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

6-iTable 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

6-iiCHAPTER 6. ENERGY AND WATER USE DETERMINATION

6.1 INTRODUCTION

To carry out the life-cycle cost (LCC) and payback period (PBP) calculations describedin 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 ( E CA ) is determined based on the following DOE test procedure equation:

O CT E CA = Eff CT

6-1where:

O CT = 173.1 kilowatt-hours (kWh) per year, annual useful cooking energy output, and Eff CT = 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:

O CT E =

CA R CT

where:

O CT = 527.6 thousand British thermal units (kBtu) per year, annual useful cooking energy output, and

R CT = 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 ( E AO ):

O O E =

AO R O where:

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

R O = Oven energy factor.

For gas self-cleaning and non-self-cleaning ovens, the annual energy consumption is composed of gas energy ( E AOG ) and electrical energy ( E AOE ). The following DOE test procedure equation is used to determine the total annual energy consumption:

O O E + E × K =

AOG AOE e R O where:

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

R O = Oven energy factor, and

6-2K

e = 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 derivedfrom 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

6-3that 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

YearAnnual 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

YearAnnual 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

6-46.2.1.2 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.

6-5Table 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.

6-6Table 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.

6-7Table 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 andmultiplying 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

6-8levels 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

6-943,158 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.

6-10Table 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:

E CA _ AVG E = Freq ×

CA _ HH C _ HH Freq C

_ AVG where:

E CA_HH = Cooktop annual energy consumption for specific RECS household, Freq C_HH = Cooktop frequency for specific RECS household,

E CA_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 Freq C_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:

E AO _ AVG E = Freq ×

AO _ HH O _ HH Freq O

_ AVG

where:

E AO_HH = Oven annual energy consumption for specific RECS household, Freq O_HH = Oven frequency for specific RECS household,

E

AO_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

6-11Freq O_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; 0.49meals/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

0.00Probability

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

6-120.00 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.

6-130.00 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

6-14Figures 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

6-150.00 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 ( E MO ) is determined based on the following DOE test procedure equation:

6-16O M E MO = R MO

where:

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

R MO = 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.

6-170 50 100 150 200 250 300

1986 1988 1990 1992 1994 1996 1998 2000 2002 2004

YearAnnual 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 ( E SP ), 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:

P SP = Standby power consumption (watts), and

Hours SP = 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 ( Hours ACTIVE )with the following expression:

E MO Hours = ACTIVE I MO

where:

6-18E MO = annual (cooking) energy consumption, and

I MO = 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:

O MO I MO = R MO

where:

O MO = 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.

6-19Table 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

HH MO

_ E

AVG MO

_ HH MO

_ Freq Freq × =

where:

E MO_HH =	 Microwave oven annual energy consumption for specific RECS household, Freq MO_HH =	 Microwave oven frequency for specific RECS household,

6-20E CA_AVG = Average microwave oven annual cooking energy consumption of 131 kWh, and Freq C_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

6-21composed 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:

HE T CW = × c + ME + D CYCLE T E e where:

CW CYCLE =	 Total commercial clothes washer per-cycle energy consumption,

HE T =	 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),

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

D E =	 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:

_ D = LAF × WGHT × 

# ( RMC 4 % 

# ) × DEF × DUF × GCF E MAX

where:

LAF =	 Load adjustment factor = 0.52,

WGHT MAX = 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.

D G = GCF × D E

where:

D G =	 Per-cycle energy consumption for removal of moisture from test load due to a gas dryer, i.e., dryer energy consumption (kWh/cycle), and

6-229 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 = CW CYCLE

Q T WF = C

where:

C = Container capacity (cubic feet), and Q T = 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

RMC cu.ft./kWh/cycle cu.ft. kWh/cycle 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%

6-23Figure 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

R 2 = 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

MEFRMC

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 electricwater 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.

6-24Table 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

6-25of 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.

6-26Table 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 & multif amily <10 units, industry value

***

4: multifamily ≥ 10 units, industry value *** Not available.

Consortium for Energy Efficiency 17 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 Efficiency 28 Laundromat Not specified. 6: No source for estimate. Not available.

Coin Laundry

Association 18 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:

CW = CW × N ANNUAL CYCLE

6-27where:

CW ANNUAL = Total annual commercial clothes washer energy consumption,

CW CYCLE = 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:

CW = CW × N ANNUAL WATER CYCLE WATER
where:

CW ANNUAL WATER = Total annual commercial clothes washer water consumption,

CW CYCLE 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

Machine Electric Gas Electric Gas

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.

6-28Table 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

Machine Electric Gas Electric Gas

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

Machine Electric Gas Electric Gas

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

Machine Electric Gas Electric Gas

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.

6-296.3.3 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

0CEEWisc/SCE/MLAEquipEquipToronFEMPPNNLPNNL<10>10to

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

6-300.00 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

6-31REFERENCES

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