

3

Each study of the potential for energy savings attempts to address the issue of reconciling the base case in the study (which involves much more detailed data than the base case in the energy forecast) with the overall results of the forecast. While such a process introduces some levels of uncertainty into the calculation, and greater levels of uncertainty to the casual reader who is trying to interpret the results without the help of the large spreadsheets used in the savings analysis, the studies reviewed seem to have done a good job of avoiding double counting or missed potentials. The errors that remain have little practical consequence because they do not affect supply resource planning, nor do they affect efficiency program planning or evaluation.

Suggested Citation:"2 Energy Efficiency in Residential and Commercial Buildings." National Academy of Sciences, National Academy of Engineering, and National Research Council. 2010. Real Prospects for Energy Efficiency in the United States. Washington, DC: The National Academies Press. doi: 10.17226/12621.
×

There is to the panel’s knowledge no literature offering such comparison and contrast or even comprehensively reviewing individual studies.

Studies of technical and economic energy-savings potential generally capture energy efficiency potential at a single point in time based on technologies that are available at the time a study is conducted. But new efficiency measures continue to be developed and to add to the long-term efficiency potential. This trend is illustrated by comparing two studies on available electricity-savings opportunities that were prepared for New York State in 1989 and 2003 (see Figure 2.7).

In the first of the two studies, Miller et al. (1989) examined more than 70 efficiency measures and found an economic potential of 27 percent electricity savings, based on a 5 percent real discount rate. This study included such measures

FIGURE 2.7 Comparison of the electricity-savings potential identified in two studies for New York State (percent of annual electricity consumption). Despite wide use by 2003 of many technologies considered in Miller (1989), which thus became part of the “baseline” for 2003, the economic potential for savings in 2003 remained large, primarily because new technologies had become available, including many that were still under development in 1989. “Technical potential” is the maximum amount of energy use that could be displaced by energy efficiency measures, disregarding factors such as cost-effectiveness and the willingness of end-users to adopt the measures. “Economic potential” is the subset of technical potential that is cost-effective compared with conventional energy supplies.

FIGURE 2.7 Comparison of the electricity-savings potential identified in two studies for New York State (percent of annual electricity consumption). Despite wide use by 2003 of many technologies considered in Miller (1989), which thus became part of the “baseline” for 2003, the economic potential for savings in 2003 remained large, primarily because new technologies had become available, including many that were still under development in 1989. “Technical potential” is the maximum amount of energy use that could be displaced by energy efficiency measures, disregarding factors such as cost-effectiveness and the willingness of end-users to adopt the measures. “Economic potential” is the subset of technical potential that is cost-effective compared with conventional energy supplies.

Source: ACEEE (2007), based on data in Miller et al. (1989) and Optimal Energy (2003).

Suggested Citation:"2 Energy Efficiency in Residential and Commercial Buildings." National Academy of Sciences, National Academy of Engineering, and National Research Council. 2010. Real Prospects for Energy Efficiency in the United States. Washington, DC: The National Academies Press. doi: 10.17226/12621.
×

as energy-saving fluorescent lamps (e.g., 34 W tubes replacing 40 W tubes) and efficient magnetic ballasts, as well as what at the time were called “very high efficiency” lamps and ballasts (e.g., T8 lamps with electronic ballasts).

In the second study, Optimal Energy, Inc. (2003) examined more than 100 efficiency measures, including many that had been added or updated after the 1989 study. The 2003 study also found that, 4 years later, the economic savings potential remained around 27 percent because of promising new technologies. Many measures included in the 1989 study were dropped because they were already widely adopted by 2003 and were therefore included in the base-case forecast (e.g., 34 W fluorescent lamps and efficient magnetic ballasts). Instead, much of the savings in the 2003 study came from measures that were still under development in 1989 (e.g., new “super T8” lamps and “pulse start” metal halide lamps) or were otherwise not included in the 1989 study.

As revealed by these studies, the potential for cost-effective energy efficiency improvements is very large. The exact potential is uncertain, but even if it is 30 percent less or 30 percent greater than the median case presented in this report, it still represents the largest, least expensive, and shortest-lead-time resource for balancing energy supply and demand.

It should be noted that the plausible uncertainty around the median savings figures reported here is not symmetric. The risk of overestimating efficiency potential is minimal, owing to the methodologies that are used in the studies. Instead, the studies openly and intentionally make assumptions that lead to “conservatively” low estimates of the efficiency resource, as discussed in Section 2.3.2.

Some states and utilities have achieved a significant share of the energy efficiency potential indicated by the studies. For example, a review was conducted recently of the degree to which the efficiency potential identified for California (Rufo and Coito, 2002) was realized through electric utility efficiency programs. Messenger (2008) found that utility DSM programs achieved about 25 percent of the projected 10-year energy-savings potential in the commercial sector and nearly 27 percent of the projected energy-savings potential in the residential sector from just 3 years (2004–2006) of utility DSM program activity. The amount of savings potential achieved varied among end-uses and building types. The utilities spent about 2 percent of their sales revenue on DSM programs in order to capture this savings. Further information on utility DSM programs is provided in Chapter 5. A study of the energy savings to date by sector in New York State relative to the potential savings that were identified reveals that the greatest energy efficiency potential for buildings remains in the residential sector, despite recent achieve-

Suggested Citation:"2 Energy Efficiency in Residential and Commercial Buildings." National Academy of Sciences, National Academy of Engineering, and National Research Council. 2010. Real Prospects for Energy Efficiency in the United States. Washington, DC: The National Academies Press. doi: 10.17226/12621.
×

ments, because energy savings are more costly and more difficult to obtain in the residential sector than in the commercial sector (DeCotis et al., 2004).

2.3.2
Limitations of Studies of Energy Efficiency Potential

Studies of the potential for energy efficiency are intended to provide specific answers to well-framed policy questions. But the question of how much efficiency is available at what price is not well framed, because the meaning of “available” is ambiguous with respect to several critical issues:

  • The timeframe over which the potential is available. The efficiency potential within 3 years from retrofitting homes is a very different policy question from the potential within 30 years from retrofitting homes, both in terms of the number and the type of efficiency measures that can be implemented.

  • The level of incentive required for realizing the potential. The greater the incentives paid to achieve the savings, all else being the same, the greater the savings achieved. The limiting case is a 100 percent payment, that is, free installation (no cost to the building occupant), in which case a very high level of implementation is possible.

  • The motivation of society in pursuing the energy savings. The amount of savings available when a nation or region is facing a crisis—for example, the need to relieve the California electricity crisis in 2001, or the need in New York City to achieve reductions in electricity demand quickly in order to maintain reliability—is much larger than in a situation in which energy efficiency merely reduces normal utility bills.

A number of biases can lead studies to understate energy efficiency potential (Goldstein, 2008), including (1) sponsoring agencies’ motivation to underestimate savings potential in order to avoid challenges to their energy-savings goals; (2) the exclusion of new and emerging technologies; (3) failure to consider that energy efficiency technologies are likely to improve in performance and decline in cost over time; (4) failure to consider the potential to adopt energy efficiency measures in an integrated manner with synergistic effects (such as the whole-building approach to improving efficiency); (5) failure to consider efficiency measures’ non-energy benefits, which in some cases are substantial and can be valued more than the energy benefits (Romm, 1999); and (6) the development of studies of potential in contexts in which the risk to the researcher of making an error is asymmetric

Suggested Citation:"2 Energy Efficiency in Residential and Commercial Buildings." National Academy of Sciences, National Academy of Engineering, and National Research Council. 2010. Real Prospects for Energy Efficiency in the United States. Washington, DC: The National Academies Press. doi: 10.17226/12621.
×

(that is, a data point that overestimates savings or underestimates cost can be much more problematic than one that does the reverse).

There are, however, cases in which studies of energy efficiency potential have been overly optimistic. For example, although CFLs had been available in the marketplace and identified as a viable energy efficiency measure since the late 1970s, they only started to gain widespread acceptance by consumers in about 2000. This slow market penetration is attributed to a variety of early CFL deficiencies, including large size relative to incandescent lamps, performance issues, poor light quality, and high first cost of CFLs produced in the 1980s and 1990s (Sandahl et al., 2006). Once these deficiencies were addressed, CFLs became more appealing to consumers. However, studies that projected large energy-savings potential from CFLs during the 1980s and 1990s (Geller et al., 1986; Rosenfeld, 1985) overestimated their potential, at least prior to 2000.

Likewise, heat-pump water heaters have been produced on a limited basis since the early 1980s. These devices use one-third to one-half as much electricity as that used by electric-resistance water heaters, with the energy savings paying back the incremental first cost in 5 years or less (Ashdown et al., 2004). However, heat-pump water heaters are not being produced on a large scale and have had little market penetration in the United States. This is due to performance problems with early heat-pump water heaters (e.g., poor reliability), lack of a supply infrastructure (e.g., no production by major water heater manufacturers), and the nature of the water heater market (e.g., split incentives and many purchases made in a rush). Once again, studies which assumed that these problems would be overcome during the past two decades (Geller et al., 1986) overestimated achievable energy-savings potential.

These examples do not reflect errors in estimates of the energy efficiency potential ultimately available. Rather, they reflect overly optimistic assumptions regarding technological maturity and/or underestimates of the difficulty of overcoming the market barriers and failures that prevent broad commercialization and market acceptance.

2.4
APPROACHES TO UNDERSTANDING ENERGY EFFICIENCY POTENTIAL

There are several approaches to reviewing the technologies and design principles available today to make buildings more energy-efficient. Each illuminates a subset of important engineering and physics issues but obscures other subsets. Each

Suggested Citation:"2 Energy Efficiency in Residential and Commercial Buildings." National Academy of Sciences, National Academy of Engineering, and National Research Council. 2010. Real Prospects for Energy Efficiency in the United States. Washington, DC: The National Academies Press. doi: 10.17226/12621.
×

approach has its advantages and disadvantages. Therefore, this report does not adopt one preferred style of presentation but instead looks at three different approaches:

  • An integrated whole-building or system-wide approach,

  • An approach by end-use and technology description, and

  • An approach by individual “widgets” or detailed energy efficiency technologies and measures.

2.4.1
Integrated Whole-Building or System-Wide Approach

The first approach looks at integrated whole-building or system-wide energy use and describes the types of technological improvements that could create savings of a given percentage for whole buildings or whole systems. For example, a small but growing subset of new commercial buildings achieve a savings of 50 percent (relative to prevailing model Energy Code ASHRAE 90.1) in regulated energy use (heating, cooling, air-conditioning, water heating, and lighting).4 Reviews of highly efficient commercial buildings (NBI, 2008; ASHRAE, 2008; Torcellini et al., 2006) show that such buildings incorporate the following measures:

  • High-efficiency electrical lighting systems that not only incorporate state-of-the-art lamps, ballasts, and luminaires (lighting fixtures), but also use luminaires to provide the desired lighting in the right places (e.g., as task lighting) and use controls that limit electrical lighting when daylighting is available;

  • Fenestration systems and designs that reduce heat gain in climates with high cooling requirements;

  • HVAC controls that provide for the effective operation of the HVAC system during part-load conditions;5 and

4

“Regulated energy use” refers to energy use covered by building energy codes. Such codes do not apply to plug-in office equipment, for example.

5

There are many reasons why efficiency at part load can be lower. Examples range from systems that do not modulate but simply turn on or off, to chiller designs that are optimized for efficiency at full load and work poorly at part load (perhaps because they are not tested or marketed on the basis of such performance), to overall systems controls that continue to operate one part of the system at full-power use even though other parts are at partial power and do not require that support.

Suggested Citation:"2 Energy Efficiency in Residential and Commercial Buildings." National Academy of Sciences, National Academy of Engineering, and National Research Council. 2010. Real Prospects for Energy Efficiency in the United States. Washington, DC: The National Academies Press. doi: 10.17226/12621.
×
  • On-site power generation such as combined heat and power systems or solar photovoltaic generation to reduce purchased energy.

Low-energy buildings do not always operate as they were designed to do. Experience shows that in order to maximize real-world energy savings, it is critical to properly commission and monitor the performance of low-energy buildings and to ensure that control systems are working properly and are adjusted to account for occupancy conditions (Torcellini et al., 2006; Mills, 2009).

The net incremental first cost of achieving a 50 percent reduction in energy use through an integrated approach6 can be at or near zero; the savings from downsizing and simplifying HVAC systems generally pay fully for the additional costs of measures such as additional insulation, better windows, and daylighting (Goldstein, 2008). But the next increment of savings, up to 60 percent, has very few exemplars.

For residential buildings, a whole-house approach can result in a 50 percent or greater savings in heating and cooling and a 30–40 percent savings in total-home energy use, and can do so cost-effectively (DOE, 2004a; Dunn, 2007).7 This conclusion is also supported by the fact that more than 8,000 applications were submitted for the federal tax credit for 50 percent savings for new, single-family homes during the first year of its availability—calendar year 2006—despite substantial delays in the availability of guidance from the Internal Revenue Service on how to perform the savings calculations and computer software for doing so. Although comprehensive evaluations of the tax credit are not yet available, the market share of new homes qualifying for the credit grew from below 1 percent before the credit to 1 percent of eligible homes in 2006 and 3 percent in 2007. For 2008, the number of qualifying homes grew to more than 23,000 (about 4.6 percent of all homes built), according to a survey of home energy raters (S. Baden, RESNET, personal communication, May 1, 2008).

6

An “integrated approach” involves integrating the design of the HVAC system with that of the envelope system and the lighting system and its controls. Current design practice involves designing the envelope of the building independent of such integrative consideration, then passing the design onto HVAC engineers, who design the HVAC system without looking back at what could be done differently at the envelope or without looking forward to how lighting designs could enable improved HVAC designs.

7

The savings are relative to a new home built to just meet the prevailing model energy code, namely, the 2006 International Energy Conservation Code.

Suggested Citation:"2 Energy Efficiency in Residential and Commercial Buildings." National Academy of Sciences, National Academy of Engineering, and National Research Council. 2010. Real Prospects for Energy Efficiency in the United States. Washington, DC: The National Academies Press. doi: 10.17226/12621.
×

2.4.2
Approach by End-Use and Technology Description

Because whole-building studies focus on the level of savings achieved and the cost of getting there, they often do not specify the kinds of energy-saving measures used and how relevant they would be to broad-scale application across the economy. Instead, the savings estimates sometimes are based on measured results from demonstration buildings or multibuilding projects, or on case studies; they sometimes consider simulated energy savings based on integrated designs of new buildings or retrofits; and they sometimes are based on more than one approach.

Other studies, however, rely on the end-use and technology description approach to identifying energy efficiency potential. This approach assigns energy use to major end-use categories and reviews the specific technologies and measures available for reducing energy use in each category (often ordered by cost-effectiveness). The end-use approach is based on text and explanation of technologies and measures. Most of these technologies and measures could be incorporated into existing buildings.

As an example, space heating is the largest user of energy in residential buildings, and cooling is the second-largest or close to second-largest user. Similar energy-saving measures and strategies can be applied to both. These efficiency measures and strategies include the following (Scheckel, 2007; Amann et al., 2007):

  • Increasing insulation in all components compared with what is done according to current practice, including the use of selective coatings on windows. These coatings are chosen on the basis of the local climate, to reduce thermal transmission (by increasing the thermal-infrared emissivity and reflectivity of the window). They are most effective on west-and east-facing windows in climates requiring cooling or in transitional climates where an efficient shell can obviate the need to buy an air conditioner.

  • Moving ducts into the conditioned space for new construction, and reducing leakage through on-site pressure testing in both new and existing homes.

  • Improving heating and cooling systems themselves, for example, by using programmable thermostats, by using higher-efficiency furnaces that condense water vapor produced by the combustion of methane (or other fuels) to extract additional energy and achieve efficiencies over

Suggested Citation:"2 Energy Efficiency in Residential and Commercial Buildings." National Academy of Sciences, National Academy of Engineering, and National Research Council. 2010. Real Prospects for Energy Efficiency in the United States. Washington, DC: The National Academies Press. doi: 10.17226/12621.
×

90 percent, by using variable-speed and higher-efficiency motors and fans for air circulation, and by using ground-source heat pumps (for electric heating) or gas-fired heat pumps.

  • Upgrading equipment for cooling, focusing on better heat transfer from evaporators and condenser coils in air conditioners and employing variable-speed drives that allow units to operate efficiently at partial loads (rather than turning on and off frequently). This measure can control humidity more effectively, as well as save energy.

  • Changing ventilation systems to provide sufficient fresh air to a system that uses the proper amount of mechanical ventilation while sealing the home to nearly airtight standards. Controlling ventilation can greatly mitigate indoor air quality and mold problems while also offering the opportunity to recover both latent and sensible heat from the exhaust airstream.

  • Using evaporative cooling. While once-through evaporative coolers work well only in desert climates, indirect systems that transfer sensible heat from the humidified airstream can provide comfort in a much broader zone of climate while using about one-quarter or less of the energy of compression-based cooling.

  • Making greater use of passive solar heating and cooling, although this design technique has not yet found widespread acceptance in the marketplace owing to the difficulties of custom designing the orientation and thermal characteristics of each home.

After space heating and cooling, the next-largest user of energy in residences is water heating. Water-heating energy use can be reduced both by improving the efficiency of the water-heating device itself and by reducing the demands for hot water, including for clothes washing and bathing, throughout a home. Substantial gains have been made in the best-performing clothes washer and showerhead products compared with standard products. For example, the highest specification for utility incentives for washing machines has a modified energy factor (MEF) of 2.2; current stock has an MEF of about 0.85. Heat-pump water heaters, which have become very popular in Japan, can reduce electricity use by two-thirds relative to an electric-resistance water heater. Older showerheads use 3.5 or more gallons per minute; newer ones meeting current standards use 2.5 or fewer gallons per minute, and a few newer models use about half this level of waterflow to provide a comfortable shower (Harrod and Hain, 2007). Similar lists of technolo-

Suggested Citation:"2 Energy Efficiency in Residential and Commercial Buildings." National Academy of Sciences, National Academy of Engineering, and National Research Council. 2010. Real Prospects for Energy Efficiency in the United States. Washington, DC: The National Academies Press. doi: 10.17226/12621.
×

gies for residential lighting and appliances are found in most studies of efficiency potential. Beyond technologies themselves, efficiency can be improved through residential lighting design that raises the ratio of productive light output (lux on the visual task) to power use in homes to a level comparable to that in office buildings.

The major sources of energy use in commercial buildings are heating, ventilation, cooling, and lighting. Studies of energy efficiency potential usually look at specific measures within these categories, such as improving the rated efficiency of rooftop air conditioners by 20–30 percent or substituting 100 lumen per watt lamp-ballast combinations for existing product combinations that provide fewer than 70 lumens per watt.

2.4.3
Approach by Individual “Widgets” or Detailed Energy Efficiency Measures

The energy end-use approach to estimating potential savings suffers from the limited ability of readers to review critically the assumptions that are made and the models that are used to derive the costs and savings for specific energy efficiency measures. This problem is accompanied by often limited guidance to program administrators about how best to achieve the savings—that is, what types of equipment or designs should be promoted.

In contrast, “widget”-based supply curves look at technologies and measures at a very detailed level. They can involve a spreadsheet of many hundreds or thousands of lines that tabulates detailed technical measures. They can cover both retrofits and new buildings by establishing separate sets of rows in the spreadsheets for retrofits compared with new buildings. This is the approach that relates most closely to the policies and programs used to obtain energy savings through improved energy efficiency.

Widget-based analyses look at the same types of technologies and measures as those considered in whole-building- or end-use-based analyses, but they also include the following for residential buildings:

  • More efficient appliances, by efficiency rating;

  • More efficient heating and cooling equipment, by efficiency rating;

  • Additions of insulation (increasing “R” values) to ceilings, walls, and floors; and

  • The substitution of CFLs and light-emitting diodes (LEDs) for incandescent lightbulbs.

Suggested Citation:"2 Energy Efficiency in Residential and Commercial Buildings." National Academy of Sciences, National Academy of Engineering, and National Research Council. 2010. Real Prospects for Energy Efficiency in the United States. Washington, DC: The National Academies Press. doi: 10.17226/12621.
×

For commercial buildings, the more detailed approaches include the following:

  • More efficient lamps, ballasts, and luminaires;

  • The substitution of more efficient lighting sources for less efficient ones (such as compact fluorescent lamps for general-service incandescents or downlights, or ceramic metal halide lamps for incandescent reflectors, or the use of infrared-reflective incandescent reflector lamps instead of conventional ones, or the use of LEDs for colored light sources);

  • Controls to reset air-conditioning system temperatures;

  • Variable-speed fans/drives and pumps;

  • Lower-pressure fan systems; and

  • Occupancy sensors for lighting and air quantities.

While widget-based analyses are easier to review and interpret, they tend to exclude many cost-effective options for systems integration, such as the following:

  • Using lighting designs that optimize the distribution of light so that it is brightest where the most light is desired and less intense elsewhere;

  • Using envelope designs that permit daylighting, especially in commercial buildings;

  • Using envelope measures that are intended to reduce the size or complexity of the HVAC system;

  • Using separate ventilation systems in which the benefits include occupant satisfaction and the ability to control the system under nontypical operating conditions; and

  • Changing the building’s orientation to take advantage of passive heating or cooling.

The amount of efficiency available at any particular cost from a widget-based, detailed end-use-and-technology analysis is generally lower than what would be estimated by a whole-building-based analysis. However, the results are easier to review and validate and may thus be more credible. The discussion of whole-building-based analysis noted that a number of commercial buildings achieve 50 percent savings with no increase in first cost. But buildings achieving such 50 percent savings are not normally included on supply curves, in part because buildings that achieve this can be seen as unrepresentative of the savings across the sector.

Suggested Citation:"2 Energy Efficiency in Residential and Commercial Buildings." National Academy of Sciences, National Academy of Engineering, and National Research Council. 2010. Real Prospects for Energy Efficiency in the United States. Washington, DC: The National Academies Press. doi: 10.17226/12621.
×

2.5
CONSERVATION SUPPLY CURVES

This section presents conservation supply curves for residential and commercial buildings developed in 2008 by researchers from the Lawrence Berkeley National Laboratory (LBNL; Brown et al., 2008). The analysis starts with the reference case from the EIA’s Annual Energy Outlook (AEO) 2007 as a business-as-usual (BAU) scenario, with disaggregation by fuel and end-use (EIA, 2007a). The researchers adjusted the published AEO end-use consumption values for 2030 to allocate some of the consumption in the “other uses” category (mainly cooking and electronics) to the traditional end-uses in which that consumption appropriately belongs. This reallocation was based on data published by the Department of Energy (DOE/EERE, 2007). Tables 2.9 and 2.10 show the revised AEO reference case that is used as the BAU scenario, with energy consumption and cost of conserved energy (CCE) presented in terms of electricity and natural gas.

The analysis considers only electricity and natural gas, which together account for approximately 92 percent of the primary energy used in U.S. buildings. Petroleum products—distillate fuel oil and liquefied petroleum gas, or LPG—account for most remaining energy use in buildings, with approximately 12 percent of homes using one of these two petroleum products as the primary heating fuel (EIA, 2007b). The analysis of the natural gas space-heating-savings potential presented below most likely applies to homes heated by fuel oil and LPG as well, but this was not explicitly analyzed by Brown et al. (2008).

The BAU scenario, which includes some level of energy efficiency improvement driven by market forces as well as by codes and standards, assumes that residential electricity use increases 1.4 percent per year and that commercial electricity use increases 1.9 percent per year on average during 2006–2030. For comparison, residential electricity use increased 2.4 percent per year and commercial use 2.8 percent per year on average over the period 1990–2006 (EIA, 2007b). With respect to the use of natural gas, the BAU scenario assumes growth rates of 0.8 percent per year in the residential sector and 1.6 percent per year in the commercial sector over the period 2006–2030. It should be noted that the effects of the Energy Independence and Security Act of 2007 (EISA; Public Law 110-140) are not included in the BAU scenario.

2.5.1
Methodology and Efficiency Measures

To calculate cost-effective energy-savings potential in 2030, Brown et al. (2008) compiled percentage savings estimates by end-use, drawn from several prior stud-

Suggested Citation:"2 Energy Efficiency in Residential and Commercial Buildings." National Academy of Sciences, National Academy of Engineering, and National Research Council. 2010. Real Prospects for Energy Efficiency in the United States. Washington, DC: The National Academies Press. doi: 10.17226/12621.
×

TABLE 2.9 Summary of Residential Building Energy Consumption, Savings Potential, and Efficiency Measure Costs in 2030, by End-Use

Fuel and End-Use

Business as Usual (BAU) 2030 U.S. Consumptiona

Technoeconomic Potential

Cost of Conserved Energyb

% Savings Relative to BAU Case

Consumption Savings

Electricity

(TWh)

(TWh)

(2007¢/kWh)

Space heatingc

164

17

28

3.5

Space coolingc

328

27

89

5.3

Water heatingc,d,e

149

27

39

2.0

Refrigerationc

121

31

38

4.6

Cookingc,e

103

0

0

N/A

Clothes dryersc,e

103

0

0

N/A

Freezersc

42

21

9

7.4

Lightingc

338

50

169

1.2

Clothes washersc

9

50

4

2.3

Dishwashersf

11

11

1

5.8

Color televisionsc

267

25

67

0.9

Personal computersf

68

57

39

4.3

Furnace fansf

40

25

10

3.7

Other usesc

154

48

74

1.9

Total electricity

1896

30

567

2.7

Natural Gas

(Quads)

(Quads)

(2007$/million Btu)

Space heatingg

3.89

30

1.15

5.5

Space coolingg

0.00

0

0.00

N/A

Water heatingg

1.20

29

0.35

11.8

Cooking

0.26

0

0.00

N/A

Clothes dryersg

0.09

3

0.00

2.9

Other usesg

0.04

10

0.00

1.1

Total natural gas

5.47

28

1.51

6.9

Note: A corresponding table for 2020 can be found in Brown et al. (2008).

a2007 AEO reference case (EIA, 2007a) end-use consumption for the “Other uses” end-use was reallocated to match the 2007 DOE Buildings Energy Databook 2007 (DOE/EERE, 2007) end-use shares.

bEnd-uses with cost of conserved energy (CCE) listed as N/A were not analyzed by the LBNL researchers.

cSource for potential savings and CCE is CEF study Table D-1.1 (IWG, 2000). Values for CCE are from the CEF Advanced Case, calculated using a real discount rate of 7 percent and lifetimes as shown in CEF study Appendix C-1.

dCCE for electric water heating was incorrect in the original CEF study (IWG, 2000) and has been corrected here.

eCEF study results (IWG, 2000) were adjusted to remove fuel switching (electric to gas) as a measure for water heaters, cooking, and clothes dryers.

fSource for potential savings and CCE is the updated LBNL analysis documented in Brown et al. (2008).

gSource for potential savings and CCE is the New York State natural gas potential study (Mosenthal et al., 2006).

Source: Brown et al., 2008.

Suggested Citation:"2 Energy Efficiency in Residential and Commercial Buildings." National Academy of Sciences, National Academy of Engineering, and National Research Council. 2010. Real Prospects for Energy Efficiency in the United States. Washington, DC: The National Academies Press. doi: 10.17226/12621.
×

TABLE 2.10 Summary of Commercial Building Energy Consumption, Savings Potential, and Efficiency Measure Costs in 2030, by End-Use

Fuel and End-Use

Business as Usual (BAU) 2030 U.S. Consumptiona

Technoeconomic Potential

Cost of Conserved Energy

% Savings Relative to BAU Case

Consumption Savings

Electricity

(TWh)

 

(TWh)

(2007¢/kWh)

Space heatingb

77

39

30

0.5

Space coolingb

238

48

115

2.8

Water heatingb

59

11

6

1.2

Ventilationb

131

45

59

0.5

Cookingc

11

30

3

8.3

Lightingb

543

25

137

5.2

Refrigerationb

89

38

34

1.3

Office equipment—PCsc

120

60

71

3.9

Office equipment—non-PCsc

271

25

68

3.2

Other usesb

523

35

182

1.4

Total electricity

2062

34

705

2.7

Natural Gas

(Quads)

 

(Quads)

(2007$/million Btu)

Space heatingb

2.30

47

1.09

1.9

Space coolingb

0.06

38

0.02

4.1

Water heatingb

1.06

15

0.16

2.3

Cookingc

0.47

31

0.14

7.3

Other usesb

0.47

20

0.09

1.9

Total natural gas

4.36

35

1.51

2.5

Note: A corresponding table for 2020 can be found in Brown et al. (2008).

aAEO reference case (EIA, 2007a) end-use consumption for the “Other uses” end-use was reallocated to match the 2007 DOE Buildings Energy Databook 2007 (DOE/EERE, 2007) end-use shares.

bSource for potential savings and CCE is CEF Table D-1.1 (IWG, 2000). Values for CCE are from the CEF Advanced Case, calculated using a real discount rate of 7 percent and lifetimes as shown in CEF report Appendix C-1.

cSource for potential savings and CCE is the updated LBNL analysis documented in Brown et al. (2008).

Source: Brown et al., 2008.

ies, and applied them to the BAU scenario. The approach was to consider specific energy efficiency measures for each end-use, as explained below. For most end-uses, Scenarios for a Clean Energy Future (IWG, 2000; hereafter referred to as the CEF study), sponsored by the DOE, was used to estimate savings potential (Koomey et al., 2001). The CEF study8 adjusted the energy-savings potential for

8

See also Box 4.2, “The Scenarios for a Clean Energy Future Study” in Chapter 4.

Suggested Citation:"2 Energy Efficiency in Residential and Commercial Buildings." National Academy of Sciences, National Academy of Engineering, and National Research Council. 2010. Real Prospects for Energy Efficiency in the United States. Washington, DC: The National Academies Press. doi: 10.17226/12621.
×

different end-uses in order to account for energy efficiency improvements in the baseline scenario and thereby avoid double counting the energy savings. For the residential natural gas end-uses, a recent study of natural-gas-savings potential in New York was used as the principal reference (Mosenthal et al., 2006). For selected end-uses that were not analyzed in the CEF study (IWG, 2000), Brown et al. (2008) compiled technical data to estimate savings percentages and the CCE. The specific data source for each end-use is identified in Tables 2.9 and 2.10.

To provide a better sense of the technologies that were used to estimate these potentials, Tables 2.11 and 2.12, respectively, list the principal residential-building and commercial-building measures or efficiency improvement assumptions used for each end-use. For the most part, the technologies are widely available in the marketplace today and are well proven. Technologies such as CFLs, T8 lamps and electronic ballasts, ENERGY STAR® appliances, horizontal-axis clothes washers, and high levels of building thermal integrity have been implemented by some consumers, but they have not been implemented in all applications in which they are technically and economically feasible owing to a wide range of market barriers and failures (see Section 2.7) A few of the technologies, such as heat-pump water heaters, are still produced on a limited scale and are considered near-term emerging technologies. However, other emerging technologies, such as LED lights, solar water heaters, and very high efficiency new buildings, are not included in the supply curves. Other excluded technologies include passive solar heating and cooling, gas-fired and geothermal heat pumps, the separation of ventilation from heating and cooling systems, products that must be special ordered (e.g., R-7 windows), non-air-based heating and cooling distribution systems in commercial buildings, and the redesign of building envelopes for daylighting and cooling load minimization.

To estimate aggregate savings potential in 2030, Brown et al. (2008) multiplied the percentage energy-savings potential shown by end-use in Tables 2.9 and 2.10 by the estimates of energy use by end-use in the BAU scenario. The CCE is reported as the levelized annual cost of the efficiency measures over their lifetime divided by the estimated annual energy savings. The CCE accounts for the costs of incremental measures only; no cost is included for public policies or programs aimed at stimulating the adoption of a measure. Consistent with the CEF study, a real discount rate of 7 percent was used to calculate these values. Cost-of-conserved-energy values from the CEF and New York studies were inflated to 2007 dollars using the GDP implicit price deflator.

Suggested Citation:"2 Energy Efficiency in Residential and Commercial Buildings." National Academy of Sciences, National Academy of Engineering, and National Research Council. 2010. Real Prospects for Energy Efficiency in the United States. Washington, DC: The National Academies Press. doi: 10.17226/12621.
×

TABLE 2.11 Residential Building Measures Included in the Conservation Supply Curve Analysis

Fuel and End-Use

Efficiency Measure Description

Electricity

 

Thermal shell

Existing electric-heated homes: no efficiency measures; new homes: up to 40% savings compared to 2006 International Energy Conservation Code

Space heating equipment

Electric furnace switched to heat pump, improved heat-pump efficiency

Space cooling equipment

Improved-efficiency central and room air conditioners, variable speed room air conditioners

Water heating

Reduced standby-loss electric-resistance water heater, heat pump water heater, horizontal axis clothes washer

Refrigeration

Best-in-class ENERGY STAR® refrigerator, 2008

Freezers

Best-in-class ENERGY STAR® freezer, 2008

Lighting

Compact fluorescent fixtures, halogen-infrared lamps, reduced-wattage incandescents, motion sensors

Clothes washers

Horizontal-axis washer with improved motor

Dishwashers

Dishwasher with improved pump design and improved motor

Color televisions

Reduced standby power use

Personal computers

ENERGY STAR®-rated PC and monitor, power-management-enabled

Furnace fans

Electronically commutated permanent magnet furnace-fan motor, single-speed operation

Other uses

More efficient motors in ceiling fans, pool pumps, and other small motors; improved fan and pump design; reduced standby power use in set-top boxes and other electronics; improved insulation for water beds, spas, and other small heating loads

Natural Gas

 

Thermal shell

Air sealing, R-19 floor insulation, R-21 wall insulation, R-49 attic insulation, integrated design for new construction (SF 30% > code, MF 50% > code), triple-pane low-e windows, insulated attic hatch

Space heating equipment

Insulated/sealed/balanced ducts, ducts placed within thermal shell condensing furnace, sensible heat recovery ventilation, direct-vent fireplace, direct-vent boiler, programmable thermostat, boiler pipe insulation

Space cooling equipment

Not applicable

Water heating

On-demand water heater, 0.63 EF gas water heater, low-flow plumbing fittings, ENERGY STAR® clothes washer, reduced water heater tank temperature, gray water heat exchanger/GFX, pipe insulation

Cooking

Not applicable

 

Humidity sensor control

Other uses

Pool and spa covers

Source: Brown et al., 2008.

Suggested Citation:"2 Energy Efficiency in Residential and Commercial Buildings." National Academy of Sciences, National Academy of Engineering, and National Research Council. 2010. Real Prospects for Energy Efficiency in the United States. Washington, DC: The National Academies Press. doi: 10.17226/12621.
×

TABLE 2.12 Commercial Building Measures Included in This Analysis

Fuel and End-Use

Efficiency Measure Description

Electricity

Thermal shell

No efficiency measures

Space heating equipment

Up to 55% savings in existing buildings from improved HVAC equipment and controls

Space cooling equipment

Up to 55% savings in existing buildings from improved HVAC equipment and controls

Water heating

20% savings compared to frozen efficiency baseline

Ventilation

Up to 55% savings in existing buildings from improved HVAC equipment and controls

Cooking

ENERGY STAR®-rated dishwasher, fryer, hot-food-holding cabinet, and steamer; more efficient broilers, griddles, and ovens

Lighting

T-8 lamps and electric ballasts; 32% combined savings from occupancy controls, daylight dimming, and improved lighting design

Refrigeration

20–45% savings compared to frozen efficiency baseline

Office equipment—PCs

ENERGY STAR®-rated personal computer and monitor, power-management-enabling software

Office equipment—non-PCs

ENERGY STAR®-rated copies and printers

Other uses

More efficient motors in ceiling fans, pool pumps, and other small motors; improved fan and pump design; reduced standby power use in electronics; improved insulation; small heating loads; up to 55% reduction in district services due to improved shell, equipment, and controls

Natural Gas

Thermal shell

No efficiency measures

Space heating equipment

Up to 55% savings in existing buildings from improved HVAC equipment and controls

Space cooling equipment

Up to 55% savings in existing buildings from improved HVAC equipment and controls

Water heating

10% savings compared to frozen efficiency baseline

Cooking

ENERGY STAR®-rated fryer and steamer; more efficient broilers, griddles, and ovens

Other uses

10% reduction in miscellaneous gas use; up to 55% reduction in district services due to improved shell, equipment, and controls

Source: Brown et al., 2008.

2.5.2
Information Sources

Technology costs were drawn by Brown et al. (2008) from the CEF advanced case, which assumed a greater penetration of more advanced efficiency technologies than in the moderate case. In using these savings potentials to estimate the

Suggested Citation:"2 Energy Efficiency in Residential and Commercial Buildings." National Academy of Sciences, National Academy of Engineering, and National Research Council. 2010. Real Prospects for Energy Efficiency in the United States. Washington, DC: The National Academies Press. doi: 10.17226/12621.
×

national savings potential in 2030, the researchers assumed that the CEF savings potential estimated for 2000–2020 would still be applicable for the 2020–2030 time period. While some efficiency measures such as CFLs, more efficient lighting devices for commercial buildings, and ENERGY STAR® personal computers and other electronic devices have been adopted to a significant degree, new efficiency measures have entered the marketplace since 2000, and others are under development and expected to be commercialized in the near future. Thus, while today’s energy efficiency baseline has improved since 2000, Brown et al. (2008) assumed that the number of efficiency technologies and practices being developed and not yet adopted have kept pace with this improvement, keeping the overall efficiency potential roughly constant.

Because the CEF study did not model the savings potential of building-shell retrofits to existing homes, the LBNL researchers instead used estimates of residential natural-gas savings derived from a recent New York study (Mosenthal et al., 2006). The applicability of that study to the national context rests on the assumption that the percentage savings (relative to baseline energy use) in New York is representative of the country as a whole. The CCE, however, depends on the absolute energy savings for a given measure, so Brown et al. (2008) scaled the CCEs to account for differences in heating degree-days between New York and the national average.9 The CCEs were calculated using a 7 percent discount rate, to be consistent with the other end-uses in this analysis. The Brown et al. (2008) study provides the details of this analysis.

Several end-uses were not analyzed in the CEF study, and savings and cost data for them were not available from other studies at that time. These end-uses were commercial office equipment, commercial cooking, residential office equipment, residential furnace fans, and residential dishwashers. For these end-uses, LBNL researchers compiled data on technology performance and cost and developed savings-potential estimates specifically for this analysis. The summary results of this analysis are shown in Tables 2.9 and 2.10; details can be found in Brown et al. (2008).

9

The researchers used the potential savings estimates for “downstate” New York (New York City and immediate vicinities) for this study. The climate scaling increased the CCEs by about 15 percent and was only applied to the space-heating end-use.

Suggested Citation:"2 Energy Efficiency in Residential and Commercial Buildings." National Academy of Sciences, National Academy of Engineering, and National Research Council. 2010. Real Prospects for Energy Efficiency in the United States. Washington, DC: The National Academies Press. doi: 10.17226/12621.
×

2.5.3
Results

Figures 2.8 and 2.9 show the potential for electricity (Figure 2.8) and natural gas (Figure 2.9) efficiency improvements over the 2010–2030 period in the residential and commercial sectors. The x-axis shows the total reduction in 2030 energy use, and the Y-axis shows the CCE in fuel-specific units. Each step on the graphs in these two figures represents the total savings for a given end-use for all the cost-effective efficiency measures analyzed for that end-use. These are referred to as “supply curves” because they indicate how much energy savings is available for a given cost. The CCE is calculated as the savings-weighted average for all the measures in that end-use cluster. End-uses that do not have technology costs reported in Tables 2.9 and 2.10 are not included in these plots (e.g., residential cooking). It should be noted that the space-heating and the space-cooling steps in Figures 2.8 and 2.9 include efficiency improvements in both the thermal shell and the HVAC equipment, analyzed in an integrated manner.

Each of the supply curves indicates that the projected BAU energy consumption in 2030 can be reduced by about 30–35 percent at a cost less than current retail energy prices. Table 2.13 compares the weighted-average cost of conserved energy from each supply curve with national average retail energy prices as of 2007. The data in the table show that the average CCE is well below the retail energy price in all areas, meaning that adopting these efficiency measures is cost-effective for households and businesses. In fact, the average CCE for these electricity-savings measures is only about one-quarter of the average retail electricity price. Of course, factors such as local energy prices and weather will influence cost-effectiveness in any particular location.

Table 2.14 presents data on the aggregate costs and benefits of efficiency technologies for the entire buildings sector. The cumulative capital investment required to achieve these savings between 2010 and 2030 is about $440 billion.10 The value of annual energy-bill savings in 2030 is nearly $170 billion. Thus, these efficiency measures in aggregate have a 2.6 year simple payback period on average, or savings over the life of the measures that are nearly 3.5 times larger than

10

The investment includes both the full “add-on” cost for new equipment or measures (e.g., attic insulation) and the incremental cost of purchasing an efficient technology (e.g., a high-efficiency boiler) compared with purchasing its conventional-technology equivalent (e.g., a standard boiler). These investments would be made by the individuals and private entities making the purchases. The costs of programs to support, motivate, or require these improvements are not included.

Suggested Citation:"2 Energy Efficiency in Residential and Commercial Buildings." National Academy of Sciences, National Academy of Engineering, and National Research Council. 2010. Real Prospects for Energy Efficiency in the United States. Washington, DC: The National Academies Press. doi: 10.17226/12621.
×
FIGURE 2.8 Estimates of the cost of conserved energy (CCE) and energy-savings potential for electricity efficiency technologies in buildings in 2030. The CCEs for potential energy efficiency measures (numbered) are shown versus the ranges of potential energy savings for these measures. The total savings potential is 567 TWh per year in the residential sector (blue solid line) and 705 TWh per year in the commercial sector (red solid line). For comparison, the national average 2007 retail price of electricity in the United States is shown for the residential sector (blue dashed line) and the commercial sector (red dashed line). For many of the technologies considered, on average the investments have positive payback without additional incentives. CCEs include the costs for add-ons such as insulation. For replacement measures, the CCE accounts for the incremental cost—for example, between purchasing a new but standard boiler and purchasing a new high-efficiency one. CCEs do not reflect the cost of programs to drive efficiency. All costs are shown in 2007 dollars.

FIGURE 2.8 Estimates of the cost of conserved energy (CCE) and energy-savings potential for electricity efficiency technologies in buildings in 2030. The CCEs for potential energy efficiency measures (numbered) are shown versus the ranges of potential energy savings for these measures. The total savings potential is 567 TWh per year in the residential sector (blue solid line) and 705 TWh per year in the commercial sector (red solid line). For comparison, the national average 2007 retail price of electricity in the United States is shown for the residential sector (blue dashed line) and the commercial sector (red dashed line). For many of the technologies considered, on average the investments have positive payback without additional incentives. CCEs include the costs for add-ons such as insulation. For replacement measures, the CCE accounts for the incremental cost—for example, between purchasing a new but standard boiler and purchasing a new high-efficiency one. CCEs do not reflect the cost of programs to drive efficiency. All costs are shown in 2007 dollars.

Source: Data from Brown et al., 2008.

the investment required on a discounted net present value basis. These averages are based on combining efficiency measures with CCE values ranging from less than 1¢/kWh to 8¢/kWh in the case of electricity saving measures, and $1/million Btu to $12/million Btu in the case of natural-gas-saving measures. There is an up-front cost to achieving substantial energy savings, but this cost is paid back a number of times over the lifetime of the energy efficiency measures.

A few other studies have developed conservation supply curves or, equivalently, the cost of reducing carbon dioxide (CO2) emissions for the United States. A recent study prepared by McKinsey and Company has received considerable attention (Creyts et al., 2007). The panel was unable to verify (owing to lack of

Suggested Citation:"2 Energy Efficiency in Residential and Commercial Buildings." National Academy of Sciences, National Academy of Engineering, and National Research Council. 2010. Real Prospects for Energy Efficiency in the United States. Washington, DC: The National Academies Press. doi: 10.17226/12621.
×
FIGURE 2.9 Estimates of the cost of conserved energy (CCE) and energy savings potential for natural gas efficiency technologies in buildings in 2030. The CCEs for potential energy efficiency measures (numbered) are shown versus the ranges of potential energy savings for these measures. The total savings potential is 1.5 quads per year in the residential sector (blue solid line) and 1.5 quads per year in the commercial sector (red solid line). For comparison, the national average 2007 retail price of natural gas in the United States is shown for the residential sector (blue dashed line) and the commercial sector (red dashed line). For many of the technologies considered, on average the investments have positive payback without additional incentives. CCEs include the costs for add-ons such as insulation. For replacement measures, the CCE accounts for the incremental cost—for example, between purchasing a new but standard boiler and purchasing a new high-efficiency one. CCEs do not reflect the cost of programs to drive efficiency. All costs are shown in 2007 dollars.

FIGURE 2.9 Estimates of the cost of conserved energy (CCE) and energy savings potential for natural gas efficiency technologies in buildings in 2030. The CCEs for potential energy efficiency measures (numbered) are shown versus the ranges of potential energy savings for these measures. The total savings potential is 1.5 quads per year in the residential sector (blue solid line) and 1.5 quads per year in the commercial sector (red solid line). For comparison, the national average 2007 retail price of natural gas in the United States is shown for the residential sector (blue dashed line) and the commercial sector (red dashed line). For many of the technologies considered, on average the investments have positive payback without additional incentives. CCEs include the costs for add-ons such as insulation. For replacement measures, the CCE accounts for the incremental cost—for example, between purchasing a new but standard boiler and purchasing a new high-efficiency one. CCEs do not reflect the cost of programs to drive efficiency. All costs are shown in 2007 dollars.

Source: Data from Brown et al., 2008.

data) the assumptions and results regarding energy efficiency potential in buildings. Nevertheless, the results of the McKinsey and Company study generally parallel those of the studies that the panel reviewed in terms of the magnitude and cost of saved energy in buildings.

2.5.4
Limitations

Owing to time and resource constraints, the Brown et al. (2008) analysis relied on data from previous efficiency-potential studies. As a result, the analysis can be improved on in several respects, some of which are highlighted below.

Suggested Citation:"2 Energy Efficiency in Residential and Commercial Buildings." National Academy of Sciences, National Academy of Engineering, and National Research Council. 2010. Real Prospects for Energy Efficiency in the United States. Washington, DC: The National Academies Press. doi: 10.17226/12621.
×

TABLE 2.13 Estimated Average Cost of Conserved (Saved) Energy in Residential and Commercial Buildings Compared with National Average Retail Energy Prices, 2007

 

Average Cost of Conserved (Saved) Energy

National Average Retail Energy Price

Residential

 

 

Electricity

2.7¢/kWh

10.6¢/kWh

Natural gas

$6.9/million Btu

$12.7/million Btu

Commercial

 

 

Electricity

2.7¢/kWh

9.7¢/kWh

Natural gas

$2.5/million Btu

$11.0/million Btu

Note: For the specific savings, see Figures 2.8 and 2.9.

Source: Brown et al., 2008. Energy prices are from EIA, 2008c.

TABLE 2.14 U.S. Efficiency Investment and Savings by 2030 (for the Buildings Sector)

Sector and Energy Type

Cumulative Capital Investment (billion 2007 $)

Annual Utility Bill Savings in 2030 (billion 2007 $)a

Simple Payback Time (years)

Residential

Electricity

137

64

2.1

Natural gas

104

19

5.5

Commercial

Electricity

163

68

2.4

Natural gas

38

17

2.3

Total

442

168

2.6

aAssumes 2007 retail electricity and natural gas prices.

Source: Brown et al., 2008.

  • The end-use technology data used in this study are mostly drawn from the CEF study (IWG, 2000), which reflects technology and market conditions in the late 1990s. Clearly, many factors have changed since then, including new technologies becoming available as well as costs falling for some energy efficiency measures owing to improved manufacturing processes, increased volumes, and the relocation of manufacturing facilities to countries where costs are lower. For example, one study found

Suggested Citation:"2 Energy Efficiency in Residential and Commercial Buildings." National Academy of Sciences, National Academy of Engineering, and National Research Council. 2010. Real Prospects for Energy Efficiency in the United States. Washington, DC: The National Academies Press. doi: 10.17226/12621.
×

that the average retail price of CFLs dropped about 75 percent between 1999 and 2007 (Itron, 2008).

  • As explained in Section 2.5.2, it is assumed that new efficiency measures compensate for the loss of savings potential due to measures adopted since 2000. This is a simplifying assumption that introduces uncertainty in the point estimates of the savings potential presented above.

  • Energy prices have risen significantly since the CEF study (IWG, 2000), which increases the number of energy efficiency technologies that are cost-effective, thus increasing the energy efficiency potential.

  • For the residential natural-gas end-uses, the New York study (Mosenthal et al., 2006) is only a rough approximation of savings potential across the country. A national study that includes all relevant technologies (including shell retrofits) would add considerable value to a study extrapolated from New York.

  • The effect of the Energy Independence and Security Act of 2007 is considered part of the remaining efficiency potential; that is, the effect of EISA is not included in the baseline. This assumption probably has the largest effect on the lighting end-use, because EISA contains aggressive provisions for lighting efficiency.

  • The results of Brown et al. (2008) are point estimates of savings potential that ignore uncertainty about how energy use in the building sector will evolve during the next 20+ years. Some of the major areas of uncertainty include energy prices, the availability and price of efficiency technologies, and potential changes in consumer behavior. They also include the policy context—for example, whether or not limits on greenhouse gas emissions are enacted, and if so, with what degree of stringency.

  • Studies of efficiency potential, such as the CEF and New York studies, are highly aggregated analyses that tend to ignore the great variability in the building stock with respect to climate, building configuration, equipment ownership, building occupancy and use, and other factors. Future studies should be conducted at a greater level of disaggregation to address variability in the building stock.

As noted above, the conservation supply-curve approach to estimating potential savings itself has limitations. The initial models of the cost of saving energy did not account for the life of energy-using equipment or for whether the new

Suggested Citation:"2 Energy Efficiency in Residential and Commercial Buildings." National Academy of Sciences, National Academy of Engineering, and National Research Council. 2010. Real Prospects for Energy Efficiency in the United States. Washington, DC: The National Academies Press. doi: 10.17226/12621.
×

technology would fit into the space available and perform the same functions, and these models generally lacked the detail to enable a determination of whether a particular technology would actually be attractive in a particular setting. The models assumed that the existing equipment needed to be replaced and could be replaced with a more efficient technology. The models were static in assuming that customers would want to buy the best technology today, instead of waiting until a better technology was available. The models did not account for the time and costs of disseminating information about the new technologies, the availability of capital to acquire the often more expensive equipment, the risks to existing production, and other barriers. Some economists expressed skepticism about the results—especially when businesses and consumers did not take advantage of the new, better technologies that promised large economic benefits. (See, for example, Stavins et al., 2007; Jaccard et al., 2003; Sutherland, 2000; Jacoby, 1999; and Jaccard and Montgomery, 1996.)

While current models are more sophisticated in considering these issues, they are still aggregate models that do not consider the specific circumstances of each energy-efficient replacement. They still do not fully account for educational and dissemination costs and other barriers. Thus, on the one hand, they tend to overstate the economic attractiveness of some new technologies; on the other hand, they are only dealing with a small number of energy-efficient technologies, so they neglect many other attractive alternatives, thus understating some potential benefits.

2.6
ADVANCED TECHNOLOGIES AND INTEGRATED APPROACHES

The conservation supply curves presented in Section 2.5 do not take into account a number of newer technologies and whole-building-design approaches. These technologies and approaches add to the energy-savings potential identified in the conservation supply curves; thus, the panel judges that these supply curves represent lower estimates of energy-savings potential.

This section reviews some of the advanced technologies that are the most promising for further improving the energy efficiency of buildings. These include discrete technologies such as solid-state lighting, advanced windows, and high-efficiency air-conditioning equipment, as well as the full integration of the technologies into new, highly efficient whole buildings, both residential and commercial. These technologies demonstrate that energy efficiency is a dynamic resource—new

Suggested Citation:"2 Energy Efficiency in Residential and Commercial Buildings." National Academy of Sciences, National Academy of Engineering, and National Research Council. 2010. Real Prospects for Energy Efficiency in the United States. Washington, DC: The National Academies Press. doi: 10.17226/12621.
×

and improved technologies now under development will reach the marketplace in the future, thereby increasing the potential for energy efficiency and energy savings.

The review below is not comprehensive; it does not address many advanced technologies related to building materials, design, and appliances.

2.6.1
Solid-State Lighting

Solid-state lighting is an important emerging technology for energy savings, given that lighting accounts for about 18 percent of primary energy use in buildings. CFLs are a major improvement over incandescent lamps with respect to efficacy (about 60 lumens per watt versus 15 lumens per watt), but they contain mercury, are difficult to dim, are not a point light source,11 and are not “instant-on.” Light-emitting diodes do not suffer from these disadvantages. As shown in Figure 2.10, the performance of white LED lamps has improved greatly in recent years. The best white LEDs are now more efficient than fluorescent lamps, with further gains expected within the next 5 years. Advances will come from improvements in the ratio of injected electrons to emitted photons in the active region, the efficiency of extracting generated photons out of the packaged part, phosphors, thermal efficiency, and scattering efficiency (Azevedo et al., 2009). The expectation is that white LEDs will reach 150 lumens per watt (Craford, 2008). LEDs last longer than fluorescent lamps do, are dimmable, and are becoming available in warm white with excellent color rendering. The dimmability and “instant-on” capability of LEDs make them especially appealing for applications such as streetlighting, gas station lighting, and display case lighting in retail stores where occupancy sensors can be used to dim them or turn them off when people are not present.

The primary issue with LEDs is cost, but their cost is decreasing rapidly. A 1000-lumen LED source that costs around $25 (wholesale cost) in 2008 is projected by the DOE to cost $2 in 2015 (DOE, 2008b). At a $50 retail cost, the CCE for an LED with a 20,000-hour lifetime and an efficacy of 60 lumens per watt replacing an incandescent lamp is about $0.13/kWh. The CCE would fall to $0.008/kWh if the cost goal of $2 wholesale ($4 retail) is achieved and performance improves to 150 lumens per watt along with a 50,000-hour lifetime. Given

11

Point light sources are easier to focus, which is important in some applications—for example, in retail stores.

Suggested Citation:"2 Energy Efficiency in Residential and Commercial Buildings." National Academy of Sciences, National Academy of Engineering, and National Research Council. 2010. Real Prospects for Energy Efficiency in the United States. Washington, DC: The National Academies Press. doi: 10.17226/12621.
×
FIGURE 2.10 White light source performance: light-emitting diodes (LEDs) compared with conventional light sources. Luminous efficacy is the ratio of luminous flux (in lumens) to power (in watts).

FIGURE 2.10 White light source performance: light-emitting diodes (LEDs) compared with conventional light sources. Luminous efficacy is the ratio of luminous flux (in lumens) to power (in watts).

Note: TL HE = tube light, high-efficiency; IR = infrared.

Source: Craford, 2008.

expected improvements, LEDs are projected to become competitive with CFLs by 2012 even if the lights are used only 2 hours a day and a 20 percent annual discount rate is assumed (Azevedo et al., 2009).

High-quality LED replacement lamps are now becoming available, and over the next 5 years a wide variety of higher-power lamps is expected. The penetration rate into the illumination market is difficult to predict and will be different for different market segments. DOE has modeled several segments as well as the overall market penetration rate (Navigant Consulting, 2006). The model projects that LEDs will yield a 12 percent savings in lighting energy use in 2017 and a 33 percent savings by 2027, relative to projected lighting energy use without LEDs. The projected 2027 electricity savings are greater than the energy consumed to illuminate all the homes in the United States today.

The penetration rate for organic LEDs (OLEDs), an alternative form of solid-state illumination, has also been independently modeled and also yields 33

Suggested Citation:"2 Energy Efficiency in Residential and Commercial Buildings." National Academy of Sciences, National Academy of Engineering, and National Research Council. 2010. Real Prospects for Energy Efficiency in the United States. Washington, DC: The National Academies Press. doi: 10.17226/12621.
×

percent lighting-energy savings by 2027. However, the OLED savings will occur later than the LED savings will (less than 6 percent in 2017 for OLED savings) and are much more speculative in view of impending technology hurdles and cost challenges.

2.6.2
Advanced Cooling

Cooling is one of the largest uses of energy in residential and commercial buildings, responsible for about 10 percent of total U.S. electricity use and 25–30 percent of total peak electricity demand (EIA, 2007a; Koomey and Brown, 2002). Significant potential exists for reducing cooling demand in buildings—or eliminating it entirely in some climates—through strategies that combine measures to reduce building cooling requirements and peak loads (e.g., highly efficient building envelopes, shading, reflective surfaces and roofs, reductions in heat gains from lights and other equipment, natural ventilation, and thermal storage) with emerging cooling technologies. These technologies are designed to supplement or replace vapor compression-based cooling with low-energy, thermally driven cooling approaches. They include indirect evaporative cooling and indirect-direct evaporative cooling (IDEC), solar thermal cooling (STC) systems, advanced controls and low-lift cooling strategies, and thermally activated desiccants. Each of the technologies has already been used commercially as individual components, but further research and development and commercial demonstration projects are needed to develop the technologies as integrated systems and to optimize their performance.

Indirect evaporative cooling systems use an evaporative process to cool a building’s interior without adding moisture to the indoor air. Various indirect evaporative systems are currently entering the marketplace, including systems that couple cooling towers with floor slabs and radiant ceilings. IDEC lowers air temperature by first passing air across a heat exchanger surface whose other side is cooled by evaporation. This precooled air then passes through a direct evaporative process, where it is cooled and humidified. Where applicable, IDEC units are capable of reducing cooling energy demand by 70–80 percent (PG&E, 2006). These advanced evaporative systems are now applicable in the dry climates of the western United States, with minimal net increase in total household water use (Kinney, 2004).

STC combines solar thermal technologies with traditional chiller-based systems to produce hot water that drives heat-driven absorption, and absorption or adsorption chillers that generate chilled water for space conditioning. Currently,

Suggested Citation:"2 Energy Efficiency in Residential and Commercial Buildings." National Academy of Sciences, National Academy of Engineering, and National Research Council. 2010. Real Prospects for Energy Efficiency in the United States. Washington, DC: The National Academies Press. doi: 10.17226/12621.
×

the systems are most cost-effective in commercial and industrial buildings with large roof areas, such as one- to three-story commercial buildings, hospitals, and food and beverage processing plants (Burns et al., 2006).

Low-lift cooling increases efficiency by reducing the temperature difference and thus the work performed by the cooling system. Options for low-lift cooling include the use of a dedicated outdoor air supply with enthalpy heat recovery from exhaust air, radiant cooling panels or floor systems, low-lift vapor compression equipment, and advanced controls. The technical energy savings potential is estimated to be 60–74 percent for temperate to hot and humid climates and 30–70 percent in milder climates (Jiang et al., 2007).

Desiccants allow the independent control of temperature and humidity within the HVAC system, thereby providing greater control over humidity loads within the building, which can also improve indoor air quality. For more than a decade, desiccant systems have been used in combination with conventional HVAC systems in specialized markets where humidity control is important, such as in supermarkets and hotels (DOE, 2004b). In humid regions, desiccant-based dehumidification could reduce residential electricity demand by 25 percent, because less energy is used to achieve dehumidification (PNNL, 1997). Combining desiccants with STC systems could achieve additional energy savings (Stabat et al., 2003). Researchers at DOE’s National Renewable Energy Laboratory are developing heat-driven liquid desiccant systems that are capable of being powered by solar thermal energy or through heat recovery from reciprocating engines, micro-turbines, and fuel cells (Lowenstein et al., 2006).

The energy-savings potential of these technologies is substantial. It is estimated that they could reduce total cooling-energy demand in residential and commercial buildings by 15 percent (0.6 quad) in 2020 and 33 percent (1.5 quads) in 2030, as shown in Figure 2.11. Incorporating advanced building-design practices that minimize cooling loads could save an additional 0.75 quad annually in 2030.

Within the next decade, the most economically competitive cooling strategies include thermal envelope improvements to reduce cooling loads, desiccant dehumidification in humid climates, and indirect-direct evaporative cooling in hot, dry climates. STC systems will become increasingly competitive with electrically driven vapor compression systems as the cost of solar collectors declines. By 2030, thermally driven cooling systems that use renewable energy or waste heat for cooling could replace conventional cooling technologies in new buildings and could be used to retrofit existing buildings.

There is also potential to use advanced building sensors and controls to

Suggested Citation:"2 Energy Efficiency in Residential and Commercial Buildings." National Academy of Sciences, National Academy of Engineering, and National Research Council. 2010. Real Prospects for Energy Efficiency in the United States. Washington, DC: The National Academies Press. doi: 10.17226/12621.
×
FIGURE 2.11 Potential reduction in cooling demand in U.S. buildings using advanced technologies.

FIGURE 2.11 Potential reduction in cooling demand in U.S. buildings using advanced technologies.

Source: Courtesy of S. Dunn, Southwest Energy Efficiency Project, Boulder, Colo., November 2007; based on data from the Annual Energy Outlook 2007 (EIA, 2007a) and the Buildings Energy Data Book 2007 (DOE/EERE, 2007).

reduce HVAC and lighting energy consumption. Currently, most advanced control approaches have a very small market share. These approaches include occupancy sensors, demand-controlled ventilation, photosensor-based lighting control, and continuous commissioning—that is, the ongoing testing of building equipment and systems to detect and diagnose faults. Brambley et al. (2005) estimate that the widespread adoption of advanced sensors and controls could reduce primary energy use by commercial buildings by about 6 percent.

2.6.3
Technologies to Reduce Energy Consumption in Home Electronics

Consumer electronics—that is, the products dealing with the processing of information—are responsible for about 13 percent of residential electricity use (Roth and McKenney, 2007; EIA, 2008a). This consumption is likely to increase simply because the growth in the number of products in homes shows little sign of abating (EIA, 2008a). Numerous efficiency improvements have been incorpo-

Suggested Citation:"2 Energy Efficiency in Residential and Commercial Buildings." National Academy of Sciences, National Academy of Engineering, and National Research Council. 2010. Real Prospects for Energy Efficiency in the United States. Washington, DC: The National Academies Press. doi: 10.17226/12621.
×

rated into—and ENERGY STAR® specifications have been adopted for—a wide range of products, but energy use continues to increase in a few important products, notably flat-panel televisions and set-top boxes. In March 2009, the Energy Information Administration projected that electricity use by televisions and set-top boxes would increase by 65 percent between 2006 and 2030 (DOE, 2009). New products are also appearing, such as digital picture frames, which will contribute to further increases in energy consumption. Many other kinds of appliances, such as dishwashers, furnaces, and water heaters, have electronic controls that are responsible for a small but noticeable fraction of those products’ overall energy consumption.

Electronic products typically consume energy both while active and while switched off. In many cases, the energy consumption while switched off exceeds that while in use, owing to the limited number of hours that many electronic devices are switched on (IEA, 2001). The average California home now contains more than 40 products that are continuously drawing power greater than 110 watts (Meier et al., 2008). An increasing number of electronic products are also connected to networks (WiFi, Ethernet, USB, Bluetooth, and others). With present designs, many products must remain in a power-intensive, fully-on mode so as not to be disconnected from the network. As with standby power use, the network connectivity of new products may become the standard situation rather than the exception.

At least five strategies exist to reduce the energy use of consumer electronics, but they are not yet widely used. First, improvements in power supplies could reduce electricity use in all power modes. Second, many products can be redesigned to exploit smaller and more efficient circuitry, which usually results in lower energy use. Third, some products can incorporate an auto-power-down feature. This feature is already required in new ENERGY STAR® specifications for digital television adapters. Fourth, protocols can be employed to allow products on a network to operate with a low-power sleep level without losing network connectivity. Finally, “power strips” can be designed more cleverly to manage energy consumption in clusters of products. In such systems, the “power” switch has migrated from individual products to a much smarter device able to take into account many other variables. For example, such a device can sense when a computer is turned off and can shut off the electricity flow to the computer and to other devices plugged into the strip at the same time. These strategies are already employed in a few products but have had minimal impact on energy use to date.

Suggested Citation:"2 Energy Efficiency in Residential and Commercial Buildings." National Academy of Sciences, National Academy of Engineering, and National Research Council. 2010. Real Prospects for Energy Efficiency in the United States. Washington, DC: The National Academies Press. doi: 10.17226/12621.
×

2.6.4
Technologies to Reduce Energy Consumption in Servers and Data Centers

Servers and data centers were responsible for about 61 billion kWh of electricity use in 2006, 1.5 percent of total national electricity use and more than double the level of 2000 (EPA, 2007b). The bulk of this electricity consumption is for site infrastructure, including cooling systems (50 percent) and what are termed “volume servers” (34 percent). The installed base of servers and external hard drives is increasing very rapidly. If current trends in server and data-center expansion and energy efficiency continue, the EPA (2007b) projects that servers and data centers will consume approximately 107 TWh by 2011, 75 percent more than in 2006.

There is large potential for cutting the electricity consumption of servers and data centers, and to do so cost-effectively. The techniques for improving efficiency include the following:

  • Virtualization, which allows data processing to be accomplished with fewer servers;

  • Improved microprocessors with higher performance per watt;

  • Servers with more efficient power supplies, fans, and microprocessors;

  • More efficient data-storage devices; and

  • More efficient cooling techniques, uninterruptible power supplies, and other “site infrastructure” systems.

The EPA (2007b) estimates that with the more widespread adoption of cost-effective energy efficiency technologies and practices already in use in some servers and data centers today, the overall electricity use of servers and data centers could be limited to 48 TWh in 2011, 55 percent less than in the current trends scenario. Furthermore, the EPA estimates that if state-of-the-art technologies and practices were fully adopted in all servers and data centers, overall electricity use could be limited to about 34 TWh in 2011, nearly a 70 percent reduction from what is projected under current trends.

In addition to saving the owners of servers and data centers money on their utility bills, utilities would benefit from reducing server and data-center electricity use because many servers and data centers are concentrated in areas such as New York City and San Francisco, which have congested transmission and distribution grids. Server and data-center energy efficiency is starting to be addressed by

Suggested Citation:"2 Energy Efficiency in Residential and Commercial Buildings." National Academy of Sciences, National Academy of Engineering, and National Research Council. 2010. Real Prospects for Energy Efficiency in the United States. Washington, DC: The National Academies Press. doi: 10.17226/12621.
×

utility and government energy efficiency programs such as the ENERGY STAR® program, but these efforts are still in their infancy; for example, an objective and credible energy performance rating for data centers, as well as ENERGY STAR® specifications for data-center equipment, are still under development. On May 15, 2009, the EPA published its initial specification for ENERGY STAR® computer servers.12

2.6.5
Advanced Window Technologies

Windows are responsible for about 2.7 quads of energy use annually in homes and about 1.5 quads in the commercial sector, and they impact another 1.0 quad of potential lighting-energy savings (Apte and Arasteh, 2006). Advances have been made over the last two decades primarily in reducing the heat-transfer coefficient (U-value) of windows through the use of low-emissivity (low-E) coatings and by reducing the solar heat gain coefficient (SHGC) by means of the use of spectrally selective low-E coatings. The window U-value is the primary determinant of winter heat loss; the window SHGC is the primary determinant of summer cooling loads. Window U-values have changed little in mainstream markets in recent years, having become “stuck” at ENERGY STAR® values that typify performance values achieved starting in the 1980s. Two new window technology advances are now available in niche markets. They currently have higher-than-acceptable cost, but they could have far-reaching implications if they could become mainstream products and systems.

The first advance is highly insulating “superwindows” that achieve U-values in the range of 0.1–0.2, compared to a typical U-value of 0.5 for double glazing and 0.35–0.4 for ENERGY STAR® windows currently being sold in cold climates (Apte and Arasteh, 2006). Such windows are available in limited quantity in Europe and in the United States but are not yet mass-produced. While research efforts continue with highly insulating aerogel and vacuum glazings, each of these approaches requires fundamental changes in glazing and window assembly and massive investment in facilities for start-up. An alternative approach is to develop a family of highly insulating window systems based on the use of two low-E-coated glazing layers in a triple-glazed assembly, with gas fills and improved edges. This combination of measures is capable of achieving overall glazing performance of U = 0.1–0.2 using existing production facilities and could have a price only

Suggested Citation:"2 Energy Efficiency in Residential and Commercial Buildings." National Academy of Sciences, National Academy of Engineering, and National Research Council. 2010. Real Prospects for Energy Efficiency in the United States. Washington, DC: The National Academies Press. doi: 10.17226/12621.
×

marginally above current gas-filled, double-glazed low-E units. These highly insulating glazings will also require a new series of companion insulating sashes and frames so that the whole window product meets target thermal performance requirements. These products are likely to have primary value in the residential sector but will find applications in commercial buildings as well.

The second opportunity is a new generation of dynamic products that reduces cooling loads in climates with substantial cooling loads and makes daytime lighting controls the preferred solution for reducing electric lighting in commercial buildings (Apte and Arasteh, 2006). The requirement here is for more dynamic control—the ability to modulate solar gain transmitted through the windows (thus minimizing cooling load), but also to admit sufficient daylight to reduce electric lighting in commercial buildings while controlling glare. This can be achieved in two ways: (1) for example, using “smart” electrochromic coat-ings that can reversibly switch properties in response to sensor input and that are capable of optimizing between cooling and lighting and can provide glare control as well; and (2) employing dynamic optical control using automated, motorized shading systems in buildings, including automated shades, blinds, shutters, and so on. These systems are commonplace in many European buildings but are rarely found in the United States. Fully automated, motorized roller shades with dimmable, addressable fluorescent lighting to capture daylight benefits were recently installed in a new 52-story office building in New York City.

Apte and Arasteh (2006) show that taken together, these two classes of emerging window technologies could produce large energy savings in the U.S. building stock if widely deployed in new and existing buildings. Tables 2.15 and 2.16 provide energy-savings estimates for the residential and commercial sectors, respectively, if the specified set of window technologies was fully deployed in the building stock. The tables show that the full penetration of ENERGY STAR® windows in residential and similar windows in commercial buildings would provide nearly 1.8 quads of energy savings per year. However, if the advanced technologies described above are commercialized and fully penetrate the buildings stock, the full technical potential for energy savings would increase to nearly 3.9 quads per year. Since the stock today accounts for approximately 4.2 quads of energy use per year, these improvements shift the role of windows in buildings to being approximately “energy neutral.” This is achieved by greatly reducing the unwanted seasonal losses and gains in all buildings in all climates and then by providing useful solar heat in winter in homes and useful daylight year round in commercial buildings. It will take many years, of course, to replace the existing

Suggested Citation:"2 Energy Efficiency in Residential and Commercial Buildings." National Academy of Sciences, National Academy of Engineering, and National Research Council. 2010. Real Prospects for Energy Efficiency in the United States. Washington, DC: The National Academies Press. doi: 10.17226/12621.
×

TABLE 2.15 Annual Energy Savings Potential of New Residential Window Technologies

Scenario

Energy Savings over Installed Window Stock in 2005 (quads)

Heat

Cool

Total

Sales (business as usual)a

0.49

0.37

0.86

ENERGY STAR® (Low-e)

0.69

0.43

1.12

Dynamic Low-e

0.74

0.75

1.49

Triple Pane Low-e

1.20

0.44

1.64

Mixed Triple, Dynamic

1.22

0.55

1.77

High-R Superwindow

1.41

0.44

1.85

High-R Dynamic

1.50

0.75

2.25

a The average properties of residential windows sold in 2004; used as a “business as usual” scenario.

Source: Apte and Arasteh, 2006.

TABLE 2.16 Annual Energy Savings Potentials of New Commercial Window Technologies

Scenario

Energy Savings over Installed Stock in 2005 (quads)

Heat

Cool

Total

Sales (business as usual)a

0.03

0.17

0.20

ENERGY STAR® (Low-e)

0.33

0.32

0.65

Dynamic Low-e

0.45

0.53

0.98

Triple Pane Low-e

0.71

0.31

1.02

High-R Dynamic

1.10

0.52

1.62

a The average properties of residential windows sold in 2004; used as a “business as usual” scenario.

Source: Apte and Arasteh, 2006.

stock with these new technologies, but a transition to “zero-net-energy windows” could provide enormous benefits eventually (Arasteh et al., 2006).

2.6.6
Low-Energy and Zero-Net-Energy New Homes

It is possible to construct homes that combine high levels of energy efficiency in the building envelope, heating and cooling systems, and appliances, along with passive and active solar features, in order to approach zero-net-energy

Suggested Citation:"2 Energy Efficiency in Residential and Commercial Buildings." National Academy of Sciences, National Academy of Engineering, and National Research Council. 2010. Real Prospects for Energy Efficiency in the United States. Washington, DC: The National Academies Press. doi: 10.17226/12621.
×

consumption.13 This is the objective of the Department of Energy’s Zero Energy Homes program. Although the market share for zero-energy homes (ZEHs) is still very low, the level of awareness and commitment among builders is growing rapidly.

A growing number of new homes being built use 50 percent as much energy as that used by typical new homes, or even less, as evidenced by the fact that more than 23,000 new homes met this performance criterion and qualified for a federal tax credit as of 2007. The following examples demonstrate the techniques used to achieve very low conventional energy use in new homes.

Two highly instrumented homes were built with the same floor plan in Lake-land, Florida, in 1998 (Parker et al., 2000). One of these was of conventional construction and served as the project control. The experimental building included an interior duct system, a high-efficiency heat pump, better wall insulation, a white reflective roof, solar water heating, efficient appliances, and efficient lighting. Over 1 year, the experimental home used 6,960 kWh of electricity and had photovoltaic (PV) system production of 5,180 kWh. For the same year, the control home used 22,600 kWh; that is, the experimental home consumed 70 percent less. Including the PV production, the experimental home’s net energy use was only 1,780 kWh, a 92 percent reduction relative to the control home.

A 3079-square-foot (286-square-meter) ZEH was built in Livermore, California, in 2002 (Parker and Chandra, 2008). The home featured fairly high levels of insulation; an innovative, computerized night cooling system (NightBreeze®) using outside air introduced by the duct system; high-performance windows with window shading; an attic radiant barrier; and highly efficient appliances and lighting. Heating was provided by a hydronic loop using a tankless gas water heater. Cooling was provided by the NightBreeze® with compressor cooling backup. In 2004, the 3.6 kW PV system produced more electricity (4890 kWh) than the house used (4380 kWh) so that net electricity consumption was negative: 510 kWh. ery little compressor cooling was ever needed. However, natural gas consumption totaled 700 million Btu per year—likely due to excess heat loss in a hot-water circulation loop.

In Lenoir City, Tennessee, the Oak Ridge National Laboratory constructed five ZEHs within a Habitat for Humanity development (Christian et al., 2004).

13

A home with zero-net-energy consumption may at times produce more energy than it consumes (for example, through photovoltaic panels on the roof), and at other times it may consume more energy than it produces.

Suggested Citation:"2 Energy Efficiency in Residential and Commercial Buildings." National Academy of Sciences, National Academy of Engineering, and National Research Council. 2010. Real Prospects for Energy Efficiency in the United States. Washington, DC: The National Academies Press. doi: 10.17226/12621.
×

The project focused on small, affordable homes while evaluating a variety of efficient building methods and technologies such as the following:

  • A heat-pump water heater linked to the refrigerator for heat recovery,

  • A crawl space with thermostat-controlled ventilation to assist with space cooling and dehumidification in the summer,

  • Ground source heat pumps using foundation heat recovery,

  • Structural insulated panels,

  • An interior duct system,

  • High-performance windows,

  • Efficient appliances, and

  • A gray water waste-heat recovery system.

Conventional energy use in these homes was reduced by 35–60 percent. Nonetheless, because a number of innovative technologies were tested in these experimental homes, the cost per unit of energy savings was relatively high (Parker and Chandra, 2008).

Another ZEH Habitat for Humanity home was built in Wheat Ridge, Colorado (Norton and Christiansen, 2006). The small home was superinsulated with R-60 ceiling, R-40 double-stud walls, and R-30 floor insulation. Ventilation was provided by a small heat-recovery ventilator. Very-high-performance, low-E solar glass with argon fill and a U-value of 0.2 was used for the east, west, and north faces, with a higher transmission U-value 0.3 glass used for the south exposure. For hot water, the home used a 9-square-meter solar collector with 757 liters of storage, backed up by a tankless gas water heater. The home was mated with a 4 kW rooftop PV system.

During a recent year, the PV system in the Wheat Ridge home produced 1,542 kWh more than the electricity used in the home. It is interesting to note that some 60 percent of the electricity use in the home was for nonappliance, nonlighting miscellaneous electric loads. Only 5.7 million Btu of natural gas were used during this period. Thus, the home was a net energy producer on both a site and a source basis. The total incremental cost of the project was $42,500, including $32,000 for the PV system and $7,100 for the solar water-heating system. The incremental cost of the efficiency measures was only about $3,400, due in part to the elimination of a full-size furnace.

Premier Gardens is a community-level project in Sacramento, California.

Suggested Citation:"2 Energy Efficiency in Residential and Commercial Buildings." National Academy of Sciences, National Academy of Engineering, and National Research Council. 2010. Real Prospects for Energy Efficiency in the United States. Washington, DC: The National Academies Press. doi: 10.17226/12621.
×

This project saw 95 entry-level homes constructed with high levels of energy efficiency: R-38 ceiling insulation and R-13 to R-19 wall insulation, tankless gas water heaters, high-efficiency gas furnaces, tightly sealed ducts buried in the attic insulation, and fluorescent lighting in all permanent fixtures (Parker and Chandra, 2008). The Premier Gardens homes also included 2.2 kW of PV on each house. Across the street from the development, a similar housing project was constructed without the energy efficiency measures or solar power. Performance monitoring in both developments showed that the Premier Gardens homes averaged 34 percent lower gas consumption and 16 percent lower electricity use. With the PV generation included, the homes averaged 54 percent lower net electrical demand and even greater savings during summer peak periods. The incremental cost of the Premier Gardens homes (not including the California PV buy-down) averaged about $19,000.

Figure 2.12 compares the performance of various ZEHs. The graph shows the energy performance as well as the incremental cost of different homes or housing projects. The costs for efficiency features are generally modest, but the solar power systems add $20,000 to $50,000 or more to project costs. Efficiency measures also reduce energy use more cost-effectively than solar systems do, as indicated by the steeper first set of data points relative to the second set of data points in Figure 2.12.

Figure 2.13, which shows the cost of saving or supplying energy for a set of homes similar to those discussed in Figure 2.12, indicates that efficiency measures are often cost-effective with a cost of saved energy at less than $0.10/kWh. However, the combination of solar PV and efficiency measures may not be cost-effective owing to the still-high cost of the solar systems, suggesting that efficiency measures should be emphasized first in low-energy homes.

Recent analysis shows that the source-energy use of a typical 2,000-square-foot, two-story house can be reduced by 50 percent at an incremental first cost of approximately $13,000. If this incremental cost is financed through a 30-year mortgage at 7 percent interest, the annualized cost for greater energy efficiency is just two-thirds of the annual utility bill savings, leading to net annual savings for the homeowner of about $450 on average (Anderson and Roberts, 2008). The efficiency measures that can be used to achieve this level of energy efficiency include additional insulation, tight sealing of the building envelope, highly efficient heating and cooling equipment, a tankless gas hot-water heater, ENERGY STAR® appliances, and fluorescent lamps in most light fixtures.

Suggested Citation:"2 Energy Efficiency in Residential and Commercial Buildings." National Academy of Sciences, National Academy of Engineering, and National Research Council. 2010. Real Prospects for Energy Efficiency in the United States. Washington, DC: The National Academies Press. doi: 10.17226/12621.
×
FIGURE 2.12 Energy use versus incremental first cost of five zero-energy and near-zero-energy homes. Baseline homes (actual or estimated) are the first point of each line (i.e., intersecting the Y-axis). The first drop in (conventional) energy use and first increase in incremental cost are a result of energy efficiency measures. The second drop in (conventional) energy use and second increase in incremental cost are due to the solar photovoltaic (PV) energy systems. The houses were constructed in Sacramento, California (Premier Gardens); Wheat Ridge, Colorado; Tucson, Arizona (Armory Park del Sol); Urbana, Illinois (Smith Passivhaus); and Lakeland, Florida.

FIGURE 2.12 Energy use versus incremental first cost of five zero-energy and near-zero-energy homes. Baseline homes (actual or estimated) are the first point of each line (i.e., intersecting the Y-axis). The first drop in (conventional) energy use and first increase in incremental cost are a result of energy efficiency measures. The second drop in (conventional) energy use and second increase in incremental cost are due to the solar photovoltaic (PV) energy systems. The houses were constructed in Sacramento, California (Premier Gardens); Wheat Ridge, Colorado; Tucson, Arizona (Armory Park del Sol); Urbana, Illinois (Smith Passivhaus); and Lakeland, Florida.

Source: Courtesy of D. Parker, Florida Solar Energy Center, Cocoa, Fla.

2.6.7
Low-Energy New Commercial Buildings

Technical innovation in the building sector will continue to drive improvements in building performance, but there is a significant gap between the potential of existing building technologies and the effective adoption of these strategies by the building sector. This gap represents a huge opportunity for improvements in building performance that will generate substantial performance improvements in the near term. New buildings as complete structures last many decades, but major

Suggested Citation:"2 Energy Efficiency in Residential and Commercial Buildings." National Academy of Sciences, National Academy of Engineering, and National Research Council. 2010. Real Prospects for Energy Efficiency in the United States. Washington, DC: The National Academies Press. doi: 10.17226/12621.
×
FIGURE 2.13 Cost of saved energy and solar photovoltaic (PV) energy supply in seven low-energy homes (those shown in Figure 2.12 plus two additional projects: one in Washington, D.C. [Hathaway House] and one in Livermore, California). Costs are shown on an annualized basis using a fixed-charge rate of 0.06 and with gas savings converted to kilowatt-hour equivalent.

FIGURE 2.13 Cost of saved energy and solar photovoltaic (PV) energy supply in seven low-energy homes (those shown in Figure 2.12 plus two additional projects: one in Washington, D.C. [Hathaway House] and one in Livermore, California). Costs are shown on an annualized basis using a fixed-charge rate of 0.06 and with gas savings converted to kilowatt-hour equivalent.

Source: Courtesy of D. Parker, Florida Solar Energy Center, Cocoa, Fla.

energy-using subsystems within such buildings are often redesigned on 5-year or 20-year cycles, so improved subsystems could be applied at least partially to existing buildings, particularly in the commercial sector.

A review of the best-performing new buildings in the country suggests that buildings that achieve energy-use reductions of 50 percent or more below standard practice do not typically incorporate cutting-edge technologies, but instead successfully integrate multiple “state-of-the-shelf”14 technologies to achieve these performance levels (Turner and Frankel, 2008).15 This approach represents a huge

14

“State-of-the-shelf” technologies represent the state-of-the-art selection of technologies that are widely available (on the shelf) today.

15

Also see http://www.gettingtofifty.org—a searchable database of information about projects whose energy performance targets 50 percent beyond ASHRAE 90.1-2001; NBI (2008).

Suggested Citation:"2 Energy Efficiency in Residential and Commercial Buildings." National Academy of Sciences, National Academy of Engineering, and National Research Council. 2010. Real Prospects for Energy Efficiency in the United States. Washington, DC: The National Academies Press. doi: 10.17226/12621.
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opportunity for improved energy performance using existing available technologies (Griffith et al., 2007).

The main difference between high-performing buildings and conventional buildings is essentially an attention to integration, interaction, and quality control throughout the design, construction, and operation of the building. This process, typically referred to as integrated design, represents a transformation not in technology but in conceptual thinking about how building systems can most effectively work together and the successful implementation of design intent (Torcellini et al., 2006).

One aspect of building performance that will grow tremendously in the next decade is the incorporation of more robust monitoring tools for building performance. A critical limitation of the ability of building designers and operators to improve building performance is the lack of good information about the impacts of design and operating decisions on actual building performance. A review of energy modeling results for 80 recently constructed Leadership in Energy and Environmental Design (LEED) buildings suggests a wide variation in the accuracy of energy modeling in predicting actual energy use (Turner and Frankel, 2008). In current practice, there is almost no mechanism through which the design community can receive real feedback on the effectiveness of its design strategies; no way to separate operational issues from design-based performance characteristics; and very little actionable feedback to building operators on real-time building performance. To address this problem, a host of efforts are currently under way for developing more effective tools to monitor and manage building operational performance using real-time data and intuitive data visualization.16

2.7
BARRIERS TO IMPROVING ENERGY EFFICIENCY IN BUILDINGS

Proponents of energy efficiency point to a wide range of market failures or barriers that inhibit greater investment in energy efficiency measures, including the following:

16

Building performance measurement protocols are currently under development by the Center for Neighborhood Technology, the New Buildings Institute, the Green Building Alliance, the U.S. Green Building Council, the American Society of Heating, Refrigerating, and Air-Conditioning Engineers, and a host of private companies.

Suggested Citation:"2 Energy Efficiency in Residential and Commercial Buildings." National Academy of Sciences, National Academy of Engineering, and National Research Council. 2010. Real Prospects for Energy Efficiency in the United States. Washington, DC: The National Academies Press. doi: 10.17226/12621.
×
  • Limited supply and availability of some energy efficiency measures;

  • Consumers lacking information or having incomplete information about energy efficiency opportunities, and the high transaction costs for obtaining such information;

  • Users of energy lacking the capital to invest in energy efficiency measures;

  • Fiscal or regulatory policies that discourage energy efficiency investments, often inadvertently;

  • Decision making that does not consider or value energy efficiency;

  • Perceived risk associated with the performance of relatively new energy efficiency measures;

  • Split incentives whereby the party designing, constructing, or purchasing a building or piece of equipment does not pay the operating costs; and

  • Energy prices that do not reflect the full costs imposed on society by energy production and use (externalities).17

It is important to recognize there is no single market for energy efficiency. The energy efficiency “market” consists of many end-uses, a myriad of intermediaries, hundreds of millions of energy users, and millions of decision points. In addition, it is useful to distinguish between what are generally viewed as market failures and market barriers (Box 2.1). Market failures occur if there is a flaw in the way that markets operate. Market barriers are not flaws in the way that markets operate, but they limit the adoption of energy efficiency measures nonetheless.

2.7.1
Market Failures

Environmental externalities are one of the most important and frequently cited examples of unpriced costs and benefits. Energy prices do include costs associated with meeting environmental standards, but other adverse environmental impacts, such as emissions of mercury or CO2, land disruption, or legal water contamination, are not factored in to energy prices. Likewise, the cost paid by society to protect and defend sources of oil and other energy imports is not included in energy

17

No attempt was made to rank the various market failures or barriers by importance in this list or in the subsequent discussion.

Suggested Citation:"2 Energy Efficiency in Residential and Commercial Buildings." National Academy of Sciences, National Academy of Engineering, and National Research Council. 2010. Real Prospects for Energy Efficiency in the United States. Washington, DC: The National Academies Press. doi: 10.17226/12621.
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BOX 2.1

Market Failures and Market Barriers Inhibiting Greater Energy Efficiency

Market Failures

Market Barriers

  • Unpriced costs and benefits

  • Distortional fiscal and regulatory policies

  • Misplaced or split incentives

  • Insufficient and inaccurate information

  • Low priority of energy issues

  • Incomplete markets for energy efficiency

  • Lack of access to capital

  • Fear of not getting value from next buyer

Sources: Brown, 2001; IEA, 2007.

prices. As a result of failing to include these costs in market prices, more fossil energy is consumed than is socially optimal (Brown et al., 2007).

Many energy economists acknowledge that not including environmental and social costs in energy prices is a problem. For example, Jaffe and Stavins (1994) stated, “While much controversy surrounds the magnitude of the value of the environmental damages associated with energy use, the direction of the effect is unambiguous … consumers face incentives to use more energy than is socially desirable if they do not bear the full costs of the pollution their energy use fosters.”

There are also barriers to recognizing and taking into account the full benefits of energy efficiency measures in consumer decision making. For example, at peak times, small reductions in demand can have a disproportionate effect in reducing price. The benefits of reducing demand accrue not only to the customers who reduce their load but to all customers, since all pay a lower price for their electricity. Because the majority of benefits accrue to customers who take no action, no customer realizes the full benefit of reducing his or her own load, and so there is less motivation to reduce demand than would be the case if a customer could realize the full benefit (Elliott and Shipley, 2005; Wiser et al., 2005; Spees and Lave, 2007).

Various types of fiscal policies discourage investments in energy efficiency. For example, capital investments in commercial buildings must be depreciated over more than 30 years, while energy purchases can be fully deducted from taxable income the year in which they occur (Brown, 2001). This puts energy effi-

Suggested Citation:"2 Energy Efficiency in Residential and Commercial Buildings." National Academy of Sciences, National Academy of Engineering, and National Research Council. 2010. Real Prospects for Energy Efficiency in the United States. Washington, DC: The National Academies Press. doi: 10.17226/12621.
×

ciency investments and upgrades at a disadvantage in terms of cost-effectiveness. Likewise, most states charge sales tax on energy efficiency measures and projects but do not tax electricity and fuel sales (Brown et al., 2007). In addition, conventional energy sources such as oil and natural gas production receive tax subsidies such as depletion allowances.

Some regulatory policies also inhibit investments in energy efficiency in buildings and industry. In particular, regulatory policies that allow public utilities to increase their profits by selling more electricity or natural gas are a disincentive to effective utility energy efficiency programs (Carter, 2001). Many utilities also have adopted tariffs and interconnection standards that discourage end users from adopting energy-efficient combined heat and power (CHP) systems (Brooks et al., 2006). The variability in the stringency and enforcement of building energy codes across states and localities is cited as another barrier to energy efficiency in buildings (Brown et al., 2007).

Misplaced incentives, also known as split incentives or principal-agent problems, exist in numerous situations. The most visible example of misplaced incentives is in rental markets, where building owners are responsible for investment decisions but tenants pay the energy bills. Nearly one-third of U.S. households rent their homes, and 40 percent of privately owned commercial buildings rent or lease their space (Brown et al., 2005). A number of studies have revealed lower levels of energy efficiency in dwellings occupied by renters compared to those occupied by owners in the United States. For example, a survey in California found that insulation, energy-efficient windows, programmable thermostats, and other energy efficiency measures are less common in rental housing compared to owner-occupied dwellings (see Figure 2.14).

Misplaced incentives also are found in new construction markets in which decisions about building designs and features are made by people who are not responsible for paying the energy bills. Architects, builders, and contractors have an incentive to minimize first cost in order to win bids and maximize their profits (Koomey, 1990; Brown et al., 2007). Also, commercial leases are often structured so that the landlord allocates energy costs to tenants on the basis of square footage leased. In that case, neither the landlord nor any of the tenants has the incentive to invest in cost-effective efficiency (Lovins, 1992).

Split incentives also exist for certain appliances and end-uses (IEA, 2007). When a homeowner installs a cable or satellite television box in his or her home, the box is purchased by the service provider, but the electricity bill is paid by the homeowner. When a retail store owner installs a beverage vending machine on

Suggested Citation:"2 Energy Efficiency in Residential and Commercial Buildings." National Academy of Sciences, National Academy of Engineering, and National Research Council. 2010. Real Prospects for Energy Efficiency in the United States. Washington, DC: The National Academies Press. doi: 10.17226/12621.
×
FIGURE 2.14 Comparison of the market penetration of energy efficiency measures in owner-occupied and rental housing in California. “Penetration” is the percentage of U.S. households with an energy-saving feature such as insulation.

FIGURE 2.14 Comparison of the market penetration of energy efficiency measures in owner-occupied and rental housing in California. “Penetration” is the percentage of U.S. households with an energy-saving feature such as insulation.

Source: CEC, 2004. Reprinted with permission.

his or her property, the machine is specified by the bottler but the utility bill is paid by the retailer. In these cases, the owner of the equipment has no incentive to spend extra money to improve energy efficiency.

In some cases the split in incentives is not between different economic actors but between different centers of responsibility within a single organization. In larger companies, energy efficiency investment decisions are often made by financial officers in charge of capital budgets, but the energy savings accrue to the division responsible for operating a particular piece of energy-efficient equipment. The operating division does not have access to capital or authority to make investment decisions, and the financial officers may end up ignoring cost-savings opportunities in the utilities area.

A large body of research documents that consumers are often poorly

Suggested Citation:"2 Energy Efficiency in Residential and Commercial Buildings." National Academy of Sciences, National Academy of Engineering, and National Research Council. 2010. Real Prospects for Energy Efficiency in the United States. Washington, DC: The National Academies Press. doi: 10.17226/12621.
×

informed about technology characteristics and energy efficiency opportunities. Some consumers do not know where to find credible information on energy efficiency options. Consumers may know how much more an energy-efficient air conditioner or water heater costs, but they would not know how much they will save per year by purchasing the more efficient technology, despite the fact that these technologies may carry mandatory energy efficiency labels. In addition, it can take many years to inform and educate a large majority of households and businesses about energy efficiency options. For example, after nearly 8 years of active promotion of—and incentives for—CFLs, nearly one-third of households surveyed in the Pacific Northwest in late 2004 were still unaware of this energy efficiency measure (Rasmussen et al., 2005). Indeed, many owners or managers of large commercial buildings have no knowledge of the size of the energy bills of their properties, despite the fact that energy is the largest cost component of net operating income, typically coming in at 15 percent. Some owners or managers even conceive of energy as a fixed cost beyond their control.

This lack of information is an even greater problem, and harder to fix, for individual end-uses. For example, when a tenant of a commercial building buys office equipment, the electricity usage of this equipment will not be metered, either at the user level or even on a level that would allow a rational decision to be made about the efficiency of the equipment. And not a single end-use in homes is ever metered separately. Thus homeowners have no direct information as to whether their computer, or videogame box, or hair dryer is a big energy user or a trivial one.

Likewise, consumers or businesses often lack the ability or time to process and evaluate the information that they do have, a situation sometimes referred to as “bounded rationality” (Koomey, 1990; Golove and Eto, 1996). And consumers often have difficulty using information on energy labels or calculating the payback period for a more efficient appliance (Sanstad and Howarth, 1994). Even when performance ratings are available (such as ENERGY STAR® labeling), consumers may not know how the energy-efficient device will function and how much energy and money will be saved in their own homes or businesses.

Consumers or businesses may perceive (rightly or wrongly) that energy efficiency technologies do not perform as well as the standard, less-efficient products they are used to.18 For example, consumers may believe that energy-efficient fluo-

18

Usually the assumption is not only wrong but reversed: the energy-efficient option performs better than what the consumer is used to. So while the popular press often reports negative con-

Suggested Citation:"2 Energy Efficiency in Residential and Commercial Buildings." National Academy of Sciences, National Academy of Engineering, and National Research Council. 2010. Real Prospects for Energy Efficiency in the United States. Washington, DC: The National Academies Press. doi: 10.17226/12621.
×

rescent lamps provide poorer-quality light compared to that from incandescent lamps; that energy-efficient homes have poorer air quality and are less healthful than leaky, inefficient homes; or that energy-efficient furnaces or air conditioners are less reliable than “low-tech” standard efficiency models (Jaffe and Stavins, 1994). Likewise, businesses may be concerned that energy-efficient devices are less reliable and could lead to costly downtime. In some cases, such concerns were legitimate when a technology was first introduced (e.g., for CFLs), but are no longer valid today.

Recent research has shown that human decision making departs from rationality in certain consistent ways, and several of those ways impact energy efficiency investments. Decisions reflect risk aversion and loss aversion, in that a $1 gain represents less positive utility than a $1 loss does negative utility. It takes a gain of $2.50 to balance a loss of $1 as a result of risk aversion, and a similarly biased ratio for loss aversion (Thaler et al., 1997). Decision makers confronted with a complicated choice will tend to leave things the way they are rather than risking failure or optimizing the situation as a decision maker with a fresh perspective would. This situation is also known as “status quo bias.”

These problems might represent a relatively minor failure of the market when the decision maker is acting on his or her own behalf, but they are serious problems when that person is an agent for others, for example, a business manager who is not the owner. Corporate shareholders do not want irrational behavior, and such behavior certainly is not consistent with the way to maximize profit (Goldstein, 2007).

The lack of information is often a market barrier rather than a market failure. In some cases, however, it rises in significance because the problem is not merely the dissemination of existing information but rather the generation of information in the first place. For example, televisions are a growing source of energy use, but information on the energy use of a particular set is unavailable because (until 2008) there was no standard on how to test a television’s energy consumption. This type of problem often occurs because the product’s trade association wants to set test standards or, in some cases, prefers that there not be any test standards.

sumer reactions to CFL color, a national survey of consumers as part of the McGraw-Hill annual construction survey found that more consumers than not consider the light quality of CFLs better than that of incandescent lamps (LeBlanc, 2007).

Suggested Citation:"2 Energy Efficiency in Residential and Commercial Buildings." National Academy of Sciences, National Academy of Engineering, and National Research Council. 2010. Real Prospects for Energy Efficiency in the United States. Washington, DC: The National Academies Press. doi: 10.17226/12621.
×

2.7.2
Market Barriers

Turning to the market barriers, businesses tend to pay limited attention to energy-use and energy-savings opportunities if energy costs are a small fraction of the total cost of owning or operating the business or factory, or if energy efficiency is not viewed as a priority by the company management. Energy costs represent less than 2 percent of the total cost of operating a factory or commercial business in many (but not all) cases. Furthermore, businesses are most concerned with developing new products, maintaining production, and increasing sales; energy consumption is usually a secondary or tertiary concern. As a result of these and other factors, many businesses limit energy efficiency investments to projects with payback periods of no more than 2 or 3 years (DeCanio, 1993; Geller, 2003).

Many individual consumers also do not value the lifetime energy savings provided by more efficient appliances, vehicles, or other energy efficiency measures. For example, consumers on average expect vehicle fuel-efficiency improvements to pay back their first cost in 3 years or less even though vehicles remain in use for about 14 years on average (Greene and Schafer, 2003). Chapter 5 discusses the strategies for overcoming this barrier as well as other market barriers discussed in this section.

Regarding incomplete markets for energy efficiency, some measures are relatively new and are still not widely available in the marketplace or not well supported by product providers (Hall et al., 2005). These include measures such as highly efficient light fixtures, reflective roofing materials, heat-pump water heaters, and modern evaporative coolers. The limited availability of these products results in a lack of consumer awareness and demand, and the lack of demand makes it difficult to expand availability. Also, some very effective energy efficiency services such as duct testing and sealing and the recommissioning of existing buildings are not widely available or marketed in many parts of the country.19

Regarding a lack of capital to invest in energy efficiency measures, this is particularly a problem for low-income households that have limited resources and limited access to credit. In addition, some businesses (particularly small businesses) have insufficient capital or borrowing ability.

19

It should be noted, however, that some energy efficiency measures such as insulation, compact fluorescent lamps, or ENERGY STAR® appliances are readily available.

Suggested Citation:"2 Energy Efficiency in Residential and Commercial Buildings." National Academy of Sciences, National Academy of Engineering, and National Research Council. 2010. Real Prospects for Energy Efficiency in the United States. Washington, DC: The National Academies Press. doi: 10.17226/12621.
×

Detailed studies of particular markets have found multiple and substantial barriers inhibiting the adoption of cost-effective energy efficiency improvements (IEA, 2007). In the motors market, for example, motor suppliers may fail to stock high-efficiency motors; buyers may lack accurate information on motor efficiency or other opportunities for cost-effectively saving energy in motor systems; facility managers often shy away from newer technologies, fearing reliability problems; and motors may be replaced on an emergency basis, resulting in little or no time to consider energy efficiency (Nadel et al., 2002). Also, many motors are purchased by original equipment manufacturers (OEMs), companies that assemble pumps, blowers, air-conditioning systems, and other items. OEMs generally purchase motors based on lowest first cost since they are not responsible for paying operating costs, another example of split incentives.

2.7.3
Implications of Market Barriers

Particular policy and program remedies are available for many of the market failures and barriers described above (Hall et al., 2005). These include educating consumers and businesses, increasing the supply and visibility of energy-efficient products and services in retail establishments, offering consumers and businesses financial incentives to get their attention and stimulate greater willingness to adopt efficiency measures, removing inefficient products or buildings from the marketplace through codes and standards, and reforming pricing and regulatory policies.

But other market failures or barriers are deeper and harder, if not impossible, to correct. Diffuse decision making, risk aversion, loss aversion, and status quo bias, in particular, would seem difficult to solve, even conceptually. Moreover, there are transactions costs related to educating consumers, addressing the split incentives problem, or convincing households or businesses to invest in energy efficiency to a greater degree. The real question is whether policy and program interventions are cost-effective mechanisms for stimulating greater investment in energy efficiency measures—that is, whether the value of the energy savings, peak-demand reduction, and nonenergy benefits (see below) exceed the costs (both for the efficiency measures and policy or program implementation). As discussed in detail in Chapter 5, many types of energy efficiency policies and programs offer effective and economically attractive ways of removing or reducing the market failures and barriers described above.

Suggested Citation:"2 Energy Efficiency in Residential and Commercial Buildings." National Academy of Sciences, National Academy of Engineering, and National Research Council. 2010. Real Prospects for Energy Efficiency in the United States. Washington, DC: The National Academies Press. doi: 10.17226/12621.
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2.8
MARKET DRIVERS

A number of factors—economic, environmental, and business related—are serving to overcome the barriers and market failures discussed above. Likewise, many energy efficiency measures provide multiple benefits, including nonenergy benefits that help to drive the adoption of these measures. In addition, numerous public policies, including state and utility efficiency programs, building energy codes, and appliance efficiency standards are stimulating a greater adoption of efficiency measures. These policies and programs are discussed further in Chapter 5.

2.8.1
Economic, Environmental, and Business Considerations

The costs of electricity, natural gas, and petroleum products are volatile but are generally rising (see Figure 2.15). Corrected for inflation, the average retail price for electricity paid by households in the United States increased 34 percent between 1975 and 1985, but then fell 24 percent during 1985–2002 (EIA, 2008b). However, the national average price increased 10 percent in real dollars during 2002–2007. Retail natural gas prices paid by residential consumers increased 45 percent on average during 2002–2007. The downturn in the world economy apparent at the time of this writing will mitigate growth in energy prices for a while, but the underlying determinants of demand growth remain in place. Higher energy prices improve the cost-effectiveness of energy efficiency measures and stimulate greater interest in and willingness to adopt such measures on the part of consumers (AIA, 2007). This is clear from the high demand for fuel-efficient vehicles and the heavy drop-off in demand for large sport-utility vehicles and other gas guzzlers in response to rapidly rising gasoline prices in late 2007 and early 2008.

Environmental awareness and concern about energy security and global climate change are also on the rise. A national survey administered by researchers from the Massachusetts Institute of Technology in 2003 and 2006 showed that citizens ranked global warming as the nation’s most pressing environment concern in 2006, whereas in 2003 global warming was ranked at number 6 out of 10 (Curry et al., 2007). Furthermore, the same survey found that support for action to address global warming is rising, as is the willingness to pay more for electricity in order to address global warming. In particular, the amount that respondents indicated they were willing to pay to address global warming increased 50 percent between 2003 and 2006. Many states and cities are adopting greenhouse gas emissions reduction goals and action plans, thereby increasing the awareness of and support for the adoption of energy efficiency measures.

Suggested Citation:"2 Energy Efficiency in Residential and Commercial Buildings." National Academy of Sciences, National Academy of Engineering, and National Research Council. 2010. Real Prospects for Energy Efficiency in the United States. Washington, DC: The National Academies Press. doi: 10.17226/12621.
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FIGURE 2.15 Average price of residential natural gas and average retail price of residential electricity.

FIGURE 2.15 Average price of residential natural gas and average retail price of residential electricity.

Source: EIA, 2008b.

Growing awareness of the ENERGY STAR® label and its increasing use in energy-related purchase decisions are other indicators that interest in energy efficiency is rising (EPA, 2008). ENERGY STAR® is promoted in part as a way for consumers to reduce polluting emissions and protect the environment. Likewise, the awareness and adoption of “green building” practices are rapidly rising. For example, 2.3 billion square feet of commercial buildings were registered or certified under the LEED rating program at the end of 2007, up more than 500 percent in 2 years (Makower, 2008).

Many corporations with forward-looking agendas are making commitments to increase energy efficiency and/or to reduce their greenhouse gas emissions and are achieving impressive results (Hoffman, 2006). These commitments often pertain to energy use and greenhouse gas emissions within the company itself. However, some large corporations such as Wal-Mart, Hewlett-Packard, and General Electric are expanding their production and/or marketing of energy- and resource-efficient products. Wal-Mart, for example, exceeded its goal of selling

Suggested Citation:"2 Energy Efficiency in Residential and Commercial Buildings." National Academy of Sciences, National Academy of Engineering, and National Research Council. 2010. Real Prospects for Energy Efficiency in the United States. Washington, DC: The National Academies Press. doi: 10.17226/12621.
×

100 million compact fluorescent lamps in 2007 and announced that it would launch its own brand of CFLs (Makower, 2008). The retailer also announced plans to cut the energy use of its stores and help increase the energy efficiency of its entire supply chain. Hewlett-Packard has introduced a wide range of more efficient personal computers that meet the ENERGY STAR® specifications issued in 2007. And General Electric recently announced that it would start manufacturing and marketing energy-efficient tankless and heat-pump water heaters, in conjunction with the DOE’s announcing ENERGY STAR® criteria for residential water heaters. Such efforts increase consumer awareness and the adoption of energy-efficient products.

2.8.2
Nonenergy Benefits

Energy efficiency is often defined in terms of using technology to reduce the amount of energy consumed in providing a given level of service. However, energy-efficient technologies in many cases provide a higher level of service as a result of “nonenergy” benefits. In some cases, the value of these nonenergy benefits exceeds the value of the energy saved over the lifetime of the product. It is also possible that energy-efficient technologies can reduce the level or quality of service—that is, they can result in nonenergy costs. But empirically, the number of cases in which this is true is small.

The CFL offers one example of nonenergy benefits. The nonenergy benefits of CFLs are primarily the increased lifetime. Compact fluorescent lamps meeting the ENERGY STAR® specifications have a minimum lifetime of 6,000 hours, but increasing numbers of products have lifetimes of 10,000 hours or more. For comparison, the lifetime for incandescent bulbs ranges from 750 hours to 2,000 hours, with 1,000 hours being most typical. For applications where lights are hard to change or where staff must be paid to change the bulbs, the value of reduced maintenance greatly exceeds the value of the energy savings.20

The color rendition of CFLs, which is different from that of incandescents, in some cases is a benefit. Incandescents are only available in a limited range of color temperatures from about 2500 K to 3000 K, with the low end of the range

20

For example, to change incandescent lamps providing illumination to a three-story atrium, maintenance crews must set up scaffolding to climb up three stories in order to change the bulbs. The cost of avoiding doing this every 1,000 hours—two or three times a year for typical usage patterns of office buildings—exceeds by an order of magnitude the value of lifetime energy savings of the lamp, which is on the order of $50–$100.

Suggested Citation:"2 Energy Efficiency in Residential and Commercial Buildings." National Academy of Sciences, National Academy of Engineering, and National Research Council. 2010. Real Prospects for Energy Efficiency in the United States. Washington, DC: The National Academies Press. doi: 10.17226/12621.
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obtainable only through dimming and the high end of the range obtainable only through halogen lamps. CFLs are available at a choice of color temperatures ranging from about 2700 K to about 6500 K; commonly available products are at 2700 K, 3500 K, and 4100 K.

LEDs used for traffic signals provide substantial cost savings to the municipalities that use them because of their longer lifetime; these savings go far beyond the value of energy savings. Longer lifetime means less expense for maintenance crews to replace burned-out lamps. LED traffic signals also have a safety advantage—if an incandescent signal fails, the entire red light or green light goes out, whereas if LEDs fail, they fail one lamp at a time, and the driver can still see a red light, green light, or amber light even if the pattern is not perfectly circular. And, because of their much lower energy use, it is technically feasible to operate LED signals with battery backups, so that traffic signals can function even in a blackout.

Energy-efficient (and water-efficient) domestic clothes washers are marketed on the basis of their superior cleaning ability and the fact that they cause less wear to fabrics, in addition to the value of the savings of energy, water, or even detergent. Many of these products can also, through their energy-efficient design, handle larger garments or those that might previously have required dry cleaning. These factors are much more important than energy savings in the marketing of these clothes washers.

Natural daylighting is another energy-saving strategy with significant non-energy benefits. High-quality daylighting has been shown to have a positive association with better student performance in schools, higher retail sales in stores, and productivity improvements in offices and other workplaces (Romm, 1999; Heschong and Wright, 2002; Kats, 2006).

Improved insulation and fenestration systems in buildings not only reduce energy use for air-conditioning and cooling but also provide greater comfort. In these cases, this benefit is a consequence of the physics of heat transfer: better-insulated walls or windows have interior surface temperatures that are closer to room temperature than do poorly insulated ones; this creates a radiant heat-transfer environment for the human body, which is more comfortable. In hotter climates, windows that reflect near-infrared solar heat result in less solar heat gain on clothes or skin than would be the case with conventional windows. Homes that are sealed to prevent air leakage from or to the outside and are better insulated also provide better acoustic isolation (i.e., less interior noise). And sealing air ducts in buildings not only saves energy but also can provide more

Suggested Citation:"2 Energy Efficiency in Residential and Commercial Buildings." National Academy of Sciences, National Academy of Engineering, and National Research Council. 2010. Real Prospects for Energy Efficiency in the United States. Washington, DC: The National Academies Press. doi: 10.17226/12621.
×

even heating and cooling within the building—for example, avoiding rooms at the end of the duct system that are not adequately heated in the winter or cooled in the summer.

The panel is unaware of any comprehensive study looking at nonenergy impacts (costs and benefits) from energy efficiency measures. This informal review finds numerous examples of nonenergy benefits (some of which are larger than the energy benefits themselves) and a few examples of nonenergy costs. Such a study would be useful, particularly if it attempted to quantify these costs and benefits.

2.9
FINDINGS

The following findings derive from the panel’s analysis of energy efficiency in buildings summarized in this chapter.

B.1

Studies assessing the potential for energy savings in buildings take several different approaches, looking at whole-building results as well as results by end-use and technology. Nevertheless, their results tend to be consistent.

B.2

The potential for large, cost-effective energy savings in buildings is well documented. Median predictions of achievable, cost-effective savings are 1.2 percent per year for electricity and 0.5 percent per year for natural gas, amounting to a 25–30 percent energy savings for the buildings sector as a whole over the next 20–25 years. If this level of savings were to be achieved, it would offset the EIA (2008a) projected increase in energy use in this sector over the same period.

B.3

Studies of energy efficiency potential are subject to a number of limitations and biases. On the one hand, factors such as not accounting for new and emerging energy efficiency technologies can lead such studies to underestimate energy-savings potential, particularly in the midterm and long term. On the other hand, some previous studies were overly optimistic about the cost and performance of certain efficiency measures, thereby overestimating energy-savings potential, particularly in the short term. Although these limitations must be acknowledged, they do not affect the panel’s overall finding that the potential for energy savings in buildings is large.

Suggested Citation:"2 Energy Efficiency in Residential and Commercial Buildings." National Academy of Sciences, National Academy of Engineering, and National Research Council. 2010. Real Prospects for Energy Efficiency in the United States. Washington, DC: The National Academies Press. doi: 10.17226/12621.
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B.4

Many advanced technologies under development and likely to become commercially available within the next decade—including LED lamps, innovative window systems, new types of cooling systems, and power-saving electronic devices—will further increase the energy-savings potential in buildings. In addition, new homes and commercial buildings with relatively low overall energy use have been demonstrated throughout the country. With appropriate policies and programs, they could become the norm in new construction.

B.5

Despite substantial barriers to widespread energy efficiency improvements in buildings, a number of countervailing factors could drive increased energy efficiency, including rising energy prices, growing concern about global climate change and the resulting willingness of consumers and businesses to take action to reduce emissions, a movement toward “green buildings,” and growing recognition of the significant nonenergy benefits offered by energy efficiency measures.

2.10
REFERENCES

ACEEE (American Council for an Energy-Efficient Economy). 2007. The Potential for Electricity Conservation in New York State, September 1989. Prepared for the New York State Energy Research and Development Authority, Niagara Mohawk Power Corporation, and the New York State Energy Office.

AHAM (Association of Home Appliance Manufacturers). 2008. Data compiled by the Association of Home Appliance Manufacturers. Washington, D.C.: AHAM. Available at http://www.aham.org.

AIA (American Institute of Architects). 2007. As home energy costs remain high, residential architects report that sustainable design motivates homeowners. AIArchitect This Week. Volume 14. September 7. Available at http://info.aia.org/aiarchitect/thisweek07/0907/0907n_econres.cfm.

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Suggested Citation:"2 Energy Efficiency in Residential and Commercial Buildings." National Academy of Sciences, National Academy of Engineering, and National Research Council. 2010. Real Prospects for Energy Efficiency in the United States. Washington, DC: The National Academies Press. doi: 10.17226/12621.
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Suggested Citation:"2 Energy Efficiency in Residential and Commercial Buildings." National Academy of Sciences, National Academy of Engineering, and National Research Council. 2010. Real Prospects for Energy Efficiency in the United States. Washington, DC: The National Academies Press. doi: 10.17226/12621.
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Suggested Citation:"2 Energy Efficiency in Residential and Commercial Buildings." National Academy of Sciences, National Academy of Engineering, and National Research Council. 2010. Real Prospects for Energy Efficiency in the United States. Washington, DC: The National Academies Press. doi: 10.17226/12621.
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Suggested Citation:"2 Energy Efficiency in Residential and Commercial Buildings." National Academy of Sciences, National Academy of Engineering, and National Research Council. 2010. Real Prospects for Energy Efficiency in the United States. Washington, DC: The National Academies Press. doi: 10.17226/12621.
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Suggested Citation:"2 Energy Efficiency in Residential and Commercial Buildings." National Academy of Sciences, National Academy of Engineering, and National Research Council. 2010. Real Prospects for Energy Efficiency in the United States. Washington, DC: The National Academies Press. doi: 10.17226/12621.
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Suggested Citation:"2 Energy Efficiency in Residential and Commercial Buildings." National Academy of Sciences, National Academy of Engineering, and National Research Council. 2010. Real Prospects for Energy Efficiency in the United States. Washington, DC: The National Academies Press. doi: 10.17226/12621.
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Suggested Citation:"2 Energy Efficiency in Residential and Commercial Buildings." National Academy of Sciences, National Academy of Engineering, and National Research Council. 2010. Real Prospects for Energy Efficiency in the United States. Washington, DC: The National Academies Press. doi: 10.17226/12621.
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Suggested Citation:"2 Energy Efficiency in Residential and Commercial Buildings." National Academy of Sciences, National Academy of Engineering, and National Research Council. 2010. Real Prospects for Energy Efficiency in the United States. Washington, DC: The National Academies Press. doi: 10.17226/12621.
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Suggested Citation:"2 Energy Efficiency in Residential and Commercial Buildings." National Academy of Sciences, National Academy of Engineering, and National Research Council. 2010. Real Prospects for Energy Efficiency in the United States. Washington, DC: The National Academies Press. doi: 10.17226/12621.
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Suggested Citation:"2 Energy Efficiency in Residential and Commercial Buildings." National Academy of Sciences, National Academy of Engineering, and National Research Council. 2010. Real Prospects for Energy Efficiency in the United States. Washington, DC: The National Academies Press. doi: 10.17226/12621.
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Suggested Citation:"2 Energy Efficiency in Residential and Commercial Buildings." National Academy of Sciences, National Academy of Engineering, and National Research Council. 2010. Real Prospects for Energy Efficiency in the United States. Washington, DC: The National Academies Press. doi: 10.17226/12621.
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Suggested Citation:"2 Energy Efficiency in Residential and Commercial Buildings." National Academy of Sciences, National Academy of Engineering, and National Research Council. 2010. Real Prospects for Energy Efficiency in the United States. Washington, DC: The National Academies Press. doi: 10.17226/12621.
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Suggested Citation:"2 Energy Efficiency in Residential and Commercial Buildings." National Academy of Sciences, National Academy of Engineering, and National Research Council. 2010. Real Prospects for Energy Efficiency in the United States. Washington, DC: The National Academies Press. doi: 10.17226/12621.
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Suggested Citation:"2 Energy Efficiency in Residential and Commercial Buildings." National Academy of Sciences, National Academy of Engineering, and National Research Council. 2010. Real Prospects for Energy Efficiency in the United States. Washington, DC: The National Academies Press. doi: 10.17226/12621.
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Suggested Citation:"2 Energy Efficiency in Residential and Commercial Buildings." National Academy of Sciences, National Academy of Engineering, and National Research Council. 2010. Real Prospects for Energy Efficiency in the United States. Washington, DC: The National Academies Press. doi: 10.17226/12621.
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Suggested Citation:"2 Energy Efficiency in Residential and Commercial Buildings." National Academy of Sciences, National Academy of Engineering, and National Research Council. 2010. Real Prospects for Energy Efficiency in the United States. Washington, DC: The National Academies Press. doi: 10.17226/12621.
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Suggested Citation:"2 Energy Efficiency in Residential and Commercial Buildings." National Academy of Sciences, National Academy of Engineering, and National Research Council. 2010. Real Prospects for Energy Efficiency in the United States. Washington, DC: The National Academies Press. doi: 10.17226/12621.
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Suggested Citation:"2 Energy Efficiency in Residential and Commercial Buildings." National Academy of Sciences, National Academy of Engineering, and National Research Council. 2010. Real Prospects for Energy Efficiency in the United States. Washington, DC: The National Academies Press. doi: 10.17226/12621.
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Suggested Citation:"2 Energy Efficiency in Residential and Commercial Buildings." National Academy of Sciences, National Academy of Engineering, and National Research Council. 2010. Real Prospects for Energy Efficiency in the United States. Washington, DC: The National Academies Press. doi: 10.17226/12621.
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Suggested Citation:"2 Energy Efficiency in Residential and Commercial Buildings." National Academy of Sciences, National Academy of Engineering, and National Research Council. 2010. Real Prospects for Energy Efficiency in the United States. Washington, DC: The National Academies Press. doi: 10.17226/12621.
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Suggested Citation:"2 Energy Efficiency in Residential and Commercial Buildings." National Academy of Sciences, National Academy of Engineering, and National Research Council. 2010. Real Prospects for Energy Efficiency in the United States. Washington, DC: The National Academies Press. doi: 10.17226/12621.
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Suggested Citation:"2 Energy Efficiency in Residential and Commercial Buildings." National Academy of Sciences, National Academy of Engineering, and National Research Council. 2010. Real Prospects for Energy Efficiency in the United States. Washington, DC: The National Academies Press. doi: 10.17226/12621.
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Suggested Citation:"2 Energy Efficiency in Residential and Commercial Buildings." National Academy of Sciences, National Academy of Engineering, and National Research Council. 2010. Real Prospects for Energy Efficiency in the United States. Washington, DC: The National Academies Press. doi: 10.17226/12621.
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Suggested Citation:"2 Energy Efficiency in Residential and Commercial Buildings." National Academy of Sciences, National Academy of Engineering, and National Research Council. 2010. Real Prospects for Energy Efficiency in the United States. Washington, DC: The National Academies Press. doi: 10.17226/12621.
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Suggested Citation:"2 Energy Efficiency in Residential and Commercial Buildings." National Academy of Sciences, National Academy of Engineering, and National Research Council. 2010. Real Prospects for Energy Efficiency in the United States. Washington, DC: The National Academies Press. doi: 10.17226/12621.
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Suggested Citation:"2 Energy Efficiency in Residential and Commercial Buildings." National Academy of Sciences, National Academy of Engineering, and National Research Council. 2010. Real Prospects for Energy Efficiency in the United States. Washington, DC: The National Academies Press. doi: 10.17226/12621.
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Suggested Citation:"2 Energy Efficiency in Residential and Commercial Buildings." National Academy of Sciences, National Academy of Engineering, and National Research Council. 2010. Real Prospects for Energy Efficiency in the United States. Washington, DC: The National Academies Press. doi: 10.17226/12621.
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Suggested Citation:"2 Energy Efficiency in Residential and Commercial Buildings." National Academy of Sciences, National Academy of Engineering, and National Research Council. 2010. Real Prospects for Energy Efficiency in the United States. Washington, DC: The National Academies Press. doi: 10.17226/12621.
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Suggested Citation:"2 Energy Efficiency in Residential and Commercial Buildings." National Academy of Sciences, National Academy of Engineering, and National Research Council. 2010. Real Prospects for Energy Efficiency in the United States. Washington, DC: The National Academies Press. doi: 10.17226/12621.
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Suggested Citation:"2 Energy Efficiency in Residential and Commercial Buildings." National Academy of Sciences, National Academy of Engineering, and National Research Council. 2010. Real Prospects for Energy Efficiency in the United States. Washington, DC: The National Academies Press. doi: 10.17226/12621.
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Suggested Citation:"2 Energy Efficiency in Residential and Commercial Buildings." National Academy of Sciences, National Academy of Engineering, and National Research Council. 2010. Real Prospects for Energy Efficiency in the United States. Washington, DC: The National Academies Press. doi: 10.17226/12621.
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Suggested Citation:"2 Energy Efficiency in Residential and Commercial Buildings." National Academy of Sciences, National Academy of Engineering, and National Research Council. 2010. Real Prospects for Energy Efficiency in the United States. Washington, DC: The National Academies Press. doi: 10.17226/12621.
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Suggested Citation:"2 Energy Efficiency in Residential and Commercial Buildings." National Academy of Sciences, National Academy of Engineering, and National Research Council. 2010. Real Prospects for Energy Efficiency in the United States. Washington, DC: The National Academies Press. doi: 10.17226/12621.
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Suggested Citation:"2 Energy Efficiency in Residential and Commercial Buildings." National Academy of Sciences, National Academy of Engineering, and National Research Council. 2010. Real Prospects for Energy Efficiency in the United States. Washington, DC: The National Academies Press. doi: 10.17226/12621.
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Suggested Citation:"2 Energy Efficiency in Residential and Commercial Buildings." National Academy of Sciences, National Academy of Engineering, and National Research Council. 2010. Real Prospects for Energy Efficiency in the United States. Washington, DC: The National Academies Press. doi: 10.17226/12621.
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Suggested Citation:"2 Energy Efficiency in Residential and Commercial Buildings." National Academy of Sciences, National Academy of Engineering, and National Research Council. 2010. Real Prospects for Energy Efficiency in the United States. Washington, DC: The National Academies Press. doi: 10.17226/12621.
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Suggested Citation:"2 Energy Efficiency in Residential and Commercial Buildings." National Academy of Sciences, National Academy of Engineering, and National Research Council. 2010. Real Prospects for Energy Efficiency in the United States. Washington, DC: The National Academies Press. doi: 10.17226/12621.
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Suggested Citation:"2 Energy Efficiency in Residential and Commercial Buildings." National Academy of Sciences, National Academy of Engineering, and National Research Council. 2010. Real Prospects for Energy Efficiency in the United States. Washington, DC: The National Academies Press. doi: 10.17226/12621.
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Suggested Citation:"2 Energy Efficiency in Residential and Commercial Buildings." National Academy of Sciences, National Academy of Engineering, and National Research Council. 2010. Real Prospects for Energy Efficiency in the United States. Washington, DC: The National Academies Press. doi: 10.17226/12621.
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Suggested Citation:"2 Energy Efficiency in Residential and Commercial Buildings." National Academy of Sciences, National Academy of Engineering, and National Research Council. 2010. Real Prospects for Energy Efficiency in the United States. Washington, DC: The National Academies Press. doi: 10.17226/12621.
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Suggested Citation:"2 Energy Efficiency in Residential and Commercial Buildings." National Academy of Sciences, National Academy of Engineering, and National Research Council. 2010. Real Prospects for Energy Efficiency in the United States. Washington, DC: The National Academies Press. doi: 10.17226/12621.
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Suggested Citation:"2 Energy Efficiency in Residential and Commercial Buildings." National Academy of Sciences, National Academy of Engineering, and National Research Council. 2010. Real Prospects for Energy Efficiency in the United States. Washington, DC: The National Academies Press. doi: 10.17226/12621.
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Suggested Citation:"2 Energy Efficiency in Residential and Commercial Buildings." National Academy of Sciences, National Academy of Engineering, and National Research Council. 2010. Real Prospects for Energy Efficiency in the United States. Washington, DC: The National Academies Press. doi: 10.17226/12621.
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Suggested Citation:"2 Energy Efficiency in Residential and Commercial Buildings." National Academy of Sciences, National Academy of Engineering, and National Research Council. 2010. Real Prospects for Energy Efficiency in the United States. Washington, DC: The National Academies Press. doi: 10.17226/12621.
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Suggested Citation:"2 Energy Efficiency in Residential and Commercial Buildings." National Academy of Sciences, National Academy of Engineering, and National Research Council. 2010. Real Prospects for Energy Efficiency in the United States. Washington, DC: The National Academies Press. doi: 10.17226/12621.
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Suggested Citation:"2 Energy Efficiency in Residential and Commercial Buildings." National Academy of Sciences, National Academy of Engineering, and National Research Council. 2010. Real Prospects for Energy Efficiency in the United States. Washington, DC: The National Academies Press. doi: 10.17226/12621.
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Suggested Citation:"2 Energy Efficiency in Residential and Commercial Buildings." National Academy of Sciences, National Academy of Engineering, and National Research Council. 2010. Real Prospects for Energy Efficiency in the United States. Washington, DC: The National Academies Press. doi: 10.17226/12621.
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Suggested Citation:"2 Energy Efficiency in Residential and Commercial Buildings." National Academy of Sciences, National Academy of Engineering, and National Research Council. 2010. Real Prospects for Energy Efficiency in the United States. Washington, DC: The National Academies Press. doi: 10.17226/12621.
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Suggested Citation:"2 Energy Efficiency in Residential and Commercial Buildings." National Academy of Sciences, National Academy of Engineering, and National Research Council. 2010. Real Prospects for Energy Efficiency in the United States. Washington, DC: The National Academies Press. doi: 10.17226/12621.
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Suggested Citation:"2 Energy Efficiency in Residential and Commercial Buildings." National Academy of Sciences, National Academy of Engineering, and National Research Council. 2010. Real Prospects for Energy Efficiency in the United States. Washington, DC: The National Academies Press. doi: 10.17226/12621.
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Suggested Citation:"2 Energy Efficiency in Residential and Commercial Buildings." National Academy of Sciences, National Academy of Engineering, and National Research Council. 2010. Real Prospects for Energy Efficiency in the United States. Washington, DC: The National Academies Press. doi: 10.17226/12621.
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Suggested Citation:"2 Energy Efficiency in Residential and Commercial Buildings." National Academy of Sciences, National Academy of Engineering, and National Research Council. 2010. Real Prospects for Energy Efficiency in the United States. Washington, DC: The National Academies Press. doi: 10.17226/12621.
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Suggested Citation:"2 Energy Efficiency in Residential and Commercial Buildings." National Academy of Sciences, National Academy of Engineering, and National Research Council. 2010. Real Prospects for Energy Efficiency in the United States. Washington, DC: The National Academies Press. doi: 10.17226/12621.
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Suggested Citation:"2 Energy Efficiency in Residential and Commercial Buildings." National Academy of Sciences, National Academy of Engineering, and National Research Council. 2010. Real Prospects for Energy Efficiency in the United States. Washington, DC: The National Academies Press. doi: 10.17226/12621.
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America's economy and lifestyles have been shaped by the low prices and availability of energy. In the last decade, however, the prices of oil, natural gas, and coal have increased dramatically, leaving consumers and the industrial and service sectors looking for ways to reduce energy use. To achieve greater energy efficiency, we need technology, more informed consumers and producers, and investments in more energy-efficient industrial processes, businesses, residences, and transportation.

As part of the America's Energy Future project, Real Prospects for Energy Efficiency in the United States examines the potential for reducing energy demand through improving efficiency by using existing technologies, technologies developed but not yet utilized widely, and prospective technologies. The book evaluates technologies based on their estimated times to initial commercial deployment, and provides an analysis of costs, barriers, and research needs. This quantitative characterization of technologies will guide policy makers toward planning the future of energy use in America. This book will also have much to offer to industry leaders, investors, environmentalists, and others looking for a practical diagnosis of energy efficiency possibilities.

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