CHAPTER 4. SCREENING ANALYSIS 

TABLE OF CONTENTS 

4.1 INTRODUCTION.................................................................................................................4-1
 

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

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

4.2.1.1 Residential Clothes Dryers ............................................................................... 4-2
 

4.2.1.2 Room Air Conditioners..................................................................................... 4-3
 

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

Table 4.2.2 Retained Design Options for Room Air Conditioners ...........................................4-5
 

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CHAPTER 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 

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Energy 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-1990s1

; and at least one major manufacturer, Whirlpool Corporation (Whirlpool), 

developed a countertop-scale version of such a product as recently as 20022

, but to date this 

technology has not been successfully commercialized. 

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Significant 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, in 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. 

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Table 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. 

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Table 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 

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REFERENCES
 

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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