CHAPTER 5. ENGINEERING ANALYSIS

TABLE OF CONTENTS

5.1 INTRODUCTION

........................................................................................................... 5-1 5.2 TECHNOLOGIES UNABLE TO BE INCL UDED IN THE ANOPR ANALYSIS

....... 5-1 5.3 PRODUCT CLASSES ANALYZED

.............................................................................. 5-4 5.4 EFFICIENCY LEVELS

................................................................................................... 5-6 5.4.1 Baseline Units

........................................................................................................... ....... 5-6 5.4.2 Incremental Efficiency Levels

......................................................................................... 5-8 5.5 METHODOLOGY OVERVIEW

.................................................................................. 5-13 5.5.1 AHAM Data Request

..................................................................................................... 5-1 4 5.5.2 Manufacturer Interviews

................................................................................................ 5- 14 5.5.3 Product Teardowns

........................................................................................................ 5-15 5.5.3.1 Selection of Units

......................................................................................... 5-15 5.5.3.2 Generation of Bill of Materials

.................................................................... 5-15 5.5.3.3 Cost Structure of the Spreadsheet Models

................................................... 5-16 5.5.4 Review of Previous Technical Support Documents

...................................................... 5-17 5.5.5 Product Testing

.......................................................................................................... .... 5-17 5.6 ANALYSIS AND RESULTS

........................................................................................ 5-18 5.6.1 Cooking Products

......................................................................................................... .. 5-18 5.6.1.1 AHAM Data

................................................................................................. 5-18 5.6.1.2 Review of Past TSDs

................................................................................... 5-23 5.6.1.3 Product Testing and Teardowns

................................................................... 5-30 5.6.2 Commercial Clothes Washers

........................................................................................ 5-58 5.6.2.1 AHAM Data

................................................................................................. 5-58 5.6.2.2 Review of the Most Recent TSD fo r Residential Clothes Washers

............. 5-60

LIST OF TABLES
Table 5.4.1 1996 TSD Baseline Energy Factors for Cooking Products

................................. 5-6 Table 5.4.2 Baseline Modified Energy Fact or and Water Factor for Commercial Clothes Washers

................................................................................................... 5-7 Table 5.4.3 Efficiency Levels for Residential Gas Cooktops

................................................. 5-8 Table 5.4.4 Efficiency Levels for Residential Electric Cooktops

........................................... 5-9 Table 5.4.5 Efficiency Levels for Residential Gas Ovens

.................................................... 5-10 Table 5.4.6 Efficiency Levels for Residential Electric Ovens

.............................................. 5-11 Table 5.4.7 Efficiency Levels for Residential Microwave Ovens

........................................ 5-12 Table 5.4.8 Standby Power Levels for Microwave Ovens

................................................... 5-12 Table 5.4.9 Efficiency Levels for Top-Lo ading Commercial Clothes Washers

................... 5-13 Table 5.4.10 Efficiency Levels for Front-Lo ading Commercial Cl othes Washers

................ 5-13 Table 5.5.1 Engineering Analysis Methods

.......................................................................... 5-14

5-iTable 5.5.2 Major Manufacturing Processes

........................................................................ 5-17 Table 5.6.1 Microwave Oven Standby Power Comparison

.................................................. 5-23 Table 5.6.2 Gas Cooktop Manufacturing Cost and Efficiency Increments

.......................... 5-24 Table 5.6.3 Electric Coil Cooktop Manufacturing Cost and Efficiency Increments

............ 5-25 Table 5.6.4 Electric Smooth Cooktop Manufacturi ng Cost and Efficiency Increments

....... 5-25 Table 5.6.5 Gas Standard Oven Manufacturi ng Cost and Efficiency Increments

................ 5-26 Table 5.6.6 Gas Self-Cleaning Oven Manufactur ing Cost and Efficiency Increments

........ 5-27 Table 5.6.7 Electric Standard Oven Manufactur ing Cost and Efficiency Increments

.......... 5-27 Table 5.6.8 Electric Self-Cleaning Oven Manufacturing Cost and Efficiency Increments

.......................................................................................................... 5-28 Table 5.6.9 Slopes and Intercepts for Oven Energy Factor versus Cavity Volume Relationship

....................................................................................................... 5-29 Table 5.6.10 Microwave Oven Manufacturi ng Cost and Efficiency Increments

................... 5-30 Table 5.6.11 Microwave Oven Feat ures (Table 1 of 4)

.......................................................... 5-31 Table 5.6.12 Microwave Oven Feat ures (Table 2 of 4)

.......................................................... 5-31 Table 5.6.13 Microwave Oven Feat ures (Table 3 of 4)

.......................................................... 5-31 Table 5.6.14 Microwave Oven Feat ures (Table 4 of 4)

.......................................................... 5-32 Table 5.6.15 Microwave Oven Input, Output, and Cooking Efficiency (1 of 4)

.................... 5-34 Table 5.6.16 Microwave Oven Input, Output, and Cooking Efficiency (2 of 4)

.................... 5-34 Table 5.6.17 Microwave Oven Input, Output, and Cooking Efficiency (3 of 4)

.................... 5-34 Table 5.6.18 Microwave Oven Input, Output, and Cooking Efficiency (4 of 4)

.................... 5-34 Table 5.6.19 Microwave Oven Rated versus Measured Output for AHAM and DOE Tests

................................................................................................................... 5-36 Table 5.6.20 Key Differences Between IEC Standard 705 and IEC Standard 60705

............ 5-39 Table 5.6.21 IEC Standard 705 versus IEC Standard 60705 Test Results

............................. 5-40 Table 5.6.22 IEC Standard 705 versus IEC Standard 60705-2006 Test Results, Without Rounding

............................................................................................................ 5-43 Table 5.6.23 DOE Microwave Oven Standby Power (Table 1 of 4)

...................................... 5-45 Table 5.6.24 DOE Microwave Oven Standby Power (Table 2 of 4)

...................................... 5-45 Table 5.6.25 DOE Microwave Oven Standby Power (Table 3 of 4)

...................................... 5-46 Table 5.6.26 DOE Microwave Oven Standby Power (Table 4 of 4)

...................................... 5-46 Table 5.6.27 DOE Standby Power Requirement s among Similar Microwave Ovens with Different Options

............................................................................................... 5-53 Table 5.6.28 Incremental Manufacturing Costs for Microwave Oven Standby Power

.......... 5-55 Table 5.6.29 AHAM Commercial Clothes Wash er Shipments and Shipment-Weighted MEF and WF Data Submittal

............................................................................ 5-58 Table 5.6.30 AHAM Baseline MEF Commercial Clothes Washer Average Energy and Water Use Data Submittal

................................................................................. 5-59 Table 5.6.31 AHAM Commercial Clothes Washer Incremental Cost Data Submittal

........... 5-59 Table 5.6.32 1996 AHAM Residential Clothes Washer Cost Data Submittal

....................... 5-62 Table 5.6.33 1996 AHAM Residential Clothes Washer Energy and Water Use Data Submittal

............................................................................................................ 5-65

5-iiLIST OF FIGURES
Figure 5.5.1 Manufacturing Cost Assessment Stages

............................................................ 5-16 Figure 5.6.1 AHAM Microwave Oven Efficiency versus Rated Output Power

.................... 5-20 Figure 5.6.2 AHAM Microwave Oven Efficiency versus Oven Cavity Volume

.................. 5-21 Figure 5.6.3 AHAM Microwave Oven Standby Power

......................................................... 5-22 Figure 5.6.4 DOE and AHAM Microwave Oven Effi ciency versus Rated Output Power

.... 5-35 Figure 5.6.5 DOE and AHAM Microwave Oven Efficiency versus Measured Output Power

................................................................................................................. 5-37 Figure 5.6.6 DOE Non-Rounded versus Rounded Test-to-Test Efficiency Variation Measured Using IEC Standard 60705

................................................................ 5-41 Figure 5.6.7 DOE Non-Rounded versus Rounde d Efficiency Measured Using IEC Standard 60705

.................................................................................................. 5-42 Figure 5.6.8 DOE Microwave Oven Standby Power Consumption as a Function of Rated Output Power

........................................................................................... 5-47 Figure 5.6.9 AHAM Microwave Oven Standby Power Consumption and a Function of Rated Output Power

........................................................................................... 5-48 Figure 5.6.10 DOE Microwave Oven Standby Power Consumption as a Function of Display Size

....................................................................................................... 5-49 Figure 5.6.11 DOE Standby Power Consumpti on as a Function of Display Size for Microwave Ovens with LED Displays

.............................................................. 5-50 Figure 5.6.12 DOE Standby Power Consumpti on as a Function of Display Size for Microwave Ovens with VFD Displays

.............................................................. 5-51 Figure 5.6.13 DOE Standby Power Consumpti on as a Function of Display Size for Microwave Ovens with LCD Displays

.............................................................. 5-52 Figure 5.6.14 DOE Standby Power Consumpti on Associated with Different Design Options

............................................................................................................... 5-54 Figure 5.6.15 Representative Variation in St andby Power Consumption as a Function of the Number of Active Elements in the Display

................................................. 5-57 Figure 5.6.16 AHAM Commercial Clothes Washer Incremental Cost Data Submittal

........... 5-60 Figure 5.6.17 2000 Low-Volume versus Hi gh-Volume Clothes Washer Cost Disadvantage

...................................................................................................... 5-69 Figure 5.6.18 2000 Cost Disadvantage of Producing 100,000 versus 1.5MM Clothes Washers per Year with Gr een Field Facility

...................................................... 5-70

5-iiiCHAPTER 5. ENGINEERING ANALYSIS

5.1 INTRODUCTION
After conducting the screening analysis, the U.S. Department of Energy (DOE) performed an engineering analysis based on th e remaining design options. The engineering analysis consists of estimating the energy a nd water consumption and costs of products at various levels of increased effi ciency. This section provides an overview of the engineering analysis (section 5.1), considers technologies that are unable to analyzed for this rulemaking (section 5.2), discusses proposed product cla sses (section 5.3), estab lishes baseline unit specifications (section 5.4.1), discusses incrementa l efficiency levels (section 5.4.2), explains the methodology used during data gathering (5.5) and di scusses the analysis a nd results (section 5.6) DOE completed a separate engineering analysis for residential cooking products and commercial clothes washers (CCWs).
The primary inputs to the engine ering analysis are baseline information from the market and technology assessment (chapter 3 of the technical support document (TSD)) and technology options from the screening anal ysis (chapter 4.) Additional inputs include cost and energy efficiency data, which DOE received from the Association of Home Appliance Manufacturers (AHAM) and qualified and supplemented through teardown analysis and manufacturer interviews. The primary output of the engineering analysis is a set of cost-efficiency curves. In the subsequent markups analysis (chapter 7), DOE determined customer ( i.e. product purchaser) prices by applying distribution ma rkups, sales tax and contractor markups. After applying these markups, they serve as the input to the buildi ng energy-use and end-use load characterization (chapter 6) and the life-cycle cost (LCC) and payback period (P BP) analyses (chapter 8).
DOE typically structures its engineering analysis around one of three methodologies. These are: (1) the design-option approach, wh ich calculates the incremental costs of adding specific design options to a baseline model; (2) the efficiency-level approach, which calculates the relative costs of achieving increases in ener gy efficiency levels, without regard to the particular design options used to achieve such increases; and/or (3) the reverse engineering or cost-assessment approach, which involves a “b ottom-up” manufacturing cost assessment based on a detailed bill of materials (BOM) derived from teardowns of the product being analyzed. Deciding which methodology to use for the engin eering analysis depends on the product, the design options under study, and any histor ical data that DOE can draw on.

5.2 TECHNOLOGIES UNABLE TO BE INCLUDED IN THE ANOPR ANALYSIS In performing the engineering analysis, DOE did not consider for analysis certain technologies that met the screeni ng criteria but were unable to be evaluated for one or more of the following reasons: (1) data are not available to evaluate consumer usage of a product incorporating the technology and, therefore, the test procedure conditions and methods may not

5-1be applicable; (2) data are not available to evalua te the energy efficiency characteristics of the technology; and (3) available data suggest that the efficiency benefits of the technology are negligible. In the first two cases, DOE is unabl e to adequately assess how these technologies impact annual energy consumption.
For technologies that lack consumer us age details, including operating conditions, duration, and frequency, DOE believes that the ex isting test procedures may specify conditions and methods that are not representa tive of actual usage. DOE furthe r believes that even if data were available to amend the test procedures, su ch changes could be ex tensive enough to require total revision, which in turn could warrant the creation of a separate product class for that technology in the event that the test pr ocedure changes indi cated unique utility.
Furthermore, certain technologies cannot be measured according to the conditions and methods specified in the existing test procedure.
In other cases, available data suggest that so me of the design options would result in such small energy savings as to be negligible. Becau se DOE intends to focus on the technologies with measurable impact on efficiency, design options with negligible energy savings have been eliminated from further consideration.
Cooking Products
Several technologies are availa ble for cooktops that allow the burners or heating elements to automatically adjust in response to cooki ng-state setpoints, such as cooking vessel temperature. These include thermostatically cont rolled gas cooktop burners as well as electronic controls for electric cooktops. However, DOE is unaware of any data to quantify the energy efficiency effects of such technologies. Further, efficiency benefits of these design options can only be realized under variable burner or el ement conditions. Because the cooktop test procedure does not account for consumer us age patterns, the energy savings of these technologies cannot be adequately measured. Therefore, DOE will not consider these design options for further analysis for the NOPR.
Similarly, DOE is unaware of any data that indicates a measurable energy efficiency impact of insulation in gas and electric coil c ooktops, so DOE will not analyze this design option in the NOPR for these product classes.
Induction cooktops require ferromagnetic cookwar e in order to transfer energy to the food contents. While the test block specified in the DOE test procedure is aluminum and thus is unable to measure the efficiency of induction co oktops, the National Bureau of Standards (NBS), now called National Institute of Standards a nd Technology (NIST), proposed an alternate method of measuring the energy consumption of such cooktops by simply attaching a ferromagnetic material to the bottom of the test block. Data obtained by this method suggested an efficiency improvement over baseline electric smooth cooktops. However, this test method has not been rigorously validated for incorporatio n into the DOE test procedure and therefore,

5-2due to the unresolved nature of the NIST data, DOE will eliminate induction elements for electric smooth cooktops from fu rther consideration in the NOPR.
Some electric cooktops and microwave ovens with electronic controls consume standby power, but the efficiency metrics do not incorp orate such power in th eir calculation. Even though DOE considers the consumer usage of these products to be well-defi ned, the current test procedure does not measure standby power. T hus DOE is unable to quantify the impact on energy savings of low-standby-loss electronic cont rols for these products and will not consider these design options during the NOPR analysis.
The only currently available gas ovens that DOE is aware of that incorporate radiant burners do so for broiling, which is a secondary cooking function that is not the focus of the DOE efficiency measurement; energy efficiency is instead measured during the primary bake function. Thus the energy benefits are not captur ed by the test procedure under these conditions. Accordingly, DOE will eliminate radiant burners in gas ovens from further analysis for the NOPR.

While there are several residential steam ovens currently on the market, DOE believes that the existing test procedure may specify conditi ons and methods that are not representative of actual usage. DOE further believes that even if data were available to am end the test procedure, such changes could be extensive enough to requir e total revision, which in turn could warrant the creation of a separate product cl ass in the event that the test procedure changes indicated unique utility. Thus, DOE will not consider steam cooking in the NOPR analysis.
For added insulation in microwave ovens, this technology will not improve the energy factor (EF), since during the shor t duration of the DOE test proc edure as well as during typical usage, the microwave oven cavity walls do not m easurably heat up. Thus, the energy savings of this design option would be so sm all as to not be measurable.
Cooking sensors, which terminate the operation of a microwave oven based upon inferred cooking state, appear to promote shorter cook times and thus lowe r energy consumption. Due to the lack of consumer usage de tails, including operati ng conditions, duration, and frequency of use, DOE believes that the existing test proced ure may specify conditions and methods that are not representative of actual usage. Thus, DOE will not consider this design option for further analysis for the NOPR.
According to AHAM, dual magnetrons in microwave ovens do not improve energy efficiency due to the added losses associated with two magnetron heaters. In addition, AHAM stated that the additional cost of dual magnetrons could not be economically justified. DOE does not have any efficiency data on dual magnetrons by which to evaluate this design option. Therefore, it will not consider dual magnetr ons for further analysis in the NOPR.
AHAM stated that virtually no residential solo-function microwav e oven still uses a ceramic stirrer. Almost all microwave ovens us e polypropylene or mica film stirrers, which have lower losses than ceramic sti rrers. According to AHAM, this design option has already been

5-3optimized so there is no opportuni ty for efficiency improvements. The stirrer cover, however, may be made of ceramic when there are browning elements that generate too much heat for a plastic cover. These covers absorb some mi crowave energy but are needed to prevent food splatter inside the wave guide. Eliminating th e ceramic cover would adversely affect consumer utility by requiring cleaning of the stirrer or by reduc ing the life of the stirre r. Therefore, DOE’s NOPR analysis will not consider eliminating or improving the ceramic stirrer cover.
According to AHAM, losses associated with th e wave guide are typi cally less than 0.5 percent of the overall energy consumption. DOE is not aware of any data demonstrating efficiency improvements associated with wave guide improvement, so DOE will not analyze this design option for the NOPR.

Commercial Clothes Washers
Although several manufacturers have made claims regarding improved wash performance and greater utility of improved drum designs for front-loading clothes washers, DOE is unaware of any publicly available data to corroborate a decrease in cycle time or water consumption or an increase in modified energy factor (MEF) as a result of implementing this design option. Therefore, DOE will not analyze this design option for the NOPR.
Even though DOE considers consumer usage of CCWs to be well-defined, the current tests procedures do not measure standby power . Also, DOE is unaware of any data demonstrating energy savings associated with low-standby power supplies for CCWs. Thus, in the context of the present rulemaking, DOE e liminated the low-standby-power design option from the NOPR analysis.

5.3 PRODUCT CLASSES ANALYZED
DOE separated residential cooking products a nd CCWs into product classes. Because DOE formulated a separate ener gy conservation standard for each product class, the criteria for separation into different classes ar e (1) type of energy used (natur al gas or electricity), and (2) capacity or other performance-relate d features such as those that provide utility to the consumer, or others deemed appropriate by the Secretary that would justify the estab lishment of a separate energy conservation standard. ( 42 U.S.C. 6295 (q) and 6316(a))

For cooking products , DOE analyzed product classes based on the energy source ( i.e. , gas or electric) and the cooking method ( i.e. cooktops, ovens, and mi crowave ovens.) These distinctions yielded five cooking product classes: (1) gas cook tops; (2) electric cooktops; (3) gas ovens; (4) electric ovens; and (5) microwave ovens. DOE’s product classes are based on the list of product classes defined by DOE in its 1996 Technical Support Document for Residential Cooking Products (1996 TSD), which was released as part of the previous standards

5-4rulemaking. 1 Gas and electric ranges a are not listed below as produc t classes. Because ranges consist of both a cooktop and oven, any potenti al cooktop and oven standa rds will apply to the individual components of the range . As a result, product classes for ranges are not necessary.

For gas cooktops , DOE’s analyzed product class is:

 Conventional burners.

For electric cooktops , DOE’s 1996 TSD determined that the ease of cleaning smooth elements provides enhanced consumer utility over coil elements. Because smooth elements typically use more energy than coil elements , DOE analyzed the following product classes for electric cooktops:

 Low or high wattage open (coil) elements; and

 Smooth elements.

For electric ovens , the 1996 TSD determined that the type of oven-cleaning system is a utility feature that affects performance. DOE found that standard ovens and ovens using a catalytic continuous-cleaning process use roughly the same amount of energy. Self-cleaning ovens use a pyrolytic process that provides enhan ced consumer utility with lower overall energy consumption as compared to either standard or catalytically lined ovens . Thus, DOE analyzed the following product classes for electric ovens:

 Standard oven with or wit hout a catalytic line; and

 Self-cleaning oven.

For gas ovens , DOE analyzed the following produc t classes based upon the same reasoning as electric ovens:

 Standard oven with or wit hout a catalytic line; and

 Self-cleaning oven.

For microwave ovens , DOE analyzed no further class breakdown. This product class can encompass microwave ovens with and with out browning elements, but does not include microwave ovens that incorporate convection systems (combination ovens). DOE will not conduct an analysis at this time of combination microwave ovens due to the inability of the test procedure to measure the perfor mance of the convection component and thus a lack of data evaluating the energy efficiency or energy effi ciency characteristics of microwave ovens incoporating convection systems.

For commercial clothes washers , DOE is proposing the follow ing product classes based on the method of access:

a DOE defines a “conventional range” under EPCA as “a class of kitchen ranges and ovens which is a household cooking appliance consisting of a conventional cooking top and one or more conventional ovens.” (10 CFR 430.2)

5-5 Top-loading; and

 Front-loading.

5.4 EFFICIENCY LEVELS

5.4.1 Baseline Units

DOE selected baseline units as reference points for each product class, against which DOE measured changes resulting from energy cons ervation standards. The baseline unit in each product class represents the basic ch aracteristics of equipm ent in that class. Typically, a baseline unit is a unit that just meets current required energy conservation standards and provides basic consumer utility.
DOE used the baseline units in the engine ering analysis and th e life-cycle-cost and payback-period analysis. To determine energy savings and changes in price, DOE compared each higher energy efficiency or lower energy effi ciency design option with the baseline unit.
The identification of baseline units required es tablishing the baseline efficiency level. For cooking products, no minimum st andards exist, so DOE selected baseline levels from the 1996 TSD. The Energy Policy Act of 2005 (E PACT 2005) (Pub. L. 109-58) established standards for CCWs that became effective Octobe r 1, 2007. DOE used these baseline levels to evaluate new standards for water factor (WF) in addition to energy conservation standards. For residential cooking products (except for the prescriptive standa rd for gas products), there are no existing minimum energy conservation standards, as previous analyses failed to determine economic justification for them. The DOE test pr ocedure uses EF to rate the efficiency of cooking products. The EF for these products is the ratio of the annual useful cooking energy output of the residential cooking appliance ( i.e. the energy conveyed to the item being heated) to its total annual energy consumption. In accordance with the 1996 TSD on residential cooking products, DOE has selected the baseline EFs for the product classes DOE is using in this rulemaking listed in Table 5.4.1.
Table 5.4.1 1996 TSD Baseline Energy Factors for Cooking Products

Product Class Baseline from 1996 TSD EF Gas Conventional Burner Cooktop 0.156 Electric Open (Coil) Element Cooktop 0.737 Electric Smooth Element Cooktop 0.742 Gas Standard Oven 0.030 Gas Self-Clean Oven 0.054 Electric Standard Oven 0.107 Electric Self-Clean Oven 0.096 Microwave Oven 0.557

5-6For microwave oven standby power, energy conservation st andard levels are expressed as a maximum average standby power consumption, in watts (W). Based on product testing (see section 5.6.1.3), DOE selected a baseline sta ndby level which was the highest typical standby power for a microwave oven to provide full consumer utility. For the purpose of this rulemaking, DOE determined consumer utility to be the ability to display complex characters, brightness, and viewing angle of the display as well as the ability to au tomatically control the cooking operation ( i.e. through the use of a cooking sensor). DOE selected a baseline standby level of 4.0 W for the single microwave oven product class.

For commercial clothes washers , energy conservation standard levels are defined by two factors normalized by wash basket volume –MEF and WF. The MEF is the quotient of the cubic foot capacity of the clothes containe r divided by the total clothes washer energy consumption per cycle. The MEF takes into co nsideration not only the energy consumption of the washer but also the amount of energy requ ired to dry clothes based on the remaining moisture content (RMC) of the cl othes. The WF is the quotient of the total weighted per-cycle water consumption divided by the cubic foot capac ity of the clothes washer. These two variables are only directly related to each other via the average hot water usage by a clothes washer as measured by the test procedure. Other measured va riables affect only one va riable or the other. For example, cold water consumption only aff ects the WF, while RMC only affects the MEF.
The Energy Policy and Conservation Ac t (EPCA) of 1975 (42 U.S.C. 6291–6309) establishes the following ener gy and water conservation standa rds for all CCWs: a minimum MEF of 1.26 cubic feet (ft 3 ) per kilowatt-hour (kWh) and a ma ximum WF of 9.5 gallons per ft 3

. (42 U.S.C. 6313(e); see also 70 FR 60416 (O ct. 18, 2005), adding 10 CFR 431.156) Based on comments and the determination at that time to consider a single pr oduct class for CCWs, DOE selected baseline levels for the advance not ice of proposed rulemaking (ANOPR), published on November 15, 2007 (November 2007 ANOPR), that were based on current Federal energy conservation standards. Because, as discussed in detail in chapter 3, the determination of two product classes for CCWs was subsequently made, DOE revised the baseline levels presented in the November 2007 ANOPR to characterize top-loadi ng and front-loading CC Ws separately. DOE has selected the baseline MEFs and WFs fo r the two product classes as listed in Table 5.4.2.
Table 5.4.2 Baseline Modified Energy Factor and Water Factor for Commercial Clothes Washers
Product Class MEF, ft

3 /kWh WF, gallons/ft 3 Top Loading 1.26 9.5 Front Loading 1.72 8.0

5-75.4.2 Incremental Efficiency Levels
For the majority of the product classes pres ented in section 5.3, DOE analyzed several efficiency levels and obtained incremental cost data at each of these levels. Table 5.4.3 through Table 5.4.10 provide efficiency levels and the re ference source of each level for each of the products under consideration. For cooking products, the maximu m levels identified Table 5.4.3 through Table 5.4.7 are based on data developed from the design opti on analysis in the previous rulemaking. For microwave oven standby power and CCWs, the highest efficiency levels were identified based on a review of av ailable product lite rature for models commercially available.

Table 5.4.3 presents the efficiency levels analyzed for residential gas cooktops . The baseline and higher efficiency levels are based on the analysis performed in 1996 for the previous rulemaking. Since the 1996 TSD took a design-option approach to the analysis, each efficiency level is associated with a particular desi gn option or combination of design options. Two higher efficiency levels for gas cooktops were included in the 1996 TSD that are not considered here due to the elim ination of design options. In the current analysis, reflective surfaces are screened out due to impacts on cons umer utility, and thermostatically controlled burners were not analyzed for the NOPR due to the inability of the DOE test procedure to adequately represent usage patterns and ther efore energy efficiency characteristics. The combination of design options that produces the maximum technologically feasible EF is designated as max-tech.
DOE has structured the analysis for standi ng pilot igntion systems as a design option associated with the baseline configuration because DOE has determined that cooktops incorporating such ignition syst ems do not provide unique utility for reasons stated in section 5.3. The first standards efficiency level correspo nds to the elimination of standing pilot lights.
Table 5.4.3 Efficiency Levels fo r Residential Gas Cooktops

Level Efficiency Level Source Conventional Burners Cooking Efficiency EF Baseline 1996 TSD Baseline (with standing pilots) 0.399 0.156 1 1996 TSD (without standing pilots) 0.399 0.399 2 Max-Tech (1996 TSD) 0.420 0.420
The 1996 TSD analyzed two efficiency levels for electric coil cooktops and three levels for electric smooth cooktops . Since the 1996 TSD took a design-option approach to the analysis, each efficiency level is associated w ith a particular design option or combination of design options. In the current analysis, however, reflective surfaces are screened out as a design option for electric coil cooktops due to impacts on consumer utility, and induction elements are not analyzed for electric smooth cooktops because the available efficiency data, while suggestive of energy savings, cannot be valida ted by the existing DOE test procedure. In addition, radiant elements for smooth electric cooktops, which were included in the 1996 TSD, were not considered as a design option for this rulemaki ng because manufacturer data provided to DOE for the 1996 TSD indicated that this technology do es not offer an efficiency improvement over the baseline according to the DOE test procedure. Therefore, only a single efficiency level

5-8beyond the baseline is being analyzed for both electric coil and smooth cooktops, and by default this level becomes the max-tech, as shown in Table 5.4.4.
Table 5.4.4 Efficiency Levels for Residential Electric Cooktops

Level Efficiency Level Source Open (Coil) Elements Smooth Elements Cooking Efficiency EF Cooking Efficiency EF
Baseline 1996 TSD Baseline 0.737 0.737 0.742 0.742 1 1996 TSD 0.769 (Max-Tech) 0.769 0.753 (Max-Tech) 0.753
Efficiency levels for gas ovens , as shown in Table 5.4.5, are based on the 1996 TSD. Since the 1996 TSD took a design-option approach to the analysis, each efficiency level is associated with a particular de sign option or combination of de sign options. The oven separator design option from the 1996 TSD was screened out in the current analys is due to consumer safety and utility issues, as we ll as a lack of practicability to design and manufacture. Lowstandby-loss electronic controls we re added as design options for both standard and self-cleaning gas ovens, but were not included as efficiency levels because DOE does not have efficiency or cost increment information on them.
The baseline efficiency level for gas standard ovens assumes that th e product is equipped with standing pilot lights, and the first standard s efficiency level corresponds to the elimination of standing pilot lights based on the same reas on as for gas cooktops. However, because the cleaning cycle of gas self-cleani ng ovens requires electrical energy use, EPCA in effect requires that such ovens currently be equipped with a non-standing pilot ignition system because such an ignition system is disallowed if there is an elect rical cord provided on the product. Therefore, the baseline efficiency level for ga s self-cleaning ovens assumes th ey lack a standing pilot light. Further, the first standards efficiency level is not based on elimination of a standing pilot, but rather on the addition of the forced convection design option.
Electronic spark ignition lowers the standby power consumption as well as the cooking efficiency of standard gas ovens, and since th e standard gas oven EF rating includes standby power, results in an overall reduction in ener gy consumption. Electric spark ignition has the same functionality as ho t surface ignition sources and is therefore listed as an alternate efficiency level to the hot surface (g lo-bar) design option.

5-9Table 5.4.5 Efficiency Levels for Residential Gas Ovens

Level Efficiency Level Source Standard Oven Self-Cleaning Oven Cooking Efficiency EF Cooking Efficiency EF

Baseline 1996 TSD Baseline (with standing pilot light) 0.059 0.0298 0.071 0.0540

1 1996 TSD 0.058 (Glo-bar ignition) 0.0536 0.088 0.0625
2 1996 TSD 0.061 0.0566 0.088 0.0627 3 1996 TSD 0.062 0.0572 0.089 (Max-Tech) 0.0632 4 1996 TSD 0.065 0.0593

- - 5 1996 TSD 0.065 0.0596

- - 6 1996 TSD/Current Analysis 0.066 (Max-Tech) 0.0600

- -

1a (1) 1996 TSD (with electronic spark ignition) 0.058 0.0583

- -

(1) Note: Standard 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. Standard level 1 is a hot surface ignition device while standard level 1a is a spark ignition device Efficiency levels for electric ovens , shown in Table 5.4.6, are primarily based on the 1996 TSD. The oven separator design option from the 1996 TSD was screened out in the current analysis due to consumer safety and utility issues, as well as a l ack of practicabil ity to design and manufacture. The bi-radiant oven was screened ou t due to a lack of tech nological feasibility and practicability to manufacture, as well as impacts on consum er utility. Low-standby-loss electronic controls were added as design options for both standa rd and self-cleaning electric ovens in this analysis, but were not included as efficiency levels because, even though the test procedure accounts for the energy consumption of electronic controls, DOE does not have incremental efficiency or cost information on them.

5-10Table 5.4.6 Efficiency Levels for Residential Electric Ovens Standard Oven Self-Cleaning Oven Level Efficiency Level Source Cooking Efficiency EF Cooking Efficiency EF
Baseline 1996 TSD Baseline 0.122 0.1066 0.138 0.1099 1 1996 TSD/Current Analysis 0.128 0.1113 0.138 0.1102
2 1996 TSD/Current Analysis 0.134 0.1163 0.142 (MaxTech) 0.1123
3 1996 TSD/Current Analysis 0.137 0.1181

- - 4 1996 TSD/Current Analysis 0.140 0.1206

- - 5 1996 TSD/Current Analysis 0.141 (MaxTech) 0.1209

- -

For microwave oven energy factor, Table 5.4.7 lists the efficiency levels that were retained from the 1996 TSD, even though recent AHAM-supplied data suggests slightly different baseline and maximum-available e fficiencies of a representative sample of current models. For example, the minimum efficiency among the microwave ovens recently tested by AHAM was 54.8 percent, while the maximum efficiency wa s 61.8 percent, compared to 55.7 percent and 60.2 percent, respectively, from the 1996 TSD. However, it was noted that the standard deviation in efficiency measurements for any given microwave oven ranged from 0.2 to 1.2 absolute percentage points. To attempt to id entify microwave oven design options associated with efficiency levels, DOE performed a reverse- engineering analysis on a representative sample of microwave ovens. DOE did not find any addi tional design options beyond those that were identified in the ANOPR. DOE also performed efficiency testing on the sample of microwave ovens, which validated data submitted by AHAM. Results from both AHAM and DOE efficiency testing showed no identifiable co rrelation between cooking e fficiency and either cavity volume or rated output power. As part of the reverse-engineering analysis, DOE also evaluated microwave oven magnetrons, magnetron pow er supplies, and fan motors (identified as design options in chapter 3 of this TSD), and determined that efficiencies for these design options have changed little si nce the 1996 analysis. For thes e reasons, it was determined by DOE that the efficiency levels from the 1996 TSD we re still representative of the state of current microwave oven technology to the ex tent that the DOE test proce dure can capture performance. Further discussion of the AHAM test data and DO E testing and analysis is provided in section 5.6.1.1.

5-11Table 5.4.7 Efficiency Levels fo r Residential Microwave Ovens Level Efficiency Level Source Efficiency Level (EF) Baseline 1996 TSD Baseline 0.557 1 1996 TSD 0.586 2 1996 TSD 0.588 3 1996 TSD 0.597 4 1996 TSD Max-Tech 0.602
DOE conducted the engineering analysis for microwave oven standby power for the single product class DOE identified for microw ave ovens. To analyze the cost-efficiency relationship for microwave oven standby power, DOE defined standby power levels expressed as a maximum average standby power, in W. These leve ls were derived from review of the Federal Energy Management Program (FEMP) proc urement efficiency recommendation, the International Energy Agency’s (IEA) One-Watt program to lower standby power consumption below 1 W for various electrica l appliances, and the current maximum microwave oven standby technology ( i.e. lowest standby power) that DOE believes is or could be comm ercially available at the time the energy conservation standards b ecome effective. DOE also added a standby power level as a gap-fill betw een the FEMP Procurement Efficiency Recommendation and IEA One-Watt Program levels. Table 5.4.8 provide s the microwave oven standby levels and the reference source for each level that DOE has analyzed.
Table 5.4.8 Standby Power Levels for Microwave Ovens

Standby Level Standby Level Source Standby Power (W)
Baseline Baseline 4.0 1 FEMP Procurement Efficiency Recommendation 2.0 2 Gap Fill 1.5 3 IEA 1-Watt Program 1.0 4 Max-Tech 0.02

EPCA mandates that DOE determine bot h a minimum MEF and a maximum WF for CCWs. The two variables are related to a limite d extent, but it was not clear initially to DOE which factor is more important in setting the energy conservation standards. DOE determined, based on comments from stakeholders, that a high MEF and low WF are not necessarily correlated, and, thus, a max-tech le vel based on the highest MEF and lowest WF is not realistic. That is, a CCW with the highest possible ME F may not achieve the lowest possible WF. Similarly, a CCW with the lowest WF may not achieve the highest MEF. Therefore, DOE selected CCWs currently available on the market that exhibit a balance of high MEF and low WF to represent the max-tech levels.
For top-loading CCWs, DOE analyzed 3 effici ency levels beyond the baseline, as listed in Table 5.4.9

. These levels were based on the CEE Co mmercial Clothes Washer Initiative, and maximum levels that are currently commercially available. Based on market surveys of currently available models, DOE selected a max-tech level of (1.76 MEF/8.3 WF) for top5-12loading CCWs. For front-loading CCWs, DOE anal yzed 4 efficiency levels beyond the baseline for CCWs, as listed in Table 5.4.10. These le vels were based on ENERGY STAR, the CEE Commercial Clothes Washer Init iative, and maximum levels that are currently commercially available. Two gap-fill levels were added base d on stakeholder input between the CEE Tier 3A and the maximum available level. For front-l oading CCWs, DOE has determined a max-tech level for front-loading CCWs of (2.35 MEF/4.4 WF), based on a currently available CCW. These units were selected after an extensive ma rket survey, and DOE’s re search suggests that their combination of high MEF and low WF re present the best-in-class balance between MEF and WF for the two product cla sses of CCWs. AHAM provided in cremental cost data only at 2 of these levels (1.42 MEF/9.5 WF and 2.00 MEF/5.5 WF).
Table 5.4.9 Efficiency Levels for Top- Loading Commercial Clothes Washers

Level Efficiency Level Source Efficiency Level MEF, ft 3 /kWh WF, gallons/ft 3 baseline DOE Standard (effective 2007) 1.26 9.5 1 CEE Tier 1 (January 1, 2004) 1.42 9.5 2 CEE Tier 2 (January 1, 2004) 1.60 8.5 3 ENERGY STAR (effective 2007)MaxTech 1.762 8.30

Table 5.4.10 Efficiency Levels for Fron t-Loading Commercial Clothes Washers

Level Efficiency Level Source Efficiency Level MEF, ft 3 /kWh WF, gallons/ft 3 baseline ENERGY STAR (effective 2007) 1.72 8.0 1 CEE Tier 3A (January 1, 2004) 1.80 7.5 2 Gap Fill 1 2.00 5.5 3 Gap Fill 2 2.20 5.1 4 Max-Tech 2.35 4.4

5.5 METHODOLOGY OVERVIEW
DOE used data submitted by AHAM as the primary source of cost information for the engineering analysis. AHAM pr ovided DOE with aggregated incremental manufacturing cost data from it member companies. DOE conducte d an independent review of the AHAM data using several methods and data sources. To ga in a better understanding of the data submitted by member companies and to be able to relate th e costs of improving effici ency to discrete (or system) technologies, DOE conducted interviews with manufacturers of residential cooking products and CCWs. For cooking products, DOE re viewed the previous TSDs and compared cost and performance information to the AHAM data and other published data. For microwave ovens, DOE performed detailed product teardo wns on a sample of product models spanning a range of efficiencies, product features, and stan dby power to generate similar cost-efficiency curves for validation of the AHAM data. Fina lly, DOE conducted detailed efficiency and standby power testing of microwave ovens to gain insight into the adequacy of the existing DOE

5-13test procedure, potential test procedure updates to incorporate the measurement of standby power, and the development and validation of cost -efficiency curves based on energy factor and standby power. Table 5.5.1 below shows whic h methods DOE used for each product.
Table 5.5.1 Engineering Analysis Methods

Method Products Cooking Products Commercial Clothes Washers AHAM Data √ √ Review of Past TSD √ √ Product Teardown √ 1 √ 2 Product Testing √ 1 Manufacturer Interviews √ √

1 Microwave ovens only 2 Limited reverse-engineering

5.5.1 AHAM Data Request
In support of this rulemaking effort, DOE requested incremental cost data from AHAM for each of the product categories. The data repr esent the average incremental production cost to improve a baseline unit to a specified effici ency level. This methodology constitutes an efficiency-level approach to the engineeri ng analysis because DOE examined aggregated incremental increases in manufacturer selling pric e at specified levels of energy efficiency. In addition, DOE requested shipments, shipment-wei ghted average efficiency, and market share efficiency data. Tables of aggregated da ta provided to DOE by AHAM are contained in appendix 5A.

5.5.2 Manufacturer Interviews
AHAM provided to DOE shipment-weighted ma nufacturer costs. These costs included the shipment-weighted average cost as well as the lowest and highest single-manufacturer cost to achieve efficiency levels above the baseline level. Presenting the data in this manner enables stakeholders to appreciate the variability in baseline units, design strategies, and cost structures that exist among manufac turers. To better understand and ex plain the causes of these cost variances, DOE supplemented th ese cost data with inform ation obtained through follow-up manufacturer interviews. These confidential interviews provide d a deeper understanding of the various combinations of technologies used to in crease product efficienc y, and their associated manufacturing costs. Sample questions asked during the follow-up interviews, which were also conducted in support of the manufacturer impact analysis, are contained in appendix 13B.
During the interviews, DOE also gathered information about the capital expenditures required to increase the efficiency of the ba seline units to various efficiency levels ( i.e. , conversion capital expenditures by efficiency or energy-use level). The interviews provided

5-14information about the size and the nature of the capital investments. DOE also requested information about the depreciation method used to expense the conversion capital.

5.5.3 Product Teardowns
Other than obtaining detailed manufacturing co sts directly from a ma nufacturer, the most accurate method for determining the production cost of a piece of equipmen t is to disassemble the equipment piece-by-piece and estimate the materi al and labor cost of each component using a process commonly called a physical teardown. A supplementary method, called a catalog teardown, uses published manufactur er catalogs and supplementary component data to estimate the major physical differences between a piec e of equipment that has been physically disassembled and another piece of similar equi pment. DOE only performed physical teardown analysis on microwave ovens. The teardown me thodology is described in detail in section 5.5.3.1 through section 5.5.3.3.

5.5.3.1 Selection of Units
During the process of selecting units for t eardown, DOE considers three main questions:

 What efficiency and/or standby power levels should be captured in the teardown analysis?

 Are there units on the market th at capture all potential efficien cy and/or standby power levels and design options?

 Which of the available units are most representative?
In responding to the preceding questions, DOE adopts the following criteria for selecting units for the t eardown analysis:

 The selected products should span the full rang e of efficiency and/or standby power levels for each product class under consideration;

 Within each product class, if possible, the se lected products should come from the same manufacturer and be within the same product series;

 The selected products should prim arily come from manufacturers with large market share in that product class, although the highest effici ency products were chosen irrespective of manufacturer; and

 The selected products should have non-efficiency and/or non-standby power-related features that are the same as, or similar to, features of other products in the same class and at the same efficiency level and/or standby power level.

5.5.3.2 Generation of Bill of Materials
The end result of each teardown is typically a structured bill of ma terials (BOM). The process is discussed here in the context of the general methodology used for teardown analysis, although it should be noted a more limited approach was used for microwave ovens due to the substantial uniformity in design and construc tion among the sample units. Structured BOMs

5-15describe each equipment part and its relationship to the other part s, in the estimated order of assembly. The BOMs describe each fabrication a nd assembly operation in detail, including the type of equipment needed ( e.g. , stamping presses, injection molding machines, spot-welders, etc.) and the process cycle times. The result is a thorough and explicit model of the production process. The BOMs incorporate all materials, components, and fasteners, classi fied as either raw materials or purchased parts and assemblies. Th e classification into raw materials or purchased parts is based on DOE’s previous industry expe rience, recent informati on in trade publications, and discussions with high- and low-volume original equipment manufacturers (OEMs).
For purchased parts, the purchase price is an estimate based on volume-variable price quotations and detailed disc ussions with suppliers. For fabricated parts, the price of intermediate materials ( e.g. , tube, sheet metal) and the cost of transforming them into finished parts are an estimate based on current industry pricing.

The cost of raw materials is determined usi ng prices for copper, steel and aluminum from the American Metals Market. 2 The price of steel drastically increased in 2005, and the price of copper has increased steadily since 2004. Because DOE is using a 5-year average in material prices from 2002–2006, these price increases are nor malized, which better represents long-term material prices.

5.5.3.3 Cost Structure of the Spreadsheet Models
The manufacturing cost assessment methodology used is a detailed, component-focused technique for rigorously calculati ng the manufacturing cost of a pr oduct (direct materials, direct labor and some overhead costs.) Figure 5.5.1 shows the three major steps in generating the manufacturing cost.

Figure 5.5.1 Manufacturing Cost Assessment Stages
The first step in the manufacturing cost a ssessment is the creation of a complete and structured BOM from the disassembly of the units selected for teardown. The units are dismantled, and each part is characterized acco rding to weight, manufacturing processes used, dimensions, material, and quantity. The BOM in corporates all materials, components, and fasteners with estimates of raw material costs and purchased part costs. Assumptions on the sourcing of parts and in-house fa brication are based on industry experience, information in trade

5-16publications, and discussions with manufacturers. Interviews and plant visits are also conducted with manufacturers to ensure accuracy on methodology and pricing.
Following the development of a detailed BOM, the major manufacturing processes are identified and developed for the spreadsheet m odel. These processes are listed in Table 5.5.2.
Table 5.5.2 Major Manufacturing Processes

Fabrication Finishing Assembly/Joining Quality Control Fixturing Washing Adhesive Bonding Inspecting & Testing Stamping/Pressing Powder Coating Spot Welding Brake Forming De-burring Seam Welding Cutting and Shearing Polishing Insulating
Fabrication process cycle times are estimated and entered into the BOM. For this analysis, $24.00 per hour was used as the average fully-burdened labor rate based on typical annual wages and benefits of industry employees. In the final step of the cost assessment, assembly times and associated direct labor costs are estimated. Once the cost estimate for each teardown unit is finalized, a detailed summary is prepared for relevant components, subassemblies and processes. The BOM thus details all aspects of unit costs.
Design options used in units subject to tear down are noted in the summary sheet of each cost model and are cost-estimated individually. Thus, various implementations of design options can be accommodated, ranging from assemblies that ar e entirely purchased to units that are made entirely from raw materials. Hybrid assemblies, consisting of purchased parts and parts made on site are thus also accommodated.

5.5.4 Review of Previous Technical Support Documents
DOE reviewed previous rulemaking TSDs to assess their applicability to the current standard setting process for c ooking products and CCWs. These previous rulemaking technical support documents served as a source for design options, baseline efficiency levels, and energy consumption analysis, in addition to other so urces. DOE utilized the 1996 cooking products TSD as a source for baseline unit efficiency as well as design options and incremental cost and efficiency data. This approach for cooking products was endorsed by stakeholders. DOE also reviewed the 2000 residential clot hes washer TSD since residential and CCWs share the same design options, are frequently built on the same chassis, and are therefore subject to similar economic impacts.

5.5.5 Product Testing
DOE conducted product testing on microwave ovens to develop a better understanding of the potential efficiency and standby power improvements associated with various design options.

5-175.6 ANALYSIS AND RESULTS

5.6.1 Cooking Products

5.6.1.1 AHAM Data
Conventional Cooking Products
AHAM did not provide DOE with cost-efficiency data for conventional cooking products ( i.e. , cooking products other than microwave ovens), in part because it stated that its members indicated that there have been no technology breakthroughs since the last rulemaking and that its members were not able to adequately assess many of the design options. In concurrence with stakeholders, DOE believes that the efficiency ch aracteristics of gas and electric cooktops and ovens from the 1996 TSD are still valid. Theref ore, the efficiency data provided in the 1996 TSD are also presumed to still be valid. Furthe rmore, DOE believes that the cost of the design options investigated in the 1996 TSD are also va lid once adjusted to reflect changes in the producer price index (PPI). The data from the 1996 TSD are detailed in section 5.6.1.2.

Microwave Ovens

In contrast to conventional cooking products, microwave ovens were presumed to have incorporated improved technology since 1996. Th erefore, AHAM provided data on microwave oven efficiency and microwave standby power fo r a sample of microwave ovens currently available in the U.S. market. 3 Microwave oven efficiency was tested according to DOE’s test procedure, which utilizes th e International Electrotechnica l Commission (IEC) Standard 705­ 1988 and Amendment 2-1993, Methods for measuring the performance of microwave ovens for household and similar purposes . Standby power was tested in accordance with IEC Standard 62301-2005, Household electrical appliances – Measurement of standby power

. The microwave oven test procedure specifi ed in IEC Standard 705-1998 and Amendment 2-1993 calls for heating a glass container contai ning one liter of water at full power until the water temperature is raised by a specified am ount. The starting temperature of the water T 1 in degrees Celsius ( ° C) is given as:

T 1 = T 0 – (10 ± 1 ° C) where,

T 0 = the ambient temperature, specified as 20 ± 2 ° C
The water is heated by the operation of the microwave oven until the final water temperature T 2 in ° C is:

T 2 = T 0 ± 1 ° C
The microwave power output P in W is then calculated from:

5-18P = (4.187 m w (T 2 – T 1 ) + 0.88 m c (T 2 – T 0 ))/t where,

m w = the mass of the water in grams (g)

m c = the mass of the container in g t = the heating time in seconds (s)
The time to heat the water load, power input P IN in W, and the total energy consumption E M in watt-hours (Wh) of the microwave oven during the test period are also recorded. This test is repeated three times, unless the power output value resulting from the second test is within 1.5 percent of the value obtained from the first test. The two or three values of P are averaged for further calculations.
Cooking efficiency Eff MO is then obtained using:

Eff MO = P/P IN For the remainder of the calculations, the te st procedure specified in 10 CFR 430 subpart B appendix I is utilized. Note th at in the following calculations, all temperatures are expressed in degrees Fahrenheit. The mi crowave oven test energy output E T in Wh (kilo-joules (kJ)) b is calculated as:

E T = C P M W (T 2 – T 1 ) + C C M C (T 2 – T 0 ))/K e where,

M W = the measured mass of the test water load in pounds (lb), (g) M C = the measured mass of the test container before filling with test water load in lb (g) T 1 = the initial test water load temperature in ° F ( ° C) T 2 = the final test water load temperature in ° F ( ° C) T 0 = the measured ambient room temperature in ° F ( ° C) C C = 0.210 British thermal units (BTU)/lb- ° F (0.88 kJ/kilogram (kg)- ° C), specific heat of the test container C P = 1.0 BTU/lb- ° F (4.187 kJ/kg- ° C), specific heat of water K e = 3,412 BTU/kWh (3,600 kJ/kWh), conve rsion factor of kWh to BTU.
The two or three values for test energy output are averaged and the microwave oven annual energy consumption E MO is calculated in kWh per year from:

E MO = (E M x O M )/E T where,

E M = the test energy consumption in Wh (kJ)

b Note that in order to correctly utilize the equation as specified in the test procedure to produce either watt-hours for standard units or kJ for metric units, additional factors must be applied. For standard units, E T must be multiplied by 1000. For metric units, E T must be divided by 3600.

5-19O M = 79.8 kWh (287,280 kJ) per year, the microw ave oven annual useful cooking-energy output Finally, the microwave oven energy factor R MO (equivalent to EF) is calculated from:

R MO = O M /E MO EF is the metric for microwave ovens on which the DOE efficiency standard is based, while AHAM provided test data in terms of cooking efficiency in their data submittal for this rulemaking. From the above equations, it can be observed that there ar e several contributing factors that can lead to significant test-to-test variations in measured EF and efficiency. First, the tolerances on the temperature specifications are s ubstantial relative to the absolute values. The range of allowable temperatures for ambient, starting, and final temperatures can lead to acceptable test load temperature rises ranging from 4–16 ° C. Since the heating time is on the order of only a few tens of seconds, power and energy output calculations are difficult to measure consistently test-to-test. In addition, the efficiency calc ulation assumes that input power is constant for the duration of the test, which may not be the case. These factors make the existing test procedure diffi cult to conduct with accuracy and repeatability.
In the recent testing for this analysis, although AHAM only tested 21 units from 9 manufacturers, the units were se lected to represent a broad spect rum of models available in the marketplace with varying capaci ties and features. Figure 5.6. 1 through Figure 5.6.3 display the AHAM microwave oven efficien cy and standby power data.

65%

60%Efficiency

55%

50%

Figure 5.6.1 AHAM Microwave Oven Effi ciency versus Rated Output Power 4

5-20 600 700 800 900 1000 1100 1200 1300 1400 Rated Output Power (W)Figure 5.6.1 illustrates a small variation in e fficiency across all rated output powers, approximately ±3.5 absolute percentage points from the average efficiency. There is a lack of a correlation between microwave oven rated output power and microwave oven efficiency. Figure 5.6.2 illustrates the relationship between micr owave oven efficiency and microwave oven volume. Similarly, there is no correlation be tween microwave oven efficiency and volume. Figure 5.6.1 and Figure 5.6.2 confirm DOE’s appro ach of creating a single product class for microwave ovens irrespective of rated output power or cavity volum e, and demonstrate that there is no basis to specify an efficiency standard th at is a function of eith er rated output power or cavity volume.

50% 55% 60% 65%Efficiency

0.0 0.5 1.0 1.5 2.0 2.5 Microwave Oven Volume (ft^3) Figure 5.6.2 AHAM Microwave Oven Effi ciency versus Oven Cavity Volume 5

Figure 5.6.3 displays AHAM-measured micr owave oven standby power data as a function of rated output power. Unlike efficiency, these data show a wide range of standby power, but there is no correlation between standby power and output power. Standby power ranged from 1.5 to 5.8 W, with 9 of the 21 microwave ovens meeting the FEMP recommendation of 2.0 W or less. The aver age standby power measured was 2.9 W. AHAM did not provide any information with which DOE could correlate st andby power with other features such as cooking sensors or displays.
DOE notes that microwave oven standby power consumption is impacted significantly by the digital clock display, with mo re complex graphical displays drawing more power. According to AHAM, the three major types of displays us ed in microwave ovens are (1) light emitting

5-21diode (LED) displays, (2) vacuum fluorescent di splays (VFDs), and (3) liquid crystal displays (LCDs). Typically, LCDs without back-lighting use the least am ount of energy while VFDs use the most. Energy consumed by LCDs would depend on whether back-lighting is present or not, and if present, the number of LEDs used for ba ck-lighting. For LED di splays, the number of segments, color, and operating temperature aff ect energy consumption. The size of the display (number of digits and icons) al so affects the energy consumed by the display. For VFDs, the size of the display is a major factor in energy consumption. 6 Standby power consumption may also be affected by the electroni c controls required for features such as cooking sensors, along with associated power supplies.

0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0Standby Power (W)

600 700 800 900 1000 1100 1200 1300 1400 Rated Output Power (W)
Figure 5.6.3 AHAM Microwave Oven Standby Power 7
Table 5.6.1 compares the AHAM-measured microwave oven standby power data with data from other studies that have examined st andby power in the United States and Canada. It can be seen that average standby power has re mained relatively constant since 1997 even though minimum and maximum levels ha ve varied by a greater amount.

5-22Table 5.6.1 Microwave Oven Standby Power Comparison Microwave Oven Standby Power

Source Min (W) Average (W) Max (W) Std Dev (W) # Samples AHAM 2006 8 1.5 2.9 5.8 0.8 21 CBEEDAC 2006 9 0.4 1.9 3.3 0.8 19 CREEDAC 2001 (New Stock) 10 0.8 3.8 12.6

- 4 CREEDAC 2001 (Existing Stock) 11 0.0 2.1 7.3

- 64 LBNL 1999 12 0.0 2.9 6.0

- 42 Florida Solar Energy Center 1998 13

- 3.0

- - 25 LBNL 1997 14

- 3.1

- - - Although the DOE test procedure currently does not measure standby power, it is recognized that annual energy consumption can be significantly affected by standby power in real-world usage. For example, a 1-W increas e in standby power corresp onds to an increase of 8.76 kWh in annual energy consumption. The microwave oven test procedure assumes an annual useful cooking energy output (O M ) of 79.8 kWh. For a baseline microwave oven that operates at 55.7 percent efficiency (E T /E M ), annual energy consumption (E MO ) not including standby power would be:

E MO = O M /(E T /E M ) = 143.3 kWh
Therefore each W of standby power included in the annual energy consumption metric would increase it by 6 percent for a baseline microwave oven. Since the highest measured standby power was 5.8 W, the increment of 3.8 W over the FEMP-recommended level of 2.0 W would represent a 23 percent increase in annua l energy consumption for a baseline microwave oven. Since the annual energy consumption of a mo re efficient unit will be lower, the standby power will have an even greater relative cont ribution for high efficiency microwave ovens.

5.6.1.2 Review of Past TSDs
After consulting with AHAM and various st akeholders and suppliers, DOE determined that the design options for cooking products other than microwaves have not changed significantly since the 19 96 TSD analysis. Also, no industry-a ggregated manufacturing cost data were supplied to DOE in the ANOPR phase of th is rulemaking. Therefore, DOE decided to update the 1996 TSD analysis using the PPI to sc ale incremental manufacturing cost data for gas and electric cooktops, and gas a nd electric standard and self-cl eaning ovens. For gas cooktops and ovens, the PPI for gas household cooking equi pment was utilized. Similarly, the PPI for electric household cooking equipment was us ed for electric cooktops and ovens.
Comparison of current microwave oven effici ency data with analogous data from the 1996 TSD shows that the range of efficiency leve ls based on EF analyzed in the 1996 TSD are still valid, although AHAM indicated in comments pr ovided along with its data submittal for this

5-23rulemaking that certain design options used to achieve those levels have already been optimized. 15 But as noted in section 5.4.2, the range of efficiency levels from the 1996 TSD is still representative of the perf ormance of current microwave ove n models. Therefore, for the purposes of this analysis, the same efficiency le vels are used. As with the conventional cooking products, the incremental manufacturing cost data from the 1996 TSD was scaled by the PPI forelectric household cooking equipment, which includes microwave ovens, to obtain the costefficiency relationship. Micr owave oven standby power was not analyzed in the 1996 TSD.
Cooktop Test Procedure
DOE’s cooktop test procedure is based on meas uring the amount of energy required to raise an aluminum block test load from room te mperature to a specified temperature above room temperature at full input heating rate, then operating the burner or element a fixed time longer at a reduced input heating rate. The size of the test block depends on the burner or element size, and the test is repeated for each burner or element. Annual energy consumption is calculated from the average cooking efficiency of the burners or elem ents. Cooktops are rated using EF, which is the ratio of the annual useful cooking-energy outpu t of the cooktop to its total annual energy consumption. The annual energy consumption incl udes the energy input during the time the load is being heated, plus the en ergy consumed by any standing pilot during standby hours for a gas cooktop. Therefore, design options that raise the cooking efficien cy of a gas or electric cooktop and/or reduce the energy consumption of a pilo t on a gas cooktop can decrease the total annual energy consumption and therefore improve EF.
Gas Cooktops
Table 5.6.2 describes the design options and de sign option combinati ons that result in increased EF of gas cooktops. The design options and efficiency levels analyzed are those presented in the 1996 engineering analysis, with several design options (reflective surfaces and thermostatically controlled burne rs) eliminated in this analys is as described in section 5.4.2.
Table 5.6.2 Gas Cooktop Manufacturing Cost and Efficiency Increments

Level Efficiency Level Description Cooking Efficiency EF Delta Manufacturer Cost from Baseline (2006$) Baseline Baseline 39.9% 0.156

- 1 Baseline + Electronic Ignition 39.9% 0.399 $12.06 2 1 + Sealed Burners 41.8% 0.420 $32.06
Notes: Baseline: Cooktop cooking efficiency = 39.9%, four conventional 9,000 BTU/hr burners, two 117 BTU/hr standing pilot lights (1) Electronic Ignition: Standing pilot lights eliminated, cooking efficiency increase = 0.0% (2) Sealed Burners: Cooking efficiency increase = 4.8% (relative percent) Electric Coil Cooktops

5-24Table 5.6.3 describes the design option that results in incr eased cooking efficiency of electric open (coil) cooktops. The design optio n and efficiency levels analyzed are those presented in the 1996 engineering analysis, wi th one design option (r eflective surfaces) eliminated in this analysis as described in section 5.4.2.
Table 5.6.3 Electric Coil Cooktop Manufactu ring Cost and Efficiency Increments

Level Efficiency Level Description Cooking Efficiency EF Delta Manufacturer Cost from Baseline (2006$) Baseline Baseline 73.7% 0.737

- 1 Baseline + Improved Contact Conductance 76.9% 0.769 $2.28

Notes: Baseline: Cooktop cooking efficiency = 73.7%, two 6-inch 1,250 W and two 8-inch 2,100 W elements (1) Improved Contact Conductance: Cooking e fficiency increase = 4.3% (relative percent) Electric Smooth Cooktops
Table 5.6.4 describes the design options that result in increased cooking efficiency of electric smooth cooktops. The design options an d efficiency levels anal yzed are those presented in the 1996 engineering analysis, wi th one design option (induction element) eliminated in this analysis as described in section 5.4.2. Another design option (radiant element) discussed in the 1996 engineering analysis was not included in this analysis because it exhibited a lower efficiency than the baseline cooktop.
Table 5.6.4 Electric Smooth Cooktop Manufacturing Cost and Efficiency Increments

Level Efficiency Level Description Cooking Efficiency EF Delta Manufacturer Cost from Baseline (2006$) Baseline Baseline 74.2% 0.742

- 1 Baseline + Halogen Lamp Element 75.3% 0.753 $89.09

Notes: Baseline: Cooktop cooking efficiency = 74.2%, two 6-inch 1,500 W and two 8-inch 2,000 W solid disk elements (1) Halogen Element: Cooking efficiency increase = 1.5% (relative percent), two small 1,200 W and two large 1,800 W circular lamps

Conventional Oven Test Procedure
DOE’s oven test procedure is based on meas uring the amount of energy required to raise an aluminum block test load from room temp erature to a specified temperature above room temperature. Ovens are rated using EF, which is the ratio of the annual useful cooking-energy output of the oven (energy conveyed to the item being heated) to its total annual energy consumption. The annual energy consumption incl udes the energy input during the time the load is being heated plus the energy consumed by ot her features such as a clock, standing pilot, electronic ignition system, and/or self-cleaning cycles. Theref ore, design options that raise the

5-25cooking efficiency of the oven and/or reduce the energy consumption of features not related to heating food can decrease the total annual energy consumpti on and therefore improve EF.

Gas Ovens
Table 5.6.5 describes the design options and de sign option combinati ons that result in increased EF of gas standard ovens. The design op tions and efficiency levels analyzed are those presented in the 1996 engineering analysis, with one design option (o ven separator) eliminated in this analysis as de scribed in section 5.4.2.
Table 5.6.5 Gas Standard Oven Manufacturing Cost and Efficiency Increments

Level Efficiency Level Description Cooking Efficiency EF Delta Manufacturer Cost from Baseline (2006$) Baseline Baseline 5.9% 0.0298

- 1 Baseline + Electric Glo-bar Ignition 5.8% 0.0536 $12.06

2 1 + Improved Insulation 6.1% 0.0566 $15.64 3 2 + Improved Door Seals 6.2% 0.0572 $16.72 4 3 + Forced Convection 6.5% 0.0593 $38.86 5 4 + Reduced Vent Rate 6.5% 0.0596 $40.48 6 5+ Reduced Conduction Losses 6.6% 0.0600 $44.11

1a Baseline + Electronic Spark Ignition 5.8% 0.0583 $15.00

Notes: Baseline: Cooking efficiency = 5.92%, 2 inches of 1.09 lb/cubic foot insulation, standing pilot light ignition = 175 BTU/hr (1) Baseline + Electric Glo-Bar Ignition: Cooking efficiency decrease = 0.152 (absolute percentage points), added electricity consumption = 176 Wh (2) 1 + Improved Insulation: Cooking effici ency increase = 4.9% (relative percent) (3) 2 + Improved Door Seals: Cooking effici ency increase = 1.0% (relative percent) (4) 3 + Forced Convection: Cooking e fficiency increase = 4.8% (relative pe rcent), added electricity consumption = 15 Wh (5) 4 + Reduced Vent Rate: Cooking effici ency increase = 0.5% (relative percent) (6) 5 + Reduced Conduction Losses: Cooking efficiency increase = 0.05 (absolute percentage points) (1a) Baseline + Electronic Spark Ignition: Cooking efficiency decrease = 0.09 (absolute percentage points), added electricity consumption = 0.0 Wh. Standard levels 1 and 1a correspond to designs that are utilized for the same purpose--eliminate the need for a standing pilot--but the technolo gies for each design are different. Standard level 1 is a hot surfa ce ignition device while standard level 1a is a spark ignition device Table 5.6.6 describes the design options and design option combinati ons that result in increased EF of gas self-cleaning ovens. The de sign options and efficiency levels analyzed are those presented in the 1996 engineering anal ysis, with one design option (oven separator) eliminated in this analysis as described in section 5.4.2.

5-26Table 5.6.6 Gas Self-Cleaning Oven Manufacturing Cost and Efficiency Increments

Level Efficiency Level Description Cooking Efficiency EF Delta Manufacturer Cost from Baseline (2006$) Baseline Baseline 7.1% 0.0540

- 1 Baseline + Forced Convection 8.8% 0.0625 $11.01 2 1 + Reduced Conduction Losses 8.8% 0.0627 $15.38 3 2 + Improved Door Seals 8.9% 0.0632 $16.60
Notes: Baseline: Cooking efficiency = 7.13%, clock power = 3.6 W, 2 inches of 1.90lb/cubic foot insulation, electronic ignition = 176 Wh, self-cleaning energy consumption = 43,158 BTU (1) Baseline + Forced Convection: C ooking efficiency increase = 23% (rel ative percent), added electricity consumption (during cooking and cleaning cycles) = 15 Wh (2) 1 + Reduced Conduction Losses: Cooking efficiency increase = 0.05 (absolute percentage points) (3) 2 + Improved Door Seals: Cooking effici ency increase = 1.0% (relative percent)

Electric Ovens
Table 5.6.7 describes the design options and de sign option combinati ons that result in increased EF of electric standard ovens. The de sign options and efficiency levels analyzed are those presented in the 1996 engi neering analysis, with several design options (bi-radiant oven and oven separator) eliminated in this analysis as descri bed in section 5.4.2.

Table 5.6.7 Electric Standard Oven Manufactu ring Cost and Efficiency Increments

Level Efficiency Level Description Cooking Efficiency EF Delta Manufacturer Cost from Baseline, (2006$) Baseline Baseline 12.2% 0.1066

- 1 Baseline + Reduced Vent Rate 12.8% 0.1113 $1.63 2 1 + Improved Insulation 13.4% 0.1163 $4.84 3 2 + Improved Door Seals 13.7% 0.1181 $8.53 4 3 + Forced Convection 14.0% 0.1206 $48.14 5 4 + Reduced Conduction Losses 14.1% 0.1209 $51.69
Notes: Baseline: Cooking efficiency = 12.15%, clock power = 3.9 W, 2 inches of 1.09 lb/cubic foot insulation (1) Baseline + Reduced Vent Rate: Cooking efficiency increase = 0.62% (absolute percentage points) (2) 1 + Improved Insulation: Cooking efficiency increase = 0.52% (relative percent) (3) 2 + Improved Door Seals: Cooking efficiency increase = 0.24 (absolute percentage points) (4) 3 + Forced Convection: Cooking e fficiency increase = 0.33 (absolute pe rcentage points), added electricity consumption = 15 Wh (5) 4 + Reduced Conduction Losses: Cooking efficiency increase = 0.05 (absolute percentage points) Table 5.6.8 describes the design options and de sign option combinati ons that result in increased EF of electric self-cleaning ovens. Th e design options and efficiency levels analyzed

5-27are those presented in the 1996 e ngineering analysis, with severa l design options (bi-radiant oven and oven separator) eliminated in this analysis as descri bed in section 5.4.2.
Table 5.6.8 Electric Self-Cleaning Oven Manufac turing Cost and Efficiency Increments

Level Efficiency Level Description Cooking Efficiency EF Delta Manufacturer Cost from Baseline, (2006$) Baseline Baseline 13.8% 0.1099

- 1 Baseline + Reduced Conduction Losses 13.8% 0.1102 $4.37

2 1 + Forced Convection 14.2% 0.1123 $43.98
Notes:Baseline: Cooking efficiency = 13.79%, clock power = 3.8 W, 2 inches of 1.09 lb/cubic foot insulation, selfcleaning energy consumption = 5,286 Wh (1) Baseline + Reduced Conduction Losses: Cooking effici ency increase = 0.05 (absolute percentage points) (2) 1 + Forced Convection: Cooking e fficiency increase = 0.33 (absolute pe rcentage points), added electricity consumption = 15 Wh Conventional Oven Energy Use versus Volume
The oven cost-efficiency relati onships detailed above are pr edicated upon baseline ovens with a cavity volume of 3.9 ft 3 . It is well documented, however, th at efficiency scales with oven cavity volume. This variation between efficiency, and thus EF , and oven volume results from the fact that larger ovens have higher thermal masses and larger vent rates than smaller ovens. Since the test procedure for establishing EF is a tr ansient test with a fixed test load, the increased energy consumption due to the increased mass of larger units yields a lower EF. The 1980 DOE engineering analysis for residential appliances 16 established a relationship between oven volume and EF from data compiled by the National Bureau of Standards (which was renamed to the National Institute of Standards and Technology (NIST)). Using these data, linear equations were derived for both electric and gas ovens. No dist inction was found to exist between standard and self-cleaning ovens for either gas or electric ovens. Intercepts fo r a particular baseline model or oven design were chosen so that the equations pass through the desired EF corresponding to a particular volume. Values from the 1996 TSD for the slopes and intercepts for gas and electric ovens are listed in Table 5.6.9. The 1996 TSD did not analyze data at every efficiency level, and higher efficiency levels are not included in because certain design options have been eliminated in the current analysis. DOE believes the slopes and intercep ts of these equations from the 1996 TSD to still be valid.

5-28Table 5.6.9 Slopes and Intercepts for Oven Energy Factor versus Cavity Volume Relationship Energy Efficiency Electric Gas Slope = -0.0157 Slope = -0.0073 Level Standard Self-Clean Standard Self-Clean Baseline

- 0.1632 0.0865 0.0865 1 0.1752

- 0.0895

- 2 0.1802

- - - 3 0.1822

- 0.0935

- Note: EF = (Slope x Volume) + Intercept where Volume is expressed in cubic feet.
Conventional Oven Standby Power
In the ANOPR, DOE stated it would consider additional design optio ns that would result in a lowering of the energy consumption of non-cooking features ( e.g. standby power) for conventional ovens during the NOPR phase. Howe ver, no data were received on standby power for any of these products, so no a dditional analysis was performed.

Microwave Ovens
Table 5.6.10 describes the design options a nd design option combina tions that result in increased EF of microwave ovens. The design opti ons and efficiency levels analyzed are those presented in the 1996 engineering analysis, with incremental manu facturing costs scaled by the PPI for electric household cooking equipment. For the NOPR, DOE sought input from stakeholders on the approach of analyzing a dditional design options th at would result in a lowering of the energy consump tion of non-cooking features ( e.g. standby power), even though the test procedure currently does not account for such usage in EF. DOE is separately considering an updated test procedure to inco rporate a measurement of standby and off mode power, and section 5.6.1.3 discusses the testing and analysis that DOE conducted to characterize the design options associated wi th reductions in standby power.

5-29Table 5.6.10 Microwave Oven Manufacturing Cost and Efficiency Increments

Level Efficiency Level Description Cooking Efficiency EF Delta Manufacturer Cost from Baseline (2006$) Baseline Baseline 55.7% 0.557

- 1 Baseline + More Efficient Power Supply 58.6% 0.586 $8.68

2 1 + More Efficient Fan 58.8% 0.588 $17.95 3 2 + More Efficient Magnetron 59.7% 0.597 $32.53 4 3 + Reflective Surfaces 60.2% 0.602 $51.11
Notes: Baseline: Cooking efficiency = 55.7% (1) Efficient Power Supply: Cooking efficiency increase = 2.9 (absolute percentage points) (2) Efficient Fan: Cooking efficiency increase = 0.23 (absolute percentage points) (3) Efficient Magnetron: Cooking efficiency increase = 0.90 (absolute percentage points) (4) Reflective Surfaces: Cooking efficiency in crease = 0.50 (absolute percentage points)

5.6.1.3 Product Testing and Teardowns
Microwave Oven Efficiency
DOE conducted product testing and tear down analysis for microwave ovens to supplement AHAM-supplied data, to validate th e approach of updating the 1996 TSD analysis, and to examine the microwave oven test procedur e for potential updates. In order to identify design options, circuit designs, a nd display options, DOE disassembled a representative sample of 32 units to gain an in-depth understandi ng of common microwave oven design elements, components, and manufacturing practices. DOE also evaluated the IEC microwave oven test standard which is referenced by the current DOE test procedure (IEC Standard 705) in comparison to the current IEC test standard (IEC Standard 60705-2006, Household microwave ovens – Methods for measuring performance (IEC Standard 60705).)

Test Units
DOE conducted a market survey of microwave oven models and their associated features to identify the primary differentiators among comme rcially-available units, and to then select a representative range of test units which incorporate these features. DOE selected 32 microwave ovens based on parameters that could be identifi ed from product literature . These included: 1) rated output power in W; 2) rated cavity volume in ft 3 ; 3) display type; 4) the presence or absence of a cooking sensor; and 5) magnetron pow er supply technology. For the latter, certain models were advertised as incorporating “invert er technology” that allows variable power output for different user-selectable cooking -level settings. The key parameters for each of the test units are presented in Table 5.6.11 thr ough Table 5.6.14. In some cases, several units were selected from a single manufacturer that appeared to have similar construction, rated power, and volume,

5-30but differed in ancillary features such as the type of display or the presence of a cooking sensor. Such similarities are noted in the tables. Nome nclature for the display entries are described in the following paragraphs.
Table 5.6.11 Microwave Oven Features (Table 1 of 4) DOE Unit Number DOE1 DOE2 DOE3 DOE4 DOE5 DOE6 DOE7 DOE8 Rated Output Power (W) 700 700 700 700 800 800 800 800 Stated Volume (ft 3 ) 0.7 0.7 0.7 0.7 1 1 0.8 0.8 Cooking Sensor

- - - - Y

- - - Inverter Power Supply

- - - - - - - - Type LED LED LED LED VFD LED LCD LCD Charactersay #, 1 x 4 #, 1 x 4 #, 1 x 4 #, 1 x 4 A, 1 x 7 #, 1 x 4 #, 1 x 4 #, 1 x 4 # of LEDs for backlightingDispl N/A N/A N/A N/A N/A N/A None None
Size 1.50" x 0.43" 1.50" x 0.43" 1.45" x 0.70" 1.90" x 0.83" 2.25" x 0.75" 1.50" x 0.80" 1.87" x 0.83" 1.87" x 0.83" Unit is Similar to

- - - - - DOE5

- - Table 5.6.12 Microwave Oven Features (Table 2 of 4) DOE Unit Number DOE9 DOE10 DOE11 DOE12 DOE13 DOE14 DOE15 DOE1 6 Rated Output Power (W) 900 1000 1000 1000 1000 1100 1100 1100 Stated Volume (ft 3 ) 0.9 1.1 1.1 1 0 1.1 1.1 1.8 Cooking Sensor

- - - - - - Y Y Inverter Power Supply

- - - - - - - - Type LED LED LED LED VFD LED LCD VFD Characters #, 1 x 4 #, 1 x 4 #, 1 x 4 #, 1 x 4 #, 1 x 4 #, 1 x 4 A, 1 x 6 A, 1 x 7 # of LEDs for backlightingDisplay N/A N/A N/A N/A N/A N/A 5 N/A

Size 2.00" x 0.65" 1.85" x 1.10" 1.75" x 0.85" 1.75" x 0.70" 2.20" x 0.65" 2.00" x 0.65" 2.53" x 0.95" 2.25" x 0.75" Unit is Similar to

- - - - - - DOE14

- Table 5.6.13 Microwave Oven Features (Table 3 of 4) DOE Unit Number DOE17 DOE18 DOE19 DOE20 DOE21 DOE22 DOE23 DOE2 4 Rated Output Power (W) 1100 1100 1100 1100 1100 1100 1150 1200 Stated Volume (ft 3 ) 1 1.4 1 1.3 1.1 1 1.4 2.2 Cooking Sensor

- - - - - - Y Y Inverter Power Supply

- - - - - - - Y Type LCD LCD LCD LED LED LCD VFD LCD Characters #, 1 x 4 A, 1 x 5 #, 1 x 4 #, 1 x 4 #, 1 x 4 #, 1 x 4 A, 1 x 7 A, 1 x 6 # of LEDs for backli g htin gDisplay 3 4 None N/A N/ A 3 N/ A 10
Size 1.83" x 0.80" 2.03" x 0.81" 1.87" x 0.83" 1.50" x 0.80" 1.47" x 0.80" 2.00" x 0.83" 2.25" x 0.75" 2.05" x 1.10" Unit is Similar to

- - DOE17

- - DOE17 DOE16 DOE3 0

5-31Table 5.6.14 Microwave Oven Features (Table 4 of 4) DOE Unit Number DOE25 DOE26 DOE27 DOE28 DOE29 DOE30 DOE31 DOE3 2 Rated Output Power (W) 1200 1200 1200 1200 1200 1250 1300 1300 Stated Volume (ft 3 ) 1.2 2.2 1.2 2 2 2.2 1.2 1.2 Cooking Sensor

- Y Y Y Y Y Y Y Inverter Power Supply

- Y

- - - Y Y Y Type LCD LCD LCD LCD LCD LCD LCD LCD Characters #, 1 x 4 A, 1 x 6 A, 1 x 7 D, 2 x 8 A, 1 x 7 A, 1 x 6 #, 1 x 4 A, 1 x 6 # of LEDs for backlightingDisplay 5 10 4 6 4 4 10 10
Size 1.85" x 0.83" 2.05" x 1.10" 2.03" x 0.78" 2.45" x 1.17" 2.03" x 0.78" 2.05" x 1.10" 1.75" x 0.80" 2.05" x 1.10" Unit is Similar to DOE17 DOE30 DOE25

- - DOE31

- DOE3 1
The range of rated output powers and cavity volumes were determ ined on the basis of manufacturer specifications. Rate d output power, which is a measur e of the power transferred to the food load at the full-scale cooking setti ng, ranged from 700 to 1,300 W. Cavity volumes, which typically roughly scale wi th output power, ranged from rated values of 0.7 to 2.2 ft 3

. Three different display tec hnologies were observed to be incorporated in the sample units: 1) LED; 2) LCD; and 3) VFD. (Details of each technology are di scussed later in this section in the context of standby power.) The display format for each microwave oven was characterized as either numeric (#), alphanumeric (A), or dot matrix (D). Whereas numeric displays can only show time, al phanumeric displays can also di splay letters (though usually in simplified format). Dot matrix displays can show various fonts, letters, and symbols via matrices of pixels, making them the most flexible disp lay technology. Since display power consumption is a function of not only the type of technology used but the overall size and number of digits in the display as well, the dimensions of each disp lay were measured and the number of rows and columns of digits were record ed. Finally, some LCDs use LEDs for backlighting, allowing a microwave oven user to read the disp lay both at night and in daylight.
All 32 microwave ovens in the DOE sample we re subjected to efficiency testing via the current DOE test procedure, which is based by reference on IEC Standard 705, which has been superseded by IEC Standard 60705. c DOE subsequently subjected 12 of the 32 microwave ovens to additional cooking efficiency test ing per IEC Standard 60705 to investigate the differences between the two test standards. DOE conducted additional testing of an inverterbased microwave oven to assess the impact of oper ating such a system at various power levels. Lastly, DOE considered possible improvement opportunities for the current cooking test procedure.

General Construction
All microwave ovens examined by DOE contain a metal cavity that is mechanically attached to the front and rear ch assis frames. Each of these pieces had been formed by stamping, joined, and then the assembly is painted. To this frame, a bottom panel is attached. This bottom

c Current IEC standards may be obtained from www.iec.ch . However, IEC does not make obsolete standards available.

5-32panel covers the turntable moto r and also acts as an electr ical ground for the magnetron power supply and the magnetron. The inner cavity occupies , on average, about 70 percent of the width and height of the microwave oven. The remaining space is used for cooling channels, the magnetron, the magnetron power supply, the cooli ng fan, the microwave oven controller, and other miscellaneous components.

All of the microwave ovens examined have a doo r that is hinged on the left side of the unit. Beneath the right edge of the door, a latch mechanism with three switches ensures that the microwave oven cannot operate its magnetron without the door being closed. To the right of the door, the user interface frame typically features a foil-based button array under a flexible plastic cover, along with the display. The display may be either attached directly to the user interface frame or integrated into the main control boar d for the microwave oven. The main control board typically consists of a single-sided printed circui t board (PCB) which features a small alternating current to direct current (AC- DC) power supply, several relays, and control logic. All power coming into the microwave oven is filtered throu gh a separate power filtration board to which the power cord is attached.

In addition to the aforemen tioned components, baseline microwave ovens contain a magnetron power supply featuring a microwave ove n transformer, a high voltage diode, and a high-voltage aluminum electrolytic capacitor. The user interf ace for these microwave baseline ovens is a simple LCD or LED display. A si ngle-speed fan keeps the magnetron and microwave oven transformer cool during operation, while a turntable may rotate the food load inside the cavity while the microwave oven is operating. A single incandescent light bulb (20 W and higher) typically provides cavity illumination during operation and when the door is open.
More sophisticated microwave ovens may contain cooking sensors, larger and multicolored displays with more complex graphics, an d/or inverter-based magnetron power supplies. Cooking sensors and displays will be discussed in more detail below in sections regarding standby power.

Because the microwave field is not unifor m inside microwave oven cavities (creating “hot” spots), manufacturers have developed various methods to improve cooking uniformity. Within the DOE sample, mode stirrers and turntables for the food were the only methods observed, although DOE is aware of other approaches that could be taken, such as utilizing dual magnetrons and associated wave guides. Mode stir rers temporally change the distribution of the microwave energy delivered to the cavity and thus cause the “hot” spots to move around the cavity. However, only one unit in the DOE sa mple (designated “DOE16”) contains a mode stirrer. Most manufacturers have shifted away from this appro ach in favor of turntables. Turntable motors were observed in all microw ave ovens sampled by DOE. By rotating the food through the “hot” spots, turntables help improve cooking uniformity. Both a turntable and mode stirrer require a motor, as does the blower, whic h provides cooling air to remove the significant heat dissipated by the magne tron and its power supply.
Efficiency Testing Using the Current DOE Test Procedure

5-33DOE conducted efficiency tests on all sa mpled units using the current DOE test procedure, which references IEC Standard 705. As can be seen in Table 5.6.15 through Table 5.6.18, the DOE test results noted similar cooking efficiencies and input and output powers as the results submitted by AHAM, which were presented in section 5.6.1.1.
Table 5.6.15 Microwave Oven Input, Output, and Cooking Efficiency (1 of 4) DOE Unit Number DOE1 DOE2 DOE3 DOE4 DOE5 DOE6 DOE7 DOE8 Stated Volume ( ft 3 ) Measured In p ut Power ( W ) 0.7 1,192.8 0.7 1,129.8 0.7 1,121.9 0.7 996.8 1.0 1,374.6 1.0 1,314.9 0.8 1,356.7 0.8 1,374.0 Rated Output Power (W) Measured Output Power (W) 700.0 686.1 700.0 654.8 700.0 627.0 700.0 593.8 800.0 818.5 800.0 767.6 800.0 781.7 800.0 786.7 Energy Factor 57.5% 58.0% 55.9% 59.6% 59.5% 58.4% 57.6% 57.3%
Table 5.6.16 Microwave Oven Input, Output, and Cooking Efficiency (2 of 4) DOE Unit Number DOE9 DOE10 DOE11 DOE12 DOE13 DOE14 DOE15 DOE16 Stated Volume ( ft 3 ) Measured In p ut Power ( W ) 0.9 1,602.4 1.1 1,769.9 1.1 1,701.8 1.0 1,713.0 0.0 1,736.4 1.1 1,886.2 1.1 1,876.3 1.8 1,566.7 Rated Output Power (W) Measured Output Power (W) 900.0 964.6 1,000.0 1,007.8 1,000.0 1,010.3 1,000.0 1,013.6 1,000.0 1,024.5 1,100.0 1,145.9 1,100.0 1,105.3 1,100.0 949.7 Energy Factor 60.2% 56.9% 59.4% 59.2% 59.0% 60.8% 58.9% 60.6%
Table 5.6.17 Microwave Oven Input, Output, and Cooking Efficiency (3 of 4) DOE Unit Number DOE17 DOE18 DOE19 DOE20 DOE21 DOE22 DOE23 DOE24 Stated Volume ( ft 3 ) Measured In p ut Power ( W ) 1.0 1,829.8 1.4 1,882.2 1.0 1,815.7 1.3 1,774.3 1.1 1,851.8 1.0 1,823.1 1.4 1,626.8 2.2 1,926.2 Rated Output Power (W) Measured Output Power (W) 1,100.0 1,046.7 1,100.0 1,114.0 1,100.0 1,057.3 1,100.0 1,072.5 1,100.0 1,134.0 1,100.0 1,038.2 1,150.0 966.7 1,200.0 1,130.8 Energy Factor 57.2% 59.2% 58.2% 60.4% 61.2% 56.9% 59.4% 58.7%
Table 5.6.18 Microwave Oven Input, Output, and Cooking Efficiency (4 of 4) DOE Unit Number DOE25 DOE26 DOE27 DOE28 DOE29 DOE30 DOE31 DOE32 Stated Volume ( ft 3 ) Measured In p ut Power ( W ) 1.2 1,871.2 2.2 1,925.1 1.2 1,812.7 2.0 1,904.5 2.0 1,904.5 2.2 1,919.8 1.2 1,917.1 1.2 1,928.2 Rated Output Power (W) Measured Output Power (W) 1,200.0 1,147.7 1,200.0 1,116.6 1,200.0 1,114.4 1,200.0 1,149.4 1,200.0 1,137.9 1,250.0 1,105.4 1,300.0 1,121.9 1,300.0 1,119.0 Energy Factor 61.3% 58.0% 61.5% 60.4% 59.7% 57.6% 58.5% 58.0% Both DOE’s and AHAM’s microwave oven samp les contained units with manufacturerrated output powers ranging from 700 to 1,300 W. DOE-tested efficiencies varied from 56 to 61 percent. These measured efficiencies were similar to the results submitted by AHAM to DOE (see section 5.6.1.1), which noted cooking e fficiencies of 55 to 62 percent.

5-3462%

61%

60%

59%

58%

57%

56%

55%

54%

Figure 5.6.4Efficiency (EF) AHAM Standard MOT AHAM Inverter Drive DOE Standard MOT DOE Inverter Drive

600 700 800 900 1,000 1,100 1,200 1,300 Rated Output Power (W)

DOE and AHAM Microwave Oven Efficiency versus Rated Output Power
DOE is unaware of the specific microwave ovens that AHAM tested. However, it is possible to infer some model features on the basi s of identified characteristics, such as rated output power. The models identified in Figure 5. 6.4 as “AHAM Inverter” units were inferred as such because all of the microwave ovens that DOE is aware of on the market that have a rated output power at or in excess of 1,250 W feature an inverter driving the magnetron. DOE was unable to ascertain if any additi onal inverter units at lower out put powers are contained within the AHAM data submittal. DOE noted that none of its microwave ovens with inverter-based magnetron power supplies achieved as high an effi ciency as comparable microwave ovens with standard magnetron power supplies and high out put powers. AHAM commented in its data submittal that inverter-based pow er supplies are 2 percent more efficient than standard power supplies (82 versus 84 percent, respectively). 17 Yet, collectively, the DOE and the inferred AHAM inverter units have lower cooking efficien cies than the highest-e fficiency non-inverter units. Thus, while it is possible that inverter systems are more efficient than the simple microwave oven transformers they can replace, the overall efficiencies of inverter-based microwave ovens on the market do not presen tly demonstrate a corresponding efficiency improvement.
In considering the issue of inverter versus non-inverter power supply efficiencies, DOE observed that besides being much more comple x, the inverter power supplies examined by DOE also feature large aluminum heat sinks and plastic tunnels to direct air flow over key components. The data sheets for th e rectifiers and insulated-gate bipolar transistors used in the inverter power supplies note maximum heat dissipation requirements in excess of 400 W. During its teardown analysis, DOE al so noted that inverter power s upplies in its test sample use 50 percent heavier fan motors, indicating a greater need for heat removal from such systems and

5-35thus implying lower efficiencies, since energy is lost through heat dissipation from the power supply. However, regardless of the type of magn etron power supply used, al most all units in the AHAM and DOE samples meet the baseline effi ciency of 55.7 percent for microwave ovens proposed in section 5.4.1.
DOE then investigated whether there was a correlation betw een microwave oven efficiency and measured output pow er. Typically, rated output pow ers in the test samples were observed to be within 50 W of measured output power, as shown in Table 5.6.19.
Table 5.6.19 Microwave Oven Rated versus Measured Output for AHAM and DOE Tests

Unit # Rated Output

( W ) Measured Output (W) Deviation from Rated Output

DOE4 700 594 -15.2% DOE3 700 627 -10.4% DOE2 700 655 -6.5% AHAM10 700 671 -4.2% DOE1 700 686 -2.0% AHAM11 700 699 -0.1% AHAM1 800 743 -7.1% DOE6 800 768 -4.1% DOE7 800 782 -2.3% DOE8 800 787 -1.7% AHAM16 800 795 -0.7% DOE5 800 818 2.3% DOE9 900 965 7.2% AHAM22 950 907 -4.5% AHAM20 1,000 930 -7.0% AHAM12 1,000 967 -3.3% AHAM4 1,000 971 -2.9% AHAM5 1,000 973 -2.7% AHAM14 1,000 986 -1.4% AHAM19 1,000 999 -0.1% DOE10 1,000 1,008 0.8% DOE11 1,000 1,010 1.0% DOE12 1,000 1,014 1.4% AHAM3 1,000 1,015 1.5% DOE13 1,000 1,025 2.5% AHAM15 1,000 1,028 2.8% Unit # Inverter Rated Output

( W ) Measured Output (W) Deviation from Rated

Out p ut DOE16 1,100 950 -13.7% DOE22 1,100 1,038 -5.6% DOE17 1,100 1,047 -4.8% DOE19 1,100 1,057 -3.9% AHAM21 1,100 1,060 -3.7% DOE20 1,100 1,073 -2.5% DOE15 1,100 1,105 0.5% DOE18 1,100 1,114 1.3% AHAM13 1,100 1,119 1.7% DOE21 1,100 1,134 3.1% DOE14 1,100 1,146 4.2% DOE23 1,150 967 -15.9% DOE27 1,200 1,114 -7.1% DOE26 Y 1,200 1,117 -7.0% DOE24 Y 1,200 1,131 -5.8% DOE29 1,200 1,138 -5.2% AHAM2 1,200 1,145 -4.6% DOE25 1,200 1,148 -4.4% DOE28 1,200 1,149 -4.2% AHAM17 1,200 1,152 -4.0% AHAM6 1,200 1,205 0.4% DOE30 AHAM8 AHAM9 Y Y Y 1,250 1,250 1,250 1,105 1,142 1,166 -11.6% -8.6% -6.7% DOE32 DOE31 AHAM7 Y Y Y 1,300 1,300 1,300 1,119 1,122 1,173 -13.9% -13.7% -9.8% The measured output for the AHAM data av eraged 2.8 percent less than rated output power, with a range in deviation fr om rated output of +3.1 percent to -9.8 percent). Most units had a measured output lower than their rated output. As ment ioned previously, the AHAM data sample did not identify whether an microwav e oven had an inverter power supply for the magnetron. Thus, the presence of an inverter in the AHAM data set is solely inferred by the DOE market survey.
Output power measurements within the DOE sample followed a similar pattern to the data submitted by AHAM, though with a greate r proportion of units having measured output

5-36power below rated output power. The divergen ce ranged from a high of about 7 percent above rated output power to a low of about 16 percen t below rated output power, with the average divergence being about -5 percent. As with the results for ra ted output power shown in Figure 5.6.4, Figure 5.6.5 shows that the DOE efficiency da ta as a function of measured output power exhibits largely similar charac teristics as the AHAM data su bmittal, and neither shows an identifiable correlation.

54% 55% 56% 57% 58% 59% 60% 61% 62%Efficiency (EF) AHAM Standard MOT AHAM Inverter Drive DOE Standard MOT DOE Inverter Drive

600 700 800 900 1,000 1,100 1,200 1,300 Measured Output Power (W)
Figure 5.6.5 DOE and AHAM Microwave Oven Efficiency versus Measured Output Power
The maximum measured output power of approximately 1,200 W represents the practical limit of residential microwave ovens currently on the market, since at even the highest measured efficiency, input power is approaching the amperage limits of residential electrical circuits. For example, the maximum input power measured by DOE in its test sample was approximately 1,925 W, while two microwave ovens in the AHAM data submittal exceeded 2,000 W of input power during cooking efficiency tests. For a standard 120 volts AC (VAC) circuit, these input powers would correspond to 16.0 and 16.7 ampere s (A), respectively. Higher output powers may thus only be achievable with microwave ovens that have even highe r efficiencies or by a transition to 240 VAC circuits for microwav e ovens. Higher input and output powers are common for commercial microwave ovens, but these products require higher line voltages.
Impacts of Design Options on Cooking Efficiency
DOE identified the following design options pr esent in its sample of microwave ovens and observed the following impacts associated with each design option on cooking efficiency:

5-37• Cooking sensors. There was no identifiable relationship between th e absence or presence of a cooking sensor and the measured efficiency. The only clear impact of some cooking sensors was on the standby power consumption.

• Improved fan efficiency. The units subjected to reverse-engineering all appeared to incorporate fans of simila r type and construction, i.e . single-speed shaded-pole-motors (SPMs) with plastic blades and presumably sim ilar efficiency characteristics. Therefore, no impacts could be quantified for the effect of improved fan efficiency on microwave oven efficiency.

• Improved magnetron efficiency. Despite th e range of magnetron manufacturers and models, there was notable consistency of rated magnetron efficiency among the data sheets that DOE was able to ob tain. All data sheets indi cated a conversion efficiency range of 71 to 72 percent. Therefore, no re lationship between microwave oven efficiency and magnetron efficiency could be evaluate d, nor did DOE have a means of evaluating the efficiency of those magnetrons for whic h data sheets were unavailable, since the magnetrons could not be tested by DOE in isolation.

• Improved microwave oven transformer power supply efficiency. Among the units torn down, only the inverter-type microwave ovens had an identifiably different efficiency performance characteristic th an the microwave ovens with standard power supplies, and the data indicate that overall efficiency is not improved by inverter power supplies. All standard microwave oven transformers appear to be similar in construction and, hence, no data was available to evaluate the effect of incremental improvements in conventional microwave oven transformers. Furthermore, DOE did not have the means of evaluating the efficiency of the microwave oven power s upplies alone, since they could not be tested by DOE in isolation.

• Low-standby-loss electronic controls. By definition, these technologies impact only standby power consumption rather than cooking efficiency.

• Modified wave guide. This design option described in the market and technology assessment (chapter 3 of the TSD), wherein special coatings are applied to the wave guide interior surfaces, was not observed in the DOE test units. However, two different orientations of the wave gui de were noted, and an attempt was made to identify any impact that wave guide orie ntation would have on measur ed efficiency. No such relationship was found.
For more detailed descriptions of each of th ese design options, see ch apter 3 of the TSD. Based on this analysis, DOE believes that the e fficiency improvements associated with these design options has changed little since the 1996 TSD analysis.
Comparison of IEC Test Procedures for Measuring Efficiency

5-38The existing DOE microwave oven test proce dure references IEC Standard 705, but this IEC test procedure has been declared obsolete by th e IEC. The current IEC test procedure is IEC Standard 60705. Because there are key differe nces between these two IEC procedures, the impact of which on efficiency measurements were not known to DOE, and because manufacturers which do conduct effi ciency testing are likely to be using the current version, a test series was conducted on a sub-sample of the microwave ovens to compare efficiency measurements made using both IEC test procedures.
The general methodology for each test procedur e is largely the same, and consists of heating 1 kg of water in a boros ilicate container from about 10 ° C below room temperature to room temperature, using the maximum power setting on the microwave oven. The input power over the duration of the test, and thus energy consumed during th e test, are compared to the energy absorbed by the test load to obtain the efficiency measurement.
DOE conducted tests per IEC Standard 60705 on 12 selected microwave ovens from its original 32 unit sample with a representative rang e of output power, effici ency, and test-to-test variation observed in the DOE testing, whic h utilizes IEC Standard 705. The table below summarizes key differences noted between the test procedures that can potentially impact the final energy efficiency calculation.
Table 5.6.20 Key Differences Between IEC Standard 705 and IEC Standard 60705 IEC Standard 705-1988 and Amendment 2-1993 IEC Standard 60705-2006

Ambient Temp.,T 0 = 20 ± 2 ° C Starting Water Temp., T 1 = T 0 – (10 ± 1 ° C) Final Water Temp., T 2 = T 0 ± 1 ° C Ambient Temp.,T 0 = 20 ± 5 ° C Starting Water Temp., T 1 = 10 ± 1 ° C Final Water Temp., T 2 = 20 ± 2 ° C Electrical Input En ergy neglects the magnetron filament heat-up time, the measurement starting when the input current reaches 90 percent of its final value. Measurement of Electrical Input Energy includes the energy consumed during the magnetron filament heat-up time.

No mention of rounding off efficiency or output power calculations Efficiency is rounded off to the nearest whole number, while output power is rounded off to the nearest 50 W Temperature measurement accurate within 0.25 ° C and linearity better than 1 percent. Time measurement accurate within 0.25 seconds. No specifications for accuracy of temperature and time measurements.

It can be noted that, for the efficiency measurement, IEC Standard 60705 includes the energy consumed during the magnetron filament h eat-up time, while IEC Standard 705 excludes filament heat-up time. Thus, the IEC Standard 60705 efficiency measurement can be considered more accurately as an overall microwave oven e fficiency measurement, while the IEC Standard

5-39705 efficiency measurement can be considered stri ctly a cooking efficiency measurement. Table 5.6.21 shows the results for the test procedure comparison. Per the IEC Standard 60705 test procedure, DOE rounded the measured output of each test to the closest 50 W and then averaged the rounded values.

Table 5.6.21 IEC Standard 705 versus IEC Standard 60705 Test Results

Test Unit # Rated Power Output (W) Efficiency (%) IEC Standard 705-1998 and Amendment 2-1993
Measured

Power Output (W) Test-to-Test Efficiency Range (%) Efficiency (%) IEC Standard 60705-2006 (rounded)
Measured Power Output (W) Test-to-Test Efficiency Range (%) DOE1 700 686 57.5 1.46 650 55.3 3.57 DOE6 DOE5 800 800 743 58.4 0.06 795 59.5 0.4 733 57.0 3.45 733 58.7 3.33 DOE9 900 965 60.2 0.48 917 58.3 5.00 DOE22 DOE19 DOE15 DOE21 1,100 1,100 1,100 1,100 1,038 56.9 0.71 1,057 58.2 0.47 1,073 58.9 0.77 1,105 61.2 0.21 1,000 55.0 3.57 1,017 56.7 3.45 1,083 58.0 3.39 1,083 59.3 1.67 DOE27 DOE29 1,200 1,200 1,114 61.5 1.07 1,131 59.7 0.92 1,067 59.3 1.67 1,100 58.0 0.00 DOE30 1,250 1,142 57.6 0.67 1,050 55.3 1.79 DOE32 1,300 1,119 58.0 1.24 1,083 57.0 5.17

There is a consistent decrease in efficiency of about 1 to 2 percent from IEC Standard 705 to IEC Standard 60705 for all of the microwave ovens. This largely-c onsistent decrease in the calculated efficiency for IEC Standard 60705 was due in significant part to the requirement that the measured input energy include the ener gy consumed during the magnetron filament heatup time, whereas IEC Standard 705 specifies that the measurement of energy input begins when the current reaches 90 percent of its maximum value. Therefore, IEC Standard 60705 factors in a higher energy consumption to the efficiency calculation than IEC Standard 705 does.
Another significant difference between test procedures is the specifications for accuracy of the test instrumentation. IEC Standard 705 specifies that temperature measurements be accurate within 0.25 °C, with linear ity better than 1 percent, as well as that time measurements be accurate within 0.25 seconds. In contrast, IEC Standard 60705 does not provide any accuracy requirements for these measurements. Using a st andard thermocouple, which typically has an accuracy no better than 0.5 °C, or a less accurate time measurement equipment could create significant test-to-test variation in efficiency results.
The variation of test-to-test efficiency re sults per IEC Standard 60705 for an individual microwave oven ranged from 0 to 5 percent of th e average value, which was much greater than the comparable variation for IEC Standard 705, whos e test-to-test variation in efficiency results ranged from 0 to 1.5 percent for the same sub-sa mple of microwave ovens . This larger range associated with IEC Standard 60705 is believed to be attributable to the effects of the procedure’s requirement to round the power output to th e nearest 50 W and the efficiency to the nearest whole number afte r each individual test, pr ior to averaging.

5-40The prescribed rounding under IEC Standard 60705 would make it more difficult to achieve an overall efficiency increase via improvements in minor components such as fan/turntable motors and oven light bulbs, which each consume less than 20 W. For any component efficiency improvements to have a m easurable effect after rounding the power output and efficiency calculations, power consumption woul d have to be reduced by at least 25 W.
To demonstrate the effect of rounding more clearly, the raw data from the IEC Standard 60705 testing were used to calcula te efficiency in the same ma nner as for IEC Standard 705; i.e., no rounding was performed on output power or efficiency from the individual tests prior to averaging. As shown in Figure 5.6.6 , the test-to-test variation in efficiency for the rounded data is on average four times higher th an that of the non-rounded data. The effect of rounding output power and efficiency also causes a significant change in the calculated efficiency, as seen in Figure 5.6.7. The rounded efficiencies varied from the non-rounded values by as much as 0.75 percentage points.

5 6 IEC Standard 60705 Non-Rounded Test-to-Test Results Range IEC Standard 60705 Rounded Test-to-Test Results Range

4Test-to-Test Range (%)

3

2

1

0 1 6 5 9 22 19 15 21 27 29 30 32 DOE Test Unit # Figure 5.6.6 DOE Non-Rounded versus Rounded Test-to-Test Efficiency Variation Measured Using IEC Standard 60705

5-4159 60 IEC Standard 60705 Non-Rounded Efficiency IEC Standard 60705 Rounded Efficiency

58

57

56

55

54 1 6 5 9 22 19 15 21 27 29 30 32 DOE Test Unit #Efficiency (%)

Figure 5.6.7 DOE Non-Rounded versus Rounded Efficiency Measured Using IEC Standard 60705

The non-rounded data obtained via IEC Sta ndard 60705 still show a consistent 1 to 2 percentage point decrease in efficiency for all of the units tested as compared to the IEC Standard 705 tests, which DOE believes to be attr ibutable to the differences in the energy input measurement. As with the rounded IEC Sta ndard 60705 results, the non-rounded data for IEC Standard 60705 also show more te st-to-test variation for a given unit (0 to 2.1 percentage points) than the variations test-to-test during the IEC St andard 705 testing (0 to 1.5 percentage points). This remaining increment in test-to-test variati on was likely due to the more lenient tolerances on the prescribed ambient and final test load temp eratures. The IEC Standard 60705 test procedure specifies ambient temperature as 20 ± 5 °C, as compared to 20 ± 2 °C for the IEC Standard 705 test procedure. For the final test load te mperature, IEC Standard 60705 specifies 20 ± 2 °C, while IEC Standard 705 specifies it as ambient temperature ± 1 °C.

5-42Table 5.6.22 IEC Standard 705 versus IEC St andard 60705-2006 Test Results, Without Rounding

Test Unit # Rated Power Output (W) Efficiency (%) IEC Standard 705-1998 and Amendment 2-1993

Measured

Power Output (W) Test-to-Test Efficiency Range (%) Efficiency (%) IEC Standard 60705-2006 (no rounding)

Measured Power Output (W) Test-to-Test Efficiency Range (%) DOE1 700 686 57.5 1.46 659 56.1 0.56 DOE6 DOE5 800 800 743 58.4 0.06 795 59.5 0.4 740 57.2 0.96
722 58.0 0.70 DOE9 900 965 60.2 0.48 925 59.0 1.66 DOE22 DOE19 DOE15 DOE21 1,100 1,100 1,100 1,100 1,038 56.9 0.71 1,057 58.2 0.47 1,073 58.9 0.77 1,105 61.2 0.21 1,012 55.6 0.50 1,023 56.8 0.20 1,075 57.5 0.53 1,087 59.4 0.76 DOE27 DOE29 1,200 1,200 1,114 61.5 1.07 1,131 59.7 0.92 1,061 59.3 1.05 1,112 58.4 0.87 DOE30 1,250 1,142 57.6 0.67 1,074 56.0 0.82 DOE32 1,300 1,119 58.0 1.24 1,087 56.4 2.14
Based on observations and analysis of test re sults, DOE believes that IEC Standard 705 is more likely to produce consistent test results than IEC Standard 60705 be cause the measurement requirements in IEC Standard 705 are more stri ngent. Therefore, DOE believes that IEC Standard 705 should be retained as the ba sis for the DOE cooking efficiency tests.
Microwave Oven Standby Power
Section 310 of the Energy Independence a nd Security Act of 2007 (EISA 2007) (Pub. L. No. 110-140) amends Section 325 of the EPCA to require DOE to incorporate standby mode and off mode energy use into a single amended or ne w standard, if feasible, for covered products, including microwave ovens, for any final rule es tablishing or revising a standard adopted after July 1, 2010. If such a single standard is not feasible, DOE shall prescribe a separate standard for standby mode and off mode energy consumption, if justified. (42 U.S.C. 6295(gg)(3)) Even though the final rule for this rulemaking is scheduled for March 2009, DOE has decided, for reasons discussed in the NOPR, to accelerate the schedule for microwave ovens to include standby and off mode power in the proposed ener gy conservation standards. Therefore, DOE conducted microwave oven standby power test ing to supplement the AHAM-supplied data, investigate design options, and develop a relatio nship between incremental manufacturing cost and standby power levels.
In the NOPR, DOE proposes to use the defi nitions of modes as specified in EPCA. EPCA defines “standby mode” as “the conditi on in which an en ergy-using product – (I) is connected to a main power source; and (II) offers 1 or more of the following user-oriented or pr otective functions: (aa) To facilitate the activation or deac tivation of other func tions (including active mode) by remote switch (including remote c ontrol), internal sensor, or timer.

5-43(bb) Continuous functions, including information or st atus displays (including clocks) or sensor-based functions.” (42 U.S.C. 6295(gg)(1)(A)(iii))

EPCA defines “off mode” as “the conditi on in which an energy-using product – (I) is connected to a main power source; and (II) is not providing a ny standby mode or ac tive mode function.” (42 U.S.C. 6295(gg)(1)(A)(ii))
EPCA defines “active mode,” which is referenced in the definition of “off mode,” as “the condition in which an energy-using product – (I) is connected to a main power source; (II) has been activated; and (III) provides 1 or more main functions.” (42 U.S.C. 6295(gg)(1)(A)(i))

DOE considers “main functions” for a microw ave oven to be those operations in which the magnetron and/or thermal element is energize d for at least a portion of the time for purposes of heating, cooking, and/or defrosting the load. According to the EPCA definitions, standby mode would thus comprise the conditions in which the microwave oven is plugged in and consuming power for features in cluding displays, cooking sensors, and sensors to reactivate the microwave oven from a low-power state after a peri od of user inactivity. For reasons discussed later in this section, DOE does not believe that any microwave ovens currently for sale in the United States are capable of operation in off mode.
Since manufacturers are not required to re port standby power for microwave ovens, DOE could not select its sample test units on the basis of standby power consumption. Instead, DOE selected its sample microwave ovens to cover a wide range of cavity sizes and output power, as well as other features such as display type, power s upply type, and presence of cooking sensors. DOE was unable to identify any microwave oven models with an automa tic powerdown feature. Within the test sample, DOE observed significant standby power differences which it believes are attributable to specific design opti ons or design option combinations.
DOE conducted product teardowns and te sting in support of its standby power investigation. DOE also analyzed IEC Standard 62301 to determine its suitability for measuring standby power in microwave ovens. DOE found the results produced by IEC Standard 62301 to be fairly consistent for many microwave ovens. However, for a few microwave ovens in the test sample, the standby power consumption varied by more than 5 percent over the course of 5 minutes, a threshold above which IEC Standard 62301 requires a longer 12 hour standby test duration. Investigating the sour ce of these variations in power consumption, DOE determined that standby power can vary significantly with clock time, depending on the display type.
DOE tested a sub-sample of microwave ove ns over 12-hour periods and subsequently developed an alternate 10-minute standby power test that achieved results for average power consumption that were within 1 to 2 percent of the 12-hour test results (see appendix 5B). Using

5-44the most consistent data from: (1)the IEC Standard 62301 5-minute test, (2) the regression analysis as described in appendix 5B, and/or (3) 12-hour tests, standby power for each microwave oven in the sub-sample was characte rized. The minimum, maximum, and average input powers were recorded, and from the aver age standby power, an annual energy consumption in kWh was calculated. Table 5.6.23 th rough Table 5.6.26 summarize these results.

Table 5.6.23 DOE Microwave Oven St andby Power (Table 1 of 4) DOE Unit Number DOE1 DOE2 DOE3 DOE4 DOE5 DOE6 DOE7 DOE8 Rated Output Power (W) 700.0 700.0 700.0 700.0 800.0 800.0 800.0 800.0 Stated Volume (ft 3 ) 0.7 0.7 0.7 0.7 1.0 1.0 0.8 0.8 Cooking Sensor

- - - - Y

- - - Type LED LED LED LED VFD LED LCD LCD Characters #, 1 x 4 #, 1 x 4 #, 1 x 4 #, 1 x 4 A, 1 x 7 #, 1 x 4 #, 1 x 4 #, 1 x 4 # of LEDs for backlightingDisplay N/A N/A N/A N/A N/A N/A None None

Size 1.50" x 0.43" 1.50" x 0.43" 1.45" x 0.70" 1.90" x 0.83" 2.25" x 0.75" 1.50" x 0.80" 1.87" x 0.83" 1.87" x 0.83" Min (W) 1.47 1.49 1.14 0.96 5.28 1.33 1.37 1.38 Average (W)Standby 1.74 1.77 1.28 1.07 5.28 1.51 1.38 1.40 Max (W) 1.85 1.90 1.35 1.14 5.53 1.60 1.41 1.41 Annual (kWh) 15.22 15.47 11.21 9.40 46.28 13.22 12.12 12.28 Unit is Similar to

- - - - - DOE5

- -
Table 5.6.24 DOE Microwave Oven St andby Power (Table 2 of 4) DOE Unit Number DOE9 DOE10 DOE11 DOE12 DOE13 DOE14 DOE15 DOE16 Rated Output Power (W) 900.0 1,000.0 1,000.0 1,000.0 1,000.0 1,100.0 1,100.0 1,100.0 Stated Volume (ft 3 ) 0.9 1.1 1.1 1.0 0.0 1.1 1.1 1.8 Cooking Sensor

- - - - - - Y Y Type LED LED LED LED VFD LED LCD VFD Characters #, 1 x 4 #, 1 x 4 #, 1 x 4 #, 1 x 4 #, 1 x 4 #, 1 x 4 A, 1 x 6 A, 1 x 7 # of LEDs for backlightingDisplay N/A N/A N/A N/A N/A N/A 5 N/A

Size 2.00" x 0.65" 1.85" x 1.10" 1.75" x 0.85" 1.75" x 0.70" 2.20" x 0.65" 2.00" x 0.65" 2.53" x 0.95" 2.25" x 0.75" Min (W) 1.26 1.09 1.11 1.42 2.46 1.16 3.08 3.08 Average (W)y db 1.49 1.23 1.26 1.75 2.48 1.40 3.10 3.08 Max (W)Stan 1.58 1.30 1.33 1.88 2.49 1.49 3.12 3.31 Annual (kWh) 13.09 10.73 11.01 15.32 21.71 12.26 27.14 26.95 Unit is Similar to

- - - - - - DOE14

-

5-45Table 5.6.25 DOE Microwave Oven St andby Power (Table 3 of 4) DOE Unit Number DOE17 DOE18 DOE19 DOE20 DOE21 DOE22 DOE23 DOE24 Rated Output Power (W) 1,100.0 1,100.0 1,100.0 1,100.0 1,100.0 1,100.0 1,150.0 1,200.0 Stated Volume (ft 3 ) 1.0 1.4 1.0 1.3 1.1 1.0 1.4 2.2 Cooking Sensor

- - - - - - Y Y Type LCD LCD LCD LED LED LCD VFD LCD Characters #, 1 x 4 A, 1 x 5 #, 1 x 4 #, 1 x 4 #, 1 x 4 #, 1 x 4 A, 1 x 7 A, 1 x 6 # of LEDs for backlightingDisplay 3 4 None N/A N/A 3 N/A 10

Size 1.83" x 0.80" 2.03" x 0.81" 1.87" x 0.83" 1.50" x 0.80" 1.47" x 0.80" 2.00" x 0.83" 2.25" x 0.75" 2.05" x 1.10" Min (W) 1.64 1.64 1.30 1.46 1.32 1.70 3.05 2.57 Average (W)y db 1.65 1.66 1.31 1.65 1.55 1.72 3.05 2.59 Max (W)Stan 1.67 1.67 1.34 1.73 1.66 1.73 3.18 2.60 Annual (kWh) 14.48 14.51 11.48 14.44 13.57 15.02 26.68 22.66 Unit is Similar to

- - DOE17

- - DOE17 DOE16 DOE30

Table 5.6.26 DOE Microwave Oven St andby Power (Table 4 of 4) DOE Unit Number DOE25 DOE26 DOE27 DOE28 DOE29 DOE30 DOE31 DOE32 Rated Output Power (W) 1,200.0 1,200.0 1,200.0 1,200.0 1,200.0 1,250.0 1,300.0 1,300.0 Stated Volume (ft 3 ) 1.2 2.2 1.2 2.0 2.0 2.2 1.2 1.2 Cooking Sensor

- Y Y Y Y Y Y Y Type LCD LCD LCD LCD LCD LCD LCD LCD Characters #, 1 x 4 A, 1 x 6 A, 1 x 7 D, 2 x 8 A, 1 x 7 A, 1 x 6 #, 1 x 4 A, 1 x 6 # of LEDs for backlightingDisplay 5 10 4 6 4 4 10 10

Size 1.85" x 0.83" 2.05" x 1.10" 2.03" x 0.78" 2.45" x 1.17" 2.03" x 0.78" 2.05" x 1.10" 1.75" x 0.80" 2.05" x 1.10" Min (W) 1.68 2.57 3.50 3.86 3.38 2.79 2.08 2.81 Average (W)Standby 1.70 2.59 3.52 3.88 3.41 2.82 2.09 2.82 Max (W) 1.71 2.60 3.60 3.93 3.46 2.86 2.10 2.86 Annual (kWh) 14.86 22.66 30.84 34.02 29.90 24.69 18.28 24.72 Unit is Similar to DOE17 DOE30 DOE25

- - DOE31

- DOE31
In the course of examining the 32 microwave ovens in the test sample, DOE noted that all power supplies for the logic boards contain similar components. Incoming AC line voltage is reduced via a small (2 to 7 VA) transformer, i nput to a bridge rectif ier, and subsequently smoothed with capacitors to produce unregulated DC voltage (VDC). Multiple voltages for logic integrated circuits (ICs) (usually 5 VDC or less) and relay control (12 to 24 VDC) are established either via multiple taps on the transformer or thr ough the use of voltage regulators. None of the microwave ovens analyzed by DOE feature an on/off switch or electromechanical controls. DOE is unaware of any microwave ovens still on the market with electromechanical controls and no displays; DOE believes that the U.S. microwave oven market has completely transitioned to electronic controls with displa ys. Thus, all sampled microwaves consume standby power while waiting for user input. DOE does not believe th at any domestic microwave ovens are capable of operating in off mode, as defined by EP CA. (42 U.S.C. 6295 (gg)(1)(A)(ii))
The average standby power, disaggregated by di splay type and the presence of a cooking sensor as shown in Figure 5.6.8, exhi bits a relatively wide range of values. These measured data correlate well with the standby power measurem ents that AHAM submitted to DOE (see Figure 5.6.9). In the DOE test sample, none of the mi crowave ovens with LED displays include a

5-46cooking sensor, and these models all consume less than 2 W in standby mode. Similar low standby power requirements were observed for microwave ovens with LCD displays and no cooking sensors. For those microwave ovens wi th LCD displays and cooking sensors, the standby power ranged from 2 to 4 W. VFD- equipped microwave ovens demonstrate fairly consistent power draw, and the microwave oven with the highest standby power uses a cooking sensor and a VFD.
In the following figures, the legend key incl udes designations for the presence of a cooking sensor (CS), backlighting (B), and inverter drive for the magnetron (I).

1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0Standby Power (W) LED
VFD VFD, CS LCD LCD, B LCD, B, CS LCD, B, CS, I

650 750 850 950 1050 1150 1250 1350 Rated Power Output (W)

Figure 5.6.8 DOE Microwave Oven Standby Po wer Consumption as a Function of Rated Output Power
While AHAM did not identify specific models in its data submittal, and thus DOE could not derive information on display type, the data do note which microwave ovens contain cooking sensors. Like the microwave ovens in the DOE test sample, AHAM units with cooking sensors have, on average, higher standby power consum ption than microwave ovens without cooking

sensors.

5-471 1.5

2 2.5

3 3.5

4 4.5

5 5.5

6Standby Power (W) No Sensor

Sensor

650 750 850 950 1050 1150 1250 1350 Rated Output Power (W) Figure 5.6.9 AHAM Microwave Oven Standby Power Consumption and a Function of Rated Output Power 18
Based on these standby power observations, DOE concludes that standby power is a function of features including the display, the presence of a cooking sensor, and controller power requirements. The following sections discuss the impact of each of these features on overall standby power consumption.
Impact of Display Type on Standby Power
DOE noted three different types of displays among the 32 microwave ovens in its sample. The sampled display capabilities ranged from only being able to display numbers, to displaying alphanumeric characters, to incorporating dot-matrix-based displays whic h allow the display of multiple fonts, symbols, and, in some cases, graphics.
Display power requirements depend on the f undamental technology as well as the size of the display, the brightness, and the number and range of characters it can display. Figure 5.6.10 illustrates measured standby power consumption as a function of display size.

5-48Standby Power (W) 5.5

5.0

4.5

4.0

3.5

3.0

2.5

2.0

1.5

1.0 LED VFD VFD, CS LCD LCD, B LCD, B, CS LCD, B, CS, I

0.5 1.0 1.5 2.0 2.5 3.0 Display size (in 2 )
Figure 5.6.10 DOE Microwave Oven Standby Power Consumption as a Function of Display Size
Figure 5.6.11 through Figure 5.6.13 show the av erage measured standby power with minimum and maximum values for each type of display. See appendix 5C for a further discussion of display technologies.

• Light Emitting Diode (LED)
LED displays operate by individu ally lighting up each element in the display to create a character or number or to illuminate a symbol. DOE confirmed that the power consumption of such displays varies depending on how many elemen ts (and hence diodes) ar e active at any given time. Thus, LED-display-equipped microwave ove ns demonstrate the greatest variation in standby power consumption over the cour se of a day as the clock cycles.
The span between the maximum and minimum standby power consumption, based on the number of elements illuminated, ranges from 0.2 to 0.4 W in the DOE test sample. Figure 5.6.11 shows the average standby power consumpti on (with maximum and minimum values) for microwave ovens with LED displays as a function of the measured size of the display in square inches. DOE found no apparent correlati on between display size and standby power consumption. DOE recognizes that diode energy efficiency charac teristics may be an important variable, but one for which DOE could not ascertain any information.

5-490.8 1.0 1.2 1.4 1.6 1.8 2.0Standby Power (W)

0.5 1.0 1.5 2.0 2.5 Display Size (in 2 ) Figure 5.6.11 DOE Standby Power Consumption as a Function of Display Size for Microwave Ovens with LED Displays

• Vacuum-Fluorescent Display (VFD)
VFDs typically require more power than LC D- or LED-based displays, but offer high brightness levels and wide view ing angles. Note that the three VFD models with cooking sensors have a feature that allo ws the display to be switched off, but selecting this option decreases standby power consumption by only 0.1 to 0.25 W. According to the IEC Standard 62301 test procedure, standby power would be measur ed with the displays powered off, resulting in a constant average value over the 12-hour pe riod. These data are denoted in Figure 5.5.1 by the symbols. DOE also measured the variations in standby power with the displays on during the 12-hour cycle for these units, and these variati ons, which are all additive from the minimum standby power levels measured with the displays turned off, are indicated on the chart by bars on each symbol.

5-502.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0Standby Power (W)

VFD VFD, CS

1.4 1.5 1.6 1.7 1.8 Display Size (in 2 ) Figure 5.6.12 DOE Standby Power Consumption as a Function of Display Size for Microwave Ovens with VFD Displays

• Liquid Crystal Display (LCD), with or without backlighting
An LCD without backlighting requires some am bient light to allow a user to read it because it relies on reflected light to create a visible contrast. LCDs without backlighting are frequently found on entry-level microwave ovens, whereas more expensive units tend to have backlit displays. LCDs with backlighting can be read regardless of ambient lighting conditions. The backlighting typically consists of multiple LEDs mounted behind the LCD display on the same circuit board. LCDs with backlighting were found on 12 of the microwave ovens in the DOE sample. As shown in Figure 5.6.13, the st andby power consumption for microwave ovens with LCDs in the DOE sample remains nearly constant over time (since the bars showing variation during 12-hour tests ar e virtually indistinguishable from the symbols denoting the average values.) Figure 5.6.13 also shows that the addition of a cooking sensor raises standby power consumption, on average, to over 2 W.

5-511.0 1.5 2.0 2.5 3.0 3.5 4.0Standby Power (W)

LCD LCD, B LCD, B, CS LCD, B, CS, I

1.0 1.5 2.0 2.5 3.0 Display size (in 2 )
Figure 5.6.13 DOE Standby Power Consumption as a Function of Display Size for Microwave Ovens with LCD Displays
Based on its research, DOE concludes that cer tain display technologies such as VFDs inherently consume more power, on average, th an comparably-sized displays using other illumination technologies. Standby power is also a function of the size and the complexity of the display; more complex and larger displays typi cally consume more power than smaller, simpler displays.
Impact of a Cooking Sensor on Standby Power
DOE noted from its testing that microwav e ovens with cooking sensors typically consume more power than comparable models th at do not feature a cook ing sensor. From its reverse-engineering activities, DOE identified tw o different types of cooking sensors generally used in microwave ovens: (1) absolute humidity sens ors; and (2) piezo-electr ic steam sensors. A literature review of id entifiable absolute humidity cooking se nsors indicates that such sensors typically supply power to a resi stive heating element whose conduc tivity changes in response to the presence of water vapor or other gases associated with food cooking proc esses. Based on its standby power observations between otherwise identical microwave ovens and information provided by sensor manufacturers, DOE concludes that the resistive elements in the cooking sensors are typically maintained at operati ng temperature during standby mode because warmup times (which can be several minutes) are l onger than many microwave oven cooking times.
The specification sheet for one representativ e absolute humidity cooking sensor notes that the sensor requires approxi mately 0.9 W to remain warm and ready for use. Based on a typical power supply efficiency of about 65 perc ent, the required microwave oven input power associated with the absolute humidity cooking sensor is thus approximately 1.6 W. Other

5-52microwave ovens in the DOE sample use absolu te humidity sensors whose power requirements appear comparable to those for the absolute humidity sensor referenced above. Testing performed on the steam sensor s used in a number of microw ave ovens in the DOE sample revealed that these sensors do not consume powe r in standby mode. For further discussion of steam cooking sensors, refer to ch apter 3 of this TSD.
Table 5.6.27 shows a comparison of standby power for three pairs of microwave ovens in the DOE sample containing the same basic part s (power conditioner, transformer, magnetron, and cavity) with and without an absolute humid ity cooking sensor. In all three cases, the microwave ovens with a cooking sensor cons ume at least 1.6 W more than comparable microwave ovens without a sensor. In the ca se of DOE test units #5 and #6, assuming the absolute humidity cooking sensor consumes abou t 1.6 W implies that the remaining differential between the two units of approximately 2.2 W of standby power consumption is attributable to the use of a VFD instead of an LED. The st andby power consumpti on of other absolute humidity sensors, which can be inferred from units #25 and 27 with similar displays, is approximately 1.8 W.
Table 5.6.27 DOE Standby Power Requirements among Similar Microwave Ovens with Different Options

Test Unit # Display Type # of LEDs used to backlight display Display Size Cooking Sensor Type Avg. Standby Power Consumption (W)

DOE21 DOE15 LED LCD N/A 5 1.47" x 0.80" 2.53" x 0.95" None Absolute Humidity 1.55 3.10 DOE6 DOE5 LED VFD N/A N/A 1.50" x 0.80" 2.25" x 0.75" None Absolute Humidity 1.51 5.28 DOE25 DOE27 LCD LCD 5 4 1.85" x 0.83" 2.03" x 0.78" None Absolute Humidity 1.70 3.52 Figure 5.6.14 shows the cumulative impact of each design option on overall standby power. The figure shows the average standby power consumption for all microwave oven models in the DOE sample which have the desi gnated design options, as well as the minimum and maximum values for each group.

5-530.0 1.0 2.0 3.0 4.0 5.0 6.0Standby Power (W) Maximum Minimum Average

LED LCD LCD Backlit LCD Backlit, LCD Backlit, VFD VFD, Absolute Absolute Steam Cooking Humidity Humidity Sensor, Inverter Cooking Sensor Cooking Sensor Figure 5.6.14 DOE Standby Power Consumption A ssociated with Different Design Options
Incremental Cost Data for Standby Power Levels
From the standby power testing and revers e-engineering, DOE observed correlations between specific components and technologies, or combinations thereof, and measured standby power. Costs for each of the components and technologies were estimated by DOE using quotes obtained from suppliers, interviews with manufacturers, interviews with subject matter experts, research and literature review, and numerical modeling. Prelim inary incremental manufacturing costs associated with the standby levels were then obtained by cons idering combinations of these components as well as other technology opti ons identified to reduce standby power. Manufacturer interviews were also conducted to obtain greater insi ght into the design strategies to improve efficiency and the associated costs.
The design options DOE considered in the en gineering analysis in clude various display technologies, cooking sensors with no standby po wer requirement, higher-efficiency controller power supplies and relays, and improved control st rategies. For details on the microwave oven standby design options, refer to chapter 3 of this TSD. DOE selected the design option(s) it believed manufactures would most likely implemen t to achieve a given standby level for a given display technology. The incremental cost, then, for each display technology was weighted by the estimated percentage of shipments currently usin g that type of display in order to obtain a weighted-average incremental cost at each stan dby level above the baseline. DOE believes that, in order to meet standby level 1, manufacturers would likely have to utilize a cooking sensor with no standby power requirements. Additionall y, for microwave ovens with VFDs and backlit LCDs, the conventional power supplies would ne ed to be upgraded to higher efficiency conventional power supplies. Standby leve l 2 would likely also require LED-equipped microwave ovens to upgrade the efficiency of the existing power supply, and DOE believes that

5-54manufacturers would have to change to sensitive-coil relays in orde r to continue using VFDs. To move from standby level 2 to standby level 3, DO E believes that manufacturers would have to additionally incorporate the sensitive-coil rela ys for LED and backlit LCD-based microwave ovens. Optionally, manufacturers of LED-equipped microwave ovens could choose to change to a switching power supply without upgrading the relays. Each of these two LED options was assumed to be equally likely since the cost of each path was similar. At standby level 3, backlit LCD-equipped microwave ovens would likely also need to be changed to a switching power supply along with implementing the sensitive- coil relays. DOE believes the only way for manufacturers of VFD-equipped microwave ovens to meet a 1 W standby threshold would be to implement an automatic powerdown feature, in which a controller turns off power to standbypower-consuming components after a certain period of inactivity. Th is feature would also allow VFD-equipped microwave ovens to meet sta ndby level 4, and would be the approach for microwave ovens with the other display technologi es to meet standby level 4 as well. Table 5.6.28 presents the incremental manufacturing co sts for each standby power level for microwave

ovens.

Based on conversations with manufacture rs and OEM suppliers, and the reverseengineering analysis, DOE believes that all manufacturers can implement zero-standby cooking sensors by the expected effective date of the pr oposed standards. Thus, DOE believes that consumer utility would not be impacted by a standard at standby levels 1 or 2, since all display types could continue to be ut ilized. At standby level 3 for VFDs and standby level 4 for all display technologies, DOE analysis suggests the need for a separate controller (auto powerdown) that automatically turns off all other power-consuming components during standby mode. Such a feature would impact the consumer utility of having a clock display only if the consumer could not opt out of auto power-down.
Table 5.6.28 Incremental Manufacturing Costs for Microwave Oven Standby Power
Standby Level Standby Power (W) Incremental Cost (2007$) Baseline 4.0 $ 0 1 2.0 $ 0.30 2 1.5 $ 0.67 3 1.0 $ 1.47 4 0.02 $ 5.13
Standby Power Test Procedure Issues
During testing, DOE identified several issues that are not addressed in IEC Standard 62301 that can affect the stability and repeatabil ity of the standby power measurements. For the 32 microwave ovens sampled by DOE, the variab ility of standby power appeared to be influenced primarily by changes in clock time over the duration of the test, the effect of which depended on the type of display technology used, and fluctuations in line voltage. The effect of each of these issues is discussed below.

• Clock Time

5-55The IEC Standard 62301 test procedure specif ies a 5-minute recording period for initially measuring standby power consumption. If the measured power fluctuations are less than 5 percent during this period, the pow er is simply averaged over the 5 minutes to obtain the standby power consumption. Conversely, if the fluctuat ions are greater than 5 percent, the standby power draw must be measured over a longer tim e period, which in the te st procedure is only defined as “representative” and which for micr owave ovens with a 12-hour clock would be reasonably interpreted as a full 12 hours. Th e test procedure, however, does not specify the starting clock time for the initial 5-minute meas urement period, so it would be possible to selectively choose a starting time that shows a minimum of actively-lit elements and whose subsequent variability of lit elements is low. For example, programming 1:12 AM into the clock at the beginning of the test offers the combina tion of a minimal number of active elements as well as minimal active element variability, since during the 5 minute test the only change would be the last digit cycling from a value of 2 to a value of 7. Thus, a ma nufacturer could report lower standby power consumption than would be realized in actual operating conditions.
To illustrate this effect more clearly, Figure 5.6.15 shows that the number of active elements in the LED display of a representative unit among the DOE test samples ranged from 6 to 18, depending on the time being displayed. For this microwave oven, a 20-percent variation in standby power was observed as a function of the clock time being displayed. By choosing a starting clock time of 1:12, the num ber of active elements ranges from 7 to 10 for the 5 minute duration of the initial measurem ent. In fact, the average 8.6 active elements under these test conditions result in an average standby power c onsumption of approximately 1.25 W, instead of the approximately 1.4 W which would be obtai ned over the 12-hour period. Therefore, an apparent 11-percent improvement in standby pow er consumption could be obtained for this microwave oven by simply choosing th is initial clock time. It shoul d be noted that since display type, size, and luminosity affect standby power variability, this apparent improvement could be different for other microwave ovens.

5-561.15 1.2 1.25

1.3 1.35

1.4 1.45

1.5Watts

5 7 9 11 13 15 17 19 Active Elements (LED)

Figure 5.6.15 Representative Variation in Sta ndby Power Consumption as a Function of the Number of Active El ements in the Display

• Line Voltage
DOE observed that line voltage fluctuations within the ± 1 percent tolerance allowed by IEC Standard 62301 resulted in greater than ± 1 percent variati ons in standby power measurements. A series of tests across multiple microwave ovens showed that a change of 2 VAC on a nominal 120 VAC line voltage, which is le ss than 2 percent, re sulted in standby power measurements that varied by as much as 5 percent.
Alternate Standby Power Test Methods
DOE considered alternate testing methods to determine whether a re presentative standby power could be measured over a shorter peri od than 12 hours so that the test burden on manufacturers could be reduce d. Thus, DOE developed an algorithm by which the power consumption and line voltage are measured as the clock is cycled through multiple digit combinations (in terms of active elements), follo wed by a regression analys is that quantifies the impact of the number of lit elements (by digi t) and line voltage on power consumption. The results are then integrated acro ss the number of minutes that ea ch active element combination is “on” through the course of the 12 hours. Th is methodology, discussed in greater detail in appendix 5B, produced standby power measurements in less than 10 minutes of test time that agree to within 1 to 2 percent with the measurements made over 12 hours.

5-57DOE recognizes, however, that this approach for accelerated standby testing offers the possibility that the rather unique combination of clock times could be detected. A microwave oven could be programmed to alter it behavior when such a test is detected in order to minimize measured standby power consumption. For example, a microwave oven could be programmed to turn off its cooking sensors and/or dim its display only during such a test. Thus, DOE is proposing in the NOPR the use of the longer 12-hour standby test.
Standby Power Test Method Conclusions

DOE has determined that the test conditi ons specified by IEC Standard 62301 were suitable for microwave oven tests. As discussed in chapter 3 of this TSD, DOE has initiated a test procedure change to inco rporate standby power in parallel with this rulemaking. The proposed test procedure would incorporate by re ference provisions from IEC Standard 62301 as well as language to clarify the application of these provisions for measuring standby mode where IEC Standard 62301 is non-specific. Specifical ly, DOE is proposing to specify a 12-hour duration for the measurement period as a qualifica tion to IEC Standard 62301 in order to provide more consistent and repeatable results.

5.6.2 Commercial Clothes Washers

5.6.2.1 AHAM Data
To support the DOE rulemaking, AHAM collect ed incremental CCW manufacturing cost data from its member companies in October 2006. Table 5.6.29 compiles unit shipment and energy efficiency data for CCWs from 2002–2005.

Table 5.6.29 AHAM Commercial Clothes Was her Shipments and Shipment-Weighted MEF and WF Data Submittal
Year Total Shipments MEF ( ft

3 /kWh) WF (gallons / ft 3 ) 2002 175,187 1.30 11.77 2003 190,720 1.33 11.42 2004 178,382 1.33 11.33 2005 177,394 1.41 10.91
Table 5.6.30 reproduces AHAM's 2006 data su bmittal for the averag e water and power consumption agitator top-loadi ng CCWs that meet the baseline 1.26 MEF energy efficiency level. Since January 2007, however, clothes wa shers manufactured at this baseline 1.26 MEF must meet a lower WF (9.5) than the one listed in the AHAM data submittal.

5-58Table 5.6.30 AHAM Baseline MEF Commercia l Clothes Washer Average Energy and Water Use Data Submittal
Attributes of Average 1.26 MEF Washer Power Consumption per Wash Cycle (kWh)

MEF ( ft

3 /kWh) WF (gallons

/ ft 3 ) Washer Capacity (ft 3 ) Water Use (gallons/cycle) Standby Power Consumption (W) Hot Water Machine Power Dryer Power 1.26 11.1 3.1 34.3 * 0.87 0.18 1.38
DOE initially requested incremental cost data for efficiency levels presented in the framework document for the single product class including both top-load ing and front-loading CCWs. Data submitted by AHAM for the November 2007 ANOPR, shown in Table 5.6.31, represents aggregated input fr om the producers of CCWs sold in the United States The shipment-weighted incremental cost at each level is the cost to upgrade the baseline efficiency machine (1.26 MEF/9.5 WF) to that efficiency level for the single product class. The CCW industry currently has only three manufacturers with more than 1 pe rcent market share, and there are a limited number of CCWs that operate at different efficiency points, restri cting the amount of data that AHAM could submit d . Four efficiency levels c ontain no cost data since AHAMrequires a minimum of three data points per efficiency level before submitting shipmentweighted results. Therefore, AHAM submitted two manufacturing cost estimates: (1) $74.63 at efficiency level 1; and (2) $316.35 at effi ciency level 5, as noted in Table 5.6.31.

Table 5.6.31 AHAM Commercial Clothes Was her Incremental Cost Data Submittal Efficiency Level 1 2 3 4 5 6 Exploratory MEF Levels – Commercial Clothes Washers 1.42 1.6 1.72 1.8 2 2.2 Exploratory WF Levels – Commercial Clothes Washers 9.5 8.5 8.0 7.5 5.5 5.1 Incremental Costs ($ Per Unit) – Shipment-Weighted $ 74.73 * * * $ 316.35 * * Insufficient data reported Figure 5.6.16 plots the efficiency levels for the single CCW product class established in the November 2007 ANOPR for which AHAM submitte d incremental manufacturing cost data, i.e. the baseline efficiency level, effici ency level 1, and efficiency level 5.

d AHAM is limited to publishing data to efficiency levels where at leas t three AHAM members can submit cost efficiency data, which AHAM then weights according to unit shipments by manufacturer.

5-59Baseline EL: 9.5WF EL 1: 9.5WF EL 5: 5.5WF

0 50 100 150 200 250 300 350Incremental Mfg. Cost ($/unit)

1.2 1.4 1.6 1.8 2 2.2 MEF EL = Efficiency Level

Figure 5.6.16 AHAM Commercial Clot hes Washer Incremental Cost Data Submittal

Manufacturers stated that the baseline e fficiency level (1.26 MEF/9.5 WF) and the efficiency level 1 (1.42 MEF/9.5WF) are attainable with agitator top-loading clothes washers. Manufacturers also stated that efficiency level 5 (2.00 MEF/5.5 WF) would require the use of front-loading clothes washers. Therefore, DOE believes the data in Table 5.6.31 is subject to a platform change from agitator top-loading to front-loading clothes wash ers between efficiency level 1 and efficiency level 5. Given the persis tent manufacturing cost difference between these platforms, an incremental cost “curve” with mo re intermediate data points would thus likely exhibit a steep step change wherever that platform change occurs.

5.6.2.2 Review of the Most Recent TSD for Residential Clothes Washers
In 2001, DOE concluded a rulemaking for residentia l clothes washers. The intent of this section is to review some of the conclusi ons drawn in the 2000 TSD that supported that rulemaking, to update the data presented in it, and to assess in which ways the residential clothes washer TSD can be used in the context of this CCW rulemaking. In particular, this review will focus on the manufacturing costs published in th e 2000 TSD. First, the 1996 AHAM residential clothes washer cost data submittal provided for the 2000 TSD will be examined, followed by the 2000 reverse-engineering analys is and an update on the low- volume manufacturer case.
1996 AHAM Cost and Energy Use Data Submittal Review

5-60In 1996, manufacturers submitted manufacturing cost and energy use estimates by efficiency level for residential clothes washer s to AHAM. This data was then aggregated by market share and efficiency level to prevent th e disclosure of confiden tial information, and the results were used in the analysis reported in the 2000 TSD. Wh ile this process yielded viable results in the residential clothes washer rulemaking, the results are not directly applicable to the current CCW rulemaking due to differences in the following key parameters: (1) intended use and cycle life, (2) production scale, (3) technica l advancements, (4) market share, (5) platform mixing, and (6) incompatibility of the MEF and WF pairings in the data submittal.
Intended Use and Cycle Life

Clothes washer manufacturers have traditiona lly designed their commercial units to share many parts with their residential platforms. Shared components typically c onsist of parts that do not affect unit life, such as cabinet stampings, th at may or may not be selectively upgraded. For example, entry-level residential clothes washer cabinets typically featur e a powder-coated plastic finish whereas commercial models may feature a more durable enameled finish. Purchased components such as motors, timers, and switches ma y also be customized to reflect the different and more rigorous usage patterns expected in commercial applications. For example, one manufacturer stated that their CCWs are expected to last 12,000 wash cycles whereas residential models are expected to last 6,000 or fewer wash cycles.

Production Scale
In 1996, a twenty-fold scale difference existe d between residential and CCW market unit shipments. Since then, residential clothes wash er shipments have grown while CCW sales have stagnated or declined. As a re sult, the current scale differenc e is more than forty-fold.
The scale difference helps explain why CC Ws have traditionally been a product extension of existing residential clothes washer platforms for most manuf acturers. By sharing many components with residential models, research and development, tooling and equipment, and other costs can be spread ove r the largest number of clothes washers. Consequently, any additional investment required for CCWs alone is depreciated over a much smaller production volume.
As efficiency standards are ra ised, manufacturers may be required to make investments in the form of capital expenditures, research and development, and implementation to meet such standards. Investments such as new tooling a nd research, in particular, are “step” functions, requiring a minimum investment regardless of production volume. A standard that affects CCWs first may thus require a substantial invest ment that can only be depreciated over a much smaller production volume.
As a result of the much lower production volumes, the per-unit conversion costs to accommodate higher efficiencies ar e greater per efficiency increm ent for CCWs than they are for residential models. Therefore, DOE believe s Table 4.2 published in the 2000 TSD (duplicated below as Table 5.6.32) is not valid for CCWs, because the fixed costs are assumed to be depreciated over a much larger product vol ume and because the higher-volume production

5-61processes manufacturers envisioned minimize variable cost increases. Most manufacturers of residential clothes washers in 1996 had production levels in excess of 300,000 units per year, with the leading manufacturer producing about 3 .5 million top-loading washers per year. In contrast, the two leading CCW manufacturers in 2007 have to tal CCW production levels of about 100,000 units per year.
Currently, as in 1996, there is a low-volume ma nufacturer (LVM) that operates in both the residential and CCW markets. While its volumes in the residential market are very small on a percentage basis, this manu facturer is very prominent in the CCW market. Unlike its diversified competitors, this company exclusively manufactures laundry equipment. A review of the Securities and Exchange Commission (SEC) 10-K documents revealed that, as of 2005, this company derived 22 percent of its total revenue from the sale of front- and top-loading clothes washers and 87 percent of that income was from the commercial market. As a result, this company will be affected disproportionately by the CCW rulemaking compared to its competitors, for whom CCWs represent about 2 percen t of total clothes washer sales. For more information on the LVM, see appendix 13A of this TSD.

Table 5.6.32 1996 AHAM Residential Clot hes Washer Cost Data Submittal

Product Characteristics Incremental Variable Costs ( $ per Unit ) Total Fixed Costs ($ per unit ) Incre

mental

Mfg. Cost ($ per unit ) No. of Res

pon dents Percent Improve

ment MEF WF Ma

terials Labor Over

head Total Baseline 0.817 13.779 5 0.860 13.732 $0.01 $0.01 $0.00 $0.02 $0.07 $0.09 5 10 0.908 13.710 $0.25 $0.04 $0.01 $0.30 $0.61 $0.91 5 15 0.961 13.670 $3.18 $0.10 $0.04 $3.32 $1.01 $4.33 5 20 1.021 13.342 $10.71 -$0.02 $1.80 $8.89 $6.21 $15.10 5 25 1.089 9.220 $36.14 $8.61 $0.09 $44.84 $19.29 $64.13 5 30 * 35 1.257 7.601 $86.73 $10.94 $7.78 $105.45 $22.72 $128.17 5 40 1.362 7.610 $87.15 $10.94 $7.78 $105.87 $22.72 $128.59 5 45 1.485 8.570 $125.58 $15.52 $14.51 $155.61 $24.67 $180.28 4 50 1.634 8.570 $132.40 $15.68 $14.51 $162.59 $24.67 $187.26 4 * No data were submitted at this efficiency level

Technical Advancements
While the general function of clothes wash ers has not changed si nce the 2000 TSD, many different technologies have been implemented. As with dishwashers and other residential appliances, clothes washers are built on platform s whose baseline performance can be improved with design options. Some platforms are inheren tly more energy and water efficient than others, allowing a manufacturer to use fe wer design options to reach a part icular efficiency level, but

5-62there are efficiency limits inherent to every pl atform regardless of how many design options are employed. These limits affect the MEF as well as the WF.
Clothes washers currently often use electroni c controllers instead of electromechanical controllers, which were more pr evalent at the time of the 2000 TSD. Electronic controllers usually carry a cost premium over electromechan ical timers, driving up manufacturing cost. However, such controllers are appealing to cust omers and are required for some design options. Besides enabling certain design options, electron ic controllers allow owners to more easily monitor washer utilization, functiona l status, and other parameters. There are potential reliability benefits as well. For example, one reason that variable-water-height sele ctors are atypical in commercial top-loading clothes washers is that ow ners prefer not to give users the ability to select water levels. If they di d, users could attempt to wash a fu ll load on a “low water” setting, potentially damaging the washer and/or the clothe s being washed. Electronic controllers may be able to detect such overload conditions and stop the wash cycle before the clothes washer is harmed. Alternatively, controller s can be programmed to “reset” to default settings after each wash cycle. This forces the end-user select the appropriate cycle fo r each use, potentially reducing the incidence of accidental overloads.
Some manufacturers have also phased out mech anical transmission a nd clutch systems, replacing them with variable-sp eed electronic drive systems. Benefits include a reduction in mechanical complexity, increased cabinet sp ace to accommodate potential expansion of the basket/tub, and greater wash program flexibility. The substitution of electronics for mechanical systems can increase overall unit co st, particularly if fixed in-house assets that had been used to manufacture mechanical transmission and clutch systems become stranded assets.
Many design options available in residential clothes washer have ye t to find application in CCWs. The reliability and longevity requir ements of CCWs combined with the production scale issues are such that manufacturers avoid adding design options unless necessary. As the part count increases, so does the probability that the clothe s washer will break down, and purchased parts sourced just for CCWs are likely to carry a cost premium. Thus, DOE expects manufacturers will continue to introduce new feat ures first in the residential markets before transitioning them to the commercial field.
Since the 2000 residential clothes washer TSD was written, there have been numerous technological advances incorpor ated into clothes washers, and the manufacturing costs submitted to AHAM were based on residential clothes wash er models that are no longer in production. Thus, even if DOE could ascertain the manufact uring cost differential between commercial and residential clothes washers in 1996, that differential would no longer be valid for current models.
Most importantly, manufacturers have been able to improve the MEF and WF of agitator clothes washers at a much lower cost than they projected in 1996. Instead of using front-loading or non-agitator top-loading clothes washers as projected to meet a 1.26 MEF, current baseline 1.26 MEF CCWs consist of agitato r models with reduced water consumption, lower wash temperatures, and improved control systems. Thus , manufacturers were able to reach the current efficiency requirements at much lower cost than projected in 1996. One ma nufacturer noted that

5-63the costs of improved control systems are substantially higher than those of the electromechanical controls they replaced and th at the wash performance and hence end-user utility of top-loading clothes washers are aff ected by lower WF and higher MEF requirements.

Market Share
The market shares that AHAM used to aggr egate manufacturer-submitted data were valid for the residential clothes washer market in 1996. However, since then th ere has been significant consolidation by domestic producers, and multiple foreign brands have started selling their clothes washers in the United States. More impor tantly, the market shar es of producers in the residential clothes washer market are not equivalent to the market shares of manufacturers in the CCW industry.

Four to five residential cl othes washer manufacturers subm itted manufacturing cost data estimates for each efficiency level for the 1996 AHAM data request. However, there are currently essentially only three U.S. CCW manufacturers: Alliance Laundry Systems LLC (Alliance), General Electric GE Consumer & Indus trial (GE), and Whirlpool (via its acquisition of Maytag Corporation (Maytag)). The low num ber of manufacturers limits current AHAM data submittals to DOE since AHAM requires a minimum of three data points per efficiency level before it publishes any results.
Since AHAM adjusts incremental manufacturing cost data submittals by efficiency level on a market-share basis, the manufacturing cost s submitted by the largest manufacturers have the greatest weight. As noted above, the distri butions of market share by manufacturer for commercial and residential clothe s washers are quite different. Since DOE does not have access to the disaggregated data, ther e is no opportunity to compensate for market share differences between markets, even if the costs of manuf acturing residential and CCWs were the same.
Platform Mixing
DOE’s efforts to update the 1996 AHAM data submittal are hindered by the submittal’s aggregation of top- and front -loading clothes washers. Based on the AHAM-supplied energy and water use data, reproduced in Table 5.6.33, DOE assumes that th e cost and energy use tables contained only agitator top-loading data for efficiency improvement levels of up to, and including, 20 percent. This assumption is driven by the consistent water usage up to that point and the low incremental costs to reach that effi ciency level. Similarly, DOE assumes that the two highest efficiency levels, 45 and 50 percent improvement, ex clusively incorporated frontloading clothes washers. The 25 to 40 per cent improvement categor ies appear to have aggregated high-efficiency top- as well as front-l oading clothes washers.

5-64Table 5.6.33 1996 AHAM Residential Clothe s Washer Energy and Water Use Data Submittal Product Characteristics Energy Use ( kWh/cycle ) Water Use

Percent Improve

-ment MEF Total Energy w/Dryer

( kWh /cycle ) Clothes Container ( ft

3 ) Hot Water Machine Energy Dryer Energy ( gal / cycle ) ( gal / ft

3 )

Baseline 0.817 3.227 2.847 1.587 0.209 1.430 39.181 13.779 5 0.860 3.165 2.817 1.543 0.209 1.413 38.613 13.732 10 0.908 3.017 2.822 1.408 0.209 1.400 38.613 13.710 15 0.961 2.833 2.832 1.216 0.209 1.407 38.621 13.670 20 1.021 2.739 2.893 1.113 0.218 1.408 38.446 13.342 25 1.089 2.292 2.866 0.715 0.304 1.273 26.600 9.220 30 * 35 1.257 1.866 2.749 0.462 0.133 1.270 21.030 7.601 40 1.362 1.859 2.749 0.462 0.133 1.263 21.030 7.610 45 1.485 1.651 2.736 0.429 0.114 1.107 23.405 8.570 50 1.634 1.574 2.736 0.413 0.114 1.047 23.405 8.570 * No data were submitted at this efficiency level. Since DOE does not have access to the disaggregated data and the clothes washer platforms that underlie the AHAM data submittals , there is no method by which DOE can assess how relevant the data submittal is to the curr ent rulemaking. It is not clear to DOE which models were submitted at each efficiency level, whether these models use the same platforms as current CCWs, nor what efficiency improvements ma nufacturers have been able to achieve with these models since 1996.
Incompatibility of the MEF and WF Pairings
Table 5.6.33 shows the lowest shipment-wei ghted WF at 1.26 MEF. No top-loading clothes washers could reach 1.634 MEF in 1996, sugge sting that the clothes washers at the two highest efficiency levels consis ted of front-loading clothes wa shers, whereas baseline units consisted of agitator top-loading cl othes washers. The WF is lowe st at 1.26 MEF, indicating that the shipment-weighted WF for that efficiency level included clothes washers that had a lower WF than residential front-loading cl othes washers did at that time.
DOE is aware of an agitator top-loading CC W platform from a major manufacturer that had achieved a 7.3 WF via spray rinse. However, this unit was withdrawn from the market a number of years ago due to e nd-user complaints regarding rinse performance. The CEC database of current CCWs lists no top-loading cl othes washers with a similar WF. The closest model is an agitator top-loading washer platfo rm with an 8.3 WF. Th e top-loading clothes washer platforms currently listed in the CEC resi dential clothes washer database that meets the 7.6 WF does not exist in a commercial vers ion and consists of a non-agitator design.

5-65Thus, the results at 1.26 MEF in Table 5.6.33 suggest multiple platforms, likely consisting of agitator top-loadi ng with spray rinse, non-agitator top-loading, and front-loading residential clothes washers. Neither spray-ri nse agitator nor non-agitat or clothes washers are currently in production for comm ercial purposes. The incompa tibility between the WF of machine properties submitted to AHAM for the 1996 data submittal and machines currently on the market is yet another indication of how the projections of manufacturers diverged from the agitator top-loading clothes washers they developed to meet the 1.26 MEF/9.5 WF requirements.

Conclusion
There are sufficient changes in market condi tions due to intended use and cycle life, production scale, technical advancements, and market share to precl ude the use of the 1996 AHAM data submittal as a basis for the curren t CCW analysis. Furthermore, the 1996 AHAM data submittal cannot be factored into the analysis due to pl atform mixing and the resulting inability to disaggregate the data into top- and front-loading machines.
2000 TSD Reverse-Engineering Review
Further manufacturing cost data by effi ciency level was developed for the 2000 residential clothes washer rulemaking by DOE. Since DOE has access to this data, DOE has decided to review and publish data that rema ins relevant to the current CCW rulemaking.

Reviewed Models

For the 2000 residential clothes washer TS D, DOE reverse-engin eered 8 residential clothes washers in 1999 from manu facturers with substantial mark et shares. DOE subsequently developed cost models to estimate the manuf acturing costs of these washers at varying production levels.
The market share covered by the residential cl othes washer platforms reverse-engineered in 1999 was about 80 percent. Three of the wash ers shared a chassis with CCWs in 1999. DOE could make estimates regarding th e costs to update these platforms for commercial use, but the market share covered by these platforms is currently less than 20 percent of the commercial market, limiting the usefulness of the results.
All three of the major manufacturers currently serving the CCW industry have introduced new models or significantly revised existing m odels since the 2000 reside ntial clothes washer TSD. Some manufacturers have updated the drive systems and other major system components to differentiate their products or improve energy efficiency. As a result, there have been significant changes in the baseli ne cost of clothes washers th at the 2000 TSD could not have analyzed, even if it had re viewed CCW models.

Market Share and Scale
The U.S. CCW market is very small compared to the residential clothes washer market. Whereas shipments of residentia l clothes washers have been increasing, with more than 9.2

5-66million units in 2005, CCW sales have stagnated or declined to about 200,000 units per year. The residential clothes washer market is dominated by the merged Whirlpool-Maytag entity, which has an approximate combined market share of 70 percent. The residential clothes washer sales of this entity exceed 6 million units pe r year, approximately 30 times the entire CCW market.
This scale difference is important in this anal ysis because agitator top-loading residential and CCWs typically share many parts to minimize tooling and equipment investments. Thus, a manufacturer that benefits from high manufacturing volumes on th e residential side has a much larger potential base of units over which to depr eciate investments. Commercial assembly lines can be repurposed towards residential clothes washer production if the commercial top-loading washer platform is no longer cost effective to produce.
While the largest competitor in the U.S. cl othes washer manufacturing business may not realize much cost benefit due to manufacturing s cale in moving to 6 million units per year versus the 1.5 million units per year modeled during th e 2001 residential clothes washer rulemaking, there are other advantages to scale. For exam ple, research and development and other overhead functions can be leaner as a percentage of sa les revenue, yet still have far more available resources than comparable departments at lower-volume competitors.
High-volume competitors have a long history of improving the performance of agitator top-loading clothes washers via add-on design options such as sp ray rinse, nutating plates, and other means. For a lower-volume manufacturer, it is inherently more difficult to assemble and defend an intellectual-property portfolio. Sim ilarly, a low-volume manufacturer may have to wait for innovations to trickle down from comm on suppliers since high- volume manufacturers typically get first (and sometimes ex clusive) access to new technologies.
Manufacturers whose production comprises a high percentage of CCWs are thus impacted disproportionately by any regulatory bu rden regarding CCWs. One low-volume U.S. clothes washer manufacturer was contractually barred from manufacturi ng residential clothes washers from 1999 until 2004. While its subsequent SEC 10-K reports show significant growth in the residential market segment, commercial sales are still substantially highe r. As a result, this LVM is not only concentrated in the CCW market, but its lack of diversification makes it particularly sensitive to any im pacts on its CCW business as well.
The Low-Volume Manufacturer Case
The LVM has been successfully competing with much larger competitors in the commercial laundry market for several years. Based on the LVM's public SEC 10-K filings, DOE has estimated that the LVM derives about a third of its total revenues from the sales of clothes washers and dryers, which are usually bundled. Clothes washer sales by themselves account for more than 20 percent of total re venue. Laundry equipmen t for institutional use largely makes up the balance. For a detail ed breakdown of LVM revenues by product line and market segment, see appendix 13A of the TSD, which details DOE's me thodology and results for the LVM analysis.

5-67As of 2005, agitator top-loading clothes wash ers sold by the LVM into the commercial market segment represented abou t 70 percent of unit shipments and about 60 percent of total CCW revenues. Thus, any legislation that elimin ates the use of such cl othes washers from the commercial market would affect the LVM dispro portionably due to the relative importance of the business and its effect on manufacturing scale. Such a transition also poses a business risk since a platform change will reduce the value of accumulated spare-parts inventories, technician training, etc. to route operators. Thus, any switchi ng cost to other brands could be substantially reduced.

The LVM released a front-loadi ng clothes washer for sale in 1999 and does not presently manufacture any non-agitator top- loading clothes washers. As of 2005, its sales of front-loading clothes washers represent approximately 20 pe rcent of total washer unit shipments and approximately 35 percent of total washer revenues. Given the scal e of the manufacturer at the time, the design was likely optimized for very low production volume. Should the entire CCW industry be forced to migrate to front-loading clothes washers, the LVM would thus have to make substantial investments to make its design more cost competitive. While the LVM is already at work to reduce front-loading unit cost s, a market transition to front-loading washers accelerated by federal standards would most likel y result in the LVM moving its front-loading manufacturing offshore.
However, unlike its larger rivals, the LVM doe s not benefit from very large scale in its residential operations to help amortize the investments in research, development, plant expenditures, and implementation expenses. The size of the CCW market by itself is simply too small to justify large lump-sum investments. The agitator top-load ing units that the LVMmanufactures have benefited from years of investments and refinements, whereas the frontloading model received its first update in 2003.
Besides benefiting from ongoing development and investments, agitator top-loading clothes washers at the LVM also benefit from well-depreciated equipment and tooling and a long-term knowledge base. In the past, the LVM had residential sales well in excess of its CCW sales before a non-compete contract cut off the LVM from the residential market from 1999 until 2004. Thus, while the LVM has gained the experi ence of producing hundreds of thousands of top-loading clothes washers per ye ar, it has yet to gain the same experience with its front-loading clothes washer line.
The loss of the commercial market for agitator top-loading clothes washers is likely to make residential models of those clothes washer s too expensive to manufacture due to the much smaller scale. Whether the LVM could remain in the front-loading clothes washer business despite the loss of the agitator top-loading clothes washer business is also uncertain. To date, the LVM has been able to grow its business despit e adverse market conditions and much larger competitors.
Implications of Scale for the Low-Volume Manufacturer

5-68As discussed previously, most of the clothes washers under review in the 2001 residential clothes washer rulemaking did not share a chassis with a commercial model. Thus, the results of the engineering analysis in the 2000 TSD do not apply to present day CCWs except for a very narrow set of observations.

A universal factor in manufact uring is scale, which descri bes how many units over which a fixed investment can be amortized. As part of the 2000 reverse-engi neering analysis for residential clothes washers, DOE tried to understand the implications of low-volume manufacturing. Figure 5.6.17, origin ally published as Figure 5.10 in the 2000 residential clothes washer TSD, averages the cost differences am ong multiple baseline top-loading vertical-axis residential clothes washers at production levels of 1.5 million and 0.3 million units per year. It also averages front-loading horizontal-axis resu lts for the residential front-loading horizontalaxis clothes washers that DOE reverse-engineered.

Figure 5.6.17 2000 Low-Volume versus High-Volume Clothes Washer Cost Disadvantage

While the units under review in the 2000 re sidential clothes washer TSD are not applicable to the current CCW analysis, the impact of manufacturing scale is still relevant to the CCW market. As manufacturing vol umes shrink, labor costs rise due to growing inefficiencies within the fabrication and assembly lines. The effect of manufacturing scale on depreciation is even more pronounced, as there are minimum too ling and equipment investments required to

5-69start operations, regardless of what the actual manufacturing volume turns out to be. Careful design will minimize the amount of additional tooling required to bring a new product to market.
Results from the 2000 TSD analysis for the effects of manufacturing scale are presented as follows, recognizing that similar results wi ll likely apply to CCWs. Figure 5.6.18 examines the case of very low-producti on volumes (100,000 units per y ear) versus producing at high volumes (1,500,000 units per year). Driven mainly by increases in deprecia tion costs, the very low-volume manufacturing cost increment over high-volume manufacturing increases to about $80 for both top-loading vertical -axis and front-loading horizonta l-axis clothes washers.

$0.00 $10.00 $20.00 $30.00 $40.00 $50.00 $60.00 $70.00 $80.00 $90.00USD Other Depreciation Labor Materials

V-Axis H-Axis

Figure 5.6.18 2000 Cost Disadvantage of Producing 100,000 versus 1.5MM Clothes Washers per Year with Green Field Facility

The agitator top-loading clothe s washer market is largely commoditized, resulting in fierce price competition. A $156 price differenc e for the end user ($80 manufacturing cost multiplied by a 1.93 total markup (see chapter 7 of this TSD)) is not likely to be sustainable. However, the LVM is aided in this product segm ent by the extant tooling and equipment, years of research and development, etc. which represent a sunk cost.
In contrast, the front-loading clothes washer manufacturing line would have to increase its output by multiples to meet the unit demand that the top-loading line currently sustains. Since the two platforms do not share many components, the top-loading line would be likely to be written off, while substantial investments would be required to expand the output of the frontloading line. Such investments may not be justified by the pote ntial market for them, and the

5-70larger rivals have a great adva ntage in terms of leveraging th eir residential clothes washer shipments to minimize depreciation on a per-unit basis.
Thus, while the LVM may be able to compet e with its bigger rivals on the agitator toploading platform due to depreciated plant and equipment, prior high-volume experience, and a long learning curve, it would be competing at a great disadvantage with it s larger rivals should front-loading CCWs become the only platform that can meet future energy efficiency standards.
Manufacturers operating at very low volumes are likely to face margin pressure for both top- and front-loading clothes washers. To c ounter pressure from hi gh-volume manufacturers, low-volume producers have to compete on the basi s of service, reliability, bundling, and product differentiation. Its long legacy in the agitator top-loading market also aids the LVM in competing successfully with larger rivals.

Conclusion
In conclusion, the LVM faces larger rivals in all of the clot hes washer markets it competes in, yet the LVM has been able to grow its revenue despite bein g heavily concentrated in the stagnant CCW market. As a result, the elimination of the agitat or top-loading clothes washer platform from the CCW market would impact this manuf acturer disproportionately and could therefore represent a mate rial risk to the company.
Other Observations Regarding the 2 000 Residential Clothes Washer TSD
Historic Background
When DOE began the 2001 residential clothe s washer rulemaking, the U.S. residential clothes washer market consisted almost exclusivel y of top-loading vertical-axis platforms. Table 3.9 in the 2000 TSD noted that top-loading ve rtical-axis clothes wa shers comprised a 99.9 percent market share as of 1995. Available fr ont-loading horizontal-axis clothes washers were limited to imported goods and two domestic platfo rms. While the majority of overall clothes washer shipments in the United States still consis t of top-loading clothes washers, the shipment levels and market share of front-loading clothes washers have grown significantly.
Unlike in 1995, all remaining U.S. manufactur ers now sell front-loading clothes washers that are either produced in thei r own factories or outsourced. Th e majority of residential frontloading clothes washers sold in the United Stat es today are manufactur ed abroad. While a greater proportion of CCWs are made domestically, significant market scale differences remain. Thus, as markets for top-loading clothes washer s decline, domestic clothes washer production will likely decline also.
In the 1996 AHAM data submittal, the maximum potential improvement was capped at an MEF of 1.634, whereas front-loading clothes washers from multiple vendors currently reach MEFs in excess of 2.00. Manufacturers have also increased the basket capacity of top- and front-loading clothes washers, reaching up to 4.7 ft 3 in some residential models. The WFs are

5-71also significantly lower on se veral current front-loading cl othes washers found in either residential or CCW markets than they were for models in the 2000 TSD.

As a result of the residential clothes wash er rulemaking, the standards for residential clothes washers were increased in two steps, reaching an MEF of 1.26 as of January 1, 2007. When that standard was issued, no front-loadi ng clothes washer MEFs were below 1.26. Thus, only top-loading clothes washers we re affected by the rulemaking. In the interim, manufacturers worked to find the most cost-effective way to mo dify their top-loading platforms to meet the current minimum MEF.
At the time of the 2000 TSD, a correlation was noted and assumed between MEF and WF (see Table 5.6.33). However, no WF was imposed in the final rulemaking. As a result, manufacturers could largely focu s on reducing the energy content of the wash and rinse water rather than having to jointly focus on the MEF and the WF. None of the agitator top-loading clothes washers that currently meet the 1.26 MEF minimum efficiency standard also reach the WF predicted for that efficiency level by the 2000 TSD. Typically, su ch current top-loading clothes washers use two more gallons of water per ft 3 of capacity than the WF associated with the 1.26 MEF standard in the 2000 TSD.
Impact of Product Test Procedures
EPACT 2005 amended EPCA to require DOE to rate CCWs with the same test procedure established for residential clothes washers. (42 U.S.C. 6314(a)(8)) DOE adopted test procedures for CCWs in a final rule published on Oc tober 18, 2005. 70 FR 60407, 60416. The testing procedure for residential clothes washers is codified in 10 CFR part 430, subpart B, appendix J1.
When calculating MEF, the DOE test procedur e factors in end-user-selectable variables including the wash and rinse water temperatures, and fill level. Thus, adaptive water levels (either user-set or automatic) a nd temperature choices are accounted for in the calculation. Some design options, such as reducing th e amount of rinse water, have an efficiency benefit regardless of the user-set program. Thes e and other design options have allowed the three highest-volume CCW manufacturers to reach the 1.26 MEF standard level at relatively low cost by making evolutionary changes to thei r top-loading platforms.
For example, the calculated MEF is a func tion of the cycle water temperatures. By requiring a cold rinse and offering more warm or cold wash programs while reducing the number of hot wash cycle options, the MEF of a washer can be raised without affecting the WF. The incremental cost of offering more wash temperat ures or lowering the temperatures overall is relatively minor. Similarly, the added cost and complexity of offering a water level selector switch is relatively minor but it allows manufacturers to take advantage of the credits that the DOE test procedure gives to washer s that have this design option.

At the time of the AHAM data submittal for the 2000 TSD, clothes washer manufacturers had little experience with the upda ted clothes washer test proce dure, which was not published in the Federal Register until August 27, 2000. The only top-load ing clothes washers on the market at the time that could reach an MEF of 1.26 were proprietary in design. Furthermore, the clothes

5-72washer manufacturing cost estimates for the 1.26 MEF levels were an amalgam of the high-cost proprietary top-loading design and se veral front-loading washers.
In conclusion, the cost of upgrading top-lo ading washers to reach an MEF of 1.26 was lower than manufacturers estimated accordi ng to the AHAM-supplied data. No expensive design options had to be employed to push the top-loading platform to that MEF level. Therefore, DOE believes that the current manufactur ing cost of an agitat or top-loading clothes washer that meets the 1.26 MEF/9.5 WF efficiency level is within 10 perc ent of the cost of a baseline washer in Table 5.6.33 once thes e costs are adjusted for inflation.
Persistence of Baseline Top-loading versu s Front-loading Clothes Washer Cost Differential
Since the publication of the 2000 TSD, the clothes washer market has been transformed by the entrance of more foreign competitors, significant market consolidation, and the appearance of residential clothe s washers that have higher load capacities than the basketcapacity limits defined by EPACT 2005. For exam ple, front-loading residential clothes washers from BSH Home Appliances Cor poration (Bosch-Siemens), GE, LG Electronics, Inc. (LG), and Whirlpool have a stated basket capacity in excess of the 3.5 ft 3 capacity product class definition limit set by EPACT 2005 for resi dential clothes washers.
Despite the entrance of multiple front-loadi ng clothes washers into the commercial and residential markets, a significant retail price diffe rence between agitator top- and front-loading clothes washer platforms persists. This suggest s that manufacturers ha ve yet to overcome the inherently higher costs associat ed with manufacturing front-loadi ng clothes washer platforms.
These cost differences are due in part to the suspensions, seals, drive systems, and stainless-steel wash baskets that front-loading clothes washers em ploy and which can be simpler, unnecessary, and/or less expensiv e in baseline top-loading models. The higher strength, stiffness, and vibration-resistan ce requirements for front-loading cl othes washers add further cost and complexity. Electronic drive systems are found in all front-loading clothes washers, whereas simpler and less expensive induction motors ar e typically found on baselin e top-loading clothes washers.
High-volume manufacturers of t op-loading clothes washers al so benefit from a plant and equipment stock that have been largely depreciate d, yet remain functional. The growth in frontloading clothes washer sales continues to demand factory expansi on and the resultant investments.
As noted above, the reverse-engineering anal ysis of the 2000 residential clothes washer TSD is largely not a valid basis upon which to compare costs in the commercial market. However, it is interesting to note how manufacturers were able to meet the current 1.26 MEF residential clothes washer standard with little to no additional manufacturi ng cost. Thus, the cost of a baseline top-loading washer has not changed much in the in terim, other than to reflect changes in raw materials costs. Front-loading clothes washer costs are similarly affected, so that

5-73the manufacturing cost differential between the two residential clothes washer platforms has remained largely the same.
The retail pricing survey for this current TSD underscores this persiste nt differential, as noted in Figure 3.11.1 in chapter 3 of this TSD. This figure demonstrates that the average retail price difference between commercial top-loadi ng and front-loading wash ers varies between $531 for washers with coin boxes and $625 for washers without coin boxes. As noted in chapter 7 of this TSD, the total markup from manufacturer to end user is 1.93 fo r CCWs. Therefore there is a manufacturing cost difference of $275 to $327 between top-loading and front-loading CCW platforms. This difference is about $100 higher than th e average difference cal culated in the 2000 residential clothes washer TSD between a baseli ne top-loading and two front-loading clothes washers that were subjected to reverse-engineering an alysis. However, the residential designs were produced at much a higher manufacturing s cale, suggesting higher co st optimization, better purchasing power, and lower ra w material costs. Higher- volume manufacturing allows a manufacturer to consider more platform and design options th at could not be economically justified at a very low manufacturing scale.
Thus, the $316 cost difference in the AHAM-s ubmitted data for top-loading and frontloading CCWs is plausible. A cost difference highe r than that found in the residential market is reasonable since CCWs are designed to be more r ugged, are required to be more reliable, and are produced at a much lower scale. As a conse quence, manufacturers cannot readily cost-optimize front-loading designs to the extent that they have been able to refine their extant top-loading units. In addition, even an optimized front-loa ding CCW will remain inherently more expensive to produce than a high-volume residential mode l built on the same platform due to the volume over which customized items like cont rollers have to be depreciated.

5-74REFERENCES

1 U. S. Department of Energy (DOE). 1996. Technical Support Document for Residential Cooking Products. Wa shington, DC. Available online at http://www.eere.energy.gov/buildings/appliance_stan dards/residential/cooking_products_0998_r.html

2 American Metals Market. Available online at http://www.amm.com/

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3 Association of Home Appliance Manufacturers (AHAM). 2006. AHAM Test Data on Microwave Ovens . October 23, 2006. Docket N o. EE-2006-STD-0127, Comment Number 17.

4 Ibid

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5 Ibid

.

6 Ibid.

7 Ibid

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8 Ibid

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9 Fish, N. et al . 2006. Standby Power Energy Use of Common Household Appliances

. Canadian Building Energy End-Use Data and Analysis Centre, CBEEDAC 2006-RP-04­ DRAFT, July 2006.

10 Aulenback, A. et al . 2001. Stand-By Power Requirements for Household Appliances

. Canadian Residential Energy End-Use Data and Analysis Cent re, CREEDAC-2001-05-04, May 2001.

11 Ibid

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12 Lawrence Berkeley National Laboratory (LBNL). 1999. Standby Power Summary Table

. Available online at http://standby.lbl.gov/Data/SummaryTable.html

.

13 Floyd, D. and Webber, C. 1998. “Leaking Elec tricity: Individual Field Measurement of Consumer Electronics.” Proceedings of American Council for an Energy-Efficient Economy , Florida Solar Energy Center, August 1998.

14 Meier, A. and Huber, W. 1997. Results from the Investigations on Leaking Electricity in the USA . Lawrence Berkeley National La boratory, Berkeley, CA, LBNL-40909, 1997.

15 AHAM. 2006. Op. cit

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5-7516 U.S. Department of Energy (DOE). 1980. Engineering Analysis . Washington, DC, DOE/CS-1066, June 1980.

17 AHAM. 2006. Op. cit

.

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