CHAPTER 6. ENERGY 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 Consum ption

.......................................................... 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

LIST OF TABLES Table 6.2.1 Annual Energy Consumption of Ba seline 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 Ener gy Consumption by Efficiency Level

....... 6-7 Table 6.2.4 Electric Smooth Cooktops: A nnual Energy Consumption by Efficiency Level

.................................................................................................................... 6-7 Table 6.2.5 Gas Cooktops: Annual Energy C onsumption 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 Ener gy 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 Standby Power Consumption

.............................................. 6-18 Table 6.2.12 Microwave Ovens: Annual Energy Consumption by Energy Factor Level

..... 6-20

LIST OF FIGURES Figure 6.2.1 Historical Estimates of A nnual Electric Range Energy Use

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

...................................... 6-5
6-iFigure 6.2.3 Distribution of Baseline Elect ric Cooktop Annual Energy Use Based on 2001 RECS Cooking Frequency

........................................................................ 6-12 Figure 6.2.4 Distribution of Baseline Ga s Cooktop Annual Energy Use Based on 2001 RECS Cooking Frequency

................................................................................. 6-13 Figure 6.2.5 Distribution of Baseline Elect ric Standard Oven Annual Energy Use Based on 2001 RECS Cooking Frequency

........................................................ 6-14 Figure 6.2.6 Distribution of Baseline Electric Self-Clean ing Oven Annual Energy Use Based on 2001 RECS Cooking Frequency

........................................................ 6-14 Figure 6.2.7 Distribution of Ba seline 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 A nnual Microwave Oven Energy Use

......................... 6-18 Figure 6.2.10 Distribution of Microwave Ov en Annual Cooking Energy Use Based on 2001 RECS Cooking Frequency

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

6-iiCHAPTER 6. ENERGY USE DETERMINATION

6.1 INTRODUCTION To carry out the life-cycle cost (LCC) a nd payback period (PBP) calculations described in Chapter 8, DOE needed to determine the op erating cost savings to consumers from moreefficient equipment. The LCC and PBP analys is requires data on annual energy use because, along with energy prices, DOE uses these data to establish the most si gnificant component of consumer operating costs. (Maintenance and repa ir costs are the other co ntributors to operating cost.) This chapter describes how DOE determined the annual energy consumption of residential electric and gas ranges and microwave ovens an d how more-efficient equipment impacts annual energy consumption. The technical support document (TSD) for DOE’s notice of proposed rulemaking (NOPR) covered conventional cooking products (i.e., cooktops and ovens), microwave oven energy factor (EF), microwave oven standby power consumption, and commercial clothes washers (CCW). 1 This chapter presents information and results pertaining solely to conventional cooking products and microwave oven EF. Th e impact of more-efficient equipment on microwave oven standby power and CCWs w ill be addressed in subsequent TSDs.

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 sup port document (TSD) identified several studies that estimated the annual energy cons umption of electric and gas ranges. 2 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 Residentia l Appliance Saturation Study (CA RASS) 3 and the Florida Solar Energy Center (FSEC) 4 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 co oking less at home.
6.2.1.1 Average Annual Energy Consumption Based on the research conducted for the 1996 TS D, DOE published revisions to its test procedure as a final rule in 1997 that include d a reduction in the annua l useful cooking energy output and a reduction in the number of self-cleaning oven cycles per year. 5 The annual useful cooking energy output relates the energy factor of the cooking appliance to the annual energy consumption.

6-1For electric cooktops, the annual energy consumption ( E CA ) is determined based on the following DOE test procedure equation:
O CT E CA = Eff CT where:
O CT = 173.1 kilowatt-hours (kWh) per year, annual useful cooking energy output, and Eff CT

= Cooktop efficiency, which is also equi valent to the cooktop energy factor. For gas cooktops, the following DOE test pr ocedure equation is us ed 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-cl eaning and non-self-cleaning ovens, the following DOE test procedure equation is used to determine th e total annual energy consumption ( E AO ):

E AO = O O 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 th e total annual energy consumption:

6-2O O E AOG + E AOE × K e = R O where:
O O = 88.8 kBtu per year, annual useful cooking energy output, R O = Oven energy factor, and K

e = 3,412 Btu/kWh, conversion fa ctor for kWh to Btus. Based on the baseline energy factors established in DOE’s 1996 TSD for cooking products, the annual energy cons umption of electric and ga s cooktops and ovens can be determined using the above DOE test procedur e 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 effi ciencies are lower than the energy factors due to the energy used by com ponents that are not dedi cated to cooking food (e.g., clock power, self cleaning). DOE considers the annual ener gy consumption values to be representative of electric and gas cooking energy usage circa the mid-1990s. Table 6.2.1 Annual Energy Consumption of Baselin e 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 kBtuElectric Standard Oven (NonSelf-Cleaning) 12.15% 0.1066 274 kWh Electric Self Cleaning Oven 13.79% 0.1099 305 kWhGas Standard Oven (Non-SelfCleaning)*** 5.92% 0.0298 2960 kBtu Gas Self-Cleaning Oven † 7.13% 0.0540 1644 kBtu
* Baseline cooking efficiencies and en ergy factors from DOE, Cooking Product TSD, 1996. Energy factor for electric standard ovens in 1996 TSD re flects 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 ener gy use: (1) the 2004 CA RASS and (2) a 2001 study conducted by FSEC. The CA RASS reported an average elec tric 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-c leaning range (234 + 274 = 508 kWh) and a selfcleaning range (234 + 305 = 539 kWh). The CA RASS also reported an average gas range

6-3annual energy consumption of 43 therms (4300 kB tu) 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 th e 1996 TSD, the CA RASS, and FSEC, Figure 6.2.1 and Figure 6.2.2 show how the annual energy cons umption of electric ra nges and gas ranges, respectively, have varied over time. The figur es 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 consumpti on of 281.5 kWh per year (t he 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

6-40 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 A nnual Gas Range Energy Use
6.2.1.2 Annual Energy Consumption of Energy-Using Components DOE performed several calculation steps to disaggregate the repr esentative 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 pres ented 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 th eir disaggregated energy use components (i.e., cooking, ignition, self-cleaning, and clock) that correspond to the baseline cooking efficiencies provided in DOE’s 1996 TS D (see Table 6.2.1). Note that, because the annual useful cooking energy output values ba sed on the updated annual energy use data are lower than those in the current DOE test proced ure, 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 pur poses of developing the cost-efficiency relationships of electric and gas range cooking pr oducts, DOE analyzed only those efficiency levels from its 1996 TSD. The following tables present the annual energy consumption of electric and gas range cooking pr oducts 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 elec tric cooktop energy factors and their corresponding annual energy consumption. Becau se there is no additional energy use beyond what is needed for cooking, the energy factor for electric cooktops is eq uivalent to the cooking efficiency. The baseline annual energy cons umption of 128.2 kWh is taken from Table 6.2.2. DOE determined the annual energy consumption fo r 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 usef ul cooking energy output rather than the value based on more recent annual energy consumption da ta. 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 pilo t 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 pilo ts. 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 Cons umption 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 ba sed on more recent annua l energy consumption data. The baseline annual energy consump tion of 149.9 kWh is taken from Table 6.2.2 and consists of two components: cooking energy an d 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 co oking efficiencies of the more efficient and baseline levels and multiplying it by the ba seline annual cooking energy consumption. DOE assumed that clock energy remains cons tant with increased efficiency.

6-7Table 6.2.6 Electric Standard Ovens: Annual Ener gy 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 fact ors and cooking efficiencies as well as their corresp onding annual energy consumption. Note that the energy factors provided in Table 6.2.7 are based on the DOE test procedur e’s annual useful cooki ng energy output rather than the value based on more recent annual en ergy 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 cloc k energy is based on a power consumption of 3.8 Watts. DOE determined the annual cooking ener gy consumption for a more efficient level by taking the ratio of the cooking e fficiencies of the more effici ent and baseline levels and multiplying it by the baseline annual cooking energy consumption. DOE assumed that both selfcleaning and clock energy remain constant with increased efficiency. Table 6.2.7 Electric Self-Cleaning Ovens: Annua l 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 ener gy factors and cooking efficiencies along with their corresponding annual en ergy 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 en ergy 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 ba seline annual energy consumption assumes that the oven is equipped with one standing pilot. The first a nd seventh (i.e., ‘1a’) efficiency

6-8levels correspond to the eliminati on of the standing pilot. The fi rst 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. Effi ciency level ‘1a’ is based on the use of an electronic ignition or spark igni tion 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 th e 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 in creased 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 k Wh/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 th e technologies for each design are di fferent. 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 fr om standard level 1. Table 6.2.9 shows the gas self-cleaning ove n energy factors and cooking efficiencies along with their corresponding a nnual energy consumption. No te 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 recen t 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, i gnition 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 consum ption 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 ener gy consumption. DOE assumed th at the self-cleaning, ignition, and clock energy remain constant with increased efficiency. Table 6.2.9 Gas Self-Cleaning Ovens: Annual Ener gy 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 c onsumption due to hot surface i gnition 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 Administrati on (EIA) conducts a Residential Energy Consumption Survey (RECS) that collects ener gy-related data for occupied primary housing units in the U.S. The 2001 RE CS collected data from 4,822 housi ng units representing almost 107 million households. 6 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 record s have standard ovens, and 1601 household records have self-cleaning ovens. With rega rd 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 se lf-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 fre quency 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 en ergy consumption while maintaining the average annual energy consump tion shown above in section 6.4.2 in Table 6.2.2. To determine the variability of cooking produc t 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 us e values from Table 6.2.2.

6-10Table 6.2.10 Annual Energy Use of Baseline Cooktops and Ovens with corresponding RECS Cooking Frequency Ovens Cooktops Electric Gas
Electric Gas with pilots Gas w/o pilots Standard SelfCleaning Std with pilot Std w/o pilot SelfCleaning Annual Energy Consumption 128.2 kWh 2.74 MMBtu 0.72 MMBtu 166.5 kWh 171.0 kWh 1.83 MMBtu 0.92 MMBtu 1.04 MMBtu RECS average cooking frequency (meals per day) 1.22 1.29 1.29 0.52 0.57 0.49 0.49 0.56
DOE then varied the annual energy consum ption for each RECS household based on its reported cooking frequency. DOE determined the annual cooking energy consumption for each RECS household with a cooktop ba sed on the following equation:
E CA

_ AVG HHCA

_ E = C Freq HH_ × C Freq 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 ener gy 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 AO _ HH = Freq 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 cons umption (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 fo r gas standard ovens without pilots; and 0.99 MMBtu for gas self-cleaning ovens, and

6-11Freq O_AVG = Average oven frequency (from Ta ble 6.2.10); 0.52 meals/day for electric standard ovens; 0.57 meals/day for electric self-cleaning ovens; 0.49 meals/day for gas standard ovens; and 0.56 meals per da y 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 probabil ity 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 distributi on of electric and gas cooktop energy use, respectively. For gas cooktops, cr itical to the determination of the distribution of annual energy consumption is the determination of which cookt ops have standing pilots. Based on shipments data from the 1996 TSD, the only cooktops that s till have standing pilots are in gas ranges without self-cleaning ovens (i.e., gas standard ranges). In othe r words, all stand-alone cooktops and gas ranges with self-clean ing ovens have pilotless igniti on systems. Based on estimates from the Appliance Recycling Information Ce nter, approximately 250,000 standard gas ranges (or approximately 20 percent of gas standard ra nge shipments) were sold in 2004 with standing pilots. 7 Of the gas cooktops in RECS households, 43 pe rcent are either in st and-alone units or in self-cleaning gas ranges while 57 pe rcent are in standard gas ranges. Therefore, for purposes of defining which RECS households with gas cooktops utilize sta nding pilots, DOE assumed that 20 percent of the standard gas ranges, or 11 percent of all gas cooktops, are equipped with standing pilots.Probability 0.04

0.03

0.02

0.01

0.00 0 50 100 150 200 250 300 350 400 450 500 Annual Energy Use (kWh/year) 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 ove ns, respectively.

6-13Probability 0.08

0.07

0.06

0.05

0.04

0.03

0.02

0.01

0.00 0 50 100 150 200 250 300 350 400 450 500 550 Annual Energy Use (kWh / year) Figure 6.2.5 Distribution of Baseline Electric Standard Oven Annual Energy Use Based on 2001 RECS Cooking FrequencyProbability 0.08

0.07

0.06

0.05

0.04

0.03

0.02

0.01

0.00 0 50 100 150 200 250 300 350 400 450 500 550 Annual Energy Use (kWh/ year) 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 de termination 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 ove ns 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 Recyclin g Information Center, approximately 250,000 standard gas ranges (or appr oximately 20 percent of gas standard range shipments) were sold in 2004 with standing p ilots. 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 range s, or 19 percent of all gas standard ovens, are equipped with standing pilots.Probability 0.10
0.09
0.08
0.07
0.06
0.05
0.04
0.03
0.02
0.01
0.00 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) Figure 6.2.7 Distribution of Baseline Gas Standard Oven Annual Energy Use Based on 2001 RECS Cooking Frequency

6-150.10
0.09
0.08
0.07Probability 0.06
0.05
0.04
0.03
0.02
0.01
0.00 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 Annual Energy Use (MMBtu/year) 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 consump tion increased from the late 1970s to the late 1980s, annual energy consumption has rema ined relatively steady si nce the late 1980s. DOE’s 1996 TSD identified studies that estimated the annual ener gy 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, s howed 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 TS D, 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. 5 The annual useful cooking en ergy output relates the energy factor of the cooking appliance to the annual energy cons umption. The annual energy consumption ( E MO ) is determined based on the following DOE test procedure equation:

6-16E MO = O M 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 fa ctor 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 consumpti on of microwave ovens. The CA RASS reported an average microwave annual energy consumpti on 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 annu al energy use values from the studies by year and indicates whether the estimates came from me tered studies, conditional demand analyses, or a combination of the two. Microwave oven ener gy use has remained relatively steady. Although the DOE test procedure produces an annual energy c onsumption that is clos e 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 consumpti on of 131 kWh per year and a baseline energy factor of 55.7 percent, DOE lowered the annua l 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 Annua l Microwave Oven Energy Use
6.2.2.2 Standby Power Energy Consumption As discussed in Section 3.14.3 of Chapter 3, Market and Technology Assessment, during the course of DOE’s investigation of micr owave oven standby power consumption, DOE and AHAM tested a combined total of 52 units. Based on these tests, DOE determined the percent at each of the standby power levels identified in the engineering analysis (see Chapter 5). Since no other data were available, DOE us ed the test data to develop the market shares of standby power consumption. As shown in Table 6.2.11, DOE de veloped a weighted-ave rage standby power consumption associated with a baseline EF microwave oven. Table 6.2.11 Microwave Ovens Standby Power Consumption Market Share Standby Power (W) 46.2% 4.0 34.6% 2.0 19.2% 1.5

0% 1.0 0% 0.02 Weighted-Average 2.83 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:

6-18E SP = P SP × Hours 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:
E MO = annual (cooking) energy consumption, and I MO = Microwave input power (watts). As discussed in Chapter 5, DOE and AHAM test ed 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 ou tput power of the 52 tested units equaled 1026 watts. The corresponding input power is based on the following expression:
O I MO = 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 hour s 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 24.5 kWh per year.
6.2.2.3 Annual Energy Consumption by Efficiency Level As discussed in Chapter 5, for the pur poses of developing the cost-efficiency relationships of microwave ovens, DOE used th e efficiency levels from its 1996 TSD.

6-19Table 6.2.12 shows how the annual energy consumption varies by microwave oven energy factor. The baseline annual energy c onsumption is 155.6 kWh. DOE determined the annual cooking energy consumption of a more ef ficient level by taking th e ratio of the more efficient and baseline cooking efficiencies and multiplying it by the baseline annual energy consumption. Table 6.2.12 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 2.83 24.6 155.6 1 0.586 58.6% 124.5 2.83 24.6 149.1 2 0.588 58.8% 124.1 2.83 24.6 148.7 3 0.597 59.7% 122.2 2.83 24.6 146.8 4 0.602 60.2% 121.2 2.83 24.6 145.8 * 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 provid e 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 en ergy consumption. Conducti ng the analysis in this manner captures the observed variability in a nnual energy consumption while maintaining the average energy consumption value. To determ ine the variability of microwave oven energy consumption, DOE first equated th e weighted-average cooking fr equency 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 hou sehold with a microwave oven based on the following equation: E MO

_ AVG E MO _ HH = Freq MO _ HH × Freq MO

_ AVG where:
E MO_HH = Microwave oven annual energy consumption for specific RECS household, Freq MO_HH = Microwave oven frequency for specific RECS household, E 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.

6-20For all RECS households, microwave oven cooking frequency varies between zero to four meals per day. Figure 6.2.10 shows the probability distri bution of annual cooking energy consumption based on correlating the average cooki ng 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.

6-21REFERENCES

1 U.S. Department of Energy-Office of Energy Efficiency and Renewable Energy. Technical Support Document: Energy Efficiency Program for Consumer Products and Commercial and Industrial Equipment: Residential Dishwa shers, Dehumidifiers, Cooking Products, and Commercial Clothes Washers , September, 2008. Washington, DC. < http://www1.eere.energy.gov/buildings/appliance_ standards/residential/home_appl_tsd.html >
2 U.S. Department of Energy- Office of Codes and Standards. Technical Support Document for Residential Cooking Products, Volume 2: Pote ntial Impact of Altern ative Efficiency Levels for Residential Cooking Products , April, 1996. Prepared for the U.S. DOE by Lawrence Berkeley National Laboratory, Berkeley, CA. Appendix A. < http://www.eere.energy.gov/buildings/appliance_standards/resi dential/cooking_pro ducts_0998_r.html >
3 California Energy Commission. California Statewide Residential Appliance Saturation Study , June 2004. Prepared for the California Energy Commission by KEMA-XENERGY, Itron, and RoperASW. Contract No. 400-04-009. < http://www.energy.ca.gov/appliances/rass/index.html >

4 Parker, D. S. Research Highlights from a Large Scale Residential Monitoring Study in a Hot Climate. Proceeding of International Symposium on Highly Efficient Use of Energy and Reduction of its Environmental Impact , January 2002. Japan Society for the Promotion of Science Research for the Future Program, Osaka, Japan. JPS-RFTF97P01002: pp. 108-116. Also published as FSEC-PF369-02, Florid a Solar Energy Center, Cocoa, FL. < http://www.fsec.ucf.edu/en/publications/html/FSEC-PF-369-02/index.htm >

5 U.S. Federal Register. Energy Conservation Program for Consumer Products: Test Procedure for Kitchen Ranges and Ovens, Cook tops, Ovens, and Microwave Ovens, Final Rule, October 3, 1997. 62 FR 51976.

6 U.S. Department of Energy-En ergy Information Administration. Residential Energy Consumption Survey, 2001 Public Use Data Files , 2001. Washington, DC. < http ://www.eia.doe.gov/emeu/recs/recs2001/publicuse2001.html >

7 Appliance Recycling Information Center. INFOBulletin #8, Applications in Appliances , March 2005. Washington, DC. < http://www.aham.org/industry/ht/a ction/GetDocumentAction/id/5370 >

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