CHAPTER 6. ENERGY AND WATER USE DETERMINATION
 

TABLE OF CONTENTS 

6.1 INTRODUCTION ........................................................................................................... 6-1
 

6.2 COOKING PRODUCTS ................................................................................................. 6-1
 

6.2.1 Cooktops and Ovens ........................................................................................................ 6-1
 

6.2.1.1 Average Annual Energy Consumption .......................................................... 6-1
 

6.2.1.2 Annual Energy Consumption of Energy-Using Components........................ 6-5
 

6.2.1.3 Annual Energy Consumption by Efficiency Level........................................ 6-6
 

6.2.1.4 Variability of Annual Energy Consumption................................................ 6-10
 

6.2.2 Microwave Ovens .......................................................................................................... 6-16
 

6.2.2.1 Average Annual Cooking Energy Consumption ......................................... 6-16
 

6.2.2.2 Standby Power Energy Consumption .......................................................... 6-18
 

6.2.2.3 Annual Energy Consumption by Efficiency Level...................................... 6-19
 

6.2.2.4 Variability of Annual Cooking Energy Consumption ................................. 6-20
 

6.3 COMMERCIAL CLOTHES WASHERS ..................................................................... 6-21
 

6.3.1 Per-Cycle Energy and Water Consumption by Efficiency Level .................................. 6-21
 

6.3.2 Average Annual Energy and Water Consumption by Efficiency Level........................ 6-25
 

6.3.3 Variability of Annual Energy and Water Consumption ................................................ 6-30
 

LIST OF TABLES 

Table 6.2.1 Annual Energy Consumption of Baseline Electric and Gas Cooktops and 

Ovens Based on DOE Test Procedure Energy Use Calculations ........................ 6-3
 

Table 6.2.2 Component Annual Energy Use of Baseline Cooktops and Ovens..................... 6-6
 

Table 6.2.3 Electric Coil Cooktops: Annual Energy Consumption by Efficiency Level ....... 6-7
 

Table 6.2.4 Electric Smooth Cooktops: Annual Energy Consumption by Efficiency
 

Level .................................................................................................................... 6-7
 

Table 6.2.5 Gas Cooktops: Annual Energy Consumption by Efficiency Level .................... 6-7
 

Table 6.2.6 Electric Standard Ovens: Annual Energy Consumption by Efficiency
 

Level .................................................................................................................... 6-8
 

Table 6.2.7 Electric Self-Cleaning Ovens: Annual Energy Consumption by Efficiency
 

Level .................................................................................................................... 6-8
 

Table 6.2.8 Gas Standard Ovens: Annual Energy Consumption by Efficiency Level .......... 6-9
 

Table 6.2.9 Gas Self-Cleaning Ovens: Annual Energy Consumption by Efficiency
 

Level .................................................................................................................. 6-10
 

Table 6.2.10 Annual Energy Use of Baseline Cooktops and Ovens with corresponding
 

RECS Cooking Frequency................................................................................. 6-11
 

Table 6.2.11 Microwave Ovens: Annual Energy Consumption by Energy Factor Level ..... 6-20
 

Table 6.2.12 Microwave Ovens: Annual Energy Consumption by Standby Power Level.... 6-20
 

Table 6.3.1 Residential Clothes Washer Energy Use Data from DOE 2000 TSD ............... 6-23
 

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Table 6.3.2 Top-Loading Commercial Clothes Washers: Per-Cycle Energy and Water
 

Use by Efficiency Level..................................................................................... 6-25
 

Table 6.3.3 Front-Loading Commercial Clothes Washers: Per-Cycle Energy and
 

Water Use by Efficiency Level.......................................................................... 6-25
 

Table 6.3.4 Commercial Clothes Washer Usage Data.......................................................... 6-27
 

Table 6.3.5 Top-Loading Commercial Clothes Washers, Multi-Family Application:
 

Annual Energy and Water Use by Efficiency Level.......................................... 6-28
 

Table 6.3.6 Top-Loading Commercial Clothes Washers, Laundromat Application:
 

Annual Energy and Water Use by Efficiency Level.......................................... 6-29
 

Table 6.3.7 Front-Loading Commercial Clothes Washers, Multi-Family Application:
 

Annual Energy and Water Use by Efficiency Level.......................................... 6-29
 

Table 6.3.8 Front-Loading Commercial Clothes Washers, Laundromat Application:
 

Annual Energy and Water Use by Efficiency Level.......................................... 6-29
 

LIST OF FIGURES 

Figure 6.2.1 Historical Estimates of Annual Electric Range Energy Use................................ 6-4
 

Figure 6.2.2 Historical Estimates of Annual Gas Range Energy Use...................................... 6-4
 

Figure 6.2.3 Distribution of Baseline Electric Cooktop Annual Energy Use Based on
 

2001 RECS Cooking Frequency........................................................................ 6-12
 

Figure 6.2.4 Distribution of Baseline Gas Cooktop Annual Energy Use Based on 2001
 

RECS Cooking Frequency................................................................................. 6-13
 

Figure 6.2.5 Distribution of Baseline Electric Standard Oven Annual Energy Use
 

Based on 2001 RECS Cooking Frequency ........................................................ 6-14
 

Figure 6.2.6 Distribution of Baseline Electric Self-Cleaning Oven Annual Energy Use
 

Based on 2001 RECS Cooking Frequency ........................................................ 6-14
 

Figure 6.2.7 Distribution of Baseline Gas Standard Oven Annual Energy Use Based on
 

2001 RECS Cooking Frequency........................................................................ 6-15
 

Figure 6.2.8 Distribution of Baseline Gas Self-Cleaning Oven Annual Energy Use
 

Based on 2001 RECS Cooking Frequency ........................................................ 6-16
 

Figure 6.2.9 Historical Estimates of Annual Microwave Oven Energy Use ......................... 6-18
 

Figure 6.2.10 Distribution of Microwave Oven Annual Cooking Energy Use Based on
 

2001 RECS Cooking Frequency........................................................................ 6-21
 

Figure 6.3.1 Residential Clothes Washer RMC versus MEF from DOE 2000 TSD ............. 6-24
 

Figure 6.3.2 Probability Distribution for Commercial Clothes Washer Usage in Multi-


Family Applications........................................................................................... 6-30
 

Figure 6.3.3 Probability Distribution for Commercial Clothes Washer Usage in
 

Laundromat Applications................................................................................... 6-31
 

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CHAPTER 6. ENERGY AND WATER USE DETERMINATION
 

6.1 INTRODUCTION
 

To carry out the life-cycle cost (LCC) and payback period (PBP) calculations described 

in Chapter 8, DOE needed to determine the operating cost savings to consumers from moreefficient equipment. The LCC and PBP analysis requires data on annual energy use, as well as 

water use for commercial clothes washers and residential dishwashers, because, along with 

energy and water prices, DOE uses these data to establish the most significant component of 

consumer operating costs. (Maintenance and repair costs are the other contributors to operating 

cost.) This chapter describes how DOE determined the annual energy and water consumption of 

residential electric and gas ranges and microwave ovens, dishwashers, dehumidifiers, and 

commercial clothes washers. 

6.2 COOKING PRODUCTS 

6.2.1 Cooktops and Ovens 

The annual energy consumption of electric and gas ranges has been in continual decline 

since the late 1970s. DOE’s 1996 technical support document (TSD) identified several studies 

that estimated the annual energy consumption of electric and gas ranges.1 The studies that 

covered the time period of 1977–1992 showed a steady decline in the annual energy 

consumption. More recent studies from the 2004 California Residential Appliance Saturation 

Study (CA RASS)2 and the Florida Solar Energy Center (FSEC)3 show a continued decline in the 

annual energy consumption. The studies seem to confirm that the U.S. populace is eating out 

more frequently and cooking less at home. 

6.2.1.1 Average Annual Energy Consumption 

Based on the research conducted for the 1996 TSD, DOE published revisions to its test 

procedure as a final rule in 1997 that included a reduction in the annual useful cooking energy 

output and a reduction in the number of self-cleaning oven cycles per year.4 The annual useful 

cooking energy output relates the energy factor of the cooking appliance to the annual energy 

consumption. 

For electric cooktops, the annual energy consumption (ECA) is determined based on the 

following DOE test procedure equation: 

OCT ECA = EffCT

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where:
 

OCT = 173.1 kilowatt-hours (kWh) per year, annual useful cooking energy output, and 

EffCT = Cooktop efficiency, which is also equivalent to the cooktop energy factor. 

For gas cooktops, the following DOE test procedure equation is used to determine the 

annual energy consumption: 

OCT E = CA RCT

where: 

OCT = 527.6 thousand British thermal units (kBtu) per year, annual useful cooking energy 

output, and 

RCT = Cooktop energy factor. 

Note that the annual energy consumption for gas cooktops does not account for any 

electrical energy consumption. The DOE test procedure implicitly assumes that any electrical 

energy consumption in a gas range is allocated to the oven rather than the cooktop. The test 

procedure also implicitly assumes that stand-alone, built-in gas cooktops do not consume 

electrical energy. 

For electric self-cleaning and non-self-cleaning ovens, the following DOE test procedure 

equation is used to determine the total annual energy consumption (EAO): 

OO E = AO RO

where: 

OO = 29.3 kWh per year, annual useful cooking energy output, and
 

RO = Oven energy factor.
 

For gas self-cleaning and non-self-cleaning ovens, the annual energy consumption is 

composed of gas energy (EAOG) and electrical energy (EAOE). The following DOE test procedure 

equation is used to determine the total annual energy consumption: 

OO E + E × K = AOG AOE e RO

where: 

OO = 88.8 kBtu per year, annual useful cooking energy output,
 

RO = Oven energy factor, and
 

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Ke = 3,412 Btu/kWh, conversion factor for kWh to Btus. 

Based on the baseline energy factors established in DOE’s 1996 TSD for cooking 

products, the annual energy consumption of electric and gas cooktops and ovens can be 

determined using the above DOE test procedure equations. Table 6.2.1 shows the associated 

annual energy consumption based on the 1996 TSD cooktop and oven energy factors. The table 

also presents the baseline cooking efficiencies. Note that the cooking efficiencies are lower than 

the energy factors due to the energy used by components that are not dedicated to cooking food 

(e.g., clock power, self cleaning). DOE considers the annual energy consumption values to be 

representative of electric and gas cooking energy usage circa the mid-1990s. 

Table 6.2.1	 Annual Energy Consumption of Baseline Electric and Gas Cooktops and 

Ovens Based on DOE Test Procedure Energy Use Calculations 

Product Type 

Baseline Cooking 

Efficiency* 

Baseline Energy 

Factor* 

Annual Energy 

Consumption 

Electric Cooktop** 74.0% 0.740 234 kWh 

Gas Cooktop*** 39.9% 0.156 3382 kBtu 

Electric Standard Oven (NonSelf-Cleaning) 12.15% 0.1066 274 kWh 

Electric Self Cleaning Oven 13.79% 0.1099 305 kWh 

Gas Standard Oven (Non-SelfCleaning)*** 5.92% 0.0298 2960 kBtu 

Gas Self-Cleaning Oven† 7.13% 0.0540 1644 kBtu 

* Baseline cooking efficiencies and energy factors from DOE, Cooking Product TSD, 1996. Energy factor for 

electric standard ovens in 1996 TSD reflects 7 self-cleaning cycles; corrected to reflect 4 self-cleaning cycles. 

** Energy Factor is the weighted-average of the baseline values for coil (73.7%) and smooth (74.2%) cooktops. 

*** Annual energy consumption reflects the use of standing pilots in the baseline products. 

† Annual energy consumption does not account for electrical energy consumption. 

DOE identified two additional studies that confirmed the continued downward trend in 

electric and gas range energy use: (1) the 2004 CA RASS and (2) a 2001 study conducted by 

FSEC. The CA RASS reported an average electric range annual energy consumption of 263 

kWh per year while the FSEC study reported an average electric range annual energy 

consumption of 300 kWh per year, both of which are lower than the consumption values derived 

from the DOE test procedure for a non-self-cleaning range (234 + 274 = 508 kWh) and a selfcleaning range (234 + 305 = 539 kWh). The CA RASS also reported an average gas range 

annual energy consumption of 43 therms (4300 kBtu) per year, but the study did not identify 

whether the energy use value was associated with ranges equipped with standing pilots. 

Using the data from the studies in the 1996 TSD, the CA RASS, and FSEC, Figure 6.2.1 

and Figure 6.2.2 show how the annual energy consumption of electric ranges and gas ranges, 

respectively, have varied over time. The figures indicate whether the estimates came from 

metered studies or conditional demand analyses. The figures below demonstrate that the annual 

energy use of cooking products has continued to decline over time. As a result, DOE believes 

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that an electric range annual energy consumption of 281.5 kWh per year (the average of the CA 

RASS and FSEC studies) is more representative of baseline annual energy use than that derived 

from the DOE test procedure. 

0 

200 

400 

600 

800 

1000 

1200 

1400 

1600 

1800 

2000 

2200 

1975 1980 1985 1990 1995 2000 2005 

Year 

Annual Electric Cooking Use (kWh/yr)

Metered 

CDA 

Figure 6.2.1 Historical Estimates of Annual Electric Range Energy Use
 

0 

20 

40 

60 

80 

100 

120 

140 

1975 1980 1985 1990 1995 2000 2005 

Year 

Annual Gas Cooking Energy (therms/yr)

CDA-pilot 

CDA-no pilot 

CDA-pilot unknown 

Metered-pilot 

Metered-no pilot 

Figure 6.2.2 Historical Estimates of Annual Gas Range Energy Use
 

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6.2.1.2 Annual Energy Consumption of Energy-Using Components 

DOE performed several calculation steps to disaggregate the representative baseline 

average annual energy consumption value for an electric range (281.5 kWh per year) into 

appropriate energy use values for the various energy-using components of electric and gas 

cooktops and ovens. The calculations are presented in Appendix 6A. Table 6.2.2 shows the 

results of these calculations. In the table, DOE presents the energy use values for electric and 

gas cooktops, standard ovens, and self-cleaning ovens with their disaggregated energy use 

components (i.e., cooking, ignition, self-cleaning, and clock) that correspond to the baseline 

cooking efficiencies provided in DOE’s 1996 TSD (see Table 6.2.1). Note that, because the 

annual useful cooking energy output values based on the updated annual energy use data are 

lower than those in the current DOE test procedure, the energy factors for each cooktop and oven 

are lower than those shown in Table 6.2.1. 

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Table 6.2.2 Component Annual Energy Use of Baseline Cooktops and Ovens
 

Ovens 

Cooktops Electric Gas 

Energy Use 

Components Electric 

Gas with 

pilots 

Gas w/o 

pilots Standard 

SelfCleaning Std with 

pilot 

Std w/o 

pilot 

SelfCleaning 

Cooking 

Efficiency 74.0% 39.9% 39.9% 12.15% 13.79% 5.92% 5.92% 7.13% 

Electric (kWh/yr) 128.2 132.4 116.6 

Gas (MMBtu/yr) 0.72 0.72 0.82 0.82 0.68 

Self-Cleaning 

Electric (kWh/yr) 21.1 0.7 

Gas (MMBtu/yr) 0.17 

Ignition 

Electric (kWh/yr) 21.1 21.1 

Gas (MMBtu/yr) 2.02 1.01 

Clock (kWh/yr) 34.2 33.3 31.5 

Total 128.2 

kWh 

2.74 

MMBtu 

0.72 

MMBtu 

166.5 

kWh 

171.0 

kWh 

1.83 

MMBtu 

0.92* 

MMBtu 

1.04* 

MMBtu 

Annual Useful Cooking 

Energy Output 

94.8 

kWh 

289.1 

kBtu 

289.1 

kBtu 

16.1 

kWh 

16.1 

kWh 

48.7 

kBtu 

48.7 

kBtu 

48.7 

kBtu 

Energy Factor 0.740 0.106 0.399 0.097 0.094 0.027 0.053 0.047 

* Total reflects electrical energy consumption converted to MMBtu. 

6.2.1.3 Annual Energy Consumption by Efficiency Level 

As discussed in Chapter 5, for the purposes of developing the cost-efficiency 

relationships of electric and gas range cooking products, DOE analyzed only those efficiency 

levels from its 1996 TSD. The following tables present the annual energy consumption of 

electric and gas range cooking products by efficiency level. DOE based the baseline annual 

energy consumption for each cooking product on the ‘total’ values shown in Table 6.2.2. 

Table 6.2.3 and Table 6.2.4 show the electric cooktop energy factors and their 

corresponding annual energy consumption. Because there is no additional energy use beyond 

what is needed for cooking, the energy factor for electric cooktops is equivalent to the cooking 

efficiency. The baseline annual energy consumption of 128.2 kWh is taken from Table 6.2.2. 

DOE determined the annual energy consumption for a more efficient level by taking the ratio of 

the energy factors of the more efficient and baseline levels and multiplying it by the baseline 

annual energy consumption. 

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Table 6.2.3 Electric Coil Cooktops: Annual Energy Consumption by Efficiency Level
 

Level Energy Factor 

Annual Energy Consumption 

kWh/year 

Baseline 0.737 128.2 

1 0.769 122.9 

Table 6.2.4 Electric Smooth Cooktops: Annual Energy Consumption by Efficiency Level
 

Level Energy Factor 

Annual Energy Consumption 

kWh/year 

Baseline 0.742 128.2 

1 0.753 126.3 

Table 6.2.5 shows the gas cooktop energy factors and cooking efficiencies as well as their 

corresponding annual energy consumption. Note that the energy factors provided in Table 6.2.5 

are based on the DOE test procedure’s annual useful cooking energy output rather than the value 

based on more recent annual energy consumption data. The baseline annual energy consumption 

of 2.74 million Btu (MMBtu) is taken from Table 6.2.2 and consists of two components: 

cooking energy (i.e., energy used to cook food) and standing pilot energy. The baseline annual 

energy consumption assumes that the cooktop is equipped with two standing pilots. The first 

efficiency level corresponds to the elimination of standing pilots. DOE determined the annual 

cooking energy consumption for a more efficient level by taking the ratio of the cooking 

efficiencies of the more efficient and baseline levels and multiplying it by the baseline annual 

cooking energy consumption. 

Table 6.2.5 Gas Cooktops: Annual Energy Consumption by Efficiency Level 

Level 

Energy 

Factor 

Cooking 

Efficiency 

Cooking Pilot* Total 

MMBtu/year MMBtu/year MMBtu/year 

Baseline 0.156 39.9% 0.72 2.02 2.74 

1 0.399 39.9% 0.72 - 0.72 

2 0.420 42.0% 0.69 - 0.69 

* Pilot light consumption based on the use of two pilot lights that each use 115 Btu/hr. 

Table 6.2.6 shows the electric standard (non-self-cleaning) oven energy factors and 

cooking efficiencies as well as their corresponding annual energy consumption. Note that the 

energy factors provided in Table 6.2.6 are based on the DOE test procedure’s annual useful 

cooking energy output rather than the value based on more recent annual energy consumption 

data. The baseline annual energy consumption of 149.9 kWh is taken from Table 6.2.2 and 

consists of two components: cooking energy and clock energy. The clock energy is based on a 

power consumption of 3.9 Watts. DOE determined the annual cooking energy consumption for a 

more efficient level by taking the ratio of the cooking efficiencies of the more efficient and 

baseline levels and multiplying it by the baseline annual cooking energy consumption. DOE 

assumed that clock energy remains constant with increased efficiency. 

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Table 6.2.6 Electric Standard Ovens: Annual Energy Consumption by Efficiency Level
 

Level 

Energy 

Factor 

Cooking 

Efficiency 

Cooking Clock† Total 

kWh/year kWh/year kWh/year 

Baseline 0.1066 12.2% 132.4 34.2 166.5 

1 0.1113 12.8% 125.9 34.2 160.1 

2 0.1163 13.4% 119.7 34.2 153.9 

3 0.1181 13.7% 117.6 34.2 151.8 

4 0.1206 14.0% 70.7 34.2 149.0 

5 0.1209 14.1% 70.6 34.2 148.6 

† Clock energy consumption based on clock power of 3.9 Watts. 

Table 6.2.7 shows the electric self-cleaning oven energy factors and cooking efficiencies 

as well as their corresponding annual energy consumption. Note that the energy factors provided 

in Table 6.2.7 are based on the DOE test procedure’s annual useful cooking energy output rather 

than the value based on more recent annual energy consumption data. The baseline annual 

energy consumption of 155.3 kWh is taken from Table 6.2.2 and consists of three components: 

cooking energy, self-cleaning energy, and clock energy. The self-cleaning energy is based on 

data from DOE’s 1996 TSD, i.e., a consumption of 5.286 kWh per self-cleaning cycle. There are 

four self-cleaning cycles per year. The clock energy is based on a power consumption of 3.8 

Watts. DOE determined the annual cooking energy consumption for a more efficient level by 

taking the ratio of the cooking efficiencies of the more efficient and baseline levels and 

multiplying it by the baseline annual cooking energy consumption. DOE assumed that both selfcleaning and clock energy remain constant with increased efficiency. 

Table 6.2.7	 Electric Self-Cleaning Ovens: Annual Energy Consumption by Efficiency 

Level 

Level 

Energy 

Factor 

Cooking 

Efficiency 

Cooking Self-Clean* Clock** Total 

kWh/year kWh/year kWh/year kWh/year 

Baseline 0.1099 13.8% 116.6 21.1 33.3 171.0 

1 0.1102 13.8% 116.2 21.1 33.3 170.6 

2 0.1123 14.2% 113.5 21.1 33.3 167.9 

* Self-cleaning energy consumption based on 5.286 kWh/cycle and 4 self-cleaning cycles per year. 

** Clock energy consumption based on clock power of 3.8 Watts. 

Table 6.2.8 shows the gas standard oven energy factors and cooking efficiencies along 

with their corresponding annual energy consumption. Note that the energy factors provided in 

Table 6.2.8 are based on the DOE test procedure’s annual useful cooking energy output rather 

than the value based on more recent annual energy consumption data. The baseline annual 

energy consumption of 1.83 MMBtu is taken from Table 6.2.2 and consists of two components: 

cooking energy and standing pilot energy. The baseline annual energy consumption assumes 

that the oven is equipped with one standing pilot. The first and seventh (i.e., ‘1a’) efficiency 

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levels correspond to the elimination of the standing pilot. The first efficiency level is based on 

the use of a globar or hot surface ignition device that, based on data from DOE’s 1996 TSD, has 

a test energy consumption of 176 Watt-hr. Efficiency level ‘1a’ is based on the use of an 

electronic ignition or spark ignition device that, according to DOE’s 1996 TSD, uses a negligible 

amount of electricity. Because the use of a globar ignition device is the technology most 

commonly used to eliminate the need for a standing pilot, efficiency levels two through six 

follow efficiency level ‘1’ as opposed to level ‘1a’. Efficiency levels four through six include 

the use of a forced-convection fan. Based on data from DOE’s 1996 TSD, the convection fan 

has a test energy consumption of 15 Watt-hr. DOE determined the annual cooking energy 

consumption for a more efficient level by taking the ratio of the cooking efficiencies of the more 

efficient and baseline levels and multiplying it by the baseline annual cooking energy 

consumption. DOE assumed that the ignition energy remains constant with increased efficiency. 

Table 6.2.8 Gas Standard Ovens: Annual Energy Consumption by Efficiency Level 

Level 

Energy 

Factor 

Cooking 

Efficiency 

Cooking* Ignition** Total 

MMBtu/yr kWh/yr MMBtu/yr kWh/yr MMBtu/yr kWh/yr 

Baseline 0.0298 5.9% 0.82 - 1.01 - 1.83 0.0 

1*** 0.0536 5.8% 0.84 - - 21.1 0.84 21.1 

2 0.0566 6.1% 0.80 - - 21.1 0.80 21.1 

3 0.0572 6.2% 0.79 - - 21.1 0.79 21.1 

4 0.0593 6.5% 0.75 1.8 - 21.1 0.75 22.9 

5 0.0596 6.5% 0.75 1.8 - 21.1 0.75 22.9 

6 0.0600 6.6% 0.74 1.8 - 21.1 0.74 22.9 

1a*** 0.0583 5.8% 0.84 - - - 0.84 0.0 

* Electrical energy consumption for cooking due to forced convection fan. Measured test energy use of 15 W-hr. 

** Gas energy consumption for ignition based on use of one pilot light that uses 115 Btu/hr. 

Electrical energy consumption for due to hot surface ignition device. Measured test energy use of 176 W-hr. 

*** For gas standard ovens, levels 1 and 1a correspond to designs that are utilized for the same purpose—eliminate 

the need for a standing pilot—but the technologies for each design are different. Level 1 is a hot surface 

ignition device while level 1a is a spark ignition device. Standard level 1a is presented at the end of the table 

because standard levels 2 through 6 are derived from standard level 1. 

Table 6.2.9 shows the gas self-cleaning oven energy factors and cooking efficiencies 

along with their corresponding annual energy consumption. Note that the energy factors 

provided in Table 6.2.9 are based on the DOE test procedure’s annual useful cooking energy 

output rather than the value based on more recent annual energy consumption data. The baseline 

annual energy consumption of 0.86 MMBtu and 39.3 kWh is taken from Table 6.2.2 and consists 

of several components: cooking energy, self-cleaning energy, ignition energy, and clock energy. 

The baseline annual energy consumption assumes that the oven uses a globar or hot surface 

ignition device which, based on data from DOE’s 1996 TSD, has a test energy consumption of 

176 Watt-hr. All efficiency levels include the use of a forced convection fan. Based on data 

from DOE’s 1996 TSD, the convection fan has a test energy consumption of 15 Watt-hr. The 

self-cleaning energy is based on data from DOE’s 1996 TSD, namely, gas consumption of 

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43,158 Btu and electrical consumption of 0.171 kWh per self-cleaning cycle. There are four 

self-cleaning cycles per year. The clock energy is based on a power consumption of 3.6 Watts. 

DOE determined the annual cooking energy consumption for a more efficient level by taking the 

ratio of the cooking efficiencies of the more efficient and baseline levels and multiplying it by 

the baseline annual cooking energy consumption. DOE assumed that the self-cleaning, ignition, 

and clock energy remain constant with increased efficiency. 

Table 6.2.9 Gas Self-Cleaning Ovens: Annual Energy Consumption by Efficiency Level 

Level 

Energy 

Factor 

Cooking 

Effcy 

Cooking* Self-Clean** Ignition*** Clock† Total 

MMBtu/yr kWh/yr MMBtu/yr kWh/yr kWh/yr kWh/yr MMBtu/yr kWh/yr 

Baseline 0.0540 7.1% 0.68 - 0.17 0.7 21.1 31.5 0.86 53.3 

1 0.0625 8.8% 0.56 1.8 0.17 0.7 21.1 31.5 0.73 55.1 

2 0.0627 8.8% 0.55 1.8 0.17 0.7 21.1 31.5 0.73 55.1 

3 0.0632 8.9% 0.55 1.8 0.17 0.7 21.1 31.5 0.72 55.1 

* Electrical energy consumption for cooking due to forced convection fan. Measured test energy use of 15 W-hr. 

** Self-cleaning energy consumption based on gas use of 43,158 Btu/cycle, electrical use of 0.171 kWh/cycle, 

and 4 self-cleaning cycles per year. 

*** Electrical energy consumption due to hot surface ignition device. Measured test energy use of 176 W-hr. 

† Clock energy consumption based on clock power of 3.6 Watts. 

6.2.1.4 Variability of Annual Energy Consumption 

DOE’s Energy Information Administration (EIA) conducts a Residential Energy 

Consumption Survey (RECS) that collects energy-related data for occupied primary housing 

units in the U.S. The 2001 RECS collected data from 4,822 housing units representing almost 

107 million households.5 The RECS indicates which households in the survey use electric and 

gas ranges, ovens, and cooktops. With regard to electric cooking products, 2895 household 

records have cooktops, 1159 household records have standard ovens, and 1601 household 

records have self-cleaning ovens. With regard to gas cooking products, 1597 household records 

have cooktops in either electric ranges or as stand-alone units, 959 household records have 

standard ovens, and 494 household records have self-cleaning ovens. The above totals represent 

cooktops and ovens in households as either a stand-alone unit or as part of a range. 

Although RECS does not provide the annual energy consumption of the cooking product 

for each household record, it does provide the frequency of cooking use. Thus, DOE can utilize 

the frequency of use to define the variability of the annual energy consumption. Conducting the 

analysis in this manner captures the observed variability in annual energy consumption while 

maintaining the average annual energy consumption shown above in section 6.4.2 in Table 6.2.2. 

To determine the variability of cooking product energy consumption, DOE first equated the 

weighted-average cooking frequency from RECS with the average energy use values reported in 

Table 6.2.2. Table 6.2.10 presents the weighted-average cooking frequency values along with 

the corresponding annual energy use values from Table 6.2.2. 

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Table 6.2.10 Annual Energy Use of Baseline Cooktops and Ovens with corresponding 

RECS Cooking Frequency 

Cooktops 

Ovens 

Electric Gas 

Gas with Gas w/o Self- Std with Std w/o SelfElectric pilots pilots Standard Cleaning pilot pilot Cleaning 

Annual Energy 128.2 2.74 0.72 166.5 171.0 1.83 0.92 1.04 

Consumption kWh MMBtu MMBtu kWh kWh MMBtu MMBtu MMBtu 

RECS average 

cooking frequency 1.22 1.29 1.29 0.52 0.57 0.49 0.49 0.56 

(meals per day) 

DOE then varied the annual energy consumption for each RECS household based on its 

reported cooking frequency. DOE determined the annual cooking energy consumption for each 

RECS household with a cooktop based on the following equation: 

ECA _ AVG ECA _ HH = FreqC _ HH ×

FreqC _ AVG

where: 

ECA_HH = Cooktop annual energy consumption for specific RECS household,
 

FreqC_HH = Cooktop frequency for specific RECS household,
 

ECA_AVG = Average cooktop annual energy consumption (from Table 6.2.10); 128.2
 

kWh for electric cooktops; 2.74 MMBtu for gas cooktops with pilots; and 

0.72 MMBtu for gas cooktops without pilots, and 

FreqC_AVG = Average cooktop frequency (from Table 6.2.10); 1.22 meals/day for electric 

cooktops; and 1.29 meals per day for gas cooktops. 

DOE determined the annual cooking energy consumption for each RECS household with an 

oven based on the following equation: 

EAO _ AVG EAO _ HH = FreqO _ HH ×

FreqO _ AVG

where: 

EAO_HH = Oven annual energy consumption for specific RECS household,
 

FreqO_HH = Oven frequency for specific RECS household,
 

EAO_AVG = Average oven annual energy consumption (from Table 6.2.10); 149.9 kWh
 

for electric standard ovens; 155.3 kWh for electric self-cleaning ovens; 1.83 

MMBtu for gas standard ovens with pilots; 0.96 MMBtu for gas standard 

ovens without pilots; and 0.99 MMBtu for gas self-cleaning ovens, and 

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FreqO_AVG = Average oven frequency (from Table 6.2.10); 0.52 meals/day for electric 

standard ovens; 0.57 meals/day for electric self-cleaning ovens; 0.49 

meals/day for gas standard ovens; and 0.56 meals per day for gas selfcleaning ovens. 

For all RECS households, cooktop and oven cooking frequency varies between zero to 

four meals per day. Figures 6.4.3 through 6.4.8 show the probability distributions of annual 

cooking energy consumption based on correlating the average cooking energy use to the cooking 

frequency data from RECS. 

Figures 6.4.3 and 6.4.4 show the distribution of electric and gas cooktop energy use, 

respectively. For gas cooktops, critical to the determination of the distribution of annual energy 

consumption is the determination of which cooktops have standing pilots. Based on shipments 

data from the 1996 TSD, the only cooktops that still have standing pilots are in gas ranges 

without self-cleaning ovens (i.e., gas standard ranges). In other words, all stand-alone cooktops 

and gas ranges with self-cleaning ovens have pilotless ignition systems. Based on estimates 

from the Appliance Recycling Information Center, approximately 250,000 standard gas ranges 

(or approximately 20 percent of gas standard range shipments) were sold in 2004 with standing 

pilots.6 Of the gas cooktops in RECS households, 43 percent are either in stand-alone units or in 

self-cleaning gas ranges while 57 percent are in standard gas ranges. Therefore, for purposes of 

defining which RECS households with gas cooktops utilize standing pilots, DOE assumed that 

20 percent of the standard gas ranges, or 11 percent of all gas cooktops, are equipped with 

standing pilots. 

0.04 

0.03 

0.02 

0.01 

0.00 

Probability 

0 50 100 150 200 250 300 350 

Annual Energy Use (kWh/year) 

400 450 500 

Figure 6.2.3 Distribution of Baseline Electric Cooktop Annual 

Energy Use Based on 2001 RECS Cooking Frequency 

6-12 

EE-2006-STD-0127 COMMENT 41.2
 

 

 

 

 

0.00 

0.01 

0.02 

0.03 

0.04 

0.05 

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 

Annual Energy Use (MMBtu/year) 

Probability 

Figure 6.2.4	 Distribution of Baseline Gas Cooktop Annual Energy 

Use Based on 2001 RECS Cooking Frequency 

Figures 6.4.5 and 6.4.6 show the distribution of annual energy use for electric standard 

and self-cleaning ovens, respectively. 

6-13 

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0.00 

0.01 

0.02 

0.03 

0.04 

0.05 

0.06 

0.07 

0.08 

0 50 100 150 200 250 300 350 400 450 500 550 

Annual Energy Use (kWh / year) 

Probability 

Figure 6.2.5	 Distribution of Baseline Electric Standard Oven 

Annual Energy Use Based on 2001 RECS Cooking 

Frequency 

0.00 

0.01 

0.02 

0.03 

0.04 

0.05 

0.06 

0.07 

0.08 

0 50 100 150 200 250 300 350 400 450 500 550 

Annual Energy Use (kWh/ year) 

Probability 

Figure 6.2.6	 Distribution of Baseline Electric Self-Cleaning Oven 

Annual Energy Use Based on 2001 RECS Cooking 

Frequency 

6-14 

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Figures 6.4.7 and 6.4.8 show the distribution of annual energy use for gas standard and 

self-cleaning ovens, respectively. For gas ovens, critical to the determination of the distribution 

of annual energy consumption is the determination of which ovens have standing pilots. Based 

on shipments data from the 1996 TSD, the only ovens still equipped with standing pilot are in 

gas ranges without self-cleaning ovens (i.e., gas standard ranges). In other words, all stand-alone 

cooktops and gas ranges with self-cleaning ovens have pilotless ignition systems. As stated 

above for gas cooktops, based on estimates from the Appliance Recycling Information Center, 

approximately 250,000 standard gas ranges (or approximately 20 percent of gas standard range 

shipments) were sold in 2004 with standing pilots. Of the gas standard ovens in RECS 

households, only four percent are in built-in units while 96 percent are in standard gas ranges. 

Therefore, for purposes of defining which RECS households with gas ovens use standing pilots, 

DOE assumed that 20 percent of standard gas ranges, or 19 percent of all gas standard ovens, are 

equipped with standing pilots. 

0.00 

0.01 

0.02 

0.03 

0.04 

0.05 

0.06 

0.07 

0.08 

0.09 

0.10 

0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 

Annual Energy Use (MMBtu/year) 

Probability 

Figure 6.2.7 Distribution of Baseline Gas Standard Oven Annual 

Energy Use Based on 2001 RECS Cooking Frequency 

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0.00 

0.01 

0.02 

0.03 

0.04 

0.05 

0.06 

0.07 

0.08 

0.09 

0.10 

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 

Annual Energy Use (MMBtu/year) 

Probability 

Figure 6.2.8 Distribution of Baseline Gas Self-Cleaning Oven 

Annual Energy Use Based on 2001 RECS Cooking 

Frequency 

As will be described later in Chapter 8 on the LCC and PBP analysis, DOE used the 

RECS household samples with their associated baseline annual cooking energy consumption to 

conduct the LCC and PBP analysis. 

6.2.2 Microwave Ovens 

After microwave oven annual energy consumption increased from the late 1970s to the 

late 1980s, annual energy consumption has remained relatively steady since the late 1980s. 

DOE’s 1996 TSD identified studies that estimated the annual energy consumption of microwave 

ovens. With the exception of one study based on the use of conditional demand analysis, the 

studies, which covered the time period 1988–1994, showed that annual energy consumption was 

no more than 200 kWh per year. A more recent study from the 2004 CA RASS is in line with 

the results from the previous studies. 

6.2.2.1 Average Annual Cooking Energy Consumption 

Based on the research conducted for the 1996 TSD, DOE published revisions to its test 

procedure for microwave ovens as a final rule in 1997 that included an increase in the annual 

useful cooking energy output.15 The annual useful cooking energy output relates the energy 

factor of the cooking appliance to the annual energy consumption. The annual energy 

consumption (EMO) is determined based on the following DOE test procedure equation: 

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OM E MO = 

RMO

where: 

OM = 79.8 kWh per year, annual useful cooking energy output, and
 

RMO = Microwave oven energy factor.
 

Based on a microwave oven baseline energy factor of 55.7 percent that DOE established 

in its 1996 TSD, the annual energy consumption of microwave ovens can be determined using 

the above DOE test procedure equation. DOE considers the resulting annual energy 

consumption of 143.2 kWh per year to be representative of microwave oven energy usage circa 

the mid-1990s. 

As with electric and gas range cooking products, DOE’s 1996 TSD also identified several 

studies estimating the annual energy consumption of microwave ovens. The CA RASS reported 

an average microwave annual energy consumption of 131 kWh per year. Figure 6.2.9 shows the 

annual energy consumption for microwave ovens based on the studies from the 1996 TSD and 

the CA RASS. The figure plots the reported annual energy use values from the studies by year 

and indicates whether the estimates came from metered studies, conditional demand analyses, or 

a combination of the two. Microwave oven energy use has remained relatively steady. Although 

the DOE test procedure produces an annual energy consumption that is close to that indicated by 

CA RASS, DOE believes that the value of 131 kWh per year is a more representative energy use 

value. Based on an annual energy consumption of 131 kWh per year and a baseline energy 

factor of 55.7 percent, DOE lowered the annual useful cooking energy output to 73.0 kWh per 

year. 

6-17 

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0 

50 

100 

150 

200 

250 

300 

1986 1988 1990 1992 1994 1996 1998 2000 2002 2004 

Year 

Annual Electric Cooking Energy (kWh/yr)

CDA 

Metered 

Metered/CDA 

Figure 6.2.9 Historical Estimates of Annual Microwave Oven Energy Use 

6.2.2.2 Standby Power Energy Consumption 

As reported in Chapter 5, a baseline microwave has a standby power consumption of four 

watts. To estimate the annual energy use associated with standby power (ESP), DOE used the 

following expression where the baseline standby power is multiplied by the number of hours in a 

year the oven is in standby mode: 

E = P × Hours SP SP SP 

where: 

PSP = Standby power consumption (watts), and
 

HoursSP = Hours in a year the microwave oven is in standby mode (kWh/yr).
 

The annual standby hours equals the total hours in a year minus the number of hours the 

microwave oven is in active operation. DOE determined the hours of active operation 

(HoursACTIVE)with the following expression: 

EMO Hours ACTIVE = I MO 

where: 

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EMO = annual (cooking) energy consumption, and
 

IMO = Microwave input power (watts).
 

As discussed in Chapter 5, DOE and AHAM tested a total of 52 microwave ovens as part 

of its analysis to determine how display and sensing technologies impact standby power 

consumption. From that testing, the average output power of the 52 tested units equaled 1026 

watts. The corresponding input power is based on the following expression: 

OMO I MO = RMO 

where: 

OMO = Microwave output power (watts). 

Based on the baseline microwave EF of 0.557 and an average output power of 1026 

watts, the average input power is 1842 W. Therefore, based on an annual cooking energy 

consumption of 131 kWh/year, there are 71 hours of active operation, resulting in 8689 hours 

that the appliance is in standby mode. 

Based on a four watt standby power, the annual standby power energy consumption 

equals 34.8 kWh per year. 

6.2.2.3 Annual Energy Consumption by Efficiency Level 

As discussed in Chapter 5, for the purposes of developing the cost-efficiency 

relationships of microwave ovens, DOE used the efficiency levels from its 1996 TSD. 

Tables 6.2.11 and 6.2.12 show how the annual energy consumption varies by microwave 

oven energy factor and standby power consumption, respectively. The baseline annual energy 

consumption is 131.0 kWh. DOE determined the annual cooking energy consumption of a more 

efficient level by taking the ratio of the more efficient and baseline cooking efficiencies and 

multiplying it by the baseline annual energy consumption. The annual standby energy 

consumption is based on the standby power associated with each standard level multiplied by the 

hours that the microwave oven is in standby mode. Chapter 5 established the standby power 

consumption corresponding to each standard level. 

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Table 6.2.11 Microwave Ovens: Annual Energy Consumption by Energy Factor Level
 

Level 

Energy 

Factor 

Cooking Consumption Standby Power Consumption Total Energy 

Consumption 

Efficiency 

Energy Use Standby Power Energy Use* 

kWh/year W kWh/year kWh/year 

Baseline 0.557 55.7% 131.0 4.0 34.8 165.8 

1a 0.586 58.6% 124.5 4.0 34.8 159.3 

2a 0.588 58.8% 124.1 4.0 34.8 158.8 

3a 0.597 59.7% 122.2 4.0 34.8 157.0 

4a 0.602 60.2% 121.2 4.0 34.8 156.0 

* Annual standby power energy consumption based on 8689 standby hours per year. 

Table 6.2.12	 Microwave Ovens: Annual Energy Consumption by Standby Power Level 

Level 

Energy 

Factor 

Cooking Consumption Standby Power Consumption Total Energy 

Consumption 

Efficiency 

Energy Use Standby Power Energy Use* 

kWh/year W kWh/year kWh/year 

Baseline 0.557 55.7% 131.0 4.0 34.8 165.8 

1b 0.557 55.7% 131.0 2.0 17.4 148.4 

2b 0.557 55.7% 131.0 1.5 13.0 144.0 

3b 0.557 55.7% 131.0 1.0 8.7 139.7 

4b 0.557 55.7% 131.0 0.02 0.2 131.2 

* Annual standby power energy consumption based on 8689 standby hours per year. 

6.2.2.4 Variability of Annual Cooking Energy Consumption 

The 2001 RECS indicates that 4,149 of the 4,822 households in the survey use 

microwave ovens. Although RECS does not provide the annual cooking energy consumption of 

the microwave ovens, it does provide the frequency of use. Thus, DOE can utilize the frequency 

of use to define the variability of the annual energy consumption. Conducting the analysis in this 

manner captures the observed variability in annual energy consumption while maintaining the 

average energy consumption value. To determine the variability of microwave oven energy 

consumption, DOE first equated the weighted-average cooking frequency from RECS with the 

average cooking energy use value of 131 kWh per year. The weighted-average cooking 

frequency from RECS is 0.40 meals per day. DOE then varied the annual energy consumption 

for each RECS household based on its reported cooking frequency. DOE determined the annual 

cooking energy consumption for each RECS household with a microwave oven based on the 

following equation: 

E MO _ AVG E MO _ HH

MO _ AVG

MO _ HH Freq

= Freq ×

where: 

EMO_HH =	 Microwave oven annual energy consumption for specific RECS 

household, 

FreqMO_HH =	 Microwave oven frequency for specific RECS household, 

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EE-2006-STD-0127 COMMENT 41.2
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

ECA_AVG = Average microwave oven annual cooking energy consumption of 131 

kWh, and 

FreqC_AVG = Average microwave oven frequency of 0.40 meals/day. 

For all RECS households, microwave oven cooking frequency varies between zero to 

four meals per day. Figure 6.2.10 shows the probability distribution of annual cooking energy 

consumption based on correlating the average cooking energy use to the cooking frequency data 

from RECS. 

0.00 

0.01 

0.02 

0.03 

0.04 

0.05 

0.06 

0.07 

0.08 

0.09 

0.10 

0 100 200 300 400 500 600 700 800 900 1000 1100 1200 

Annual Energy Use (kWh/yr) 

Probability 

Figure 6.2.10 Distribution of Microwave Oven Annual Cooking 

Energy Use Based on 2001 RECS Cooking Frequency 

As will be described later in Chapter 8 on the LCC and PBP analysis, DOE used the 

RECS household samples with their associated baseline annual cooking energy consumption to 

conduct the LCC and PBP analysis. 

6.3 COMMERCIAL CLOTHES WASHERS 

DOE established the annual energy and water consumption of commercial clothes 

washers by multiplying the per-cycle energy and water use by the number of cycles per year. 

6.3.1 Per-Cycle Energy and Water Consumption by Efficiency Level 

Commercial clothes washer per-cycle energy consumption is composed of three 

components: water-heating energy, machine energy, and drying energy. The machine energy is 

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composed of the motor energy for turning an agitator or rotating the wash basket. Based on 

language in the Energy Policy Act of 2005 (EPACT 2005), DOE is required to rate commercial 

clothes washers with the same test procedure established for residential clothes washers.7 DOE 

adopted test procedures for commercial clothes washers in a final rule published on October 18, 

2005.8 The DOE test procedure provides the following equations to calculate the total per-cycle 

dishwasher energy consumption: 

HET CWCYCLE	 = × c + MET + DE e

where: 

CWCYCLE =	 Total commercial clothes washer per-cycle energy consumption, 

HET =	 Per-cycle water heating consumption (kWh/cycle), 

e =	 Efficiency of electric water heater (100%) or gas water heater (75%), 

c =	 Conversion factor if water heater is gas (3,412 Btu/kWh), 

MET =	 Per-cycle machine electrical energy consumption (kWh/cycle), and 

DE =	 Per-cycle energy consumption for removal of moisture from test load, i.e., 

dryer energy consumption (kWh/cycle). 

The following equation from the DOE test procedure determines the per-cycle energy 

consumption for the removal of moisture: 

_ DE	 = LAF ×WGHTMAX × (RMC 4%)× DEF × DUF ×GCF

where: 

LAF =	 Load adjustment factor = 0.52, 

WGHTMAX = Maximum test-load weight (lbs/cycle), 

RMC =	 Remaining moisture content (lbs), 

DEF =	 Nominal energy required for a clothes dryer to remove moisture from 

clothes = 0.5 kWh/lb, and 

DUF =	 Dryer usage factor, percentage of washer loads dried in a clothes dryer = 

0.84. 

In the case of gas drying, DOE multiplies the dryer energy consumption by a gas correction 

factor to account for the additional energy required by a gas dryer to dry clothes relative to an 

electric dryer. The following equation determines per-cycle gas drying energy consumption. 

DG = GCF × DE

where: 

DG =	 Per-cycle energy consumption for removal of moisture from test load due to 

a gas dryer, i.e., dryer energy consumption (kWh/cycle), and 

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9 GCF = Gas correction factor = 1.12.

DOE establishes the energy and water efficiencies of commercial clothes washers with a 

modified energy factor (MEF) and a water factor (WF). The following equations from the DOE 

test procedure determine the MEF and WF: 

C

MEF = 

CWCYCLE

QT WF = C

where: 

C = Container capacity (cubic feet), and
 

QT = Per-cycle water consumption (gal/cycle).
 

The energy required to remove moisture from clothes, i.e., the dryer energy, is a 

significant component of total clothes washer energy consumption. In the above equation to 

determine dryer energy use, the only unknown quantity is the remaining moisture content (RMC) 

of the clothes. Because data were not provided by manufactures, DOE used its residential 

clothes washer analysis from the year 2000 to determine a relationship between RMC and MEF 

for the purpose of calculating the dryer energy for commercial clothes washers. Talbe 6.3.1 

shows the summary data for residential clothes washers from DOE’s 2000 TSD.10 As shown in 

Talbe 6.3.1, DOE determined the RMC using the dryer energy, the clothes container volume, and 

the resulting maximum test-load weight. 

Table 6.3.1 Residential Clothes Washer Energy Use Data from DOE 2000 TSD 

MEF Clothes Container Dryer Energy Max Test Load Weight 

cu.ft./kWh/cycle cu.ft. kWh/cycle RMC lb/cycle 

0.817 2.847 1.430 11.7 60.0% 

0.860 2.817 1.413 11.7 59.3% 

0.908 2.822 1.400 11.7 58.8% 

0.961 2.832 1.407 11.7 59.1% 

1.021 2.893 1.408 11.7 59.1% 

1.089 2.866 1.273 11.7 53.8% 

1.257 2.749 1.270 11.3 55.5% 

1.362 2.749 1.263 11.3 55.2% 

1.485 2.736 1.107 11.3 48.9% 

1.634 2.736 1.047 11.3 46.4% 

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Figure 6.3.1 plots the MEF and RMC data in Talbe 6.3.1 against each other. As indicated in the
 

figure, the relationship between MEF and RMC is approximately linear. Therefore, knowing the 

MEF, DOE was able to use this relationship to determine an RMC and, in turn, a per-cycle dryer 

energy consumption. 

RMC = -0.1560278 * MEF + 0.7337259 

R2 = 0.8651900 

45% 

50% 

55% 

60% 

65% 

0.8 0.9 1 1.1 1.2 1.3 1.4 1.5 1.6 1.7 

MEF 

RMC 

Figure 6.3.1 Residential Clothes Washer RMC versus MEF from DOE 2000 TSD 

As discussed in Chapter 5, DOE analyzed specific efficiency levels for top-loading and 

front-loadig commercial clothes washers. Tables 6.3.2 and 6.3.3 show the efficiency levels for 

top-loading and front-loading commercial clothes washers, respectively, and their corresponding 

per-cycle energy and water use. Per-cycle energy use is disaggregated into water heating, 

machine, and clothes drying. DOE determined the per-cycle clothes drying energy use by first 

establishing the RMC based on the relationship between RMC and MEF in Figure 6.3.1. DOE 

then calculated the per-cycle clothes-drying energy use using the equation that determines the 

per-cycle energy consumption for the removal of moisture. DOE determined the per-cycle 

machine energy use from its 2000 TSD for residential clothes washers. In the 2000 TSD, for 

MEFs up to 1.40, machine energy is 0.133 kWh/cycle. For MEFs greater than 1.40, machine 

energy is 0.114 kWh/cycle. With the per-cycle clothes drying and machine energy known, DOE 

determined the per-cycle water-heating energy use by first determining the total per-cycle energy 

use (the clothes container volume divided by the MEF) and then subtracting from it the per-cycle 

clothes-drying and machine energy. The water-heating energy use assumes the use of an electric 

water heater. DOE determined the per-cycle hot water use by dividing the per-cycle waterheating energy use by an assumed temperature rise of 75 oF (21.1 oC) and a specific heat of 

0.0024 kWh/gal-oF (4.186 joule/gram-oC). DOE determined the total water use by multiplying 

the WF by the clothes container volume. 

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Table 6.3.2 Top-Loading Commercial Clothes Washers: Per-Cycle Energy and Water 

Use by Efficiency Level 

Level 

MEF WF 

RMC* 

Energy Use Water Use 

Machine** Dryer*** Water Heat† Hot Total 

cu.ft./kWh/cyc gal/cu.ft. kWh/cyc kWh/cyc kWh/cyc gal/cyc gal/cyc 

Baseline 1.26 9.50 53.7% 0.133 1.27 0.82 4.5 26.6 

1 1.42 9.50 51.2% 0.133 1.21 0.63 3.5 26.6 

2 1.60 8.50 48.4% 0.114 1.13 0.50 2.8 23.8 

3 1.76 8.30 45.9% 0.114 1.07 0.41 2.3 23.2 

* Based on the relationship: RMC = -0.156* MEF + 0.734
 

** Based on residential clothes washer data from DOE 2000 TSD, Table 4.1.
 

*** Based on a container volume of 2.8 cu.ft. and a maximum test-load weight of 11.7 lb/cycle.
 

† Based on the use of an electric water heater at 100% efficiency. 

Table 6.3.3	 Front-Loading Commercial Clothes Washers: Per-Cycle Energy and Water 

Use by Efficiency Level 

Level 

MEF WF 

RMC* 

Energy Use Water Use 

Machine** Dryer*** Water Heat† Hot Total 

cu.ft./kWh/cyc gal/cu.ft. kWh/cyc kWh/cyc kWh/cyc gal/cyc gal/cyc 

Baseline 1.72 8.00 46.5% 0.114 1.09 0.43 2.4 22.4 

1 1.80 7.50 45.3% 0.114 1.06 0.39 2.1 21.0 

2 2.00 5.50 42.2% 0.114 0.98 0.31 1.7 15.4 

3 2.20 5.10 39.0% 0.114 0.90 0.26 1.5 14.3 

4 2.35 4.40 36.7% 0.114 0.84 0.24 1.3 12.3 

* Based on the relationship: RMC = -0.156* MEF + 0.734
 

** Based on residential clothes washer data from DOE 2000 TSD, Table 4.1.
 

*** Based on a container volume of 2.8 cu.ft. and a maximum test-load weight of 11.7 lb/cycle.
 

† Based on the use of an electric water heater at 100% efficiency. 

6.3.2 Average Annual Energy and Water Consumption by Efficiency Level 

DOE determined the average annual energy and water consumption by multiplying the 

per-cycle energy and water consumption by the number of cycles per year. Because the 

predominant applications of commercial clothes washers are in multi-family buildings and 

laundromats, DOE focused only on these two building applications to determine the appropriate 

number of commercial clothes washer cycles per year. Other applications include lodging 

establishments (e.g., hotels and motels), inpatient health care facilities, and nursing homes. 

Relative to multi-family buildings and laundromats, these other applications are a small segment 

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of the market. Therefore, DOE believes it is not critical to the analysis to accurately characterize 

commercial clothes washer usage for these applications. 

Talbe 6.3.4 below shows the usage of commercial clothes washers from several studies. 

The last column of the table shows the variation in usage from each of the studies. Note that the 

variation shown for the City of Toronto and Multi-Housing Laundry Association (MLA) studies 

is based on the range of average values for either specific buildings or cities. Thus, if individual 

machine data were made available, the variation in usage would likely be much greater than 

indicated by the average data. For multi-family applications, the usage ranges from 1 to almost 

11 cycles per day. Assuming each study has equal representation, the average value from all 

studies performed on multi-family applications is 3.4 cycles per day. The sparse data on 

commercial clothes washer use in laundromats show a usage variation of 3 to 8 cycles per day 

with an average value of 6 cycles per day. Based on 365 days per year of use, the minimum, 

average, and maximum usage data for multi-family applications of 1.0, 3.4, and 10.9 cycles per 

day yield 365, 1241, and 3979 cycles per year, respectively. For laundromats, the minimum, 

average, and maximum usage data of 3, 6, and 8 cycles per day yield 1095, 2190, and 2920 

cycles per year, respectively. As a comparison, DOE assumed that residential clothes washers 

have an annual average usage of 392 cycles per year. 

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Table 6.3.4 Commercial Clothes Washer Usage Data
 

Study Application Population 

Usage per Machine 

(cycles/day) 

Variation 

(cycles/day) 

Multi-Family Buildings 

City of Toronto 

(1999)11 

Multifamily coinoperated (6 buildings, 

945 apartments, 39 

machines) 

3 family; 

1 mixed; 

1 seniors & 

singles; and 1 

seniors 

4.3: metered 3.3 to 6.0 (variation 

based on average 

values from 6 

buildings) 

FEMP (2000)12 Military housing 

on-premise laundry (30 

machines; free use) 

Family 6.4: metered 3.2 to 10.9 

SCE/PNNL (2000)13 Multifamily coinoperated (12 machines) 

Seniors 2.2 : metered 1 to 4 

MLA (2002)14 Multifamily coinoperated 

(4 buildings in 4 cities, 

50 common area 

machines) 

General 2.9: metered * 

2.7: coin * 

4.5: survey * 

2.6 to 3.1 (variation 

based on average 

values from 4 cities) 

Wisconsin/ 

PNNL (2004)15 

Multifamily coinoperated (9 machines) Apartments & 

Condos 

1.5: metered ** 1 to 3 

Lightwash/ 

Equipoise (2004)16 

Multifamily & 

Businesses 

Not specified. 3: businesses & multifamily 

<10 units, industry value 

*** 

4: multifamily ≥10 units, 

industry value *** 

Not available. 

Consortium for 

Energy Efficiency17 

Multifamily Not specified. 3: No source for estimate. Not available. 

Laundromats 

Lightwash/ 

Equipoise (2004)27 

Laundromat & 

Institutional 

Not specified. 6: industry value *** Not available. 

Consortium for 

Energy Efficiency28 

Laundromat Not specified. 6: No source for estimate. Not available. 

Coin Laundry 

Association18 

Laundromat Not specified. Not available. 3 to 8: No source for 

estimate. 

* Usage per machine values derived based on water usage of 32 gallons per cycle.
 

** Report states that multifamily industry average is 2.5 cycles per day and attributes the lower reported usage per
 

machine value to a lower ratio of tenants to machines. 

*** Usage per machine values are “industry values.” Study says that survey data in report may be unreliable. 

DOE calculated commercial clothes washer annual energy consumption with the 

following equation: 

CWANNUAL = CWCYCLE × N

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where:
 

CWANNUAL = Total annual commercial clothes washer energy consumption, 

CWCYCLE = Total per-cycle commercial clothes washer energy consumption, and 

N = Representative average commercial clothes washer use. 

DOE calculated commercial clothes washer annual water consumption with the following 

equation: 

CWANNUAL WATER = CWCYCLE WATER × N

where: 

CWANNUAL WATER = Total annual commercial clothes washer water consumption, 

CWCYCLE WATER = Total per-cycle commercial clothes washer water consumption, and 

N = Representative average commercial clothes washer use. 

Tables 6.3.4 and 6.3.5 show the annual energy and water consumption for multi-family 

buildings and laundromats, respectively, for top-loading washers. Tables 6.3.6 and 6.3.7 show 

the annual energy and water consumption for multi-family buildings and laundromats, 

respectively, for front-loading washers. The energy and water consumption values provided 

below are based on average use cycles of 3.4 cycles per day for multi-family buildings and 6 

cycles per day for laundromats. The annual water-heating and clothes-drying energy 

consumption reflects the use of either an electric or a gas water heater. 

Table 6.3.5	 Top-Loading Commercial Clothes Washers, Multi-Family Application: 

Annual Energy and Water Use by Efficiency Level 

Level 

MEF WF 

Annual Energy Use* 

Annual 

Water Use 

Water Heating** Drying 

Electric Gas Electric Gas Machine 

cu.ft./kWh/cyc gal/cu.ft. kWh/yr MMBtu/yr kWh/yr MMBtu/yr kWh/yr 1000 gal/year 

Baseline 1.26 9.50 1020 4.64 1583 6.05 166 33.1 

1 1.42 9.50 788 3.58 1503 5.74 166 33.1 

2 1.60 8.50 625 2.84 1414 5.40 142 29.7 

3 1.76 8.30 506 2.30 1334 5.10 142 29.0 

* Annual usage based on 3.4 cycles per day (1241 cycles per year).
 

** Electric and gas water heating based on water heater efficiencies of 100% for electric and 75% for gas.
 

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Table 6.3.6 Top-Loading Commercial Clothes Washers, Laundromat Application: 

Annual Energy and Water Use by Efficiency Level 

Level 

MEF WF 

Annual Energy Use* 

Annual 

Water Use 

Water Heating** Drying 

Electric Gas Electric Gas Machine 

cu.ft./kWh/cyc gal/cu.ft. kWh/yr MMBtu/yr kWh/yr MMBtu/yr kWh/yr 1000 gal/year 

Baseline 1.26 9.50 1793 8.16 2782 10.63 291 58.3 

1 1.42 9.50 1385 6.30 2642 10.10 291 58.3 

2 1.60 8.50 1098 4.99 2485 9.50 250 52.1 

3 1.76 8.30 889 4.04 2345 8.96 250 50.9 

* Annual usage based on 6 cycles per day (2190 cycles per year).
 

** Electric and gas water heating based on water heater efficiencies of 100% for electric and 75% for gas.
 

Table 6.3.7	 Front-Loading Commercial Clothes Washers, Multi-Family Application: 

Annual Energy and Water Use by Efficiency Level 

Level 

MEF WF 

Annual Energy Use* 

Annual 

Water Use 

Water Heating** Drying 

Electric Gas Electric Gas Machine 

cu.ft./kWh/cyc gal/cu.ft. kWh/yr MMBtu/yr kWh/yr MMBtu/yr kWh/yr 1000 gal/year 

Baseline 1.72 8.00 532 2.42 1354 5.18 142 27.9 

1 1.80 7.50 482 2.19 1315 5.02 142 26.2 

2 2.00 5.50 387 1.76 1215 4.64 142 19.2 

3 2.20 5.10 328 1.49 1116 4.26 142 17.8 

4 2.35 4.40 301 1.37 10.41 3.98 142 15.4 

* Annual usage based on 3.4 cycles per day (1241 cycles per year).
 

** Electric and gas water heating based on water heater efficiencies of 100% for electric and 75% for gas.
 

Table 6.3.8	 Front-Loading Commercial Clothes Washers, Laundromat Application: 

Annual Energy and Water Use by Efficiency Level 

Level 

MEF WF 

Annual Energy Use* 

Annual 

Water Use 

Water Heating** Drying 

Electric Gas Electric Gas Machine 

cu.ft./kWh/cyc gal/cu.ft. kWh/yr MMBtu/yr kWh/yr MMBtu/yr kWh/yr 1000 gal/year 

Baseline 1.72 8.00 935 4.25 2380 9.10 250 49.1 

1 1.80 7.50 847 3.85 2310 8.83 250 46.0 

2 2.00 5.50 680 3.10 2136 8.16 250 33.7 

3 2.20 5.10 576 2.62 1961 7.49 250 31.3 

4 2.35 4.40 529 2.41 1830 6.99 250 27.0 

* Annual usage based on 6 cycles per day (2190 cycles per year).
 

** Electric and gas water heating based on water heater efficiencies of 100% for electric and 75% for gas.
 

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6.3.3 Variability of Annual Energy and Water Consumption 

DOE determined the variability in annual energy and water consumption using the 

average usage data above from Talbe 6.3.3. From the above table, there are eight average usage 

values for multi-family buildings ranging from a low of 1.5 cycles per day to a high of 6.4 cycles 

per day. For laundromats, the low and high values are 3 and 8 cycles per day, respectively. 

DOE weighted the usage from each study to vary the annual energy and water 

consumption of commercial clothes washers when it conducted the LCC and PBP analysis. As 

shown in Figure 6.3.2, DOE weighted the usage studies equally for multi-family applications. 

As shown in Figure 6.3.3, for laundromats, DOE used a triangular distribution that ranged from 3 

to 8 cycles per day and skewed it in order to yield a mean value of 6 cycles day. As will be 

described later in Chapter 8 on the LCC and PBP analysis, DOE used the usage variability to 

vary the annual energy and water consumption for multi-family and laundromat applications 

when it conducted the LCC and PBP analysis. Probability

0.14 

0.12 

0.1 

0.08 

0.06 

0.04 

0.02 

0 

CEE 

Wisc/SCE/

MLA

Equip 

Equip 

Toron

FEMP 

PNNL

PNNL

<10

>10

to

0 1 2 3 4 5 6 7 

Usage (cycles/day) 

Figure 6.3.2 Probability Distribution for Commercial Clothes Washer 

Usage in Multi-Family Applications 

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EE-2006-STD-0127 COMMENT 41.2
 

 

 

0.00 

0.05 

0.10 

0.15 

0.20 

2 3 4 5 6 7 8 9 

Usage (cycles/day) 

Probability 

Figure 6.3.3 Probability Distribution for Commercial Clothes Washer 

Usage in Laundromat Applications 

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Berkeley National Laboratory, Berkeley, CA. Appendix A. 

<http://www.eere.energy.gov/buildings/appliance_standards/residential/cooking_products_0998_r.html> 

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<http://www.energy.ca.gov/appliances/rass/index.html> 

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Rule, October 3, 1997. 62 FR 51976. 

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Consumption Survey, 2001 Public Use Data Files, 2001. Washington, DC. 

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<http://www.aham.org/industry/ht/action/GetDocumentAction/id/5370> 

7	 Energy Policy Act of 2005, Title 1—Energy Efficiency, Subtitle C—Energy Efficient 

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70 FR 60407. 

9	 Biermayer, P.J. Preliminary Engineering Analysis for Clothes Washers, October 1996. 

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Washers, December, 2000. Washington, DC. Chapter 4, Table 4.1. 

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<http://www.eere.energy.gov/buildings/appliance_standards/residential/clothes_washers.html> 

11	 City of Toronto Works and Emergency Services and Toronto Community Housing 

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DOE by Pacific Northwest National Laboratory, Richland WA. Report No. DOE/EE-0218. 

13	 G. P. Sullivan, J. W. Currie, T.C. Hillman, and G.B. Parker, Southern California Edison 

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Report, December 2000. Prepared for Southern California Edison Company by Battelle 

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14	 National Research Center, Inc., A National Study of Water & Energy Consumption in 

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15	 Sullivan, G.P., G. B. Parker, and J. W. Currie. Wisconsin Focus on Energy Resource Efficient 

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16	 Equipoise Consulting, Inc. Final Report for Local Energy Efficiency Program No. 148-02 

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17	 Consortium for Energy Efficiency. Commercial Programs, Commercial, Family-Sized 

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18	 Coin Laundry Association. Industry Overview. Downers Grove, IL. 

<http://www.coinlaundry.org/resources/industryoverview.cfm> 

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