CHAPTER 6. ENERGY AND WATER USE DETERMINATION 

TABLE OF CONTENTS 

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

6.2 DISHWASHERS ............................................................................................................. 6-1

6.2.1 Per-Cycle Energy and Water Consumption by Efficiency Level .................................... 6-1 

6.2.2 Average Annual Energy and Water Consumption by Efficiency Level.......................... 6-4 

6.2.3 Variability of Annual Energy and Water Consumption .................................................. 6-6 

6.3 DEHUMIDIFIERS .......................................................................................................... 6-7 

6.3.1 Average Annual Usage .................................................................................................... 6-7 

6.3.2 Average Annual Energy Consumption ............................................................................ 6-9 

6.3.3 Average Annual Energy Consumption by Efficiency Level ......................................... 6-10 

6.3.4 Variability of Annual Energy Consumption .................................................................. 6-12 

6.4 COOKING PRODUCTS ............................................................................................... 6-14 

6.4.1 Cooktops and Ovens ...................................................................................................... 6-14 

6.4.1.1 Average Annual Energy Consumption ........................................................ 6-14 

6.4.1.2 Annual Energy Consumption of Energy-Using Components...................... 6-18 

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

6.4.1.4 Variability of Annual Energy Consumption ................................................ 6-23 

6.4.2 Microwave Ovens .......................................................................................................... 6-29 

6.4.2.1 Average Annual Energy Consumption ........................................................ 6-29 

6.4.2.2 Annual Energy Consumption by Efficiency Level...................................... 6-31 

6.4.2.3 Variability of Annual Energy Consumption ................................................ 6-32 

6.5 COMMERCIAL CLOTHES WASHERS ..................................................................... 6-33 

6.5.1 Per-Cycle Energy and Water Consumption by Efficiency Level .................................. 6-33 

6.5.2 Average Annual Energy and Water Consumption by Efficiency Level........................ 6-37 

6.5.3 Variability of Annual Energy and Water Consumption ................................................ 6-40 

LIST OF TABLES 

Table 6.2.1 Standard Dishwashers: Per-Cycle Energy and Water Use by Efficiency 

Level .................................................................................................................... 6-4 

Table 6.2.2 Standard Dishwashers: Annual Energy and Water Use by Efficiency 

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

Table 6.3.1 Dehumidifier Annual Usage Data........................................................................ 6-8 

Table 6.3.2 Dehumidifier Monthly Hourly Usage.................................................................. 6-9 

Table 6.3.3 Dehumidifier Annual Energy Consumption Derived from Hourly Usage ........ 6-10 

Table 6.3.4 25 Pints/Day or Less Dehumidifiers: Annual Energy Use by Efficiency 

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

Table 6.3.5 25.01-35 Pints/Day Dehumidifiers: Annual Energy Use by Efficiency 

Level .................................................................................................................. 6-11 

6-i 

EE-2006-STD-0127 COMMENT 39.2
Table 6.3.6 35.01-45 Pints/Day Dehumidifiers: Annual Energy Use by Efficiency 

Level .................................................................................................................. 6-11 

Table 6.3.7 45.01-54 Pints/Day Dehumidifiers: Annual Energy Use by Efficiency 

Level .................................................................................................................. 6-11 

Table 6.3.8 54.01-74.99 Pints/Day Dehumidifiers: Annual Energy Use by Efficiency 

Level .................................................................................................................. 6-12 

Table 6.3.9 75 Pints/Day or More Dehumidifiers: Annual Energy Use by Efficiency 

Level .................................................................................................................. 6-12 

Table 6.4.1 Annual Energy Consumption of Baseline Electric and Gas Cooktops and 

Ovens Based on DOE Test Procedure Energy Use Calculations ...................... 6-16 

Table 6.4.2 Component Annual Energy Use of Baseline Cooktops and Ovens ................... 6-19 

Table 6.4.3 Electric Coil Cooktops: Annual Energy Consumption by Efficiency Level ..... 6-20 

Table 6.4.4 Electric Smooth Cooktops: Annual Energy Consumption by Efficiency 

Level .................................................................................................................. 6-20 

Table 6.4.5 Gas Cooktops: Annual Energy Consumption by Efficiency Level .................. 6-20 

Table 6.4.6 Electric Standard Ovens: Annual Energy Consumption by Efficiency 

Level .................................................................................................................. 6-21 

Table 6.4.7 Electric Self-Cleaning Ovens: Annual Energy Consumption by Efficiency 

Level .................................................................................................................. 6-21 

Table 6.4.8 Gas Standard Ovens: Annual Energy Consumption by Efficiency Level ........ 6-22 

Table 6.4.9 Gas Self-Cleaning Ovens: Annual Energy Consumption by Efficiency 

Level .................................................................................................................. 6-23 

Table 6.4.10 Annual Energy Use of Baseline Cooktops and Ovens with corresponding 

RECS Cooking Frequency................................................................................. 6-24 

Table 6.4.11 Microwave Ovens: Annual Energy Consumption by Efficiency Level ........... 6-31 

Table 6.5.1 Residential Clothes Washer Energy Use Data from DOE 2000 TSD ............... 6-35 

Table 6.5.2 Commercial Clothes Washers: Per-Cycle Energy and Water Use by 

Efficiency Level................................................................................................. 6-37 

Table 6.5.3 Commercial Clothes Washer Usage Data.......................................................... 6-38 

Table 6.5.4 Commercial Clothes Washers, Multi-Family Application: Annual Energy 

and Water Use by Efficiency Level ................................................................... 6-39 

Table 6.5.5 Commercial Clothes Washers, Laundromat Application: Annual Energy 

and Water Use by Efficiency Level ................................................................... 6-40 

LIST OF FIGURES 

Figure 6.2.1 Historical Dishwasher Per-Cycle Energy and Water Consumption .................... 6-2 

Figure 6.2.2 Dishwasher Per-Cycle Water Consumption as a Function of Per-Cycle 

Energy Consumption ........................................................................................... 6-3 

Figure 6.2.3 Distribution of Dishwasher Annual Energy Consumption Based on 2001 

RECS Usage Data ................................................................................................ 6-7 

Figure 6.3.1 Percent of Households with Dehumidifiers Disaggregated by Region and 

Presence of Basement ........................................................................................ 6-13 

6-ii 

EE-2006-STD-0127 COMMENT 39.2
Figure 6.3.2 Probability Distribution for Dehumidifier Usage .............................................. 6-14 

Figure 6.4.1 Historical Estimates of Annual Electric Range Energy Use.............................. 6-17 

Figure 6.4.2 Historical Estimates of Annual Gas Range Energy Use .................................... 6-18 

Figure 6.4.4 Distribution of Baseline Gas Cooktop Annual Energy Use Based on 2001 

Figure 6.4.9 Historical Estimates of Annual Microwave Oven Energy Use ......................... 6-31 

Figure 6.4.8 Distribution of Baseline Gas Self-Cleaning Oven Annual Energy Use 

Based on 2001 RECS Cooking Frequency ........................................................ 6-29 

Figure 6.4.7 Distribution of Baseline Gas Standard Oven Annual Energy Use Based on 

2001 RECS Cooking Frequency........................................................................ 6-28 

Figure 6.4.6 Distribution of Baseline Electric Self-Cleaning Oven Annual Energy Use 

Based on 2001 RECS Cooking Frequency ........................................................ 6-27 

Figure 6.4.5 Distribution of Baseline Electric Standard Oven Annual Energy Use 

Based on 2001 RECS Cooking Frequency ........................................................ 6-27 

Figure 6.4.3 Distribution of Baseline Electric Cooktop Annual Energy Use Based on 

2001 RECS Cooking Frequency........................................................................ 6-25 

RECS Cooking Frequency................................................................................. 6-26 

Figure 6.4.10 Distribution of Microwave Oven Annual Cooking Energy Use Based on 

2001 RECS Cooking Frequency........................................................................ 6-33 

Figure 6.5.1 Residential Clothes Washer RMC versus MEF from DOE 2000 TSD ............. 6-36 

Figure 6.5.2 Probability Distribution for Commercial Clothes Washer Usage in MultiFamily Applications........................................................................................... 6-41 

Figure 6.5.3 Probability Distribution for Commercial Clothes Washer Usage in 

Laundromat Applications................................................................................... 6-41 

6-iii 

EE-2006-STD-0127 COMMENT 39.2
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 DISHWASHERS 

DOE established the annual energy and water consumption of dishwashers by 

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

6.2.1 Per-Cycle Energy and Water Consumption by Efficiency Level 

Dishwasher per-cycle energy consumption is composed of three components: waterheating energy, machine energy, and drying energy. The machine energy is composed of the 

motor energy (for water pumping and food disposal) and booster heater energy. The DOE test 

procedure provides the following equations to calculate the total per-cycle dishwasher energy 

consumption: 

K

DWCYCLE = T V × + E M × + D e 

where: 

DWCYCLE = Total dishwasher per-cycle energy consumption, 

V = Water consumption in gallons per cycle, 

T = Nominal water temperature rise = 70 oF (assuming a nominal inlet water 

temperature of 120 oF), 

K = Specific heat of water in kWh per gallon per degree Fahrenheit (0.0024), or 

Btus per gallon per degree Fahrenheit (8.2), 

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

V•T•K/e = Water-heating energy consumption, 

M = Machine energy consumption, and 

ED = Drying energy consumption. 

6-1 

EE-2006-STD-0127 COMMENT 39.2
The largest component of dishwasher energy consumption is water-heating energy use. 

Water-heating energy use is directly dependent on water use. The Association of Home 

Appliance Manufacturers (AHAM) provided data showing how per-cycle energy use and percycle water has changed over time since 1993 (see Figure 6.2.1).1 

1992 2004 2006 

/

0 

2 

4 

6 

8 

10 

12 

/ ) 

0.0 

0.5 

1.0 

1.5 

2.0 

2.5 

3.0 

1994 1996 1998 2000 2002 

Year 

Energy Use (kWh cyc) 

Water Use (gal cyc

Energy 

Water 

Figure 6.2.1 Historical Dishwasher Per-Cycle Energy and Water Consumption 

Figure 6.2.2 plots the energy and water use data in Figure 6.2.1 against each other. As indicated 

in the figure below, the relationship between energy and water use is nearly linear. Therefore, 

knowing the per-cycle energy use, DOE can determine the per-cycle water use and, in turn, the 

per-cycle water heating consumption. 

6-2 

EE-2006-STD-0127 COMMENT 39.2
R2

5 

6 

7 

8 

9 

10 

11 

/ ) 

Water Use = 4.6415* Energy Use - 1.9295 

 = 0.9608 

Water Use (gal cyc

1.7 1.9 2.1 2.3 2.5 2.7 

Energy Use (kWh/cyc) 

Figure 6.2.2 Dishwasher Per-Cycle Water Consumption as a Function of 

Per-Cycle Energy Consumption 

As discussed in Chapter 5, DOE analyzed specific efficiency levels for standard-sized 

dishwashers. Table 6.2.1 shows the efficiency levels for standard-sized dishwashers and their 

corresponding per-cycle energy and water use. Per-cycle energy use is disaggregated into two 

general categories: (1) water heating; and (2) machine (e.g., motor energy for pumping) and dish 

drying from an electrical heating element. DOE determined the per-cycle energy use by taking 

the inverse of the energy factor. It determined the per-cycle water consumption based on the 

relationship shown in Figure 6.2.2. DOE determined the per-cycle water heating consumption 

by assuming the use of an electric water heater and multiplying the per-cycle water consumption 

by an assumed temperature rise of 70 oF (21 oC) and a specific heat of 0.0024 kWh/gal-oF (4.186 

joule/gram-°C). The per-cycle machine and drying energy were determined by DOE by 

subtracting the water heating energy consumption from the total energy consumption. DOE also 

provides the standby power consumption in the tables below. 

6-3 

EE-2006-STD-0127 COMMENT 39.2
Table 6.2.1 Standard Dishwashers: Per-Cycle Energy and Water Use by Efficiency Level 

Level 

EF Energy Use* Water Use** 

Energy Use Components 

Standby† 

Water 

Heating*** 

Machine + 

Drying 

cycles/kWh kWh/cyc gal/cyc kWh/cyc kWh/cyc kW 

Baseline 0.46 2.17 8.16 1.37 0.80 0.002 

1 0.58 1.72 6.07 1.02 0.70 0.002 

2 0.62 1.61 5.56 0.93 0.68 0.002 

3 0.65 1.54 5.21 0.88 0.66 0.002 

4 0.68 1.47 4.90 0.82 0.65 0.002 

5 0.72 1.39 4.52 0.76 0.63 0.002 

6 0.80 1.25 3.87 0.65 0.60 0.002 

7 1.11 0.90 2.25 0.38 0.52 0.002 

* Based on 1/EF. 

** Based on the relationship: Water Use = 4.6415* Energy Use - 1.9295 

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

† Based on standby power consumption of 2 watts. 

6.2.2 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. In 2003, DOE 

revised its test procedure for dishwashers to more accurately establish their efficiency and energy 

and water use. The 2003 test procedure amendments included a reduction in the average-use 

cycles per year.2

 Arthur D. Little (ADL) conducted a comprehensive analysis of dishwasher 

usage in 2001 that revealed that dishwashers are used, on average, 215 cycles per year.3 

The 2001 RECS provides data indicating the annual usage of households with 

dishwashers. Of the more than 4800 households in RECS, almost 2500 have dishwashers. The 

average-use value for dishwashers is 180 cycles per year with minimum and maximum values of 

26 and 500 cycles per year, respectively. 

In the joint comment submitted by the American Council for an Energy Efficient 

Economy, the Alliance to Save Energy, the Appliance Standards Awareness Project, the Natural 

Resources Defense Council, and the Northeast Energy Efficiency Partnerships on the 

Rulemaking Framework Document for this rulemaking, the above organizations argued that 

DOE should continue to use 215 cycles per year in its analysis of dishwashers.4 The 

organizations maintained that any estimate derived from the 2001 RECS is not nearly as robust 

as the estimate derived from the work conducted by ADL to revise the dishwasher test 

procedure. For example, they stated that the RECS represents a much smaller sample than the 

one ADL used (about 2,500 households versus 26,000 households) and that the questions 

6-4 

EE-2006-STD-0127 COMMENT 39.2
pertaining to dishwashers in RECS are just one component in a very large and complex survey 

instrument dealing with all aspects of home energy use. 

Because the ADL survey is a much more comprehensive and larger survey than the 

survey performed for RECS, DOE chose an average usage of 215 cycles per year as the most 

representative value for average dishwasher use. 

DOE calculated dishwasher annual energy consumption with the following equation: 

L N H ) _ ( ×

DWANNUAL = DWCYCLE × N + • Sm × 

1000 

where: 

DWANNUAL = Total annual dishwasher energy consumption, 

DWCYCLE = Total per-cycle dishwasher energy consumption, 

N = Representative average dishwasher use of 215 cycles per year, 

Sm = Average standby power in Watts, 

H = Total number of hours per year = 8766, and 

L = Average duration of dishwasher cycle. 

DOE calculated dishwasher annual water consumption with the following equation: 

DWANNUAL WATER = DWCYCLE WATER × N 

where: 

DWANNUAL WATER = Total annual dishwasher water consumption, 

DWCYCLE WATER = Total per-cycle dishwasher water consumption, and 

N = Representative average dishwasher use of 215 cycles per year. 

The annual energy and water consumption shown in Table 6.2.2 reflects an annual usage of 215 

cycles per year. The annual water-heating energy consumption reflects the use of either an 

electric, gas, or oil water heater. 

6-5 

EE-2006-STD-0127 COMMENT 39.2
Table 6.2.2 Standard Dishwashers: Annual Energy and Water Use by Efficiency Level 

Energy 

Annual Energy Use Annual 

Water Heating* Machine + Drying Water

Level 

Factor Electric Gas Oil + Standby** Use 

cycle/kWh kWh/year MMBtu/year MMBtu/year kWh/year 1000 gal/year 

Baseline 0.46 295 1.34 1.24 190 1.8 

1 0.58 219 1.00 0.92 168 1.3 

2 0.62 201 0.91 0.85 163 1.2 

3 0.65 188 0.86 0.79 160 1.1 

4 0.68 177 0.80 0.74 156 1.1 

5 0.72 163 0.74 0.69 153 1.0 

6 0.80 140 0.64 0.59 146 0.8 

7 1.11 81 0.37 0.34 129 0.5 

* Electric, gas, and oil water heating based on water heater efficiencies of 100% for electric, 75% for gas, 81% for oil. 

** Standby annual energy use based on an assumed dishwasher cycle of one hour. 

Standby hours = 8766 hours – 215 * 1 hour = 8551 hours. 

6.2.3 Variability of Annual Energy and Water Consumption 

The 2001 RECS indicates that 2,476 of the 4,822 households in the survey use 

dishwashers. To determine the variability of dishwasher usage, DOE normalized the household 

usage values from RECS so that the average-use value equaled 215 cycles per year rather than 

the weighted-average value of 180 cycles per year as indicated by RECS. DOE determined the 

usage for each RECS household with a dishwasher based on the following equation: 

N 

N DOE _ AVG 

DW = N _ DW HH × 

N RECS _ AVG 

where: 

NDW = Modified dishwasher usage for specific RECS household, 

NDW_HH = Dishwasher usage for specific RECS household as specified by RECS, 

NDOE_AVG = Average dishwasher usage of 215 cycles per year as established in the DOE 

test procedure, and 

NRECS_AVG = Average dishwasher usage of 180 cycles per year as established by RECS. 

With the normalized dishwasher usage known for each RECS household, DOE 

determined the corresponding annual energy and water consumption. For all RECS households, 

dishwasher use frequency varies from 1 to 500 cycles per year. Figure 6.2.3 shows the 

probability distribution of annual dishwasher energy consumption based on the modified 

dishwasher usage that DOE determined for each RECS household. 

6-6 

EE-2006-STD-0127 COMMENT 39.2
0 100 250 300 350 400 450 500 550 600 

/ ) 

0.00 

0.01 

0.02 

0.03 

0.04 

0.05 

0.06 

0.07 

0.08 

50 150 200 

Usage (cycles year

Probability 

Figure 6.2.3 Distribution of Dishwasher Annual Energy 

Consumption Based on 2001 RECS Usage Data 

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 energy consumption to conduct 

the LCC and PBP analysis. 

6.3 DEHUMIDIFIERS 

DOE established the annual energy consumption of dehumidifiers by first dividing the 

capacity (in pints per day) by the unit efficiency (in liters per kWh) and then multiplying it by the 

usage in hours per year. 

6.3.1 Average Annual Usage 

Table 6.3.1 below summarizes the annual usage of dehumidifiers based on several studies 

and sources. Unfortunately, none of the studies is based on metered data. The studies rely on 

power measurements and assumptions regarding usage to derive the annual energy consumption 

values. 

6-7 

EE-2006-STD-0127 COMMENT 39.2
Table 6.3.1 Dehumidifier Annual Usage Data 

Operating 

Annual Energy Use Power Use Hours 

Study/Source kWh/year Watts Hours/year 

LBNL (1992)5 Average: 400 

Range: 200–1000 NA NA 

ADL (1998)6 Average: 972 Average: 600 1620 

LBNL (2005)7 Range: 500–4650 Range: 520–710 1620, 4320 

Energy Center of 

Wisconsin (2005)8 

Average: 600 

Range: +/- 300 (WI only) 

Average: 350 

Range: +/- 250 NA 

Central Maine Power Co. 

(2006)9 Average: 540 (Maine only) NA NA 

Energy Star Fact Sheet 

(from website, 2006)10 

EStar: 2161 

non-EStar: 2378 

EStar: 1334 

Non-EStar: 1368 1620 

Energy Star Calculator 

(from website, 2006)11 

Range, EStar: 937–2061 

Range, non-EStar: 1022–2616 

Range, EStar: 329–723 

Range, non-EStar: 358– 918 2851 

In its comment on the Rulemaking Framework Document for this rulemaking, AHAM 

commented that it is not aware of any data related to the typical annual hours of operation for 

dehumidifiers. It further notes that dehumidifiers are normally used on a regional basis in 

basements during humid summer hours in northern climates. In consultation with manufacturers 

and others familiar with the product, AHAM provided estimates of typical dehumidifier usage in 

annual operating hours. AHAM provided an annual usage of 1095 operating hours per year with 

low and high values of 875 and 1315 hours per year, respectively. AHAM and some of the 

sources identified in Table 6.3.1 also provided their annual usage disaggregated by month. Table 

6.3.2 summarizes the monthly usage data. 

6-8 

EE-2006-STD-0127 COMMENT 39.2
Table 6.3.2 Dehumidifier Monthly Hourly Usage 

Source 

Jan-Mar Apr May June July Aug Sept Oct Nov-Dec Annual 

Hours/month Hours/year 

AHAM Low 0 0 70 210 245 245 70 35 0 875 

AHAM Mid 0 14 86 231 288 288 130 58 0 1095 

AHAM High 0 37 110 256 329 329 183 73 0 1315 

ADL* 0 0 180 360 360 360 180 180 0 1620 

Energy Star# 0 0 475 475 475 475 475 475 0 2851 

LBNL-High† 1080 360 360 360 360 360 360 360 720 4320 

* Based on peak dehumidification period of three months (at 360 hours/month) with half the usage 

(180 hours/month) during the remaining three months. 

# Based on six-month operation with 0.66 duty cycle. 

† Monthly operation equal to ADL peak dehumidification period. 

6.3.2 Average Annual Energy Consumption 

DOE based the annual energy consumption of a dehumidifier on the following equation: 

CAP × 24 × 473 0( . ) Hours 

DEH ENERGY = Eff 

where: 

DEHENERGY = Dehumidifier annual energy consumption (kWh/year), 

CAP = Dehumidifier capacity (pints/day), 

0.473 = Conversion factor for liters in a pint, 

24 = Number of hours in a day 

Hours = Annual operating hours, and 

Eff = Dehumidifier efficiency (liters/kWh). 

For the six product classes of dehumidifiers, DOE calculated the annual energy 

consumption based on the annual usage assumptions presented above in Table 6.3.2. To 

calculate annual energy consumption, DOE used an efficiency level for each product class that 

was equal to the minimum efficiency standards that take effect in 2007. Table 6.3.3 presents the 

annual energy consumption resulting from DOE’s calculations. The calculated annual energy 

usage has an extensive range based on the capacity and efficiency of the dehumidifier and the 

assumed hours of operation. 

6-9 

EE-2006-STD-0127 COMMENT 39.2
Table 6.3.3 Dehumidifier Annual Energy Consumption Derived from Hourly Usage 

Product Class Average Size EF 

Annual Energy Use (kWh/year) 

AHAM 

ADL 

Energy 

Star 

LBNL -

pints/day pints/day liters/day liters/kWh Low Mid High High

≤ 25.00 20.0 9.5 1.0 345 432 519 639 1124 1703 

25.01-35.00 30.0 14.2 1.2 431 540 648 798 1405 2129 

35.01-45.00 40.0 18.9 1.3 531 664 798 983 1730 2621 

45.01-54.00 50.0 23.7 1.3 664 830 997 1228 2162 3276 

54.01-74.99 64.5 30.5 1.5 742 928 1115 1373 2417 3662 

≥ 75.00 85.0 40.2 2.25 652 816 979 1207 2123 3218 

6.3.3 Average Annual Energy Consumption by Efficiency Level 

As discussed in Chapter 5, DOE analyzed specific efficiency levels for the six product 

classes of dehumidifiers. Based on an annual usage corresponding to AHAM’s mid-estimate of 

annual hourly operation, Tables 6.3.4 through 6.3.9 show the efficiency levels for the six product 

classes and their corresponding annual energy consumption. 

Table 6.3.4 25 Pints/Day or Less Dehumidifiers: Annual Energy Use by Efficiency Level 

Efficiency Annual Energy Use* 

Level liters/kWh kWh/year 

Baseline 1.00 432 

1 1.10 393 

2 1.20 360 

3 1.25 345 

4 1.30 332 

5 1.38 313 

* Capacity = 20 pints/day; Annual Usage = 1095 hours (AHAM mid-estimate). 

6-10 

EE-2006-STD-0127 COMMENT 39.2
Table 6.3.5 25.01-35 Pints/Day Dehumidifiers: Annual Energy Use by Efficiency Level 

Efficiency Annual Energy Use* 

Level liters/kWh kWh/year 

Baseline 1.20 540 

1 1.25 518 

2 1.30 498 

3 1.35 480 

4 1.40 463 

5 1.45 447 

* Capacity = 30 pints/day; Annual Usage = 1095 hours (AHAM mid-estimate). 

Table 6.3.6 35.01-45 Pints/Day Dehumidifiers: Annual Energy Use by Efficiency Level 

Efficiency Annual Energy Use* 

Level liters/kWh kWh/year 

Baseline 1.30 664 

1 1.35 640 

2 1.40 617 

3 1.45 596 

4 1.50 576 

5 1.74 496 

* Capacity = 40 pints/day; Annual Usage = 1095 hours (AHAM mid-estimate). 

Table 6.3.7 45.01-54 Pints/Day Dehumidifiers: Annual Energy Use by Efficiency Level 

Efficiency Annual Energy Use* 

Level liters/kWh kWh/year 

Baseline 1.40 763 

1 1.45 737 

2 1.50 712 

3 1.55 690 

4 1.60 668 

5 2.02 529 

* Capacity = 49.5 pints/day; Annual Usage = 1095 hours (AHAM mid-estimate). 

6-11 

EE-2006-STD-0127 COMMENT 39.2
Table 6.3.8 54.01-74.99 Pints/Day Dehumidifiers: Annual Energy Use by Efficiency 

Level 

Efficiency Annual Energy Use* 

Level liters/kWh kWh/year 

Baseline 1.50 928 

1 1.55 898 

2 1.60 870 

3 1.65 844 

4 1.70 819 

5 1.80 774 

* Capacity = 64.5 pints/day; Annual Usage = 1095 hours (AHAM mid-estimate). 

Table 6.3.9 75 Pints/Day or More Dehumidifiers: Annual Energy Use by Efficiency 

Level 

Efficiency Annual Energy Use* 

Level liters/kWh kWh/year 

Baseline 2.25 768 

1 2.38 726 

2 2.50 691 

3 2.55 677 

4 2.60 664 

5 2.75 628 

* Capacity = 80 pints/day; Annual Usage = 1095 hours (AHAM mid-estimate). 

6.3.4 Variability of Annual Energy Consumption 

The 2001 RECS indicates that 578 of the 4,822 households in the survey use 

dehumidifiers. Of the 578 households that use dehumidifiers, most have basements and are 

located in the Northeast or upper Midwest regions of the country. For the RECS households 

with dehumidifiers, Figure 6.3.1 disaggregates the households into thirteen regions based on 

Census Division and large states. There are nine Census Divisions in the U.S. In the figure 

below, DOE further broke down four of the Census Divisions by separating out the large states 

from each Division (i.e., it took New York out of the Middle Atlantic, Florida out of the South 

Atlantic, Texas out of the West South Central, and California out of the Pacific). Within each 

region, the figure further shows the percentage of households with and without basements. 

Figure 6.3.1 demonstrates that the RECS data are consistent with recent dehumidifier shipments 

data that indicate that an overwhelming majority of these products are sold in northern climates 

(i.e., 81 percent of dehumidifiers are in the New England, Middle Atlantic, New York state, East 

North Central, and West North Central regions). The RECS data also seem to confirm 

conventional wisdom that dehumidifiers are primarily used in basements (i.e., 89 percent of 

dehumidifiers are in households with basements). 

6-12 

EE-2006-STD-0127 COMMENT 39.2
0% 

5% 

10% 

15% 

20% 

25% 

30% 

35% 

land 

l l 

l

Flori

l l 

ific li

wi

New 

Eng

Mid 

Atlantic 

w /o NY 

New 

York 

East 

North 

Centra

West 

North 

Centra

South 

At antic 

w /o FL 

da East 

South 

Centra

West 

South 

Centra

w /o TX 

Texas Mountain Pac

w /o CA 

Ca fornia 

Percent of Households with Dehumidifiers

no Basement 

th Basement 

Figure 6.3.1 Percent of Households with Dehumidifiers Disaggregated by Region and 

Presence of Basement 

Unfortunately, RECS does not have any data that indicate the usage or annual energy 

consumption of dehumidifiers. Therefore, DOE did not use RECS to determine the variability of 

annual energy consumption. Rather, variability was established based on the usage data 

provided by AHAM above in Table 6.3.1. Because the AHAM data was developed based on the 

experience of manufacturers, DOE believed that the AHAM data was most representative of 

actual usage. DOE characterized the variability of usage with a triangular probability 

distribution as shown below in Figure 6.3.2. Table 6.3.3 shows how the baseline annual energy 

consumption for each product class varies based on the three usage estimates from AHAM. As 

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

variability as shown in Figure 6.3.2 to vary the annual energy consumption when it conducted 

the LCC and PBP analysis. 

6-13 

EE-2006-STD-0127 COMMENT 39.2
0 

/ ) 

/

0.1 

0.2 

0.3 

0.4 

0.5 

850 900 950 1000 1050 1100 1150 1200 1250 1300 1350 

Usage (hours year

Probability 

Mean = 1095 hours year 

Figure 6.3.2 Probability Distribution for Dehumidifier Usage 

6.4 COOKING PRODUCTS 

6.4.1 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.12 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)13 and the Florida Solar Energy Center (FSEC)14 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. 

6.4.1.1 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.15 The annual useful 

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

consumption. 

6-14 

EE-2006-STD-0127 COMMENT 39.2
For electric cooktops, the annual energy consumption (ECA) is determined based on the 

following DOE test procedure equation: 

OCT ECA = EffCT 

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 ECA = 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 EAO = 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: 

6-15 

EE-2006-STD-0127 COMMENT 39.2
OO EAOG + EAOE × Ke = 

RO 

where: 

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

RO = Oven energy factor, and 

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 6.4.1 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 6.4.1 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 weightged-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 

6-16 

EE-2006-STD-0127 COMMENT 39.2
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 6.4.1 

and Figure 6.4.2 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 

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 

Annual Electric Cooking Use (kWh yr

Metered 

CDA 

1975 1980 1985 1990 1995 2000 2005 

Year 

Figure 6.4.1 Historical Estimates of Annual Electric Range Energy Use 

6-17 

EE-2006-STD-0127 COMMENT 39.2
0 

20 

40 

60 

80 

100 

120 

140

l i ( / )

l

l

l

Annua Gas Cook ng Energy therms yr

CDA-pilot 

CDA-no pi ot 

CDA-pi ot unknown 

Metered-pilot 

Metered-no pi ot 

1975 1980 1985 1990 1995 2000 2005 

Year 

Figure 6.4.2 Historical Estimates of Annual Gas Range Energy Use 

6.4.1.2 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 6.4.2 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 6.4.1). 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 6.4.1. 

6-18 

EE-2006-STD-0127 COMMENT 39.2
Table 6.4.2 Component Annual Energy Use of Baseline Cooktops and Ovens 

Ovens 

Cooktops Electric Gas 

Energy Use Gas with Gas w/o Self- Std with Std w/o SelfComponents Electric pilots pilots Standard Cleaning pilot pilot Cleaning 

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 

128.2 2.74 0.72 166.5 171.0 1.83 0.92* 1.04* Total kWh MMBtu MMBtu kWh kWh MMBtu MMBtu MMBtu 

Annual Useful Cooking 94.8 289.1 289.1 16.1 16.1 48.7 48.7 48.7 

Energy Output kWh kBtu kBtu kWh kWh kBtu kBtu 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. 

6.4.1.3 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 6.4.2. 

Table 6.4.3 and Table 6.4.4 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 6.4.2. 

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. 

6-19 

EE-2006-STD-0127 COMMENT 39.2
Table 6.4.3 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 6.4.4 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 6.4.5 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 6.4.5 

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 6.4.2 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 6.4.5 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 6.4.6 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 6.4.6 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 6.4.2 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. 

6-20 

EE-2006-STD-0127 COMMENT 39.2
Table 6.4.6 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 6.4.7 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 6.4.7 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 6.4.2 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 6.4.7 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 6.4.8 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 6.4.8 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 6.4.2 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 

6-21 

EE-2006-STD-0127 COMMENT 39.2
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 6.4.8 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 6.4.9 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 6.4.9 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 6.4.2 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 

6-22 

EE-2006-STD-0127 COMMENT 39.2
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 6.4.9 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. 

6.4.1.4 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.16 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 6.4.12 in Table 

6.4.2. 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 6.4.2. Table 6.4.10 presents the weighted-average cooking frequency values 

along with the corresponding annual energy use values from Table 6.4.2. 

6-23 

EE-2006-STD-0127 COMMENT 39.2
Table 6.4.10 Annual Energy Use of Baseline Cooktops and Ovens with corresponding 

RECS Cooking Frequency 

Ovens 

Cooktops 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 6.4.10); 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 6.4.10); 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 

EAO _ AVG 

AO 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 6.4.10); 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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EE-2006-STD-0127 COMMENT 39.2
FreqO_AVG = Average oven frequency (from Table 6.4.10); 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.17 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. 

0 100 150 200 250 350 400 450 500 

( / ) 

0.00 

0.01 

0.02 

0.03 

0.04 

50 300 

Annual Energy Use kWh year

Probability 

Figure 6.4.3 Distribution of Baseline Electric Cooktop Annual 

Energy Use Based on 2001 RECS Cooking Frequency 

6-25

EE-2006-STD-0127 COMMENT 39.2
/ ) 

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 6.4.4 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. 

6-26 

EE-2006-STD-0127 COMMENT 39.2
0 100 150 200 250 300 450 500 550 

( / ) 

0.00 

0.01 

0.02 

0.03 

0.04 

0.05 

0.06 

0.07 

0.08 

50 350 400 

Annual Energy Use kWh year

Probability 

Figure 6.4.5 Distribution of Baseline Electric Standard Oven 

Annual Energy Use Based on 2001 RECS Cooking 

Frequency 

0 100 150 200 250 300 450 500 550 

/ ) 

0.00 

0.01 

0.02 

0.03 

0.04 

0.05 

0.06 

0.07 

0.08 

50 350 400 

Annual Energy Use (kWh year

Probability 

Figure 6.4.6 Distribution of Baseline Electric Self-Cleaning Oven 

Annual Energy Use Based on 2001 RECS Cooking 

Frequency 

6-27 

EE-2006-STD-0127 COMMENT 39.2
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 6.4.7 Distribution of Baseline Gas Standard Oven Annual 

Energy Use Based on 2001 RECS Cooking Frequency 

6-28 

EE-2006-STD-0127 COMMENT 39.2
/ ) 

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 6.4.8 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. 

6.4.2 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. 

6.4.2.1 Average Annual 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: 

6-29 

EE-2006-STD-0127 COMMENT 39.2
E MO = 

MO 

OM

R 

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 6.4.9 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. 

6-30 

EE-2006-STD-0127 COMMENT 39.2
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 6.4.9 Historical Estimates of Annual Microwave Oven Energy Use 

6.4.2.2 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. 

Table 6.4.11 shows the microwave oven energy factors and their corresponding annual 

energy consumption. 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. 

Table 6.4.11 Microwave Ovens: Annual Energy Consumption by Efficiency Level 

Level 

Energy 

Factor 

Cooking 

Efficiency 

Total 

kWh/year 

Baseline 0.557 55.7% 131.0 

1 0.586 58.6% 124.5 

2 0.588 58.8% 124.1 

3 0.597 59.7% 122.2 

4 0.602 60.2% 121.2 

6-31 

EE-2006-STD-0127 COMMENT 39.2
6.4.2.3 Variability of Annual 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 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 

E MO _ AVG 

MO HH _ = FreqMO HH _ × 

FreqMO _ AVG 

where: 

EMO_HH = Microwave oven annual energy consumption for specific RECS 

household, 

FreqMO_HH = Microwave oven frequency for specific RECS household, 

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 6.4.10 shows the probability distribution of annual cooking energy 

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

from RECS. 

6-32 

EE-2006-STD-0127 COMMENT 39.2
0 100 200 300 400 500 600 700 900 1000 1200 

( / ) 

0.00 

0.01 

0.02 

0.03 

0.04 

0.05 

0.06 

0.07 

0.08 

0.09 

0.10 

800 1100 

Annual Energy Use kWh yr

Probability 

Figure 6.4.10 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. 

6.5 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. 

6.5.1 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 

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.18 DOE 

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

2005.19 The DOE test procedure provides the following equations to calculate the total per-cycle 

dishwasher energy consumption: 

HET CWCYCLE = × c + MET + DE e 

6-33 

EE-2006-STD-0127 COMMENT 39.2
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 

GCF = Gas correction factor = 1.12.20 

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 

6-34 

EE-2006-STD-0127 COMMENT 39.2
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. Table 6.5.1 

shows the summary data for residential clothes washers from DOE’s 2000 TSD.21 As shown in 

Table 6.5.1, DOE determined the RMC using the dryer energy, the clothes container volume, and 

the resulting maximum test-load weight. 

Table 6.5.1 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 lb/cycle RMC

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% 

Figure 6.5.1 plots the MEF and RMC data in Table 6.5.1 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. 

6-35 

EE-2006-STD-0127 COMMENT 39.2
R2

1 

RMC = -0.1560278 * MEF + 0.7337259 

 = 0.8651900 

45% 

50% 

55% 

60% 

65% 

0.8 0.9 1.1 1.2 1.3 1.4 1.5 1.6 1.7 

MEF 

RMC 

Figure 6.5.1 Residential Clothes Washer RMC versus MEF from DOE 2000 TSD 

As discussed in Chapter 5, DOE analyzed specific efficiency levels for commercial 

clothes washers. Table 6.5.2 shows the efficiency levels for commercial clothes washers 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 6.5.1. 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 water-heating 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. 

6-36 

EE-2006-STD-0127 COMMENT 39.2
Table 6.5.2 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 1.72 8.00 46.5% 0.114 1.09 0.43 2.4 22.4 

4 1.80 7.50 45.3% 0.114 1.06 0.39 2.1 21.0 

5 2.00 5.50 42.2% 0.114 0.98 0.31 1.7 15.4 

6 2.20 5.10 39.0% 0.114 0.90 0.26 1.5 14.3 

* 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. 

6.5.2 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 

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

commercial clothes washer usage for these applications. 

Table 6.5.3 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 

6-37 

EE-2006-STD-0127 COMMENT 39.2
cycles per year, respectively. As a comparison, DOE assumed that residential clothes washers 

have an annual average usage of 392 cycles per year. 

Table 6.5.3 Commercial Clothes Washer Usage Data 

Usage per Machine Variation 

Study Application Population (cycles/day) (cycles/day) 

Multi-Family Buildings 

City of Toronto 

(1999)22 

Multifamily coinoperated (6 buildings, 3 family; 

1 mixed; 

4.3: metered 3.3 to 6.0 (variation 

based on average 

945 apartments, 39 1 seniors & values from 6 

machines) singles; and 1 buildings) 

seniors 

FEMP (2000)23 Military housing Family 6.4: metered 3.2 to 10.9 

on-premise laundry (30 

machines; free use) 

SCE/PNNL (2000)24 Multifamily coin- Seniors 2.2 : metered 1 to 4 

operated (12 machines) 

MLA (2002)25 Multifamily coinoperated 

(4 buildings in 4 cities, 

50 common area 

General 2.9: metered * 

2.7: coin * 

4.5: survey * 

2.6 to 3.1 (variation 

based on average 

values from 4 cities) 

machines) 

Wisconsin/ 

PNNL (2004)26 

Multifamily coinoperated (9 machines) Apartments & 

Condos 

1.5: metered ** 1 to 3 

Lightwash/ 

Equipoise (2004)27 

Multifamily & 

Businesses 

Not specified. 3: businesses & multifamily 

<10 units, industry value 

*** 

Not available. 

4: multifamily ≥10 units, 

industry value *** 

Consortium for 

Energy Efficiency28 

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 

Association29 

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: 

6-38 

EE-2006-STD-0127 COMMENT 39.2
CWANNUAL = CWCYCLE × N 

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. 

Table 6.5.4 and Table 6.5.5 show the annual energy and water consumption for multifamily buildings and laundromats, respectively. 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 6.5.4 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 1.72 8.00 532 2.42 1354 5.18 142 27.9 

4 1.80 7.50 482 2.19 1315 5.02 142 26.2 

5 2.00 5.50 387 1.76 1215 4.64 142 19.2 

6 2.20 5.10 328 1.49 1116 4.26 142 17.8 

* 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. 

6-39 

EE-2006-STD-0127 COMMENT 39.2
Table 6.5.5 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 1.72 8.00 935 4.25 2380 9.10 250 49.1 

4 1.80 7.50 847 3.85 2310 8.83 250 46.0 

5 2.00 5.50 680 3.10 2136 8.16 250 33.7 

6 2.20 5.10 576 2.62 1961 7.49 250 31.3 

* 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. 

6.5.3 Variability of Annual Energy and Water Consumption 

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

average usage data above from Table 6.5.3. 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 6.5.2, DOE weighted the usage studies equally for multi-family applications. 

As shown in Figure 6.5.3, 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. 

6-40 

EE-2006-STD-0127 COMMENT 39.2
Probability

0.14 

0.12 

0.1 

0.08 

0.06 

0.04 

0.02 

0 

Wisc/PNNL SCE/PNNL 

MLA

Equip <10 CEE 

Equip >10 

Toronto 

FEMP 

0 1 2 3 4 5 6 7 

Usage (cycles/day) 

Figure 6.5.2 Probability Distribution for Commercial Clothes Washer 

Usage in Multi-Family Applications 

2 3 4 5 6 7 8 9 

/ ) 

0.00 

0.05 

0.10 

0.15 

0.20 

Usage (cycles day

Probability 

Figure 6.5.3 Probability Distribution for Commercial Clothes Washer 

Usage in Laundromat Applications 

6-41 

EE-2006-STD-0127 COMMENT 39.2
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EE-2006-STD-0127 COMMENT 39.2
<http://www.energystar.gov/index.cfm?c=dehumid.pr_dehumidifiers> Accessed March 8, 

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Berkeley, CA. LBNL-47889: Appendix D. 

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21 U.S. Department of Energy-Office of Building Research and Standards. Final Rule Technical 

Support Document (TSD): Energy Efficiency Standards for Consumer Products: Clothes 

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

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

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

Corporation. Multi-Unit Residential Clothes Washer Replacement Pilot Project 1999, May, 

2003. Toronto, Ontario, Canada. 

23 U.S. Department of Energy-Federal Energy Management Program. Assessment of HighPerformance, Family-Sized Commercial Clothes Washers, May, 2000. Prepared for the U.S. 

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

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

High-Performance Clothes Washer Demonstration at Leisure World Laguna Woods, Final 

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

Pacific Northwest National Laboratory, Richland, WA. 

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

Multifamily Housing, November 2002. Prepared for the Multi-Housing Laundry Association 

by National Research Center, Inc, Boulder, CO. 

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

Laundry (REL) Room Demonstration, Final Report, June 2004. Prepared for Wisconsin 

Focus on Energy by Battelle Pacific Northwest National Laboratory, Richland, WA. Report 

No. PNWD-3445. 

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

Energy Solutions’ 2002/03 LightWash Program, June 30, 2004. Prepared by Equipoise 

Consulting Incorporated. 

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

Clothes Washer Initiative, Fact Sheet. <http://www.cee1.org/com/cwsh/cwsh-main.php3> 

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

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

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