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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

4.2.2 Remaining Design Options.............................................................................................. 4-3

LIST OF TABLES

Table 4.2.1 Retained Design Options for Portable ACs............................................................. 4-3
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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 design options identified in the market and technology assessment for

portable air conditioners (ACs) (chapter 3 of this preliminary technical support document 

(TSD)). In the market and technology assessment, DOE presented an initial list of technologies 

or design options that can be used to reduce energy consumption for portable ACs. The goal of 

the screening analysis is to identify any design options that will be eliminated from further 

consideration in the rulemaking analyses.

The candidate design options are assessed based on DOE analysis as well as inputs from 

interested parties including manufacturers, trade organizations, and energy efficiency advocates. 

Design options that are judged to be viable approaches for improving energy efficiency are 

retained as inputs to the subsequent engineering analysis. Design options that 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 design option is 

detailed in the following sections.

4.2 DISCUSSION OF DESIGN OPTIONS

For portable ACs, the screening criteria specified in section 4.1 were applied to the 

design options to either retain or eliminate each technology from the engineering analysis. 

4.2.1 Screened-Out Design Options

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. 6291–6309) EPCA provides criteria for prescribing new or amended 

standards, which will achieve the maximum improvement in energy efficiency the Secretary of 

Energy determines is technologically 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)) 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 
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“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. 6295 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 design options that were screened out for this 

rulemaking, and the reasons why they were eliminated.

Ducting Insulation

In the market and technology assessment, chapter 3 of this preliminary TSD, DOE 

identified duct insulation as a potential means for improving portable AC efficiency. Heat lost 

from ducts to the conditioned space offsets a significant amount of cooling capacity provided by 

the portable AC. If manufacturers insulate the product ducting, more heat will be exhausted 

outside of the conditioned space rather than transferred through the duct.

During manufacturer interviews, DOE requested feedback on the potential use of 

insulated ducts to reduce heat loss to the conditioned space. Manufacturers provided feedback 

that they have considered insulated ducts to improve performance, but have not identified any 

insulated ducts that may be collapsed for packaging. DOE notes that no units in its test and 

teardown sample included insulated ducts; all units incorporated accordion-style plastic ducts 

that ship in a compacted state. When expanded, the ducts typically span more than 6 feet. In the 

absence of a collapsible insulated duct, product packaging would have to house the ducting in its 

expanded configuration. 
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DOE has screened out insulated ducting based on factors 1, 2, and 3 listed above. For 

technological feasibility, DOE is not aware of collapsible insulated ducts in any commercially 

available products or working prototypes. Accordingly, insulated ducts would not be practicable 

to manufacture and ship and would have an adverse impact on consumer utility due to the 

significantly larger package that would be required to accommodate the insulated ducts.

4.2.2 Remaining Design Options

Table 4.2.1 lists the design options for portable ACs that were retained by DOE for at 

least one of the analyzed product classes. Each of these technologies will be evaluated further in 

the subsequent engineering analysis.

Table 4.2.1 Retained Design Options for Portable ACs

Increased Heat-Transfer Surface Area

1. Increased frontal coil area 

2. Increased depth of coil (add tube rows) 

3. Increased fin density 

4. Add subcooler to condenser coil 

Increased Heat-Transfer Coefficients 

5. Improved fin design 

6. Improved tube design 

7. Spray condensate onto condenser coil 

8. Microchannel heat exchangers 

Component Improvements 

9. Improved compressor efficiency

10. Improved blower/fan efficiency 

11. Low-standby-power electronic controls

12. Improved duct connections

13. Case insulation

Part-Load Technology Improvements 

14. Variable-speed compressors 

15. Thermostatic or electronic expansion valves