CHAPTER 4. SCREENING ANALYSIS

TABLE OF CONTENTS

4.1 INTRODUCTION

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4.2 DISCUSSION OF DESIGN OPTIONS

.............................................................................. 4-1

4.2.1 Screened-Out Design Options

.............................................................................................. 4-1

4.2.1.1 Residential Clothes Dryers

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4.2.1.2 Room Air Conditioners

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4.2.2 Remaining Design Options

................................................................................................... 4-3

4.2.2.1 Residential Clothes Dryers

............................................................................... 4-3

4.2.2.2 Room Air Conditioners

..................................................................................... 4-4

LIST OF TABLES

Table 4.2.1 Retained Design Options for Residential Clothes Dryers

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Table 4.2.2 Retained Design Options for Room Air Conditioners

........................................... 4-5

4-iCHAPTER 4. SCREENING ANALYSIS

4.1 INTRODUCTION

This chapter discusses the screening analysis conducted by the U.S. Department of Energy (DOE) of the technology options identified in the market and technology assessment for residential clothes dryers and room air conditioners (chapter 3 of the preliminary notice of proposed rulemaking (pre-NOPR) technical support document (preliminary 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 technology options that will be eliminated from further consideration in the rulemaking analyses.

For each product, the corresponding candidate technology options are assessed based on DOE analysis as well as inputs from stakeholders including manufacturers, trade organizations, and energy efficiency advocates. Technology options which are judged to be viable approaches for improving energy efficiency are retained as inputs to the subsequent engineering analysis. Technologies that pass through the screening analysis are referred to as “design options” in the engineering analysis. Technology options which are not incorporated in commercial products or in working prototypes, or that fail to meet certain criteria as to practicability to manufacture, install and service, as to impacts on product utility or availability, or as to health or safety will be

eliminated 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 36974, section 4(a)(4) and 5(b). 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 clothes dryers and room air conditioners, the screening criteria specified in section 4.1 were applied to the technology options to either retain or eliminate each technology from the engineering analysis.

4.2.1 Screened-Out Technologies

The following section details the specific technology options that were screened out prior to the engineering analysis, along with the rationale for elimination.

The technologies identified in the market and technology assessment were evaluated pursuant to the criteria set out in The Energy Policy and Conservation Act, as amended (EPCA or the Act). (42 U.S.C. 6311-6317) EPCA provides criteria for prescribing new or amended standards, which will achieve the maximum improvement in energy efficiency the Secretary of

4-1Energy determines is technologically feasible. (42 U.S.C. 6313(a)(6)(A)) It also establishes guidelines for determining whether a standard is economically justified. (42 U.S.C. 6313(a)(6 )(B)) In view of the EPCA requirements for determining whether a standard is technologically feasible and economically justified, Appendix A to subpart C of Title 10 Code of Federal Regulations Part 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 efficiency standards under EPCA. These procedures elaborate on the statutory criteria provided in 42 U.S.C. 6313 and in part eliminate problematic technologies early in the process of revising an energy efficiency standard. Under the guidelines, 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 working prototypes, then that 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 and reliable installation and servicing of the technology 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 product type with performance 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 covered by this rulemaking and the reasons why each were eliminated.

4.2.1.1 Residential Clothes Dryers

For residential clothes dryers , DOE screened out microwave, water-cooling, and indirect heating, for the reasons that follow

Microwave, electric only Due to the large energy savings associated with microwave drying, this technology was the subject of a multiyear development effort at the Electric Power Research Institute (EPRI) in

the mid-1990s 1 ; and at least one major manufacturer, Whirlpool Corporation (Whirlpool), developed a countertop-scale version of such a product as recently as 2002 2 , but to date this technology has not been successfully commercialized.

4-2Significant technical and safety issues are introduced by the potential arcing from metallic objects in the fabric load, including zippers, buttons, or “stray” items such as coins

. While efforts have been made to mitigate the conditions that are favorable to arcing, or to detect incipient arcing and terminate the cycle, the possibility of fabric damage cannot be completely

eliminated. 3 In addition to consumer utility impacts, these conditions can also pose a safety hazard. For these reasons, microwave drying was not considered further for analysis.

Water-cooling, vent-less electric only Water-cooling for vent-less electric dryers, which uses water as a cooling fluid to condense the moisture in the air exiting the drum, would require significant plumbing in order to circulate water through a heat exchanger in the dryer. In addition, this technology option would add to the complexity of maintenance. Therefore, the water-cooling for vent-less electric dryers technology option does not meet the criterion of practicability to install and service on a scale necessary to serve the relevant market at the time of the effective date of a new standard and will be screened out of the analysis.

Indirect heating Indirect heating would only be viable in residences which use a hydronic heating system. Also, i n order to derive dryer heat energy from the home’s heating system, significant plumbing work would be required to circulate heated water through a heat exchanger in the dryer. Therefore, this technology option does not meet the criterion of practicability to install on a scale necessary to serve the relevant market at the time of the effective date of a new standard and will not be considered for further analysis.

4.2.1.2 Room Air Conditioners

For room air conditioners , DOE did not screen out any technologies.

4.2.2 Remaining Design Options

The following sections list the design options for both products covered by this rulemaking that were retained by DOE. Each of these technologies will be evaluated further in the subsequent engineering analysis.

4.2.2.1 Residential Clothes Dryers

For residential clothes dryers , DOE will consider the following design options for further analysis.

4-3Table 4.2.1 Retained Design Options for Residential Clothes Dryers Dryer Control or Drum Upgrades Improved termination

Increased insulation Modified operating conditions Improved air circulation

Reverse tumble Improved drum design
Methods of Exhaust Heat Recovery (vented models only) Recycle exhaust heat Inlet air preheat Inlet air preheat, condensing mode
Heat Generation Options Heat pump, electric only Modulating, gas only
Component Improvements Improved motor efficiency Improved fan efficiency
Standby Power Improvements Switching Power Supply Transformerless Power Supply with Auto-Powerdown

4.2.2.2 Room Air Conditioners

For room air conditioners , DOE will consider the following design options for further analysis.

4-4Table 4.2.2 Retained Design Options for Room Air Conditioners

Increased Heat Transfer Surface Area

Increased frontal coil area Increased depth of coil (add tube rows) Increased fin density

Add subcooler to condenser coil

Increased Heat Transfer Coefficients Improved fin design Improved tube design Hydrophilic film coating on fins Spray condensate onto condenser coil Microchannel heat exchangers
Component Improvements Improved indoor blower and outdoor fan efficiency Improved blower/fan motor efficiency Improved compressor efficiency
Part-Load Technology Improvements Two-speed, variable-speed, or modulating-capacity compressors Thermostatic or electronic expansion valves Thermostatic cyclic controls Standby Power Improvements Switching Power Supply

4-5REFERENCES

1 S. Ashley. 1998. “ Energy-Efficient Appliances”, Mechanical Engineering Magazine

, March, 1998, pp. 94

– 97.

2 E. Spagat. 2002. “Whirlpool Goes Portable to Sell Dryers to Gen Y”, Wall Street

Journal , June 4, 2002.

3 J.F. Gerling. 2003. “Microwave Clothes Drying— Technical Solutions to Fundamental Challenges”, Appliance Magazine , April, 2003, p. 120.

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