CHAPTER 4. SCREENING ANALYSIS

TABLE OF CONTENTS
4.1 INTRODUCTION

........................................................................................................... 4-1 4.2 DISCUSSION OF TECHNOLOGY OPTIONS

.............................................................. 4-1 4.2.1 Screened-Out Technology Options

.................................................................................. 4-2 4.2.1.1 Gas Cooktops

................................................................................................. 4-3 4.2.1.2 Electric Open (Coil) Cooktops

....................................................................... 4-4 4.2.1.3 Electric Smooth Cooktops

............................................................................. 4-5 4.2.1.4 Electric and Gas Ovens

.................................................................................. 4-5 4.2.1.5 Microwave Ovens

.......................................................................................... 4-7 4.2.2 Remaining Design Options

.............................................................................................. 4-7 4.2.2.1 Gas Cooktops

................................................................................................. 4-7 4.2.2.2 Electric Open (Coil) Cooktops

....................................................................... 4-8 4.2.2.3 Electric Smooth Cooktops

............................................................................. 4-8 4.2.2.4 Electric and Gas Ovens

.................................................................................. 4-8 4.2.2.5 Microwave Ovens

.......................................................................................... 4-9

LIST OF TABLES Table 4.2.1 Retained Design Options for Gas Cooktops

........................................................ 4-8 Table 4.2.2 Retained Design Options for El ectric Open (Coil) Element Cooktops

............... 4-8 Table 4.2.3 Retained Design Options fo r Electric Smooth Element Cooktops

...................... 4-8 Table 4.2.4 Retained Design Options for Electric and Gas Ovens

......................................... 4-9 Table 4.2.5 Retained Design Options for Microwave Ovens–Energy Factor

........................ 4-9

4-iCHAPTER 4. SCREENING ANALYSIS

4.1 INTRODUCTION This chapter discusses the screening anal ysis conducted by the U.S. Department of Energy (DOE) of the technology options identified in the market and technology assessment for residential cooking products a(chapter 3 of this technical support document (TSD)). In the market and technology assessment, DOE presented an initial list of technology options that can be used to reduce energy consumption of each of the products covered in this rulemaking. The goal of the screening analysis is to identify any technologies that wi ll be eliminated from further consideration in the rule making analyses. As described in se ction 1.3 of chapter 1 of this TSD, DOE is continuing the rulemaking for energy co nservation standards fo r commercial clothes washers and microwave oven standby power, and analyses related to these products will be published in separate TSDs. For each product, the corresponding candidate technology options are assessed based on DOE analysis as well as inputs from intere sted parties, includi ng manufacturers, trade organizations, and energy efficien cy advocates. Technology options th at are judged to be viable approaches for improving energy efficiency are reta ined as inputs to the subsequent engineering analysis, and are designated as design options. Technology options that ar e not incorporated in commercial products or in working prototypes, or that fail to meet certain criteria as to practicability to manufactu re, install and service, as to imp acts on product utility or availability, or as to health or safety will be elimin ated from consideration in accordance with Energy Conservation Program for Consumer Products: Procedures for Consideration of New or Revised Energy Conservation Standards for Consumer Products . 61 FR at 36974 (July 15, 1996). The rationale for either screening out or retaining each technology option is detailed in the following sections.

4.2 DISCUSSION OF TECHNOLOGY OPTIONS For residential cooking products, information us ed for applying the screening criteria to most of the technology options was derived fr om the previous rulemaking’s TSD, DOE’s 1996 Technical Support Document for Residential Cooking Products (1996 TSD). The framework document for this rulemaking, entitled Rulemaking Framework for Commercial Clothes Washers and Residential Dishwashers, Dehumidifiers, and Cooking Products , March 15, 2006, describes which technology options DOE reevaluated for the engineering analys is in the current rulemaking. The approach proposed in the framework document for conventional cooking products is to retain the same screening results as put forth in the 1996 TSD. In addition, lowaThe term “cooking products” refers to residential electric and gas kitchen ranges and ovens, including microwave ovens. The term “conventional cooking products” refers to cooking products other than microwave ovens.
4-1standby-loss electronics, which DOE identified for cooking products through literat ure searches and interested parties’ inputs, we re evaluated. It should also be noted that radiant elements for smooth cooktops, which were included as a technology option in the 1996 TSD, were not included in the current rulemaking because ma nufacturer data provided to DOE for the 1996 TSD indicated that this tec hnology did not demonstrate an efficiency improvement over the baseline according to the DOE test procedure, and DOE is unaware of any more recent data that indicates otherwise. For microwave ovens, technology options from the 1996 TSD for improving energy factor (EF) were screened in the same manner as in the previ ous rulemaking. However, three additional technologies–—cooking sensors, dual magnetrons, a nd low-standby-loss electronic controls—were evaluated. DOE identified cooking sensors from product literature, while dual magnetrons were added based on informa tion from the February 2006 edition of Appliance Design . DOE identified low-standby-loss electronic controls by reviewin g the Association of Home Appliance Manufacturers (AHAM) data for standby power.
4.2.1 Screened-Out Technology Options The following section details the specific techno logy options that were screened out prior to the engineering analysis, along wi th the rationale for elimination. The technologies identified in the market and technology assessment were evaluated pursuant to the criteria set out in the Energy Po licy and Conservation Act (EPCA) for prescribing new or amended standards which will achieve the maximum improvement in energy efficiency the Secretary of Energy determines is technol ogically feasible. (42 U.S.C. 6295(o)(2)(A)) It also establishes guidelines for determining whether a standard is economically justified. (42 U.S.C. 6295(o)(2)(B)(i)) In view of the EPCA requirements for determining whether a standard is technologically feasib le and economically justified, appendix A to subpart C of Title 10 Code of Federal Regulations pa rt 430 (10 CFR part 430), Procedures, Interpretations and Policies for Consideration of New or Revised Energy Conservation Standards for Consumer Products (the “Process Rule”), sets forth procedures to guide DOE in the consideration and promulgation of new or revised product energy c onservation standards under EPCA. These procedures elaborate on the statutory criteria provide d in 42 U.S.C. 6295(o)(2) and, in part, eliminate problematic technologies early in the pro cess of revising an energy cons ervation standard. Under the guidelines, before publishing an advance not ice of proposed rulemaking (ANOPR), DOE eliminates from consideration technologies that present unacceptable problems with respect to the following four factors: (1) Technological feasibility. If it is determined that a technology has not been incorporated in commercial products or in work ing prototypes, then th at technology will not be considered further. (2) Practicability to manufacture, install, and service. If it is determined that mass production of a technology in commercial products a nd reliable installation and servicing of the

4-2technology could not be achieved on the scale necessary to serve the relevant market at the time of the effective date of the standard, then that technology will not be considered further. (3) Impacts on product utility to consumers. If a technology is determined to have significant adverse impact on the utility of the product to significant subgroups of consumers, or results in the unavailability of any covered pr oduct type with perfor mance characteristics (including reliability), features, size, capacities, and volumes that are substantially the same as products generally available in the United States at the time, it will not be considered further. (4) Safety of technologies. If it is determined that a technology will have significant adverse impacts on health or safety, it will not be considered further. The following sections detail the technology options that were screened out for each product class covered by this rulemaking a nd the reasons why each were eliminated.
4.2.1.1 Gas Cooktops For gas cooktops, DOE screened out catalyt ic burners, radiant gas burners, reduced excess air at burner, and reflective su rfaces for the reasons that follow. Catalytic burners DOE is not aware of any commercialized catalytic burners for gas cooktops, so DOE believes that it would not be practicable to ma nufacture, install and se rvice this technology on the scale necessary to serve the relevant market at the time of the effective date of an amended standard. Also, because this technology is in th e research stage, it is not possible to assess whether it will have any adverse impacts on utilit y to consumers or product availability, or any adverse impacts on consumers' health or safety. Radiant gas burners In the previous rulemaking, ma nufacturers asserted that the op erating characteristics of an infrared (IR)-jet radiant burner ar e such that it is difficult to main tain a low burner input rate for many cooktop functions. They stated that field testing for residential ranges was discontinued because test users were unable to turn down the bur ner satisfactorily. 1 Without an adequate “turn down” capability, the burner would not be able to pass the American National Standards Institute (ANSI) Standard Z21.1-2005, Household Cooking Gas Appliances

. Although a silicon carbide radiant burner has been tested to the Japanese Industrial Standard (JIS) S 2103:1996, Gas burning cooking appliances for domestic use , it is also not known how either type of radiant burner woul d perform under DOE test conditions. Since DOE lacks relevant test data to evaluate potentia l impacts on consumers’ health and safety, this technology option was not an alyzed for gas cooktops.

4-3Reduced excess air at burner For the 1996 TSD, the Gas Research Inst itute (GRI, now known as the Gas Technology Institute) submitted a report that analyzed this technology option and was submitted as a comment to the NOPR in the previous rulemaking. 2 GRI concluded that the efficiency increase of this technology option was not measurable at that time. They pointed out that the burner described by DOE did not exist on the market a nd thus there were no designs that could be evaluated. DOE is unaware of any changes to that situation. GRI also noted that use of this technology option may cause a safety issue due to the possibility of increased carbon monoxide production.
Reduced excess air at the burner has not b een commercialized, and DOE believes that it would not be practicable to manufacture, inst all and service this technology on the scale necessary to serve the relevant market at the time of the effective date of an amended standard. Also, because this technology is undeveloped, it is not possible to assess whether it will have any adverse impacts on utility to consumers or pr oduct availability, or any adverse impacts on consumers' health or safety. . Reflective surfaces As reported in the 1996 TSD, ma nufacturers stated that any in crease in efficiency due to a reflective surface could easily be negated if the consumer fails to regularly clean the surface or uses an abrasive pad to clean the surface. Ther efore, it would be necessary to replace reflective pans periodically at a high replacement cost. Also, because this technology has not been commercialized, it is not possible to assess whether it will have any other adverse impacts on utility to consumers or product availability or any adverse impacts on consumers’ health or safety.

4.2.1.2 Electric Open (Coil) Cooktops For electric open (coil) cooktops, DOE scr eened out reflective surfaces, for the reasons that follow. Reflective surfaces As reported in the 1996 TSD, ma nufacturers stated that any in crease in efficiency due to a reflective surface could easily be negated if the consumer fails to regularly clean the surface or uses an abrasive pad to clean the surface. Ther efore, it would be necessary to replace reflective pans periodically at a high replacement cost. Also, because this technology has not been commercialized, it is not possible to assess whether it will have any other adverse impacts on utility to consumers or product availability, or any adverse impacts on consumers’ health or safety.

4-44.2.1.3 Electric Smooth Cooktops For electric smooth cooktops, all tec hnologies meet the screening criteria.

4.2.1.4 Electric and Gas Ovens For electric and gas, DOE screened out a dded insulation, bi-radiant oven, halogen lamp oven, no oven door window, oven separator, reduced thermal mass, and reflective surfaces, for the reasons that follow. Added insulation Although some analyses indicated energy c onsumption could be reduced by increasing the thickness of the insulation in the cabinet walls and doors from 2 inches to 4 inches, consumer utility would be negatively impacted, since the oven cavity volume would have to be reduced to maintain standardized exterior dimensions. Th e reduced oven cavity volu me would limit the size of large items that could be c ooked in the oven. For this reason, this technology option was not analyzed. However, it should be noted that improved insulation, consisting of higher-density insulation with the baseline 2-inch thickness, wa s still analyzed for standard gas and electric ovens. This higher-density insula tion is already used for self-clean gas and electric ovens. Bi-radiant oven (electric only) The 1996 TSD assumed that three major condit ions would have to be met in order to consider the bi-radiant oven as a viable technology option. Thes e included the use of (1) lowemissivity cavity lining materials; (2) electron ic controls; and (3) high ly-absorptive baking and roasting utensils. While electroni c controls are currently in wide spread use in electric ovens, cavity maintenance issues and the requiremen t for specialized cookw are negatively impact consumer utility. In addition, there is currently no such product on the market and the last working prototype known to DOE was tested in the 1970s. Halogen lamp oven (electric only) While GE Consumer & Industrial (GE) curren tly markets a line of electric ovens that incorporates halogen elements along with conve ntional resistance heati ng elements, microwave heating, and a convection system, DOE is not aw are of any ovens that utilize halogen lamps alone as the heating element, and no data were found or submitted to demonstrate how efficiently halogen elements alone perform relative to conv entional ovens. DOE believes that it would not be practicable to manufacture, install and service halogen lamps for use in consumer cooking products on the scale necessary to serve the rele vant market at the time of the standard’s effective date.

4-5No oven door window GRI issued a topical report 3 that discussed this tec hnology option in the previous rulemaking. The report was submitted as a written comment to the associated NOPR. GRI’s experimental tests showed a small savings in an nual energy usage (increase in efficiency) for both the standard and self-clean ovens by eliminating the door window. However, GRI reported there could actually be a net energy loss due to c onsumer practices, which would be a function of the number of times a consumer would open the door to inspect the f ood while cooking. With four door openings per test (per the DOE test procedure), a standard oven would realize a net energy savings of 34 thousand British thermal units per year (kBtu/yr). For a self-clean oven there is a net energy loss of 3 kBtu/yr. The re port also stated there w ould be reduced consumer utility and the possibility of fa ilure of delicate food items ( e.g. , soufflés), as well as decreased safety without the window due to increased risk of burns from additional door openings while the oven is in use. Oven separator
U.S. manufacturers stated in the previous rulemaking that the use of an oven separator has been researched but has never been put in to production because of problems it would cause both manufacturers and consumers. With regard to conventional gas ovens, manufacturers stated that the separator could not be economically designed for improved efficiency, though an acceptable design for gas convection ovens might be possible. With regard to electric ovens, manufacturers asserted that the separator would require the instal lation of an additional element and a non-conventional oven-control system. Manufacturers also stated thatit would be difficult to obtain Underwriters Laboratory (UL) and Am erican Gas Associati on (AGA) approvals and meet existing ANSI standards because of the e ffect the separator would have on safety and performance. Manufacturers further stated th at consumer acceptance would probably be low because appliances such as micr owave and toaster ovens already ex ist to cook small loads. In addition, the separator would have to be designed to be “fool-proof” to prevent consumers from accidentally installing it incorrectly. With regard to energy use, the additional metal added to the oven by the separator (increased thermal mass) might result in increased energy losses, although data provided by AHAM indicated an increase in efficiency of approximately 0.82 percentage points in an electric oven. However, the anti cipated negative impacts on consumer utility and safety, along with practicabil ity to manufacture, resulted in DOE screening out the oven separator from further analysis. Reduced thermal mass Manufacturers commented in the 1996 TSD th at thermal mass reduction was not possible for then-manufactured electric and gas ovens. They stated that the oven walls must provide strong enough support to hold racks when baking heavy items ( i.e. , turkeys or large roasts.) Oven metal gauges could not be reduced any further without risking crack ing and greater heat losses. 4 DOE believes this situation is still the case in current ovens. Due to issues of structural integrity during use and transportation as well as the issue of consumer product safety, this technology option was not analyzed.

4-6Reflective surfaces Manufacturers stated in the pr evious rulemaking that it has been very difficult to obtain satisfactory cooking performance with reflective su rfaces. The reflective ma terials degrade after the first baking function and continue to degr ade through the life of th e product. This is especially true of self -cleaning ovens, as the self-cleaning process damages the reflective walls and negates any possible energy savings. 5
GRI 6 performed tests on this technology option that measured a decrease in energy efficiency. The reflective surface interfered with the convective currents and the thermostat, thus fooling the thermostat into cycl ing. GRI reported that increased reflectance from the chromeplated inner surface of the oven cau sed repeated thermostat cycling that “might have contributed to the higher energy consumption” which re sulted in a 12.61 percen t decrease in energy efficiency. Arthur D. Little Inc. (ADL) 7 also commented that the reflected radiation was different from the normal radiation emitted by the oven cavities in use at the time. Based on these studies, it is uncertain whethe r, or how much, energy savings is realizable with this technology option. A smarter controller for the oven could potentially compensate for the thermostat problems. However, there is a ge neral lack of sophistica tion in the technology in terms of maintaining clean, reflective surfaces over the lifetime of the product. For these reasons, this technology option was not analyzed.

4.2.1.5 Microwave Ovens For microwave ovens, all technologies which im pact EF meet the screening criteria.
4.2.2 Remaining Design Options The following sections list the technology op tions for each product class covered by this rulemaking that were retained by DOE and subse quently designated as design options. Each of these technologies were evaluated further in the subsequent engineering analysis.
4.2.2.1 Gas Cooktops For gas cooktops, DOE retained the technol ogies listed below for further analysis.

4-7Table 4.2.1 Retained Design Options for Gas Cooktops 1. Electronic ignition 2. Insulation 3. Sealed burners 4. Thermostatically controlled burners
4.2.2.2 Electric Open (Coil) Cooktops For electric open (coil) cooktops, DOE c onsidered the following design options for further analysis. Table 4.2.2 Retained Design Options for Electri c Open (Coil) Element Cooktops

1. Electronic controls 2. Improved contact conductance 3. Insulation 4. Low-standby-loss electronic controls

4.2.2.3 Electric Smooth Cooktops For electric smooth cooktops, DOE retained the following technologies for further analysis. Table 4.2.3 Retained Design Options for El ectric Smooth Element Cooktops 1. Electronic controls 2. Halogen elements 3. Induction elements 4. Low-standby-loss electronic controls

4.2.2.4 Electric and Gas Ovens For electric and gas ovens, DOE retained th e following technologies for further analysis.

4-8Table 4.2.4 Retained Design Options for Electric and Gas Ovens 1. Forced convection 2. Improved door seals 3. Improved insulation 4. Low-standby-loss electronic controls 5. Pilotless ignition (gas only) 6. Radiant burner (gas only) 7. Reduced conduction losses 8. Reduced vent rate 9. Steam cooking

4.2.2.5 Microwave Ovens For microwave oven energy factor, DOE reta ined the technologies listed below for further analysis. Table 4.2.5 Retained Design Options for Microwave Ovens–Energy Factor

1. Added insulation 2. Cooking sensors 3. Dual magnetrons 4. Eliminate or improve ceramic stirrer cover 5. Improved fan efficiency 6. Improved magnetron efficiency 7. Improved power supply efficiency 8. Low-standby-loss electronic controls 9. Modified wave guide 10. Reflective surfaces

4-9REFERENCES

1 U.S. Department of Energy (U.S. DOE). 1998. Technical Support Document: Energy Conservation Standards for Consum er Products: Cooking Products , Washington, DC, September, 1998.

2 Gas Research Institute (GRI). 1994. Topical Report: Tech nical Input to NAECA Rulemaking for Gas-Fired Ranges . Prepared by Battelle, Columbus, OH, American Gas Association Laboratories, Clev eland, OH, and Arthur D. Little, Cambridge, MA for Gas Appliance Technology Center, Chicago, IL, submitted as comment No. 001 to the NOPR, GRI-94/0195, July 1994.

3 Ibid.

4 U.S. DOE. 1998. Op. cit.

5 Ibid.

6 GRI. 1994. Op. cit.

7 Arthur D. Little Inc. (ADL). 1994. Electric Oven and Cooktop Data Analysis . Prepared by ADL, Cambridge, MA, for Association of Home Appliance Manufacturers, Reference 47066, submitted as comment No. 001 to the NOPR, July 15, 1994.

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