CHAPTER 5. ENGINEERING ANALYSIS 

TABLE OF CONTENTS 

5.1 INTRODUCTION.................................................................................................................5-1
 

5.2 TECHNOLOGIES UNABLE TO BE INCLUDED IN THE ANALYSIS.......................5-1
 

5.2.1 Clothes Dryers.......................................................................................................................5-2
 

5.2.1.1 Reverse tumble .................................................................................................. 5-2
 

5.2.1.2 Improved termination........................................................................................ 5-2
 

5.2.2 Room Air Conditioners.........................................................................................................5-3
 

5.2.2.1 Improved Fin Design......................................................................................... 5-3
 

5.2.2.2 Improved Tube Design...................................................................................... 5-3
 

5.2.2.3 Hydrophilic-film coating on fins ...................................................................... 5-3
 

5.2.2.4 Spray condensate onto condenser coil ............................................................. 5-3
 

5.2.2.5 Improved indoor blower and outdoor fan efficiency ...................................... 5-4
 

5.2.2.6 Two-speed, Variable-speed, or Modulating-capacity Compressors .............. 5-4
 

5.2.2.7 Thermostatic or Electronic Expansion Valves ................................................ 5-4
 

5.2.2.8 Thermostatic Cyclic Controls ........................................................................... 5-5
 

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

5.4 EFFICIENCY LEVELS .......................................................................................................5-7
 

5.4.1 Baseline Units........................................................................................................................5-7
 

5.4.1.1 Active Modes..................................................................................................... 5-8
 

5.4.1.2 Standby Mode and Off Mode ......................................................................... 5-12
 

5.4.1.3 Integrated Efficiency ....................................................................................... 5-16
 

5.4.2 Incremental Efficiency and Standby Levels ..................................................................... 5-18
 

5.4.2.1 Active Mode .................................................................................................... 5-18
 

5.4.2.2 Standby Mode and Off Mode ......................................................................... 5-24
 

5.4.2.3 Integrated Efficiency ....................................................................................... 5-25
 

5.5 METHODOLOGY OVERVIEW ..................................................................................... 5-29
 

5.5.1 AHAM Data Request ......................................................................................................... 5-30
 

5.5.2 Manufacturer Interviews.................................................................................................... 5-30
 

5.5.3 Product Teardowns............................................................................................................. 5-31
 

5.5.3.1 Generation of Bill of Materials....................................................................... 5-32
 

5.5.3.2 Cost Structure of the Spreadsheet Models ..................................................... 5-32
 

5.5.3.3 Cost Model and Definitions............................................................................ 5-34
 

5.5.3.4 Cost Model Assumptions................................................................................ 5-35
 

5.5.4 Review of Previous Technical Support Documents and Models .................................... 5-35
 

5.5.5 Product Testing................................................................................................................... 5-35
 

5.6 ANALYSIS AND RESULTS ........................................................................................... 5-35
 

5.6.1 Clothes Dryers.................................................................................................................... 5-35
 

5.6.1.1 AHAM Data..................................................................................................... 5-36
 

5.6.1.2 Product Testing................................................................................................ 5-41
 

5.6.1.3 Product Teardown ........................................................................................... 5-53
 

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5.6.1.4 Cost-Efficiency Curves ................................................................................... 5-70
 

5.6.1.5 Manufacturer Interviews – Preliminary Analysis.......................................... 5-79
 

5.6.1.6 Manufacturer Interviews – Final Rule ........................................................... 5-83
 

5.6.2 Room Air Conditioners...................................................................................................... 5-85
 

5.6.2.1 AHAM Data..................................................................................................... 5-85
 

5.6.2.2 Manufacturer Interviews ................................................................................. 5-87
 

5.6.2.3 Product Teardowns.......................................................................................... 5-89
 

5.6.2.4 Energy Testing................................................................................................. 5-99
 

5.6.2.5 R-410A Conversion Costs ............................................................................ 5-100
 

5.6.2.6 Analysis Treatment of Design Options ........................................................ 5-101
 

5.6.2.7 Summary of Analysis Adjustments.............................................................. 5-119
 

5.6.2.8 Active Mode Analysis................................................................................... 5-120
 

5.6.2.9 Incremental Costs by CEER ......................................................................... 5-128
 

5.6.2.10 Product Class Modifications......................................................................... 5-133
 

5.6.2.11 Analysis Extension to All Product Classes.................................................. 5-138
 

LIST OF TABLES 

Table 5.3.1 Residential Clothes Dryer Product Classes..................................................................5-6
 

Table 5.3.2 Room Air Conditioner Product Classes .......................................................................5-7
 

Table 5.4.1 Clothes Dryer Baseline Active Mode Unit Efficiencies..............................................5-9
 

Table 5.4.2 DOE Test Results to Evaluate the Effects of the Test Procedure Amendments
 

on Measured EF ..................................................................................................... 5-11
 

Table 5.4.3 Clothes Dryer Baseline Active Mode Unit Efficiencies Revised for Test
 

Procedure Amendments ........................................................................................ 5-11
 

Table 5.4.4 Room Air Conditioner Baseline Active Mode Unit Efficiencies ............................ 5-12
 

Table 5.4.5 Clothes Dryer Standby and Off Mode Power Input Measurements ........................ 5-15
 

Table 5.4.6 Room Air Conditioner Standby and Off Mode Power Input Measurements.......... 5-16
 

Table 5.4.7 Baseline Clothes Dryer IEF........................................................................................ 5-17
 

Table 5.4.8 Baseline Clothes Dryer CEF ...................................................................................... 5-17
 

Table 5.4.9 Baseline Room Air Conditioner CEER for Analyzed Product Classes .................. 5-18
 

Table 5.4.10 Vented Clothes Dryer Active Mode Efficiency Levels – Preliminary
 

Analysis .................................................................................................................. 5-19
 

Table 5.4.11 Ventless Clothes Dryer Active Mode Efficiency Levels – Preliminary
 

Analysis .................................................................................................................. 5-20
 

Table 5.4.12 Vented Clothes Dryer Active Mode Efficiency Levels (Vented Electric
 

Standard and Vented Electric Compact (120V)) ................................................. 5-21
 

Table 5.4.13 Vented Clothes Dryer Active Mode Efficiency Levels (Vented Electric
 

Compact (240V) and Vented Gas) ....................................................................... 5-21
 

Table 5.4.14 Ventless Clothes Dryer Active Mode Efficiency Levels ....................................... 5-22
 

Table 5.4.15 Room Air Conditioner Active Mode Efficiency Levels--Product Classes 1 


and 3 – Preliminary Analysis................................................................................ 5-22
 

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Table 5.4.16 Room Air Conditioner Active Mode Efficiency Levels--Product Classes 5 


and 8 – Preliminary Analysis................................................................................ 5-23
 

Table 5.4.17 Room Air Conditioner Active Mode Efficiency Levels--Product Classes 1 


and 3 ....................................................................................................................... 5-23
 

Table 5.4.18 Room Air Conditioner Active Mode Efficiency Levels--Product Classes 5A
 

and 5B..................................................................................................................... 5-23
 

Table 5.4.19 Room Air Conditioner Active Mode Efficiency Levels--Product Classes 8A
 

and 8B..................................................................................................................... 5-24
 

Table 5.4.20 Clothes Dryer Standby Power Levels...................................................................... 5-24
 

Table 5.4.21 Room Air Conditioner Standby Power Levels ....................................................... 5-25
 

Table 5.4.23 Preliminary Analysis Clothes Dryer Integrated Efficiency Levels (IEF) –
 

Vented Product Classes......................................................................................... 5-25
 

Table 5.4.24 Preliminary Analysis Clothes Dryer Integrated Efficiency Levels (IEF) –
 

Ventless Electric Compact (240V) ....................................................................... 5-26
 

Table 5.4.25 Preliminary Analysis Clothes Dryer Integrated Efficiency Levels (IEF) –
 

Ventless Electric Combination Washer/Dryers ................................................... 5-26
 

Table 5.4.26 Clothes Dryer Integrated Efficiency Levels (CEF) – Vented Product Classes .... 5-27
 

Table 5.4.27 Clothes Dryer Integrated Efficiency Levels (CEF) – Ventless Electric
 

Compact (240V) .................................................................................................... 5-27
 

Table 5.4.28 Clothes Dryer Integrated Efficiency Levels (CEF) – Ventless Electric
 

Combination Washer/Dryers................................................................................. 5-27
 

Table 5.4.29 Preliminary Analysis Room Air Conditioner Integrated Efficiency Levels
 

(IEER)--Product Classes 1 and 3 .......................................................................... 5-28
 

Table 5.4.30 Preliminary Analysis Room Air Conditioner Integrated Efficiency Levels
 

(IEER)--Product Classes 5 and 8 .......................................................................... 5-28
 

Table 5.4.31 Room Air Conditioner Integrated Efficiency Levels (CEER)--Product
 

Classes 1 and 3....................................................................................................... 5-28
 

Table 5.4.32 Room Air Conditioner Integrated Efficiency Levels (CEER)--Product
 

Classes 5A and 5B ................................................................................................. 5-29
 

Table 5.4.33 Room Air Conditioner Integrated Efficiency Levels (CEER)--Product
 

Classes 8A and 8B ................................................................................................. 5-29
 

Table 5.5.1 Engineering Analysis Methods .................................................................................. 5-30
 

Table 5.5.2 Major Manufacturing Processes ................................................................................ 5-33
 

Table 5.6.1 AHAM Clothes Dryer Market Share Data Submittal............................................... 5-36
 

Table 5.6.2 AHAM Clothes Dryer Shipments and Shipment-Weighted Efficiency Data
 

Submittal ................................................................................................................ 5-37
 

Table 5.6.3 AHAM Clothes Dryer Incremental Cost Data Submittal......................................... 5-38
 

Table 5.6.4 AHAM Shipment-Weighted Clothes Washer RMC Data Submittal ...................... 5-41
 

Table 5.6.5 Vented Electric Standard Clothes Dryer Test Unit Features ................................... 5-42
 

Table 5.6.6 Vented Electric Compact (240 V), Gas, and Ventless Clothes Dryer Test Unit
 

Features .................................................................................................................. 5-43
 

Table 5.6.7 Average Change in Clothes Dryer Energy Factor as a Function of Initial
 

RMC as Compared to Initial RMC of 70 Percent................................................ 5-52
 

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Table 5.6.8 Results from DOE Testing of Maximum-Available Vented Gas Clothes 

Dryers ..................................................................................................................... 5-53
 

Table 5.6.9 Vented Electric Standard Clothes Dryer Incremental Manufacturing Costs .......... 5-71
 

Table 5.6.10 Vented Electric Compact (120V) Clothes Dryer Incremental Manufacturing 


Costs ....................................................................................................................... 5-72
 

Table 5.6.11 Vented Electric Compact (240V) Clothes Dryer Incremental Manufacturing 


Cost ......................................................................................................................... 5-73
 

Table 5.6.12 Vented Gas Clothes Dryer Incremental Manufacturing Cost ................................ 5-74
 

Table 5.6.13 Ventless Electric Compact (240V) Clothes Dryer Incremental
 

Manufacturing Cost ............................................................................................... 5-75
 

Table 5.6.14 Ventless Electric Combination Washer/Dryer Incremental Manufacturing
 

Cost ......................................................................................................................... 5-76
 

Table 5.6.15 Standby Power Incremental Manufacturing Cost ................................................... 5-77
 

Table 5.6.16 Cost-Efficiency Relationship for Vented Electric Standard Clothes Dryers ........ 5-77
 

Table 5.6.17 Cost-Efficiency Relationship for Vented Electric Compact (120V) Clothes
 

Dryers ..................................................................................................................... 5-78
 

Table 5.6.18 Cost-Efficiency Relationship for Vented Electric Compact (240V) Clothes
 

Dryers ..................................................................................................................... 5-78
 

Table 5.6.19 Cost-Efficiency Relationship for Vented Gas Clothes Dryers .............................. 5-78
 

Table 5.6.20 Cost-Efficiency Relationship for Ventless Electric Compact (240V) Clothes
 

Dryers ..................................................................................................................... 5-78
 

Table 5.6.21 Cost-Efficiency Relationship for Ventless Electric Combination
 

Washer/Dryers ....................................................................................................... 5-79
 

Table 5.6.22 AHAM Room Air Conditioner Product Class Market Share Data Submittal:
 

Product Classes 1 Through 5 ................................................................................ 5-85
 

Table 5.6.23 AHAM Room Air Conditioner Product Class Market Share Data Submittal:
 

Product Classes 6 through 16................................................................................ 5-86
 

Table 5.6.24 AHAM Room Air Conditioner Shipment Weighted Efficiency Data (EER)
 

Submittal: Product Classes 1 through 5 ............................................................... 5-86
 

Table 5.6.25 AHAM Room Air Conditioner Shipment Weighted Efficiency Data (EER)
 

Submittal: Product Classes 6 through 16 ............................................................. 5-86
 

Table 5.6.26 R-410A Teardown Products selected for validation of analysis............................ 5-90
 

Table 5.6.27 R-410A Characteristics of Selected R-410A 6,000 Btu/h 12.0 EER Units .......... 5-96
 

Table 5.6.28 Manufacturing Cost Increase for Drop-In Conversion to R-410A...................... 5-101
 

Table 5.6.29 Retained Design Options for Room Air Conditioners ......................................... 5-101
 

Table 5.6.30 Sizes and Weights of Product Class 1, 3, 5A, and 5B Teardown Units.............. 5-103
 

Table 5.6.31 Adjusted Baseline Size for Product Class 3 – 12,000 Btu/h Analysis ................ 5-105
 

Table 5.6.32 Product Class 5B – R-410A Product Sizes ........................................................... 5-106
 

Table 5.6.33 Size Increases Examined During Room Air Conditioner Design Option
 

Analysis ................................................................................................................ 5-106
 

Table 5.6.34 Baseline Product Weights of the Units for the Analyzed Product Classes......... 5-108
 

Table 5.6.35 Comparison of DOE Analysis Chassis Size and Market Chassis Size ............... 5-108
 

Table 5.6.36 Microchannel Condenser Costs - Preliminary Analysis ..................................... 5-111
 

Table 5.6.37 Motor Power Rating by Product Capacity ............................................................ 5-112
 

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Table 5.6.38 Comparison of a typical range of sizes for a 70W PSC Double-Shafted 

Motor and a 70W BLDC Motor ......................................................................... 5-114
 

Table 5.6.39 Maximum Compressor EER Levels ...................................................................... 5-117
 

Table 5.6.40 Standby Energy Consumption by Component...................................................... 5-119
 

Table 5.6.41 Summary of Key Adjustments to the Engineering Analysis during Final
 

Rule Analysis ....................................................................................................... 5-120
 

Table 5.6.44 Room Air Conditioner Cost-Standby/Off Mode Power Relationship................. 5-130
 

Table 5.6.45 Room Air Conditioner Cost-Efficiency Relationships for Product Classes 1 .... 5-130
 

Table 5.6.46 Room Air Conditioner Cost-Efficiency Relationship for Product Class 3 –
 

8,000 Btu/h Capacity Unit................................................................................... 5-131
 

Table 5.6.47 Room Air Conditioner Cost-Efficiency Relationship for Product Class 3 –
 

12,000 Btu/h Capacity Unit................................................................................. 5-131
 

Table 5.6.48 Room Air Conditioner Cost-Efficiency Relationships for Product Class 5A
 

– 24,000 Btu/h...................................................................................................... 5-131
 

Table 5.6.49 Room Air Conditioner Cost-Efficiency Relationships for Product Class 5B –
 

Table 5.6.50 Room Air Conditioner Cost-Efficiency Relationship for Product Class 8A –
 

Table 5.6.51 Room Air Conditioner Cost-Efficiency Relationship for Product Class 8B –
 

Table 5.6.52 Room Air Conditioner Cost-Efficiency Relationship for Product Class 3 –
 

Table 3.3.4 Size Increases Examined During Room Air Conditioner Design Option
 

28,000 Btu/h......................................................................................................... 5-132
 

8,000 Btu/h........................................................................................................... 5-132
 

12,000 Btu/h......................................................................................................... 5-132
 

Average ................................................................................................................ 5-133
 

Table 3.3.3 Comparison of 24,000 Btu/h and 28,000 Btu/h Incremental Costs ....................... 5-135
 

Analysis – Product Classes 5A and 5B .............................................................. 5-135
 

Table 3.3.5 Comparison of 8,000 Btu/h and 12,000 Btu/h Incremental Costs ......................... 5-137
 

Table 5.6.53 Product Class Grouping Criteria ............................................................................ 5-138
 

Table 5.6.54 Room Air Conditioner Representative Capacities and Operating Hours............ 5-139
 

Table 5.6.55 Room Air Conditioner Product Class Groupings ................................................. 5-139
 

LIST OF FIGURES 

Figure 5.5.1 Manufacturing Cost Assessment Stages .................................................................. 5-33
 

Figure 5.6.1 AHAM Clothes Dryer Cost-Efficiency Curves....................................................... 5-39
 

Figure 5.6.2 AHAM Data Submittal for Impact of Initial RMC on Clothes Dryer EF ............. 5-40
 

Figure 5.6.3 Measured Clothes Dryer Cycle Time versus Rated EF .......................................... 5-46
 

Figure 5.6.4 Measured Clothes Dryer Energy Consumption versus Rated EF .......................... 5-47
 

Figure 5.6.5 Measured versus Rated Clothes Dryer EF ............................................................... 5-48
 

Figure 5.6.6 Disaggregated Clothes Dryer Power Consumption................................................. 5-49
 

Figure 5.6.7 Impact of Initial RMC on Clothes Dryer EF (Calculated According to the
 

Existing DOE Test Procedure).............................................................................. 5-51
 

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Figure 5.6.8 Impact of Initial RMC on Clothes Dryer EF (Calculated Using Adjusted 

Scaling Factors) ..................................................................................................... 5-52
 

Figure 5.6.9 Baseline Vented Electric Standard Clothes Dryer Full Production Cost
 

Distribution ............................................................................................................ 5-56
 

Figure 5.6.10 Baseline Vented Electric Standard Clothes Dryer Materials Cost
 

Distribution ............................................................................................................ 5-57
 

Figure 5.6.11 Baseline Vented Electric Compact (240V) Clothes Dryer Full Production
 

Cost Distribution.................................................................................................... 5-58
 

Figure 5.6.12 Baseline Vented Electric Compact (240V) Clothes Dryer Materials Cost
 

Distribution ............................................................................................................ 5-59
 

Figure 5.6.13 Baseline Vented Gas Clothes Dryer Full Production Cost Distribution .............. 5-60
 

Figure 5.6.14 Baseline Vented Gas Clothes Dryer Materials Cost Distribution ........................ 5-61
 

Figure 5.6.15 Baseline Ventless Electric Compact (240V) Clothes Dryer Full Production
 

Cost Distribution.................................................................................................... 5-62
 

Figure 5.6.16 Baseline Ventless Electric Compact (240V) Clothes Dryer Materials Cost
 

Distribution ............................................................................................................ 5-63
 

Figure 5.6.17 Baseline Ventless Combination Washer/Dryer Full Production Cost
 

Distribution ............................................................................................................ 5-64
 

Figure 5.6.18 Baseline Ventless Combination Washer/Dryer Materials Cost Distribution ...... 5-65
 

Figure 5.6.19 Vented Electric Standard Clothes Dryer Cost-Efficiency Curves ....................... 5-71
 

Figure 5.6.20 Vented Electric Compact (120V) Clothes Dryer Cost-Efficiency Curve............ 5-72
 

Figure 5.6.21 Vented Electric Compact (240V) Clothes Dryer Cost-Efficiency Curve............ 5-73
 

Figure 5.6.22 Vented Gas Clothes Dryer Cost-Efficiency Curves.............................................. 5-74
 

Figure 5.6.23 Ventless Electric Compact (240V) Clothes Dryer Cost-Efficiency Curve.......... 5-75
 

Figure 5.6.24 Ventless Electric Combination Washer/Dryer Cost-Efficiency Curves.............. 5-76
 

Figure 5.6.25 Efficiency Range of Room Air Conditioner Teardowns ...................................... 5-90
 

Figure 5.6.26 Baseline HCFC-22 Product Class 3 (12,000 Btu/h) Room Air Conditioner
 

Material Cost Distribution ($157 total) ................................................................ 5-92
 

Figure 5.6.27 Baseline HCFC-22 Product Class 3 12,000 Btu/h Room Air Conditioner
 

Full Production Cost Distribution ($195 total) .................................................... 5-93
 

Figure 5.6.28 ENERGY-STAR R-410A Product Class 3 (12,000 Btu/h) Room Air
 

Conditioner Material Cost Distribution ($150 total) ........................................... 5-94
 

Figure 5.6.29 ENERGY-STAR R-410A Product Class 3 12,000 Btu/h Room Air
 

Conditioner Full Production Cost Distribution ($211 total) ............................... 5-95
 

Figure 5.6.30 Comparison of Energy Modeling Results with Rated Air Conditioner
 

Performance ........................................................................................................... 5-98
 

Figure 5.6.31 Energy Modeling Results for R-410A Drop-In..................................................... 5-98
 

Figure 5.6.32 Room Air Conditioner Energy Test Results.......................................................... 5-99
 

Figure 5.6.33 Size Distributions of Baseline-Efficiency Room Air Conditioners – HCFC
 

Products on the Market........................................................................................ 5-104
 

Figure 5.6.34 Size Distributions of Baseline-Efficiency Room Air Conditioners – R-410A
 

Products on the Market........................................................................................ 5-105
 

Figure 5.6.35 Cost Differential for Increasing PSC Motor Efficiency from 50% to 70%....... 5-113
 

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Figure 5.6.36. Cost Differential for Replacing a Baseline PSC Motor with a BLDC 

Motor. ................................................................................................................... 5-114
 

Figure 5.6.37 Compressor Performance Specifications – Preliminary Analysis...................... 5-116
 

Figure 5.6.38 R-410A Compressor Performance Characteristics – Final Rule Analysis ........ 5-117
 

Figure 5.6.39 R-410A Compressor Cost..................................................................................... 5-118
 

Figure 5.6.40 Product Class 1 Cost-Efficiency Curve ............................................................... 5-122
 

Figure 5.6.41 Product Class 3 - 8,000 Btu/h Capacity Cost-Efficiency Curve ........................ 5-123
 

Figure 5.6.42 Product Class 3 - 12,000 Btu/h Capacity Cost-Efficiency Curve ...................... 5-124
 

Figure 5.6.43 Product Class 5A – 24,000 Btu/h Cost-Efficiency Curve .................................. 5-125
 

Figure 5.6.44 Product Class 5B – 28,000 Btu/h Cost-Efficiency Curve................................... 5-126
 

Figure 5.6.45 Product Class 8A - 8,000 Btu/h Capacity Cost-Efficiency Curve ..................... 5-127
 

Figure 5.6.46 Product Class 8B - 12,000 Btu/h Capacity Cost-Efficiency Curve ................... 5-128
 

Figure 5.6.47 Comparison of the Cost-Effectiveness of Active and Standby Mode Design
 

Options ................................................................................................................. 5-129
 

Figure 3.3.1 R-410A Louvered Products – Efficiency versus Capacity ................................... 5-134
 

Figure 3.3.2 R-410A Products from DOE Survey of Non-louvered, Non-reverse-cycle
 

Products ................................................................................................................ 5-137
 

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CHAPTER 5. ENGINEERING ANALYSIS
 

5.1 INTRODUCTION
 

After conducting the screening analysis, the Department of Energy (DOE) performed an 

engineering analysis based on the remaining design options. The engineering analysis consists of 

estimating the energy consumption and costs of products at various levels of increased 

efficiency. This section provides an overview of the engineering analysis (section 5.1), considers 

technologies which are unable to be analyzed for this rulemaking (section 5.2), discusses 

established product classes (section 5.3), defines baseline unit specifications (section 5.4.1), 

discusses incremental efficiency levels (section 0), explains the methodology used during data 

gathering (5.4.2.3) and discusses the analysis and results (section 5.6). DOE completed separate 

engineering analysis for residential clothes dryers and room air conditioners. 

The primary inputs to the engineering analysis are baseline product information from the 

market and technology assessment (chapter 3 of the technical support document (TSD)) and 

technology options that are not eliminated in the screening analysis (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 tear-down analysis, 

energy modeling, 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 markups, sales tax and 

contractor markups. After applying these markups, they serve as the input to the building energyuse and end-use load characterization (chapter 6) and the life-cycle cost (LCC) and payback 

period (PBP) analysis (chapter 8). 

DOE typically structures its engineering analysis around one of three methodologies. 

These are: (1) the design-option approach, which 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 energy 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 “bottom-up” manufacturing cost assessment based 

on a detailed bill of materials derived from teardowns of the product being analyzed. Deciding 

which methodology to use for the engineering analysis depends on the product, the design 

options under study, and any historical data that DOE can draw on. 

5.2 TECHNOLOGIES UNABLE TO BE INCLUDED IN THE ANALYSIS 

In performing the engineering analysis, DOE did not consider for analysis certain 

technologies that met the screening criteria but were unable to be evaluated for one or more of 

the following reasons: (1) data are not available to evaluate the energy efficiency characteristics 

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of the technology; (2) available data suggest that the efficiency benefits of the technology are 

negligible; and (3) certain technologies cannot be measured according to the conditions and 

methods specified in the existing test procedure. In the first case, DOE is unable to adequately 

assess how these technologies impact annual energy consumption. In other cases, available data 

suggested that some of the design options resulted in such small energy savings as to be 

negligible. Because DOE intends to focus on the technologies with measurable impact on 

efficiency, design options with negligible energy savings have been eliminated from further 

consideration. 

5.2.1 Clothes Dryers 

5.2.1.1 Reverse tumble 

Manufacturers interviewed as part of the preliminary manufacturer interview analysis 

indicated that such a feature is used primarily for fabric care. The benefits of reverse tumbling 

include prevention of balling and wrinkling of the clothes load. No manufacturer indicated they 

use, or would consider, reverse tumble for increasing efficiency. Tests conducted by one 

manufacturer, in fact, found that the small size of the test cloths in the DOE test procedure 

prevents balling and thus no energy efficiency benefit can be measured.1

 At least one 

manufacturer stated that reverse tumble could actually reduce efficiency by stopping the drum 

rotation while it is changing directions. For reasons of no demonstrable energy savings and 

uncertainty as to whether its impacts can be measured by the existing test procedure, DOE will 

not further analyze reverse tumble. 

5.2.1.2 Improved termination 

Improved cycle termination is potentially possible by means of more accurate moisture 

sensors or by incorporating temperature and moisture sensors together. Alternatively, algorithms 

may be developed to more accurately detect end-of-cycle conditions. While each of these 

approaches may produce real-world energy savings by preventing consumers from over-drying 

the clothes load, the DOE test procedure requires that the test be terminated as soon as a certain 

level of dryness is achieved. A fixed field use factor is then applied to the measured energy 

consumption depending on whether timed or automatic cycle termination is present. Therefore, 

improved cycle termination cannot be measured by the test procedure. As discussed in chapter 3 

of this TSD, DOE proposed amendments to the clothes dryer test procedure to more accurately 

account for automatic cycle termination. However, DOE determined that the proposed 

amendments for automatic cycle termination do not adequately measure the energy consumption 

of clothes dryers equipped with such systems using the test load specified in the DOE test 

procedure. As a result, in the test procedure final rule published in the Federal Register on 

January 6, 2011 (76 FR 972) (hereafter the January 2011 TP Final Rule), DOE did not adopt the 

proposed amendments for automatic cycle termination (see chapter 3 of this TSD for more 

details). As a result, for this analysis, DOE did not further analyze improved termination. 

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5.2.2 Room Air Conditioners 

5.2.2.1 Improved Fin Design 

The louvered, raised-lance, or slit-fin fin designs currently used in nearly all room air 

conditioners are the most effective technologies for heat transfer to air. These designs work by 

repeatedly interrupting the surface in the flow direction, which prevents thermal boundary layers 

from growing. The air near the fin remixes with the bulk flow at the end of each louver, and a 

new boundary layer forms on the next louver. A similar approach is used in high performance 

heat exchangers in nearly all applications for which high heat transfer is required without 

incurring high penalties for air-side pressure drop. DOE is not aware of any other improved fin 

technology that can make further improvements in heat exchanger performance for room air 

conditioners. Hence, DOE did not further analyze this technology. 

5.2.2.2 Improved Tube Design 

Rifled tubes are currently used in nearly all room air conditioners. Variants of 

conventional spiral rifling have been developed, but they have not been shown to be more 

effective than the rifling which has become standard for tubes used in all air conditioning 

applications. DOE is not aware of any other improved tube technology that can make further 

improvements in heat exchanger performance for room air conditioners. Hence, DOE did not 

further analyze this technology. 

DOE did consider use of smaller diameter tubes in the engineering analysis, especially 

for use with R-410A refrigerant. 

5.2.2.3 Hydrophilic-film coating on fins 

During interviews conducted during the preliminary analysis phase, manufacturers 

indicated that hydrophilic film coatings do improve room air conditioner efficiency. However, 

they indicated that use of these coatings is standard practice for room air conditioners. Hence, 

DOE did not further analyze this technology. 

5.2.2.4 Spray condensate onto condenser coil 

Spraying of condensate onto the condenser coil is currently used in all room air 

conditioners. DOE questioned manufacturers during interviews about more effective approaches 

for use of the condensate, but no viable alternatives were identified. DOE measured the 

condenser fan power impact of the slinger ring on a typical room air conditioner and determined 

that filling the condensate pan with water and thus initiating slinging action made no noticeable 

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impact on fan power input. The engineering analysis incorporated use of condensate spraying 

into the energy use analysis. However, in no case was this technology used as the basis for 

estimates of possible efficiency improvement, since all baseline products were analyzed 

assuming they already have this feature. The effect of condensate spray on room air conditioner 

performance was based upon research to determine the effect that water spray had on heat 

exchanger performance.2 Hence, DOE did not further analyze this technology. 

5.2.2.5 Improved indoor blower and outdoor fan efficiency 

The indoor blowers and outdoor fans of current room air conditioners are molded plastic 

parts with complex geometries. The performance of these blowers and fans has improved as 

compared to stamped sheet metal fan blades used in the past. DOE expects that there may be 

potential for incremental improvement in air moving efficiency for some room air conditioners. 

However, there are no data available which can be used to predict this improvement. During 

manufacturer interviews, improvement in air moving efficiency through use of better fan blades 

or blower impellers was not identified as a viable option for improvement in room air 

conditioner efficiency. Hence, DOE did not further analyze these technologies. 

5.2.2.6 Two-speed, Variable-speed, or Modulating-capacity Compressors 

Two-speed, variable-speed, or modulating-capacity compressors can increase efficiency 

over a broad operating range, but they do not inherently increase the efficiency at the room air 

conditioner rating point. Because the DOE energy test procedure specifies steady-state 

maximum-capacity conditions for evaluation of active mode efficiency, the speed of a variablespeed compressor would remain at a constant maximum capacity (e.g. highest speed) during the 

test. As a result, there is no opportunity to measure the energy savings that such compressors can 

provide during part-load conditions, when, instead of cycling at high speed, they operate a 

reduced capacity to satisfy the load. In fact, the losses associated with the inverter board of a 

variable-speed compressor would decrease the maximum-capacity energy efficiency ratio (EER). 

Therefore, DOE did not further analyze this technology in the engineering analysis. 

5.2.2.7 Thermostatic or Electronic Expansion Valves 

Thermostatic or electronic expansion valves have the capability of maintaining optimum 

room air conditioner operating parameters over a broad range of operating conditions (outdoor 

and room temperature levels, during startup transients, and in case of high or low refrigerant 

charge). However, because the DOE energy test procedure for room air conditioners specifies 

steady state operating conditions, the benefit of these technologies will not be measured by the 

test. The design of a capillary expansion device can be adjusted to provide optimum operating 

conditions for the steady-state test. Therefore, DOE did not consider these technologies further in 

the engineering analysis. 

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5.2.2.8 Thermostatic Cyclic Controls 

Advanced thermostatic cyclic controls would be designed to control room air conditioner 

operation if the load is less than the room air conditioner capacity. The DOE energy test 

procedure, however, measures room air conditioner efficiency at full-capacity steady conditions. 

Hence, the test procedure cannot measure the efficiency benefits of alternative thermostatic 

controls which might improve control of the cycling (or modulation for variable capacity units) 

of the room air conditioner. Therefore, DOE did not further consider this technology in the 

engineering analysis. 

5.3 PRODUCT CLASSES ANALYZED 

DOE separated residential clothes dryers and room air conditioners into product classes. 

Because DOE formulated a separate energy conservation standard for each product class, the 

criteria for separation into different classes are: (1) type of energy used (natural gas or 

electricity), and (2) capacity or other performance-related features such as those that provide 

utility to the consumer, or others deemed appropriate by the Secretary that would justify the 

establishment of a separate energy conservation standard. (42 United States Code (U.S.C.) 6295 

(q))

 For residential clothes dryers, DOE considered four product classes for vented and two 

product classes for ventless clothes dryers, as shown in Table 5.3.1. This is a new analytical 

structure for clothes dryers, recognizing the unique utility that ventless clothes dryers offer to 

consumers. (Previously, DOE has described ventless clothes dryers as condensing clothes dryers. 

The new designation reflects the actual consumer utility (i.e., no external vent required) and the 

potential market availability of vented clothes dryers that also condense). Another new entry 

with unique utility is the combination washer/dryer (i.e., a device which washes and then dries 

clothes in the same basket/cavity in a combined cycle). Combination washer/dryers are suitable 

for space-constrained environments (e.g., apartments, recreational vehicles), and all products of 

this type appear to utilize ventless operation. Thus, like other ventless clothes dryers, such 

combination washer/dryers can be installed in locations where venting dryers would be 

precluded due to venting restrictions. As discussed in chapter 3 of this TSD, DOE recently 

adopted amendments to the clothes dryer test procedure in the January 2011 TP Final Rule to 

include provisions for testing ventless clothes dryers, thus allowing the consideration of ventless 

product classes. The amendments for ventless clothes dryers are discussed in more detail in 

chapter 3 of this TSD. 

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Table 5.3.1 Residential Clothes Dryer Product Classes 

Vented dryers 

1. Electric, Standard (4.4 cubic feet (ft3) or greater capacity) 

2. Electric, Compact (120 volts (v)) (less than 4.4 ft3 capacity) 

3. Electric, Compact (240 v) (less than 4.4 ft3 capacity) 

4. Gas 

Ventless dryers 

5. Electric, Compact (240 v) (less than 4.4 ft3 capacity) 

6. Electric, Combination Washer/Dryer

 For room air conditioners, amendments to the Energy Policy and Conservation Act 

(EPCA) of 1975, Pub. L. 94-163, (42 U.S.C. 6291–6309) in the National Appliance Energy 

Conservation Act of 1987 (NAECA), Pub. L. 100-12, initially specified 12 product classes for 

products designed for single- or double-hung window installation or through-the-wall installation 

and based on the following criteria: (1) cooling capacity; (2) the presence of louvered sides (LS); 

and (3) the capability of reverse cycle (i.e., the unit can function as a heat pump). (42 U.S.C. 

6295(c)(1)) Capacity is measured in British Thermal Units (Btu) per hour (h) (Btu/h). In the final 

rule published in the Federal Register on September 24, 1997, DOE established an updated set 

of performance standards (effective October 1, 2000) which included four additional product 

classes.a 

As detailed in chapter 3 of this TSD, DOE is establishing in this final rule four new product 

classes by splitting existing product classes 5 and 8 into two product classes each. Table 5.3.2 

lists the 18 resulting product classes for room air conditioners. See chapter 3 for additional 

discussion of the creation of these new product classes. 

Based on DOE’s estimate that higher-capacity units may be constrained by space limitations in 

their ability to incorporate design options that could raise energy efficiency, and the assumption 

that the increments in energy efficiency among the other product classes are well-defined by the 

increments in their associated minimum efficiency standards, DOE conducted a full analysis of 

product classes 1, 3, 5, and 8 during the preliminary analysis. For this final rule, DOE conducted 

full analyses of product classes 1, 3, 5A, 5B, 8A, and 8B. Product classes 1, 3, 5A, and 5B span 

the range of capacities of room air conditioners without reverse cycle and with louvered sides. 

Product classes 8A and 8B are intermediate-capacity product classes for room air-conditioners 

without reverse cycle and without louvered sides. These two product classes represent the 

a

 DOE divided the product class covering units with reverse cycle and with louvered sides into units of capacity less 

than 20,000 Btu/h and units 20,000 Btu/h or more. DOE split the product class covering units with reverse cycle and 

without louvered sides into units of capacity less than 14,000 Btu/h and units 14,000 Btu/h or more. In addition, 

DOE established two new product classes for units that are designed to be installed in casement-slider and casementonly windows. Due to the size constraints imposed by casement windows, casement units are small in size and 

typically deliver 5,000 to 10,000 Btu/h in cooling capacity. 

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majority of shipments of products without reverse cycle without louvered sides (see Figure 

3.15.10 in chapter 3). DOE then grouped each of the remaining 12 product classes with an 

analyzed product class that provided the best representation of cost effectiveness for improving 

its efficiency. This grouping is discussed in greater detail in section 5.6.2.11. 

Table 5.3.2 Room Air Conditioner Product Classes 

Without reverse cycle and with louvered sides 

1. Less than 6,000 Btu/h 

2. 6,000 to 7,999 Btu/h 

3. 8,000 to 13,999 Btu/h 

4. 14,000 to 19,999 Btu/h 

5A. 20,000 to 27,999 Btu/h 

5B. 28,000 Btu/h or more 

Without reverse cycle and without louvered sides 

6. Less than 6,000 Btu/h 

7. 6,000 to 7,999 Btu/h 

8A. 8,000 to 10,999 Btu/h 

8B. 11,000 to 13,999 Btu/h 

9. 14,000 to 19,999 Btu/h 

10. 20,000 Btu/h or more 

With reverse cycle 

11. With louvered sides and less than 20,000 Btu/h 

12. Without louvered sides and less than 14,000 Btu/h 

13. With louvered sides and 20,000 Btu/h or more 

14. Without louvered sides and 14,000 Btu/h or more 

Casement 

15. Casement-Only 

16. Casement-Slider 

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 conservation standards. The baseline unit in each 

product class represents the basic characteristics of equipment 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 engineering analysis and the LCC and PBP analysis. 

To determine energy savings and changes in price, DOE compared each higher-energyefficiency or lower-energy-efficiency design option with the baseline unit. 

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As discussed in chapter 3 of this TSD, EPCA requires that the test procedures for clothes 

dryers and room air conditioners be amended to include measurement of standby mode and off 

mode power, except where current test procedures fully address such energy consumption or 

such a procedure is technically infeasible. EPCA also requires that any final rule establishing or 

revising a standard for a covered product, adopted after July 1, 2010, shall incorporate standby 

mode and off mode energy use into a single amended or new standard, if feasible. If not feasible, 

the Secretary shall prescribe within the final rule a separate standard for standby mode and off 

mode energy consumption. (42 U.S.C. 6295(gg)) As discussed in chapter 3 of this TSD, DOE 

published the January 2011 TP Final Rule in which it amended the test procedures to include 

testing methods for measuring standby and off mode energy use for clothes dryers and room air 

conditioners. As part of the January 2011 TP Final Rule, DOE adopted new methods to calculate 

clothes dryer and room air conditioner standby and off mode energy use and new measures of 

energy efficiency (Combined Energy Factor (CEF) and Combined Energy Efficiency Ratio 

(CEER), respectively) that integrate standby and off mode energy use with the active mode 

energy use for both products. As a result, the engineering analysis and the energy conservation 

standards for clothes dryers and room air conditioners are based on these integrated metrics (CEF 

and CEER). The CEER is identical to the Integrated Energy Efficiency Ratio (IEER) metric used 

in the preliminary analysis documents, but renamed to avoid confusion with an existing industry 

standard. The “inactive” mode of this metric is now referred to simply as the standby mode. The 

CEF differs from the IEF metric previously used, in that it is based on a different number of 

annual cycles for the active mode analysis. 

Test data based on CEF and CEER, as defined in the January 2011 TP Final Rule, are not 

available for any products. As a result, baseline units for these metrics are defined using the 

baseline efficiency characteristics of products using current efficiency metrics and an 

understanding of the typical energy use of the products in standby and off modes. The following 

sections discuss active mode, standby/off mode(s), and integrated metric characteristics for 

baseline products. 

5.4.1.1 Active Modes 

The current minimum energy conservation standards for residential clothes dryers, as 

measured by energy factor (EF) in pounds (lb) per kilowatt-hour (kWh) under the previous DOE 

clothes dryer test procedure (found at 10 Code of Federal Regulations (CFR) part 430, subpart B, 

appendix D), became effective on May 14, 1994. Table 5.4.1 sets forth the standards for the four 

vented clothes dryer product classes. (10 CFR part 430.32(h)(2)) DOE used these existing energy 

conservation standards to characterize the baseline active mode unit efficiency for each of the 

vented product classes. DOE estimated baseline efficiencies for ventless dryers based upon 

testing it conducted on representative units, using the previous DOE clothes dryer test procedure 

without the exhaust simulator. 

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Table 5.4.1 Clothes Dryer Baseline Active Mode Unit Efficiencies 

Product Class EF (lb/kWh) 

Vented dryers 

1. Electric, Standard (4.4 ft3 or greater capacity) 3.01 

2. Electric, Compact (120 v) (less than 4.4 ft3 capacity) 3.13 

3. Electric, Compact (240 v) (less than 4.4 ft3 capacity) 2.90 

4. Gas 2.67 

Ventless dryers 

5. Electric, Compact (240 v) (less than 4.4 ft3 capacity) 2.37 

6. Electric, Combination Washer/Dryer 1.95 

In addition to adopting provisions for the measurement of standby mode and off mode 

power use, as discussed above, DOE also adopted amendments to the clothes dryer test 

procedure in the January 2011 TP Final Rule concerning the active mode. In particular, DOE 

adopted amendments to include provisions for the testing of ventless products. The amendments 

also included the following changes to reflect the current usage and capabilities of products to: 

(1) change the clothes dryer use cycles per year from 416 to 283, (2) change the initial remaining 

moisture content (RMC) of clothes dryer loads from 70 ± 3.5 percent to 57.5 ± 3.5 percent, and 

(3) change the clothes dryer test load size from 7.00 ± .07 pounds (lbs) to 8.45 ± .085 lbs for 

standard-size clothes dryers. In addition, the January 2011 TP Final Rule also amends the DOE 

clothes dryer test procedure to: (1) revise the detergent specifications for test cloth 

preconditioning due to obsolescence of the detergent specified in the test procedure, (2) revise 

the water temperature for test load preparation from 100 degrees Fahrenheit (°F) ± 5 °F to 60 °F 

± 5 °F, (3) update references to industry test standards, (4) eliminate an unnecessary reference to 

an obsolete industry test standard, (5) clarify the required gas supply conditions for testing gas 

clothes dryers (6) amend the provisions for measuring the drum capacity, (7) amend the 

provisions for the application of the field use factor for automatic cycle termination, (8),add the 

calculations of EF and CEF to 10 CFR part 430, subpart B, appendix D1. 76 FR 972, 993–1020 

(Jan. 6, 2011). 

EPCA requires that DOE must determine to what extent, if any, the proposed test 

procedure would alter the measured energy efficiency of any covered product as determined 

under the existing test procedure. (42 U.S.C. 6293(e)(1)) If DOE determines that the amended 

test procedure would alter the measured efficiency of a covered product, DOE must amend the 

applicable energy conservation standard accordingly. In determining the amended energy 

conservation standard, DOE shall measure, pursuant to the amended test procedure, the energy 

efficiency, energy use, or water use of a representative sample of covered products that 

minimally comply with the existing standard. The average of such energy efficiency, energy use, 

or water use levels determined under the amended test procedure shall constitute the amended 

energy conservation standard for the applicable covered products. (42 U.S.C. 6293(e)(2)) EPCA 

also states that models of covered products in use before the date on which the amended energy 

conservation standard becomes effective (or revisions of such models that come into use after 

such date and have the same energy efficiency, energy use, or water use characteristics) that 

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comply with the energy conservation standard applicable to such covered products on the day 

before such date shall be deemed to comply with the amended energy conservation standard. (42 

U.S.C. 6293(e)(3)) DOE notes that these EPCA requirements apply only when there is no 

concurrent energy conservation standards rulemaking. However, DOE has adjusted the measured 

efficiency values as part of this rulemaking, consistent with these requirements. 

As part of the January 2011 TP Final Rule, DOE conducted testing on a sample of 17 

representative clothes dryers to evaluate the effects of the amendments to the clothes dryer test 

procedure on the measured EF. DOE tested these units according to the amended clothes dryer 

test procedure in the January 2011 TP Final Rule, conducting up to three tests for each test unit 

and averaging the results. The results from this testing are shown below in Table 5.4.2. DOE 

noted in its testing that the amendments to the initial RMC, water temperature for test load 

preparation, and load size had an effect on the measured EF as compared to the existing test 

procedure. For vented electric standard-size clothes dryres, the measured EF increases by an 

average of about 20.1 percent as a result of the amendments to the test procedure. For vented gas 

clothes dryers, the measured EF increased by an average of about 19.8 percent. For vented 

electric compact-size 120V and 240V clothes dryers, the measured EF increased by an average 

of about 15.6 and 12.8 percent, respectively. For ventless electric compact 240V clothes dryers 

and ventless electric combination washer-dryers, the measured EF increased by an average of 

about 13.6 and 11.4 percent, respectively, as compared to the measured EF using the existing test 

procedure with only the amendments for ventless clothes dryers (without the changes to the 

initial RMC, water temperature for test load preparation, etc.). DOE noted that the increase in 

measured EF is greater for the standard-size products (i.e., vented electric standard-size and 

vented gas dryers) than for compact-size products due to the additional amendments to increase 

the test load size for standard-size products. 76 FR 972, 1022–28 (Jan. 6, 2011). 

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Table 5.4.2 DOE Test Results to Evaluate the Effects of the Test Procedure Amendments 

on Measured EF 

Test Unit 

Average EF (lb/kWh) 

% Change 

Previous Test 

Procedure 

(Appendix D) 

Amended Test 

Procedure 

(Appendix D1) 

Vented Electric Standard 

Unit 1 3.07 3.69 20.4% 

Unit 2 3.14 3.77 19.5% 

Unit 3 3.20 3.83 19.6% 

Unit 4 3.28 3.92 19.4% 

Unit 5 3.24 3.96 22.5% 

Unit 6 3.12 3.72 19.1% 

Vented Gas 

Unit 7 2.78 3.36 20.6% 

Unit 8 2.83 3.40 19.9% 

Unit 9 2.85 3.42 20.2% 

Unit 10 2.80 3.37 20.5% 

Unit 11 2.98 3.50 17.6% 

Vented Electric Compact 

(240V) 

Unit 12 3.19 3.56 11.4% 

Unit 13 2.93 3.35 14.2% 

Vented Electric Compact 

(120V) Unit 14 3.23 3.74 15.6% 

Ventless Electric Compact 

(240V) Unit 15 2.37 2.69 13.6% 

Ventless Electric Combo 

Washer-Dryer 

Unit 16 2.01 2.27 12.5% 

Unit 17 2.50 2.76 10.3% 

DOE applied these separate average percentage increases in the measured EF based on 

the test procedure amendments discussed above for each product class to the efficiency levels 

presented above in Table 5.4.1. Table 5.4.3 shows the revised baseline efficiency levels values 

for each product class. 

Table 5.4.3 Clothes Dryer Baseline Active Mode Unit Efficiencies Revised for Test 

Procedure Amendments 

EF (lb/kWh) 

Product Class Previous Test 

Procedure 

Amended Test 

Procedure 

Vented dryers 

7. Electric, Standard (4.4 ft3 or greater capacity) 3.01 3.62 

8. Electric, Compact (120 v) (less than 4.4 ft3 capacity) 3.13 3.62 

9. Electric, Compact (240 v) (less than 4.4 ft3 capacity) 2.90 3.27 

10. Gas 2.67 3.20 

Ventless dryers 

11. Electric, Compact (240 v) (less than 4.4 ft3 capacity) 2.37 2.69 

12. Electric, Combination Washer/Dryer 1.95 2.17 

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The minimum energy conservation standards for room air conditioners, as measured by 

EER in Btu/h per watt (W), became effective on October 1, 2000. Table 5.4.4 sets forth the 

current minimum energy conservation standards for the 16 room air conditioner product classes. 

(10 CFR Part 430.32(b)) DOE used the existing energy conservation standards to characterize 

the baseline active mode unit efficiency for each product class, including using the existing 

standards of the currently still combined product classes for classes that DOE split in this 

rulemaking. As mentioned in section 5.3, DOE fully analyzed only product classes 1, 3, 5A, and 

5B (room air conditioners without reverse cycle and with louvered sides, with capacities of less 

than 6,000 Btu/h; 8,000 to 13,999 Btu/h; 20,000 to 27,999 Btu/h; and 28,000 Btu/h or more, 

respectively), and product classes 8A and 8B (room air conditioners without reverse cycle and 

without louvered sides, with capacities of 8,000 to 10,999 Btu/h; and 11,000 to 13,999 Btu/h, 

respectively) and subsequently extended the analyses to the other product classes. 

Table 5.4.4 Room Air Conditioner Baseline Active Mode Unit Efficiencies 

Product Class EER (Btu/h-W) 

Without reverse cycle and with louvered sides 

1. Less than 6,000 Btu/h 9.7 

2. 6,000 to 7,999 Btu/h 9.7 

3. 8,000 to 13,999 Btu/h 9.8 

4. 14,000 to 19,999 Btu/h 9.7 

5A. 20,000 to 27,999 Btu/h 8.5* 

5B. 28,000 Btu/h or more 8.5* 

Without reverse cycle and without louvered sides 

6. Less than 6,000 Btu/h 9.0 

7. 6,000 to 7,999 Btu/h 9.0 

8A. 8,000 to 10,999 Btu/h 8.5* 

8B. 11,000 to 13,999 Btu/h 8.5* 

9. 14,000 to 19,999 Btu/h 8.5 

10. 20,000 Btu/h or more 8.5 

With reverse cycle and with louvered sides 

11. Less than 20,000 Btu/h 9.0 

12. 20,000 Btu/h or more 8.5 

With reverse cycle and without louvered sides 

13. Less than 14,000 Btu/h 8.5 

14. 14,000 Btu/h or more 8.0 

Casement 

15. Casement-Only 8.7 

16. Casement-Slider 9.5 

* Products of these two pairs of classes are covered in the current energy conservation standards under their 

“combined” classes of the current standards. 

5.4.1.2 Standby Mode and Off Mode 

In the January 2011 TP Final Rule, DOE adopted clothes dryer and room air conditioner 

test procedure amendments to measure standby and off mode energy use. Among other 

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provisions, “active mode,” “standby mode,” and “off mode” are defined based on the definitions 

in IEC Standard 62301 Second Edition, Committee Draft for Vote (CDV). 

“Active mode” is defined as a mode which “includes product modes where the energy 

using product is connected to a mains power source, has been activated and provides one 

or more main functions.” 

“Standby mode” is defined as a mode category which “includes any product modes
 

where the energy using product is connected to a mains power source and offers one or
 

more of the following user oriented or protective functions which may persist for an 


indefinite time:
 

To facilitate the activation of other modes (including activation or deactivation of
 

active mode) by remote switch (including remote control), internal sensor, timer;
 

Continuous function: information or status displays including clocks;
 

Continuous function: sensor-based functions.”
 

With the additional clarification that “a timer is a continuous clock function (which may 


or may not be associated with a display) that provides regular scheduled tasks (e.g., 


switching) and that operates on a continuous basis.”
 

“Off mode” is defined as a mode which “includes any product modes where the energy
 

using product is connected to a mains power source and is not providing any standby
 

mode or active mode function and where the mode may persist for an indefinite time. An
 

indicator that only shows the user that the product is in the off position is included within
 

the clasification of off mode.” 76 FR 972, 980–985 (Jan. 6, 2011).
 

In addition, the amendments provide that if power consumption drops from a higherpower state to a lower-power state in a given mode, as discussed in Section 5, Paragraph 5.1, 

note 1 of IEC Standard 62301, to allow sufficient time for the product to reach the lower power 

state before proceeding with the test measurement. 76 FR 972, 985–986 (Jan. 6, 2011). 

DOE measured standby and off mode energy use of residential clothes dryers in its 

sample of reverse-engineered units. (See section 5.6.1.3 for a discussion of the reverse 

engineering test sample, methodology, and results.) The results of the standby and off mode 

measurements are shown in Table 5.4.5 below. The compact (240 V) ventless and one electric 

standard vented clothes dryer in the test sample were unable be measured for standby/off mode 

power consumption because components energized in standby and off mode were powered off 

240 V line power, which could not be accommodated by the power meter used by DOE. 

Additionally, DOE was unable to obtain any test units for electric compact (120 V) vented 

clothes dryers, so no data is presented for this product class. 

Standby and off modes were determined for clothes dryers by observing unit function and 

power consumption for various operating states other than when the dryer was actively drying or 

tumbling the clothing. The operating conditions identified for the clothes dryers which are 

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potential standby and off modes included (1) the unit plugged in, but the power switch turned 

off; (2) the unit plugged in and powered on, but no drying cycle setting selected; (3) the unit 

plugged in and powered on, with a “normal” setting selected but the drying cycle not started; and 

(4) the active cycle completed. DOE did not measure power consumption during a delay start 

condition because none of the clothes dryers in DOE’s test sample were equipped with such a 

feature. For some clothes dryers in the test sample with electronic controls, DOE observed that at 

the completion of the active cycle, power consumption initially was measured at a higher level, 

then after a period of inactivity of typically several tens of seconds, would drop to a lower level. 

After another period of inactivity of typically several minutes, these dryers then changed to a 

state with even lower power consumption, in which all displays were turned off and the on/off 

“soft” power switch reset to the “off” condition. In this state, power consumption was the same 

as when the unit was initially plugged in but not powered on. In other cases, at the completion of 

the active cycle, the power consumption initially was measured at a higher level, then after a 

period of inactivity of typically tens of seconds, would drop to a lower level for which only a 

single light emitting diode (LED) was illuminated to indicate that the cycle was complete. This 

mode persisted until the dryer door was opened, at which point the LED turned off and the dryer 

reverted to an even lower power state in which all displays were turned off and the on/off “soft” 

power switch reset to the “off” condition. As for the previously discussed case, in this state, the 

power consumption was the same as for when the unit was initially plugged in but not powered 

on. Since, for the clothes dryers equipped with electronic controls, the unit would only be 

powered on in anticipation of starting a drying cycle and would revert to the lowest power 

consumption state after a period of several minutes after the cycle completed or after the clothes 

have been removed from the drum, DOE believes that the lowest power state represents 

standby/off mode energy use. Further, since DOE observed that all clothes dryers with displays 

deactivate them in this lowest power state but include a soft switch for initiating active mode, 

such units would be operating in a standby mode rather than in off mode. In contrast, clothes 

dryers with electromechanical controls do not consume any power when the unit is plugged in 

and not in active mode or once the active cycle has completed, and can thus be considered to 

operate in off mode. DOE also noted that for operating conditions (2) and (3) defined above, 

after a period of user inactivity (generally between 5 and 10 minutes), the display turns off and 

the on/off “soft” power switch resets to the “off’ condition, reverting the clothes dryer to the 

lower power consumption state. 

Table 5.4.5 summarizes the power consumption measurements in standby/off mode for 

each of the clothes dryers in the DOE test sample for which standby power could be measured. 

Review of this data, along with information on design options obtained during reverseengineering activities, resulted in DOE proposing a level of 2.0 W for baseline power 

consumption in standby/off mode. This value is based on a maximum measured input power of 

1.51 W for a unit with electronic controls, and thus which provides the consumer utility of a 

display. The model in the DOE test sample with this standby power consumption, however, was 

observed to incorporate a switching power supply, which DOE identified as a design option to 

reduce standby power consumption. In order to define the baseline level for an assumed clothes 

dryer that uses a conventional power supply, DOE increased the 1.51 W by the estimated change 

in standby power associated with changing from a conventional to switching power supply. DOE 

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also measured standby power of approximately 0.7 W for other clothes dryers equipped with 

electronic controls and displays that were observed to differ only by having fewer available cycle 

settings. Because DOE does not intend to restrict consumer utility associated with the number of 

different cycles, the baseline was chosen to allow the maximum number of settings. 

Table 5.4.5 Clothes Dryer Standby and Off Mode Power Input Measurements 

Product Class Test Unit 

EF 

(lb/kWh) Control Type 

Power Input 

(W) Mode 

Vented Electric, 

Standard 

1 3.06 Electromechanical 0.00 Off 

2 3.10 Electromechanical 0.00 Off 

3 3.15 Electronic 0.69 Standby 

4 3.20 Electromechanical 0.00 Off 

5 3.40 Electromechanical Standby 

Vented Electric, 

Compact (120 V) 6 2.98 Electromechanical 0.00 Off 

Vented Gas 

7 2.67 Electromechanical 0.00 Off 

8 2.76 Electronic 0.69 Standby 

9 2.8 Electronic 1.51 Standby 

10 3.00 Electronic 0.08 Standby 

Ventless Combination 

Washer/Dryer 11 - Electronic 0.83 Standby 

DOE measured standby/off mode energy use of room air conditioners in order to 

determine the appropriate energy use baseline for these modes. The results of these 

measurements are shown in Table 5.4.6 below. Note that products with electronic controls were 

capable of operation in standby mode, as defined in the January 2011 TP Final Rule, while 

products with electromechanical controls were capable of operation in off mode. For simplicity, 

DOE defined baseline characteristics for room air conditioners assuming use of electronic 

controls. Based on the test data, DOE established a baseline standby/off mode power 

consumption level of 1.4 W. This power input level was higher than all but four of the 

electronic-control products tested, and the highest power measurement was only 13.5 percent 

higher than this level. 

5-15 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Table 5.4.6 Room Air Conditioner Standby and Off Mode Power Input Measurements 

Product 

Class 

Capacity 

(Btu/h) 

EER 

(Btu/h-W) Control Type 

Power Input (W) 

Standby 

Mode Off Mode 

1 5,000 9.7 Electronic 1.59 

1 5,200 9.7 Electromechanical 0.20 

1 5,200 10.7 Electronic 1.28 

1 5,200 11 Electronic 1.46 

3 11,800 11.8 Electronic 1.30 

3 11,800 10.8 Electronic 0.68 

3 12,000 9.8 Electronic 1.36 

3 8,400 11.4 Electronic 1.34 

3 8,000 9.8 Electronic 0.91 

3 8,000 10.8 Electronic 1.40 

3 12,000 9.5* Electronic 1.21 

5 24,500 8.5 Electronic 0.74 

5 24,000 9.4 Electronic 1.404 

8 8,000 10.5 Electronic 1.27 

8 8,000 9.4 Electronic 1.44 

8 8,000 9.6 Electronic 1.52 

8 11,600 9.5 Electromechanical 0.03 

8 11,500 8.5 Electromechanical 0.03 

11 11,600 9.5 Electromechanical 0.03 

16 8,000 9.5 Electronic 1.41 

*This product was advertised as being through-the-wall (i.e. product class 8), but it has louvered sides and no way to 

allow air flow into the condenser fan intake if the louvers were blocked off by a wall sleeve. 

5.4.1.3 Integrated Efficiency 

For the preliminary analysis, DOE based its analysis for residential clothes dryers on 

the Integrated Energy Factor (IEF) metric proposed as an alternative option in the December 

2008 TP NOPR. Baseline IEF levels were determined from the baseline EF and standby energy 

use as discussed in sections 5.4.1.1 and 0. The IEF is calculated as the clothes dryer test load 

weight in lb divided by the sum of “active mode” per-cycle energy use and “standby mode” percycle energy use in kWh. As noted above, inactive mode was defined in the December 2008 

NOPR as a standby mode other than delay start mode or cycle finished mode that facilitates the 

activation of active mode by remote switch (including remote control), internal sensor, or timer, 

or that provides continuous status display. This is the standby mode measured under the 

discussion in section 0 above. The per-cycle energy consumption associated with this standby 

mode for residential clothes dryers is calculated assuming 416 clothes dryer cycles in a year and 

8,620 hours associated with standby mode. Table 5.4.7 shows the baseline IEF for each 

residential clothes dryer product class. 

5-16 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Table 5.4.7 Baseline Clothes Dryer IEF 

Product Class EF (Previous Test 

Procedure) 

(lb/kWh) 

Standby 

Power 

(W) 

IEF 

(lb/kWh) 

Vented dryers 

1. Electric, Standard (4.4 ft3 or greater capacity) 3.01 2.0 2.96 

2. Electric, Compact (120 v) (less than 4.4 ft3 capacity) 3.13 2.0 3.00 

3. Electric, Compact (240 v) (less than 4.4 ft3 capacity) 2.90 2.0 2.79 

4. Gas 2.67 2.0 2.63 

Ventless dryers 

5. Electric, Compact (240 v) (less than 4.4 ft3 capacity) 2.37 2.0 2.29 

6. Electric, Combination Washer/Dryer 1.95 2.0 1.90 

As discussed above, DOE recently published the January 2011 TP Final Rule in which it 

adopted clothes dryer test procedure amendments to measure standby and off mode energy use. 

Therefore, DOE based its analysis for this final rule for residential clothes dryers on the CEF 

metric adopted in the January 2011 TP Final Rule. Baseline CEF levels were determined from 

the baseline EF under the amended test procedure (as discussed above in section 5.4.1.1) and the 

same standby power levels analyzed for the preliminary analysis, as discussed above in section 

5.4.2.2. The per-cycle energy consumption associated with standby mode for residential clothes 

dryers is calculated assuming 283 clothes dryer cycles in a yearb

 and 8,620 hours associated with 

standby mode. Table 5.4.8 shows the baseline CEF for each residential clothes dryer product 

class. 

Table 5.4.8 Baseline Clothes Dryer CEF 

Product Class 

EF (Amended 

Test Procedure) 

(lb/kWh) 

Standby 

Power 

(W) 

CEF 

(lb/kWh) 

Vented dryers 

7. Electric, Standard (4.4 ft3 or greater capacity) 3.62 2.0 3.55 

8. Electric, Compact (120 v) (less than 4.4 ft3 capacity) 3.62 2.0 3.43 

9. Electric, Compact (240 v) (less than 4.4 ft3 capacity) 3.27 2.0 3.12 

10. Gas 3.20 2.0 3.14 

Ventless dryers 

11. Electric, Compact (240 v) (less than 4.4 ft3 capacity) 2.69 2.0 2.55 

12. Electric, Combination Washer/Dryer 2.17 2.0 2.08 

For the preliminary analysis, DOE based its analysis for room air conditioners on the 

IEER metric proposed as an alternative option in the December 2008 NOPR. As discussed 

above, DOE recently published the January 2011 TP Final Rule, in which it modified the name 

of the integrated metric to CEER to avoid conflict with another pre-existing use of the term 

b

 DOE revised the number of active mode cycles per year in the January 2011 TP Final Rule from 416 to 283 cycles 

per year based on analysis of more recent consumer usage data. 

5-17 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

IEER. DOE determined baseline CEER levels from the baseline EER and standby energy use as 

discussed in sections 5.4.1.1 and 0. CEER is equal to capacity times active mode hours (equal to 

750) divided by the sum of active mode annual energy use and standby mode annual energy use, 

as defined above. This is the standby mode measured under the discussion in section 0 above. 

The number of hours associated with this standby mode for room air conditioners is 5,115 hours 

per year. 

Because CEER depends on capacity, calculating its baseline value for a product class 

requires specification of that capacity. For the four product classes and the capacities analyzed in 

detail for the preliminary analysis, the baseline CEERs are as indicated in Table 5.4.9 below. 

Table 5.4.9 Baseline Room Air Conditioner CEER for Analyzed Product Classes 

Product Class Capacity 

(Btu/h) 

EER 

(Btu/h-W) 

Standby Power 

(W) 

CEER 

(Btu/h-W) 

1 5,000 9.7 1.4 9.52 

3 8,000 9.8 1.4 9.69 

3 12,000 9.8 1.4 9.72 

5A 24,000 8.5 1.4 8.47 

5B 28,000 8.5 1.4 8.48 

8A 8,000 8.5 1.4 8.41 

8B 12,000 8.5 1.4 8.44 

5.4.2 Incremental Efficiency and Standby Levels 

5.4.2.1 Active Mode 

For the majority of the product classes presented in section 5.3, DOE analyzed several 

efficiency levels and obtained incremental cost data at each of these levels. Table 5.4.10 through 

Table 5.4.16 provide efficiency levels and the reference source of each level for each of the 

products under consideration. For most of the product classes, the highest efficiency level was 

identified based on a review of available product literature for products commercially available 

(this applied for gas vented clothes dryers and all room air conditioner product classes). For 

electric vented and ventless clothes dryers, the maximum levels identified in Table 5.4.10 and 

Table 5.4.11 are based on available research and product literature on heat pump clothes dryers 

as well as discussions with manufacturers. 

As part of the preliminary analysis for residential clothes dryers, DOE considered four 

efficiency levels beyond the baseline efficiency level for electric standard vented clothes dryers 

and electric compact (120V and 240V) vented clothes dryers, and three efficiency levels for the 

gas vented product class, as listed in Table 5.4.10. These levels were derived primarily from data 

contained within the California Energy Commission (CEC) and Natural Resources Canada 

(NRCan) product databases. For gas clothes dryers, the highest efficiency level (which is the 

maximum technologically feasible (max-tech) level) is based on the value proposed in the 

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framework document that was based on data contained in the CEC product database. AHAM 

submitted aggregated incremental manufacturing cost data in support of this max-tech efficiency 

level for vented gas clothes dryers. As discussed in section 5.6.1.5, multiple manufacturers stated 

during interviews that the current maximum efficiency that is listed for vented gas clothes dryers 

in the CEC product database is not achievable. Also, as discussed in section 0, DOE testing of 

the “maximum-available” gas clothes dryer determined that this unit did not achieve the rated 

efficiency. For these reasons, DOE proposed for the preliminary analysis to use the vented gas 

clothes dryer max-tech value for which AHAM submitted aggregated incremental manufacturing 

costs. This max-tech level was supported by multiple manufacturers during interviews. DOE also 

added two levels to fill the gap between the baseline and the max-tech for this product class. 

Since no data was available from either database for electric compact (120 V) clothes dryers, 

efficiency levels above the baseline for this product class were obtained by scaling the efficiency 

levels for electric standard units by the ratio of the baseline efficiencies. For electric standard and 

electric compact (240V) clothes dryers, the max-tech level corresponds to the efficiency 

improvement associated with incorporating heat pump technology, which was based upon 

manufacturer interviews and available research on heat pump dryers, while the three gap fill 

levels are derived from certification data. Some of these efficiency levels were changed from 

those proposed in the framework document, based on comments from interested parties, 

manufacturer interviews, and more recent certification data. Because DOE only recently 

amended the clothes dryer test procedure, the efficiency levels developed for the preliminary 

analysis were based on EF using the previous DOE clothes dryer test procedure. Table 5.4.10 

below shows the efficiency level values for each vented clothes dryer product class proposed in 

the preliminary analysis. 

Table 5.4.10 Vented Clothes Dryer Active Mode Efficiency Levels – Preliminary Analysis 

Level Efficiency Level 

Description 

Efficiency Level (EF) (lb/kWh) 

Electric 

Standard 

Electric 

Compact 

(120V) 

Electric 

Compact 

(240V) 

Gas 

Baseline DOE Standard 3.01 3.13 2.90 2.67 

1 Gap Fill 3.10 3.22* 2.98 2.75 

2 Gap Fill 3.16 3.29* 3.09 2.85 

3 Gap Fill/Maximum 

Available 3.40 3.54* 3.20 3.02 (maxtech) 

4 Max-Tech 4.51 4.70* 4.35 

* Estimated by scaling from electric standard clothes dryer efficiency levels. 

For ventless clothes dryers, DOE considered three efficiency levels above the baseline for 

both electric compact (240 V) and electric combination washer/dryer product classes for the 

preliminary analysis. For ventless electric compact (240 V) clothes dryers, DOE estimated 

efficiency level (EL) 1 using methodology based on a waiver DOE provided to Miele, Inc. 

(Miele) for its condenser clothes dryer. In that waiver, Miele voluntarily agreed to maintain the 

performance of its condenser clothes dryer to within 82.5 percent of the existing energy 

conservation standard for electric standard clothes dryers. 60 FR 9332 (Feb. 17, 1995). That 

same percentage was applied to the existing energy conservation standard for electric compact 

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(240 V) vented clothes dryers (EF = 2.90) to obtain an EF of 2.39 for electric compact (240 V) 

ventless clothes dryers. A gap-fill level for EL 2 was derived based upon test data from the 

National Institute of Standards and Technology (NIST). For ventless electric combination 

washer/dryers, EL 1 was based upon the efficiency improvement credit for incorporating 

automatic termination control per the DOE test procedure. A gap-fill level for EL 2 was derived 

using the efficiency improvement from design changes to reach EL 3c for electric standard 

dryers, scaled based upon the inherently lower efficiency of combination washer/dryers. The 

max-tech for both ventless electric compact (240 V) and combination washer/dryers was derived 

from the efficiency improvements associated with heat pump technology, as described above for 

electric standard dryers. DOE recognizes there is some uncertainty associated with the values 

based upon data from product databases, as it is unclear what test procedure was used to measure 

EF. As discussed above, because DOE only recently amended the clothes dryer test procedure, 

the efficiency levels developed for the preliminary analysis were based on EF using the previous 

DOE clothes dryer test procedure without the exhaust simulator, as discussed above in section 

5.4.1.1. Table 5.4.11 below shows the efficiency level values for each ventless clothes dryer 

product class proposed in the preliminary analysis. 

Table 5.4.11 Ventless Clothes Dryer Active Mode Efficiency Levels – Preliminary Analysis 

Level Efficiency Level 

Description 

Efficiency Level (EF) (lb/kWh) 

Electric Compact (240 V) Electric Combination 

Washer/Dryer 

Baseline DOE Test Data 2.37 1.95 

1 Gap Fill 2.39* 2.21 

2 Gap Fill 2.59† 2.42 

3 Max Tech 3.55 3.32 

*Determined by scaling the existing Federal standard for vented electric compact (240V) clothes dryers based on 

Miele’s voluntary plan to maintain its condenser clothes dryer EF within 82.5 percent of the existing non-condenser 

clothes dryer standard. 60 FR 9332. 

† Based on NIST test data.3 

As discussed above in section 5.4.1.1, DOE conducted product testing in order to convert 

the EF values for each vented clothes dryer product class measured under the previous DOE 

clothes dryer test procedure to EF values measured under the amended test procedure. As 

presented above in section 5.4.1.1, DOE test results showed that the measured EF according to 

the amended test procedure resulted in an average increase of about 20.1 percent for vented 

electric standard clothes dryers. For vented gas clothes dryers, the measured EF increased by an 

average of about 19.8 percent. For vented electric compact-size 120V and 240V clothes dryers, 

the measured EF increased by an average of about 15.6 and 12.8 percent, respectively. DOE 

applied these results for each product class to adjust the active mode efficiency levels to account 

for the amendments to the DOE clothes dryer test procedure in the January 2011 TP Final Rule. 

In addition, DOE revised the active mode efficiency level 1 for vented electric standard clothes 

c

 The design changes associated with EL 2 for electric standard clothes dryers are not technologically feasible for 

combination washer/dryers. 

5-20 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

dryers and vented gas clothes dryers from 3.10 EF to 3.11 EF and from 2.75 to 2.76 EF, 

respectively, based on discussions with manufacturers and the efficiency improvement 

associated with the design options modeled by DOE, presented in section 5.6.1.3. Table 5.4.12 

and Table 5.4.13 below show the revised active mode efficiency level values for each vented 

clothes dryer product class. 

Table 5.4.12 Vented Clothes Dryer Active Mode Efficiency Levels (Vented Electric 

Standard and Vented Electric Compact (120V)) 

Level Efficiency Level 

Description 

Efficiency Level (EF) (lb/kWh) 

Electric Standard Electric Compact (120V) 

Previous Test 

Procedure 

Amended Test 

Procedure 

Previous Test 

Procedure 

Amended Test 

Procedure 

Baseline DOE Standard 3.01 3.62 3.13 3.62 

1 Gap Fill 3.11 3.74 3.22 3.72 

2 Gap Fill 3.17 3.81 3.29 3.80 

3 Gap Fill/Maximum 

Available 3.40 4.08 3.54 4.09 

4 Max-Tech 4.52 5.43 4.70 5.44 

Table 5.4.13 Vented Clothes Dryer Active Mode Efficiency Levels (Vented Electric 

Compact (240V) and Vented Gas) 

Level Efficiency Level 

Description 

Efficiency Level (EF) (lb/kWh) 

Electric Compact (240V) Gas 

Previous Test 

Procedure 

Amended Test 

Procedure 

Previous Test 

Procedure 

Amended Test 

Procedure 

Baseline DOE Standard 2.90 3.27 2.67 3.20 

1 Gap Fill 2.98 3.36 2.76 3.31 

2 Gap Fill 3.09 3.49 2.86 3.41 

3 Gap Fill/Maximum 

Available 3.20 3.61 3.02 (maxtech) 3.62 

4 Max-Tech 4.35 4.91 

For ventless clothes dryers, the preliminary analyses were based on the DOE test 

procedure with only the proposed amendments for ventless clothes dryers. As discussed above in 

section 5.4.1.1, DOE also conducted testing according to the final amended test procedure, 

including changes to the initial RMC, water temperature for test load preparation, etc., which 

showed that for ventless electric compact 240V clothes dryers and ventless electric combination 

washer/dryers, the measured EF increased by an average of about 13.6 and 11.4 percent, 

respectively. DOE similarly applied the percentage increases in the measured EF, developed 

based on product testing, to the EF values proposed for the preliminary analysis to account for 

the amendments to the DOE clothes dryer test procedure in the January 2011 TP Final Rule, as 

discussed above in section 5.4.1.1. Based on discussions with manufacturers and based on the 

efficiency improvement associated with the design options modeled by DOE (discussed in detail 

below in section 5.6.1.4), active mode efficiency level 2 for ventless electric combination 

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washer-dryers was revised from 2.59 to 2.47 EF.d Table 5.4.14 below shows the revised 

efficiency level values for each ventless clothes dryer product class. 

Table 5.4.14 Ventless Clothes Dryer Active Mode Efficiency Levels 

Level Efficiency Level 

Description 

Efficiency Level (EF) (lb/kWh) 

Electric Compact (240 V) Electric Combination 

Washer/Dryer 

Previous Test 

Procedure 

Amended Test 

Procedure 

Previous Test 

Procedure 

Amended Test 

Procedure 

Baseline DOE Test Data 2.37 2.69 1.95 2.17 

1 Gap Fill 2.39 2.72 2.21 2.46 

2 Gap Fill 2.47 2.81 2.30 2.56 

3 Max Tech 3.56 4.04 3.32 3.70 

For room air conditioners, during the preliminary analysis, DOE considered varying 

numbers of efficiency levels, depending on the product class, as indicated in Table 5.4.15 and 

Table 5.4.16 below. DOE determined these levels based on the range of efficiency levels 

associated with products as listed in the CEC, ENERGY STAR, and AHAM product databases 

and verified to be on sale by a listing on either a manufacturer’s website or a retailer’s website. 

DOE added a gap fill efficiency level between the current DOE standard and the ENERGY 

STAR efficiency level. The maximum available level exceeds the CEE Tier 2 level for product 

class 1, and matches the CEE Tier 2 level for product class 3. For product classes 5 and 8, the 

CEE Tier 2 levels are higher than the maximum available product EER, and thus are not 

included as efficiency levels. 

Table 5.4.15 Room Air Conditioner Active Mode Efficiency Levels--Product Classes 1 and 

3 – Preliminary Analysis 

EER (Btu/h-W) 

Level Efficiency Level 

Description 

Product Class 1: Without Reverse 

Cycle, With Louvered Sides, 

< 6,000 Btu/h 

Product Class 3: Without Reverse 

Cycle, With Louvered Sides, 

8,000 - 13,999 Btu/h 

Baseline DOE Standard 9.7 9.8 

1 Gap Fill 10.2 10.3 

2 Energy Star 10.7 10.8 

3 CEE Tier 1 11.2 11.3 

4 CEE Tier 2 11.6 11.8 

5 Maximum 

Available* 12.0 

* Based on ENERGY STAR-qualified room air conditioners as of July, 2008 and verification of availability through 

retailer website searches. 

d

 EL 2 was derived using the efficiency improvement from design changes to reach EL 3 for electric standard dryers, 

scaled based upon the inherently lower efficiency of combination washer/dryers. 

5-22
 
 

 

 

 

 

 

 

 

 

 

Table 5.4.16 Room Air Conditioner Active Mode Efficiency Levels--Product Classes 5 and 

8 – Preliminary Analysis 

EER (Btu/h-W) 

Level Efficiency Level 

Description 

Product Class 5: Without Reverse 

Cycle, With Louvered Sides, 

≥ 20,000 Btu/h 

Product Class 8: Without Reverse 

Cycle, Without Louvered Sides, 

8,000 – 13,999 Btu/h 

Baseline DOE Standard 8.5 8.5 

1 Gap Fill 9.0 9.0 

2 Energy Star 9.4 9.4 

3 CEE Tier 1 9.8 9.8 

4 Maximum 

Available* 10.0 10.8 (8,000 Btu/h) 9.8 (12,000 Btu/h) 

* Based on ENERGY STAR-qualified room air conditioners as of July, 2008 and verification of availability through 

retailer website searches. CEE Tier 2 level is higher than the maximum available EER for these product classes. 

For the final rule analysis, DOE again considered varying numbers of efficiency levels, 

depending on the product class, as indicated in Table 5.4.17 to Table 5.4.18 below. DOE based 

the max-tech levels on the analysis, rather than the maximum available units. DOE also adjusted 

the gap-fill levels to provide reasonable increments between successive levels. When possible, 

DOE selected efficiency levels equivalent to CEE Tier 1 and Tier 2. For example the level 

following the ENERGY-STAR level matches CEE Tier 1 for product classes 1, 5A, and 5B. 

Table 5.4.17 Room Air Conditioner Active Mode Efficiency Levels--Product Classes 1 and 

3 

Level Efficiency Level 

Description 

EER (Btu/h-W) 

Product Class 1: Without Reverse 

Cycle, With Louvered Sides, 

< 6,000 Btu/h 

Product Class 3:Without Reverse 

Cycle, With Louvered Sides, 

8,000 - 13,999 Btu/h 

Baseline DOE Standard 9.7 9.8 

1 Gap Fill 10.2 10.3 

2 Energy Star 10.7 10.8 

3 Gap Fill 2 11.2 11.0 

4 Gap Fill 3 11.5 11.6 

5 Max-Tech 11.8** 12.0 

** This level is lower than the max-available efficiency of 12.0 identified by DOE. This reflects the 50 lb product 

weight limit discussed in section 5.6.2.6. 

Table 5.4.18 Room Air Conditioner Active Mode Efficiency Levels--Product Classes 5A 

and 5B 

Level Efficiency Level 

Description 

EER (Btu/h-W) 

Product Class 5A:Without Reverse 

Cycle, With Louvered Sides, 

20,000-27,999 Btu/h 

Product Class 5B:Without Reverse 

Cycle, With Louvered Sides, 

≥ 28,000 Btu/h 

Baseline DOE Standard 8.5 8.5 

1 Gap Fill 1 9.0 9.0 

2 Energy Star 9.4 9.4 

3 Gap Fill 2 9.8 9.8 

4 Max-Tech 10.2 

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Table 5.4.19 Room Air Conditioner Active Mode Efficiency Levels--Product Classes 8A 

and 8B 

Level Efficiency Level 

Description 

EER (Btu/h-W) 

Product Class 8A: Without Reverse 

Cycle, Without Louvered Sides, 

8,000-10,999 Btu/h 

Product Class 8B:Without Reverse 

Cycle, Without Louvered Sides, 

11,000 - 13,999 Btu/h 

Baseline DOE Standard 8.5 8.5 

1 Energy Star 9.4 9.4 

2 Gap Fill 1 9.7 9.6 

3 Gap Fill 2 10.1 9.8 

4 Max-Tech 10.4 10.1 

5.4.2.2 Standby Mode and Off Mode

 For clothes dryers DOE observed through testing and teardowns that several different 

features could be associated with successively lower standby power levels (SLs). Therefore, 

DOE was able to define several standby power levels for analysis. Only standby power is 

addressed because no power consumption was observed in the off mode for test units capable of 

such a mode. At the baseline standby power level of 2.0 W, the clothes dryer is estimated to be 

equipped with a full complement of cycle settings, a linear regulated control board power supply, 

and a display which powers down after a period of user inactivity. The automatic deactivation of 

electronic displays was observed in all tested units so equipped and was therefore considered a 

baseline feature. 

SL 1 is associated with changing from a conventional power supply to a switch-mode 

power supply. For SL 2, a transformerless power supply enables a microcontroller to remain on 

at all times while disabling the main power supply whenever the clothes dryer is “asleep”. The 

control logic monitors the clothes dryer for key-presses, door openings, etc., and when user 

activity is detected, the logic activates the main power supply. These standby power levels, 

shown in Table 5.4.20, are believed to be the same for all clothes dryer product classes. 

Table 5.4.20 Clothes Dryer Standby Power Levels 

Level Standby Power Source Power Input (W) 

Baseline DOE Test Data and Analysis 2.0 

1 DOE Test Data 1.5 

2 DOE Test Data (Max-Tech) 0.08 

For room air conditioners, DOE selected a single incremental standby power level for 

standby mode, based on the data presented in Table 5.4.6 above. The standby mode power input 

at SL 1 is 0.7 W, which was observed in one of the room air conditioners in the test sample and 

nearly achieved by a second unit. 

Baseline room air conditioners with electronic controllers featured a linear regulated 

power supply and an infrared detector for the remote control. All sampled units with electronic 

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controllers featured a remote control. SL 1 was met by one of the room air conditioners in the 

test sample and was nearly achieved by a second unit. DOE research suggests that SL1 can be 

achieved through the substitution of a switch-mode power supply, since both units that met or 

nearly met SL1 used such power supplies. All other electronic-controlled units used conventional 

linear regulated power supplies. The selected standby power levels are summarized in Table 

5.4.21 below. 

Table 5.4.21 Room Air Conditioner Standby Power Levels 

Level Standby Power Source Power Input (W) 

Baseline DOE Test Data 1.4 

1 DOE Test Data 0.7 

5.4.2.3 Integrated Efficiency 

As part of the preliminary analysis for clothes dryers, incremental IEF efficiency levels 

were determined by assuming that a clothes dryer with baseline energy efficiency (EF) 

performance would incorporate baseline standby power consumption (i.e., 2.0 W). DOE 

recognizes that many clothes dryers that just meet the current Federal energy conservation 

standards for EF utilize electromechanical controls, which consume no standby power. There 

are, however, a significant number of models rated at baseline energy efficiency performance 

that incorporate electronic controls. Thus, DOE assumed that the baseline IEF level for a 

minimally-compliant unit should include the 2.0 W of standby power. At higher IEF levels, DOE 

estimated for the preliminary analysis that standby power would remain at 2.0 W for those levels 

that do not strictly require electronic controls to achieve. For those higher levels that do require 

electronic controls, DOE added in the design options for standby power improvements in order 

of cost effectiveness. This resulted in the incremental IEF efficiency levels proposed for the 

preliminary analysis shown in Table 5.4.22 through Table 5.4.24. 

Table 5.4.22 Preliminary Analysis Clothes Dryer Integrated Efficiency Levels (IEF) – 

Vented Product Classes 

Level Efficiency Level Description 

Integrated Efficiency Level (IEF) (lb/kWh) 

Electric 

Standard 

Electric 

Compact 

(120V) 

Electric 

Compact 

(240V) 

Gas 

Baseline DOE Standard + 2.0 W Standby 2.96 3.00 2.79 2.63 

1 Gap Fill + 2.0 W Standby 3.04 3.08 2.86 2.71 

2 Gap Fill + 2.0 W Standby 3.10 3.15 2.96 2.80 

3 Gap Fill/Maximum Available + 2.0 W Standby 3.33 3.37 3.06 2.97 

4 Maximum Available + 1.5 W Standby 3.35 3.41 3.10 2.98 

5 Maximum Available + 0.08 W Standby 3.40 3.53 3.19 3.02 

6 Heat Pump (Max Tech) + 0.08 W Standby 4.52 4.69 4.34 

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Table 5.4.23 Preliminary Analysis Clothes Dryer Integrated Efficiency Levels (IEF) – 

Ventless Electric Compact (240V) 

Level Efficiency Level Description 

Integrated Efficiency Level (IEF) 

(lb/kWh) 

Electric Compact (240 V) 

Baseline Baseline + 2.0 W Standby 2.29 

1 Baseline + 1.5 W Standby 2.31 

2 Baseline + 0.08 W Standby 2.37 

3 Gap Fill + 0.08 W Standby 2.39 

4 Gap Fill + 0.08 W Standby 2.59 

5 Heat Pump (Max-Tech) + 0.08 W Standby 3.54 

Table 5.4.24 Preliminary Analysis Clothes Dryer Integrated Efficiency Levels (IEF) – 

Ventless Electric Combination Washer/Dryers 

Level Efficiency Level Description 

Integrated Efficiency Level (IEF) 

(lb/kWh) 

Electric Combination Washer/Dryer 

Baseline Baseline + 2.0 W Standby 1.90 

1 Gap Fill + 2.0 W Standby 2.15 

2 Gap Fill + 2.0 W Standby 2.34 

3 Gap Fill + 1.5 W Standby 2.36 

4 Gap Fill + 0.08 W Standby 2.42 

5 Heat Pump (Max-Tech) + 0.08 W Standby 3.31 

Based on the revised active mode efficiency levels for the final rule analyses presented 

above in section 5.4.2.1 and the standby power levels presented in section 5.4.2.2, DOE revised 

the incremental CEF efficiency levels. As discussed above, for the preliminary analysis, DOE 

only incorporated incremental standby power levels into IEF efficiency levels above which 

electronic controls would be required as part of the active mode design option changes. At that 

point, DOE then incorporated the incremental standby power levels where it determined them to 

be most cost effective. However, DOE believes that the low cost of the standby power design 

options should result in these technologies being layered in at the efficiency levels where these 

design options are most cost-effective (regardless of whether electronic controls are required for 

the active mode design options). As a result, for the final rule, DOE revised the order of the 

design options and efficiency levels presented in the preliminary analysis such that the standby 

power levels are applied immediately above the baseline level. DOE also noted that for the 

integrated efficiency levels where electronic controls are not required for the design changes, the 

standby power level changes would impact only those clothes dryers that consume standby 

power (i.e., those products with electronic controls). DOE analyzed baseline efficiency products 

available on the U.S. market, and weighted the efficiency improvement and incremental 

manufacturing cost associated with standby power based on the percentage of baseline efficiency 

products that have electronic controls. DOE’s review of currently available models with baseline 

efficiency showed that roughly 74 percent of models have electronic controls. For the integrated 

efficiency levels for which electronic controls are required as part of the active mode design 

changes, DOE assumed that the standby power levels and incremental manufacturing costs 

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(presented below in section 5.6.1.4) affected 100 percent of clothes dryer models. The 

incremental CEF efficiency levels are shown in Table 5.4.25 through Table 5.4.27. 

Table 5.4.25 Clothes Dryer Integrated Efficiency Levels (CEF) – Vented Product Classes 

Level Efficiency Level Description 

Integrated Efficiency Level (CEF) (lb/kWh) 

Electric 

Standard 

Electric 

Compact 

(120V) 

Electric 

Compact 

(240V) 

Gas 

Baseline DOE Standard + 2.0 W Standby 3.55 3.43 3.12 3.14 

1 DOE Standard + 1.5 W Standby 3.56 3.48 3.16 3.16 

2 DOE Standard + 0.08 W Standby 3.61 3.61 3.27 3.20 

3 Gap Fill + 0.08 W Standby 3.73 3.72 3.36 3.30 

4 Gap Fill + 0.08 W Standby 3.81 3.80 3.48 3.41 

5 Gap Fill/Maximum Available + 0.08 W 

Standby 4.08 4.08 3.60 3.61 

6 Heat Pump (Max-Tech) + 0.08 W Standby 5.42 5.41 4.89 

Table 5.4.26 Clothes Dryer Integrated Efficiency Levels (CEF) – Ventless Electric Compact 

(240V) 

Level Efficiency Level Description 

Integrated Efficiency Level (CEF) 

(lb/kWh) 

Electric Compact (240 V) 

Baseline Baseline + 2.0 W Standby 2.55 

1 Baseline + 1.5 W Standby 2.59 

2 Baseline + 0.08 W Standby 2.69 

3 Gap Fill + 0.08 W Standby 2.71 

4 Gap Fill + 0.08 W Standby 2.80 

5 Heat Pump (Max-Tech) + 0.08 W Standby 4.03 

Table 5.4.27 Clothes Dryer Integrated Efficiency Levels (CEF) – Ventless Electric 

Combination Washer/Dryers 

Level Efficiency Level Description 

Integrated Efficiency Level (CEF) 

(lb/kWh) 

Electric Combination Washer/Dryer 

Baseline Baseline + 2.0 W Standby 2.08 

1 Gap Fill + 2.0 W Standby 2.35 

2 Gap Fill + 1.5 W Standby 2.38 

3 Gap Fill + 0.08 W Standby 2.46 

4 Gap Fill + 0.08 W Standby 2.56 

5 Heat Pump (Max-Tech) + 0.08 W Standby 3.69 

During the preliminary analysis, incremental IEER efficiency levels for room air 

conditioners were established at values rounded to the nearest tenth, except for the baseline 

levels described in section 5.4.1.3. The levels were chosen to correspond to the EER efficiency 

levels in the preliminary analysis discussed in section 5.4.2.1 as closely as was feasible. The 

selected levels are summarized in Table 5.4.28 and Table 5.4.29 below. 

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Table 5.4.28 Preliminary Analysis Room Air Conditioner Integrated Efficiency Levels 

(IEER)--Product Classes 1 and 3 

IEER (Btu/h-W) 

Level 1: Without Reverse Cycle, 

With Louvered Sides, 

< 6,000 Btu/h 

3:Without Reverse Cycle, 

With Louvered Sides, 

8,000 - 13,999 Btu/h 

Baseline 9.52 9.71 

1 10.1 10.3 

2 10.6 10.8 

3 11.1 11.3 

4 11.6 11.5 

5 12.0 

Table 5.4.29 Preliminary Analysis Room Air Conditioner Integrated Efficiency Levels 

(IEER)--Product Classes 5 and 8 

Level 

IEER (Btu/h-W) 

5:Without Reverse Cycle, With 

Louvered Sides, 

≥ 20,000 Btu/h 

8:Without Reverse Cycle, Without 

Louvered Sides, 

8,000 – 13,999 Btu/h 

Baseline 8.47 8.43 

1 9.0 8.9 

2 9.4 9.3 

3 9.8 9.8 

4 10.0 -

As detailed in the section above, DOE modified its active mode efficiency levels for the 

final rule analysis, and renamed the integrated metric. Based on these changes, incremental 

CEER efficiency levels for room air conditioners were established at values rounded to the 

nearest tenth, except for the baseline levels described in section 5.4.1.3. The levels were chosen 

to correspond to the extent feasible with the EER efficiency levels selected for the active mode 

efficiency , which are discussed in section 5.4.2.1. The selected integrated efficiency levels are 

summarized in Table 5.4.30 to Table 5.4.32 below. 

Table 5.4.30 Room Air Conditioner Integrated Efficiency Levels (CEER)--Product Classes 

1 and 3 

Level 

CEER (Btu/h-W) 

1: Without Reverse Cycle, 

With Louvered Sides, 

< 6,000 Btu/h 

3:Without Reverse Cycle, 

With Louvered Sides, 

8,000 - 13,999 Btu/h 

Baseline 9.52 9.71 

1 10.1 10.2 

2 10.6 10.7 

3 11.1 10.9 

4 11.4 11.5 

5 11.7 12.0 

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Table 5.4.31 Room Air Conditioner Integrated Efficiency Levels (CEER)--Product Classes 

5A and 5B 

Level 

CEER (Btu/h-W) 

5A:Without Reverse Cycle, With 

Louvered Sides, 

20,000-27,999 Btu/h 

5B:Without Reverse Cycle, With 

Louvered Sides, 

≥ 28,000 Btu/h 

Baseline 8.47 8.48 

1 9.0 8.9 

2 9.4 9.4 

3 9.8 9.8 

4 10.15 -

Table 5.4.32 Room Air Conditioner Integrated Efficiency Levels (CEER)--Product Classes 

8A and 8B 

Level 

CEER (Btu/h-W) 

8A:Without Reverse Cycle, Without 

Louvered Sides, 

8,000 – 10,999 Btu/h 

8B:Without Reverse Cycle, Without 

Louvered Sides, 

11,000 – 13,999 Btu/h 

Baseline 8.41 8.44 

1 9.3 9.3 

2 9.6 9.5 

3 10.0 9.8 

4 10.4 10.0 

5.5 METHODOLOGY OVERVIEW 

DOE typically uses data submitted by AHAM as the primary source of cost information 

for the engineering analysis. AHAM provided DOE with aggregated incremental manufacturing 

cost data from its member companies for several product classes of vented clothes dryers. 

However, AHAM did not receive enough responses from members to allow aggregation and 

reporting of data for the remaining clothes dryer product classes and all room air conditioner 

product classes. 

For clothes dryers, DOE conducted an independent review of the AHAM data using 

several methods and data sources. To gain a better understanding of the data submitted by 

member companies and to be able to relate the costs of improving efficiency to discrete (or 

system) technologies, DOE reviewed the TSD from the previous rulemaking and conducted 

interviews with clothes dryer manufacturers. DOE also performed detailed product teardowns 

and cost modeling on several clothes dryer models spanning a range of efficiencies to generate 

cost-efficiency curves. These cost-efficiency relationships were compared to the AHAM data for 

validation. Finally, DOE conducted standby power testing, as well as detailed energy 

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performance testing at an independent laboratory to gain insights into energy performance in 

active, standby, and off modes, and disaggregated energy use of components and subsystems. 

For room air conditioners, in the absence of industry-supplied data, DOE conducted 

energy modeling analysis of the products obtained for reverse engineering analysis, product 

designs for R-410A refrigerant based on the reverse engineering products, and product designs 

using R-410A that incorporate energy-saving design options. The manufacturing cost model 

developed in conjunction with the reverse-engineering work was used to determine the 

incremental costs associated with the high-efficiency product designs evaluated in the energy 

modeling in order to allow development of cost-efficiency relationships for products using R410A refrigerant. DOE supplemented these analysis with a review of the TSD from the previous 

rulemaking, product testing at an independent laboratory, and manufacturer interviews. Table 

5.5.1 below shows which methods DOE used for each product. 

Table 5.5.1 Engineering Analysis Methods 

Method Product 

Clothes Dryers Room Air Conditioners 

AHAM Data √ 

Review of Previous TSD √ √ 

Product Teardown and 

Manufacturing Cost 

Modeling 

√ √ 

Product Testing √ √ 

Manufacturer Interviews √ √ 

Energy Modeling √ 

5.5.1 AHAM Data Request 

In support of this rulemaking effort, DOE requested incremental cost data from AHAM 

for both of the product categories. (See appendix 5A of this TSD for the data request sheets.) The 

data represent the average incremental production cost to improve a baseline unit to a specified 

efficiency level. This methodology constitutes an efficiency-level approach to the engineering 

analysis because DOE examined aggregated incremental increases in manufacturer selling price 

at specified levels of energy efficiency. In addition, DOE requested shipments, shipmentweighted average efficiency, and market share efficiency data. As noted in section 5.4.2.3, 

AHAM did not receive enough responses from members in order to allow aggregation and 

reporting of incremental cost data for room air conditioners. Tables of aggregated data for 

clothes dryers provided to DOE by AHAM are contained in appendix 5B of this TSD. 

5.5.2 Manufacturer Interviews 

AHAM provided to DOE shipment-weighted average manufacturer costs and capital 

expenditures. To better understand the manufacturer costs, DOE supplemented these data with 

information obtained through follow-up manufacturer interviews. These confidential interviews 

provided a deeper understanding of the various combinations of technologies used to increase 

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product efficiency, and their associated manufacturing costs. Sample questions asked during 

interviews are contained in appendix 5C of this TSD. 

During the interviews, DOE also gathered information about the capital expenditures 

required to increase the efficiency of the baseline units to various efficiency levels (i.e., 

conversion capital expenditures by efficiency or energy-use level). The interviews provided 

information 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 costs directly from a manufacturer, the most 

accurate method for determining the production cost of a product is to disassemble the unit 

piece-by-piece and estimate the material and labor cost of each component using a process 

commonly called a physical teardown. A supplementary method, called a catalog teardown, uses 

published manufacturer catalogs and supplementary component data to estimate the major 

physical differences between a product that has been physically disassembled and another similar 

product. DOE performed physical teardown analysis on both clothes dryers and room air 

conditioners. The teardown methodology is explained in section 5.5.3.1 and section 5.5.3.2. 

Selection of Units 

During the process of selecting units for teardown, DOE considered 3 main questions: 

� What efficiency levels should be captured in the teardown analysis? 

� Are there units on the market that capture all potential efficiency levels and design options? 

� Which of the available units are most representative? 

In responding to the preceding questions, DOE generally adopts the following criteria for 

selecting units for teardown analysis: 

� The selected products should span the full range of efficiency levels for each product class 

under consideration; 

� Within each product class, if possible, the selected products should come from the same 

manufacturer and be within the same product series; 

� The selected products should primarily come from manufacturers with large market share in 

that product class, although the highest efficiency products were chosen irrespective of 

manufacturer; and 

� The selected products should have non-efficiency-related features that are the same as, or 

similar to, features of other products in the same class and at the same efficiency level. 

Additional criteria for selecting the teardown units specific to each product category are 

described in section 5.6.1.3 for clothes dryers and section 5.6.2.3 for room air conditioners. 

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5.5.3.1 Generation of Bill of Materials 

The end result of each teardown is a structured bill of materials (BOM). Structured 

BOMs describe each equipment part and its relationship to the other parts, in the estimated order 

of assembly. The BOMs describe each fabrication and 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, classified as either raw 

materials or purchased parts and assemblies. The classification into raw materials or purchased 

parts is based on DOE’s previous industry experience, recent information 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 discussions with suppliers. For parts fabricated in-house, the prices of 

“raw” metals (e.g., tube, sheet metal) are estimated on the basis of 5-year averages. Other “raw” 

materials such as plastic resins, insulation materials, etc. are estimated on a current-market basis. 

The cost of raw materials was determined using prices for copper, steel and aluminum 

from the American Metals Market.4 The prices for rifled and unrifled copper tubing were 

obtained directly from a tubing manufacturer. 

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 2005-2009, 

these price increases are normalized, which better represents long-term material prices. 

In order to assure that raw material prices DOE used in manufacturing cost estimates are 

representative of actual costs paid by OEMs, DOE sent a separate material cost questionnaire to 

the manufacturers that participated in the technical interviews. 

5.5.3.2 Cost Structure of the Spreadsheet Models 

The manufacturing cost assessment methodology used is a detailed, component-focused 

technique for rigorously calculating the manufacturing cost of a product (direct materials, direct 

labor and some overhead costs). Figure 5.5.1 shows the three major steps in generating the 

manufacturing cost. 

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Figure 5.5.1 Manufacturing Cost Assessment Stages 

The first step in the manufacturing cost assessment was the creation of a complete and 

structured BOM from the disassembly of the units selected for teardown. The units were 

dismantled, and each part was characterized according to weight, manufacturing processes used, 

dimensions, material, and quantity. The BOM incorporates all materials, components, and 

fasteners with estimates of raw material costs and purchased part costs. Assumptions on the 

sourcing of parts and in-house fabrication were based on industry experience, information in 

trade publications, and discussions with manufacturers. Interviews and plant visits were 

conducted with manufacturers to ensure accuracy on methodology and pricing. 

Following the development of a detailed BOM, the major manufacturing processes were 

identified and developed for the spreadsheet model. 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 Packaging 

Insulating Refrigerant Charging 

Turret Punch 

Tube Forming 

Enameling 

Fabrication process cycle times were estimated and entered into the BOM. In the final 

step of the cost assessment, assembly times and associated direct labor costs were estimated. 

Once the cost estimate for each teardown unit was finalized, a detailed summary was prepared 

for relevant components, subassemblies and processes. The BOM thus details all aspects of unit 

costs. 

Design options used in units subject to teardown 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 are 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. 

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5.5.3.3 Cost Model and Definitions 

Once DOE disassembled selected units, gathered information from manufacturer catalogs 

on additional products, and identified technologies, DOE created an appropriate manufacturing 

cost model that could translate physical information into manufacturing production costs. The 

cost model is based on production activities and divides factory costs into the following 

categories: 

Materials: Purchased parts (i.e., gas valves, blower motors, etc.), raw materials, (i.e., cold 

rolled steel, copper tube, etc.), and indirect materials that are used for processing and 

fabrication. 

Labor: Fabrication, assembly, indirect, and supervisor labor. Fabrication and assembly 

labor cost are burdened with benefits and supervisory costs. 

Overhead: Equipment, tooling, and building depreciation, as well as utilities, equipment 

and tooling maintenance, insurance, and property taxes. 

Cost Definitions 

Because there are many different accounting systems and methods to monitor costs, DOE 

defined the above terms as follows: 

Direct material: Purchased parts (out-sourced) plus manufactured parts (made in-house
 

from raw materials).
 

Indirect material: Material used during manufacturing (e.g., welding rods, adhesives).
 

Fabrication labor: Labor associated with in-house piece manufacturing.
 

Assembly labor: Labor associated with final assembly.
 

Indirect labor: Labor costs that scaled with fabrication and assembly labor. This included
 

the cost of technicians, manufacturing engineering support, stocking, etc. that were
 

assigned on a span basis.
 

Equipment and plant depreciation: Money allocated to pay for initial equipment 


installation and replacement as the production equipment is amortized.
 

Tooling depreciation: Cost for initial tooling (including non-recurring engineering and 


debugging of the tools) and tooling replacement as it wears out or is rendered obsolete. 


Building depreciation: Money allocated to pay for the building space and the conveyors
 

that feed and/or make up the assembly line.
 

Utilities: Electricity, gas, telephones, etc.
 

Maintenance: Annual money spent on maintaining tooling and equipment.
 

Insurance: Appropriated as a function of unit cost.
 

Property Tax: Appropriated as a function of unit cost.
 

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5.5.3.4 Cost Model Assumptions 

As discussed in the previous section, assumptions about manufacturer practices and cost 

structure played an important role in estimating the final product cost. In converting physical 

information about the product into cost information, DOE reconstructed manufacturing processes 

for each component using internal expertise and knowledge of the methods used by the industry. 

DOE used assumptions regarding the manufacturing process parameters (e.g., equipment use, 

labor rates, tooling depreciation, and cost of purchased raw materials) to determine the value of 

each component. DOE then summed the values of the components into assembly costs and, 

finally, the total product cost. The product cost included the material, labor, and overhead costs 

associated with the manufacturing facility. The material costs included both direct and indirect 

materials. The labor costs included fabrication, assembly, indirect, direct, and supervisor labor 

rates, including the associated overhead. The labor costs were determined by the type of product 

(clothes dryer and room air conditioner) manufactured at the factory. Overhead costs included 

equipment depreciation, tooling depreciation, building depreciation, utilities, equipment, tooling 

maintenance, insurance, property, and taxes. 

5.5.4 Review of Previous Technical Support Documents and Models 

DOE reviewed previous rulemaking TSDs to assess their applicability to the current 

standard setting process for residential clothes dryers and room air conditioners. These previous 

rulemaking TSDs served as a source for design options and energy consumption analysis, in 

addition to other sources. For room air conditioners, the energy model used in the previous 

rulemaking was updated for use in the current one. 

5.5.5 Product Testing 

DOE conducted product testing on clothes dryers and room air conditioners according to 

the relevant DOE test procedures to develop a better understanding of the potential efficiency 

improvements of design options and to develop disaggregated efficiency data. In addition, DOE 

performed standby and off mode testing to help evaluate possible standby and off modes, energy 

use in each mode, and strategies manufacturers may take to reduce standby power. 

5.6 ANALYSIS AND RESULTS 

5.6.1 Clothes Dryers 

The clothes dryer engineering analysis was performed by considering cost and efficiency 

information from multiple sources. AHAM provided incremental manufacturing costs for all but 

the highest efficiency levels of interest to DOE for vented electric standard and gas clothes 

dryers. No data were provided for vented electric compact (120 V) and (240 V) or ventless 

5-35 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

electric compact (240 V) and electric combination washer/dryer product classes. DOE 

supplemented these data points by conducting its own engineering analysis, comprised of 

performance testing at an independent laboratory, standby power testing, and manufacturing cost 

estimates from detailed teardowns of currently-available clothes dryers. Manufacturer interviews 

were also conducted to obtain greater insight into the design strategies to improve efficiency and 

the associated costs. DOE conducted preliminary manufacturer interviews after the framework 

document. DOE also conducted additional manufacturer interviews for the final rule analysis. 

5.6.1.1 AHAM Data 

AHAM provided to DOE shipment data from its member companies for clothes dryers. 

Table 5.6.1 shows market share by EFe

 ranges for electric standard and gas clothes dryer 

shipments in the years 2005 and 2006. AHAM noted that, in order to maintain confidentiality, 

market share for electric standard dryers between EF of 3.20 and 3.29 were incorporated into the 

EF range between 3.10 and 3.19. Similarly, market share for gas clothes dryers with an EF > 

2.94 was incorporated into the EF > 2.85 efficiency bin. AHAM stated it was not able to obtain 

sufficient data for vented electric compact (120 V) and (240 V). In addition, market share data 

for ventless dryers was unavailable since EF is not currently measured. 

Table 5.6.1 AHAM Clothes Dryer Market Share Data Submittal 

Vented Electric Standard Vented Gas 

EF Range 

(lb/kWh) 

Market Share 

for 2005 (%) 

Market Share 

for 2006 (%) 

EF Range 

(lb/kWh) 

Market Share 

for 2005 (%) 

Market Share 

for 2006 (%) 

3.01-3.09 

(Baseline = 3.01) 26 33 2.67-2.74 (Baseline = 2.67) 25 28 

3.10-3.29 74 67 2.75-2.84 42 44 

3.20-3.29 >2.85 32 27 

>3.29 

On a shipment-weighted basis, the average efficiencies of electric standard and gas 

clothes dryers sold in the United States have been stable for the past few years, according to the 

AHAM-submitted data shown in Table 5.6.2. 

e

All clothes dryer EF data provided by AHAM is based on EF values as measured by the previous DOE clothes 

dryer test procedure. 

5-36 

 

 

 

 

 

 

 

 

Table 5.6.2 AHAM Clothes Dryer Shipments and Shipment-Weighted Efficiency Data 

Submittal 

Year 

Shipments, Domestic + Imports 

(Thousands of Units) 

Shipment-Weighted Average 

Efficiency(EF, cycles/kWh) 

Vented Ventless Vented 

Electric 

Gas 

Electric Electric 

Gas 

All 

Electric Standard 

All 

Compact 

Compact 

240 V Combo Standard 

Compact 

120 V 

Compact 

240 V 

1993 3,674 1,156 

1994 3,838 1,239 

1995 3,823 1,169 

1996 3,947 1,193 

1997 4,115 1,195 

1998 4,482 1,307 

1999 4,865 1,444 

2000 5,095 1,480 

2001 5,117 1,384 

2002 5,402 1,490 

2003 5,718 5,622 96 1,616 

2004 6,262 6,159 103 1,660 

2005 6,408 6,330 78 1,707 3.10 2.70 

2006 6,360 6,246 114 1,614 3.10 2.70 

AHAM provided incremental manufacturing cost data for the first three efficiency levels 

for vented electric standard and gas clothes dryers presented in the framework document, as 

shown in Table 5.6.3. At the time DOE requested data from AHAM, the efficiency levels of 

interest were specified as those in the framework document, which were subsequently updated 

during the preliminary analysis based on more recent market information, comments from 

interested parties, and manufacturer interviews. Therefore, the AHAM cost data are presented at 

the original values of EF to which the aggregated data correspond, while DOE’s cost estimates 

are presented at the updated levels. 

5-37 

 

 

 

 

 

 

 

 

 

Table 5.6.3 AHAM Clothes Dryer Incremental Cost Data Submittal 

Vented Electric Standard Vented Gas 

Efficiency Level 1 2 3 1 2 3 

EF Level, [Original] (lb/kWh) 3.10 3.16 3.39 2.75 2.77 3.02 

Average Shipment-Weighted 

Incremental Cost ($) for each EF 

level 

Material 9 42 140 20 60 81 

Labor 2 11 45 2 6 32 

Overhead 2 4 12 2 4 12 

Conversion Capital Expenditure 

Assumptions, (Million $), Total 

for all Manufacturers 

Building 

Tooling and 

Equipment 

0.25 

5.25 

9.02 

37.68 

50.18 

118.93 

0.46 

2.62 

29.83 

37.24 16.15 

Avg. One-Time Product 

Conversion Expenses, (Million $), 

Total for all Manufacturers 

R&D 3.62 15.87 58.97 2.99 15.46 12.91 

Marketing 

Notes 

1. While all members use straight-line depreciation, AHAM was not able to obtain a consistent
 

response on the years used in the calculation.
 

2. Shaded cells indicate that AHAM did not receive enough input to aggregate incremental cost data. 

Figure 5.6.1 plots the average incremental cost as a function of EF (based on the previous 

DOE clothes dryer test procedure) for the AHAM clothes dryer data. The lowest point on the 

graph indicates the baseline level and therefore has a cost increment of $0. Note that the gas 

curve exhibits a steep increase between EL 2 and EL 3. Based on manufacturer interviews, DOE 

believes that AHAM members suggested fairly significant design changes in order to reach EL 3, 

even though the original EF values for EL 2 and EL 3 were quite close. 

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 Shipment-Weighted Average Incremental Cost
 

$250 

$200 

$150 

$100 

$50 

$0 

Electric Standard 

Gas 

2.50 2.70 2.90 3.10 3.30 3.50
 

EF 

Figure 5.6.1 AHAM Clothes Dryer Cost-Efficiency Curves 

In addition to the cost and efficiency data, AHAM provided information to help DOE 

evaluate a potential change to the clothes dryer test procedure to reflect more current product 

characteristics. The previous DOE clothes dryer test procedure assumed an initial RMC of the 

test cloth load of 70.0 ± 3.5 percent. However, DOE noted that this RMC value is likely no 

longer representative of typical residential clothes washers that use higher spin speeds to remove 

moisture at the end of the wash cycle. Therefore, DOE requested data from AHAM to help 

evaluate the effect of a lower initial RMC on measured EF, as well as to characterize the trends 

in shipment-weighted clothes washer RMC. Figure 5.6.2 illustrates the data AHAM provided for 

the change in EF that is measured when RMC is reduced from nominally 70 percent to nominally 

56 percent. It can be seen that, in AHAM’s test sample of 11 baseline clothes dryers, EF 

decreased by an average of 4 percent when RMC was reduced as described and the existing test 

procedure was used to calculate EF. Average EF decreased from 3.09 to 2.97 lb/kWh. The test 

procedure, however, contains a provision in the calculation of per-cycle energy consumption that 

is intended to normalize EF by the reduction in RMC over the course of the drying cycle. There 

is a scaling factor applied of 66, which is supposed to represent the nominal change in percent 

from the starting RMC to the ending one, which is derived from the assumption that the nominal 

starting RMC is 70 percent and the nominal ending RMC is 4 percent. If the calculation in the 

test procedure is adjusted to maintain what DOE believes is the intent for normalization of the 

results, the scaling factor should be changed to 52 to reflect a starting point of 56 percent RMC 

rather than 70 percent. If that adjustment is made to the AHAM data, EF increases by an average 

of 22 percent by changing from 70 to 56 percent initial RMC. 

5-39 

 

 

 

 

 

 

 

 

Change in EF at 56% RMC (lb/kWh)
 

1 

0.8 

0.6 

0.4 

0.2 

0
 

-0.2
 

-0.4
 

Corrected Scale Factor 

Existing Scale Factor 

2.95 3 3.05 3.1 3.15 3.2 3.25 3.3 

EF at 70% RMC (lb/kWh) 

Figure 5.6.2 AHAM Data Submittal for Impact of Initial RMC on Clothes Dryer EF 

AHAM also provided data for shipments of residential clothes washers for which RMC 

was reported, along with shipment-weighted RMC. (See Table 5.6.4) These data sets, each of 

which were disaggregated for front-loading and top-loading clothes washers as well as reported 

as overall values for all clothes washers, provide insight into what initial clothes dryer RMC 

would be most representative of current clothes washers. RMC has been decreasing consistently, 

and the data suggest that the initial RMC in the clothes dryer test procedure of nominally 70 

percent is higher than the current shipment-weighted clothes washer average. 

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Table 5.6.4 AHAM Shipment-Weighted Clothes Washer RMC Data Submittal 

Year 

Clothes Washer Shipments for Which 

RMC was Reported Shipment-Weighted RMC* (%) 

FrontLoading TopLoading Total FrontLoading TopLoading Overall 

2000 232,714 686,440 919,154 43.6 57.4 53.9 

2001 235,989 473,629 709,618 41.3 57.7 52.2 

2002 280,667 529,265 809,932 41.5 58.1 52.3 

2003 351,411 1,676,877 2,028,288 43.1 54.5 52.5 

2004 1,179,813 5,270,285 6,450,098 42.2 52.8 50.9 

2005 1,563,108 5,394,511 6,957,619 40.8 52.7 50.1 

2006 1,851,218 15,528,279 17,379,497 39.3 51.8 50.5 

2007 1,973,825 15,271,142 17,244,967 38.3 51.8 50.2 

2008 2,043,024 4,492,059 6,535,083 38.1 51.0 47.0 

* Shipment-weighted average clothes washer RMC data measured using the DOE clothes washer test procedure 

which applies an RMC correction factor 

5.6.1.2 Product Testing 

For the preliminary analysis, DOE conducted a market survey of clothes dryer models 

and their associated features and selected five electric standard, one electric compact (240 V), 

and four gas vented clothes dryers from multiple manufacturers. For ventless clothes dryers, 

DOE selected one electric compact (240 V) and one electric combination washer/dryer model. 

These selections were based on the proposed efficiency levels and the range of product 

efficiencies available on the market. Because there is no EnergyGuide label required for 

residential clothes dryers, DOE based the selection of units for teardown on the efficiency data 

available in the CEC product database. DOE was unable to test an electric compact (120 V) 

clothes dryer since no such model was found to be on the market in the United States. Table 

5.6.5 and Table 5.6.6 list features of the tested units. 

5-41 

 

Table 5.6.5 Vented Electric Standard Clothes Dryer Test Unit Features 

Feature 

Clothes Dryer Test Unit Designation 

Vented Electric Standard 

#1 #2 #3 #4 #5 

Rated EF 

(cycle/kWh) 3.06 3.10 3.15 3.20 3.4 

Rated Drum 

Capacity (ft3) 7 7 7 5.9 6.1 

Controls Electromech 

anical 

Electromech 

anical with 

Moisture 

Sensor PCB 

Electronic Electromech 

anical Electronic 

Drum Type Full Cylinder Open 

Cylinder 

Open 

Cylinder 

Open 

Cylinder Full Cylinder 

Number of 

Motors 2 1 1 1 1 

Motor Type(s) PSC + 

Induction Induction Induction Induction PSC 

Air Flow 

Direction 

Back to 

Front 

Back to 

Back 

Back to 

Back 

Back to 

Back 

Back to 

Front 

Dedicated Hot 

Air Duct? No Yes Yes Yes Yes 

Inlet Air 

Preheat? No No No No No 

Heating 

Modulation? No No No No No 

Automatic Cycle 

Termination? Yes Yes Yes Yes Yes 

Sensor Type(s) Temp Temp + 

Moisture 

Temp + 

Moisture 

Temp + 

Moisture 

Temp + 

Moisture 

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Table 5.6.6 Vented Electric Compact (240 V), Gas, and Ventless Clothes Dryer Test Unit 

Features 

Feature 

Clothes Dryer Test Unit Designation 

Vented 

Electric 

Compact 

(120 V) 

Vented Gas 

Ventless 

Electric 

Compact 

(240 V) 

Ventless 

Electric 

Combo 

#6 #7 #8 #9 #10 #11 #12 

Rated EF 

(cycle/kWh) 2.98 2.67 2.76 2.80 3.00 

Rated Drum 

Capacity (ft3) 3.4 5.2 6.7 7 7,3 2.5 2.5 

Controls Electrome 

chanical 

Electrome 

chanical Electronic Electronic Electronic Electronic Electronic 

Drum Type Open 

Cylinder 

Full 

Cylinder 

Open 

Cylinder 

Open 

Cylinder 

Open 

Cylinder 

Full 

Cylinder 

Full 

Cylinder 

Number of 

Motors 1 1 1 1 1 1 2 

Motor Type(s) Induction Induction Induction Induction Induction PSC PSC + 

Induction 

Air Flow 

Direction 

Back to 

Back 

Back to 

Front 

Back to 

Front 

Back to 

Front 

Back to 

Front 

Back to 

Front 

Front to 

Back 

Dedicated Hot 

Air Duct? Yes No Yes Yes Yes Yes Yes 

Inlet Air 

Preheat? No No No No No No No 

Heating 

Modulation? No No No No No No No 

Automatic Cycle 

Termination? Yes Yes Yes Yes Yes Yes No 

Sensor Type(s) Temp + 

Moisture Temp Temp + Moisture 

Temp + 

Moisture 

Temp + 

Moisture Temp 

Active Mode Testing 

Clothes dryer testing was performed for the preliminary analysis on the twelve units in 

the test sample. The test results included not only the measurements required to evaluate the 

performance according to the previous DOE test procedure, but sub-metered component energy 

consumption data as well, which enabled DOE to quantify patterns of energy consumption 

during various stages of the cycle and identify energy efficiency and other drying performance 

strategies. Each clothes dryer was tested at an independent laboratory according to the previous 

DOE test procedure (10 CFR 430 subpart B, appendix D). For the ventless units, the test was run 

without the use of the exhaust simulator. 

The test procedure consisted of running a load of preconditioned test cloth in the clothes 

dryer at the maximum temperature setting and, if equipped with a timer, at the maximum time 

setting. For standard-size dryers (i.e., with a drum capacity of 4.4 cubic feet (ft3

) or greater), the 

nominal test load weight is 7.00 lb. For compact-size dryers (i.e., with a drum capacity less than 

4.4 ft3

), the nominal test load weight is 3.00 lb. Prior to loading the drum, the cloth is dampened 

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and spun to obtain an RMC of 66.5–73.5 percent. Once the cycle is started, the test load is dried 

until the RMC is 2.5–5.0 percent, resetting the timer or automatic dry control if necessary. 

During this test cycle, the total kWh of electric energy consumed by the clothes dryer is 

measured, in addition to the “bone dry”f

 weight of the test load and the starting and ending RMC. 

For gas clothes dryers, the measurements also include the cubic feet of gas used during the cycle 

and, for gas dryers equipped with a continuously burning pilot light, the cubic feet of gas 

consumed by the pilot light during 1 hour. In order to calculate EF according to the DOE test 

procedure, the following calculations are performed. 

For electric clothes dryers, the total per-cycle electric dryer energy consumption, Ece, is 

defined as: 

Ece = (66/Ww - Wd) x Et x FU where, 

66	 = an experimentally established value for the percent reduction in the moisture content of 

the test load during a laboratory test cycle, expressed as a percent 

Ww = the moisture content of the wet test load 

Wd = the moisture content of the dry test load 

Et = the total kWh of electrical energy measured during the test 

FU = a Field Use factor 

= 1.18 for time termination control systems
 

= 1.04 for automatic termination control systems
 

For gas clothes dryers, the total per-cycle gas dryer electrical energy consumption, Ege, is 

calculated in the same manner as for electric dryers. Total per-cycle gas dryer energy 

consumption expressed in kWh, Ecg, is defined as: 

Eg = Ege + [(66/Ww - Wd) x Etg x FU x GEF + Epg x (8760-140/416) x GEF]/3412 where, 

Etg	 = the cubic feet of gas used during the cycle 

GEF	 = the corrected gas heat value (Btu/ft3

) 

= 1.18 for time termination control systems 

= 1.04 for automatic termination control systems 

Epg = the cubic feet of gas used by a continuously burning pilot light in 1 hour 

8760 = the number of hours in a year 

416 = the representative average number of clothes dryer cycles in a year 

140 = the estimated number of hours that the continuously burning pilot light is on during the 

operation of the clothes dryer for the representative average use cycle for clothes dryers 

(416 cycles per year) 

f “Bone dry” means a condition of a load of test clothes which has been dried in a dryer at maximum temperature for 

a minimum of 10 minutes, removed and weighed before cool down, and then dried again for 10-minute periods until 

the final weight change of the load is 1 percent or less. 

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3412 = the conversion factor of Btu/kWh
 

The value of 66, Ww, Wd, FU, and GEF are the same as were defined for electric clothes dryers.
 

Finally, EF, expressed in lb per kWh, is derived from the per-cycle electrical energy 

consumption according to: 

EF = M/ Ece for electric clothes dryers

 = M/ Eg for gas clothes dryers 

M = the test load size in lb 

Additional instrumentation was provided during these tests to measure disaggregated 

component energy consumption in order to assess which strategies and features could have the 

greatest impact on efficiency. Watt meters were attached to the following major components 

which together account for virtually all of the electrical energy usage of the clothes dryer: 

� heating element for electric units; 

� gas valve for gas units; 

� drum motor; 

� blower motor, if separate from the drum motor; 

� controller; 

� pump for ventless units, which removes condensate; and 

� water valve for ventless electric combination washer/dryer. 

Overall trends in key parameters of the clothes dryers under DOE testing are shown in 

Figure 5.6.3 and Figure 5.6.4, including average drying times and total per-cycle electrical 

energy consumption. Each data point represents the average of three tests. DOE also compared 

measured EF to rated EF for each of the clothes dryers in the test sample because manufacturers 

indicated during interviews that the tolerances in the existing test procedure can introduce 

uncertainty in the EF measurement. By ensuring the testing was conducted under consistent test 

conditions, DOE intended to normalize the data against allowable variations in ambient 

conditions and test parameters. Because the ventless clothes dryers have not been rated, the EF 

for these units could only be represented by the value measured during testing. 

5-45 

 

 

 

 

 

 

 

 

 

Cycle Time (min)
 

60 

50 

40 

30 

20 

10 

0 

1.5 1.7 1.9 2.1 2.3 2.5 2.7 2.9 3.1 3.3 3.5 

Vented Electric 

Standard 

Vented Electric 

Compact (120 V) 

Vented Gas 

Vent-less Electric 

Compact (240 V) 

Vent-less 

Combination 

EF (lb/kWh) 

Figure 5.6.3 Measured Clothes Dryer Cycle Time versus Rated EF 

These data show that cycle times for vented electric standard and gas clothes dryers are 

shorter between baseline and mid-efficiency units. However, in both product classes, this trend 

reverses at the higher efficiency levels. The data also show that, for the compact-size dryers, a 

ventless unit requires about 35 percent more time to dry than the vented version, although this 

result is likely somewhat skewed by the fact that the vented clothes dryer heating element draws 

about 10 percent more power than the ventless dryer’s heater. Finally, these data show a 

significantly longer drying time associated with the ventless electric combination washer/dryer. 

For that particular model tested, the heating element drew less than half the power than that in 

the other compact clothes dryers (vented and ventless). 

5-46 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Total Per-Cycle Energy Consumption (kWh)
 

3.00 

2.50 

2.00 

1.50 

1.00 

0.50 

0.00 

1.5 1.7 1.9 2.1 2.3 2.5 2.7 2.9 3.1 3.3 3.5 

Vented Electric 

Standard 

Vented Electric 

Compact (120 V) 

Vented Gas 

Vent-less Electric 

Compact (240 V) 

Vent-less 

Combination 

EF (lb/kWh) 

Figure 5.6.4 Measured Clothes Dryer Energy Consumption versus Rated EF 

The data for total per-cycle energy consumption demonstrate the expected trend of 

measured energy use decreasing as a function of rated EF, again with the ventless data plotted as 

a function of measured rather than rated EF. The slope for compact units (which include the 

ventless combination washer/dryer) is fairly consistent with the slope for gas clothes dryers, with 

a somewhat steeper slope observed for vented electric standard clothes dryers. This potentially 

demonstrates uncertainty in the EF measurement, since EF should scale directly with total energy 

consumption. The test procedure may allow enough variation in the measurement of EF due to 

the specified tolerances to introduce uncertainty in the correlation between measured energy 

consumption and rated EF. 

Such uncertainty can be explored by comparing the rated EFs, which are obtained under 

varying allowable conditions in multiple test laboratories, to DOE’s measured EFs, whi ch were 

obtained under consistent conditions in a single laboratory. Figure 5.6.5 presents the comparison 

for the clothes dryers for which rated EF was available, with a trend-line included to show what 

the correlation ideally would be. It can be seen that, for many of the units, measured EF does not 

correlate particularly closely with rated EF. In particular, the measured EFs for gas clothes dryers 

showed little variation among the four test units. In addition, the max-tech units in both vented 

5-47 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

electric standard and gas clothes dryers had measured EFs that were lower than the certification 

data would indicate. Measured EF (lb/kWh)
 

3.5 

3.4 

3.3 

3.2 

3.1 

3 

2.9 

2.8 

2.7 

2.6 

2.5 

Vented Electric 

Standard 

Vented Electric 

Compact (120 V) 

Vented Gas 

2.5 2.7 2.9 3.1 3.3 3.5
 

Rated EF (lb/kWh) 

Figure 5.6.5 Measured versus Rated Clothes Dryer EF 

DOE believes that the lack of strong correlation between measured and rated clothes 

dryer EF can be traced to the tolerances that are allowed in the test procedure, notably for the 

ambient test room conditions. Whirlpool Corporation (Whirlpool) submitted data to DOE that 

demonstrates the effect of a change in ambient relative humidity and temperature on EF. 

Parametric variations in relative humidity from 40 to 60 percent and ambient temperature from 

72 to 78 °F, which are the limits allowed under the test procedure, produce measured EFs for an 

electric compact (120 V) clothes dryer that range from 2.98 to 3.35 lb/kWh. The Whirlpool data 

submission is reproduced in appendix 5B of this TSD. These data and their implications are 

currently being considered in a clothes dryer test procedure rulemaking. 

Component-level data recorded from the watt meters during the DOE tests disaggregated 

the power consumption of individual components, allowing DOE to evaluate what strategies a 

manufacturer might choose to pursue higher energy efficiency. Figure 5.6.6 shows the 

component average power consumption while in use during the cycle for each of the test units. 

Within a product class, the models are arranged in the figure from lowest to highest EF. For 

purposes of visualization, heater power consumption and the gas use in equivalent W have been 

5-48 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

divided by a factor of 10, so that relative contributions from the other components can be 

compared. Also, it is recognized that the heater and gas burner are cycled on and off towards the 

end of the drying cycle. While the heating element watts are averages of instantaneous 

measurements during the periods when the heater is energized, and thus the power measurement 

is meaningful, the equivalent gas W are obtained from the total gas energy consumption during 

the cycle divided by the cycle time. Such an approach does not account for the periods during the 

cycle when the burner is off, but a comparison of instantaneous gas flow rates to the total cubic 

feet of gas used during the test shows that the assumption of constant burner usage introduces at 

most a 3 percent error. Therefore, it can be determined from Figure 5.6.6 that the heating 

element/gas burner is by far the largest contributor to per-cycle energy consumption, and 

therefore optimization of its usage and design will have a significant effect on efficiency. The 

drum motor (and potentially separate blower motor) have a second-order impact, while the gas 

valve, pump, and water valve (if any) are negligible in comparison. 

0 

200 

400 

600 

800 

1000 

1200 

Power Consumption (W) 

Water Valve 

Pump 

Gas Valve 

Blower Motor 

Drum Motor 

Gas Equivalent (Watts/10) 

Heater (Watts/10) 

Figure 5.6.6 Disaggregated Clothes Dryer Power Consumption 

It is difficult to generalize from these data what strategies manufacturers are taking to 

improve efficiency. Among vented electric standard clothes dryers, it appears that manufacturers 

are reducing heating element and motor power to achieve higher EFs, although the trend is not 

strong. That trend is even weaker among the tested gas clothes dryers. However, DOE notes that 

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it did not see significant differences in measured EF among these units, so potentially the test 

sample did not fully capture possible design improvements. 

To summarize key findings from the testing of a small number of clothes dryers, DOE 

observed that: 

� Test procedure tolerances introduce uncertainty in the EF measurement that is significant in 

comparison to the EF range between a baseline and high efficiency clothes dryer. 

� Improvements in the heating element or gas burner may provide a key opportunity for 

improving EF. A second-order impact could be achieved by improvements in the motor(s). 

� Modest increases in EF over the baseline can result in reduced drying cycle times. 

� Ventless electric compact (240 V) clothes dryers do not require drying times that are longer 

than those acceptable to consumers (i.e., typical drying times associated with vented electric 

standard clothes dryers. 

Standby Mode and Off Mode Testing 

For the preliminary analysis, DOE measured standby and off mode power for 10 of the 

12 clothes dryers in the test sample, using methodology provided in the International 

Electrotechnical Commission (IEC) Standard 62301 Ed. 1.0 (2005-06), Household electrical 

appliances – Measurement of standby power. The remaining two clothes dryers, both ventless 

units, incorporated components contributing to standby power that were energized by 240 V line 

power that could not be measured with the standby power meter used for these tests. Data 

obtained from this testing are presented in section 0. 

RMC Testing 

DOE also conducted tests for four representative clothes dryers (one each of vented 

electric standard, vented electric compact (120 V), vented gas, and ventless electric compact 

(240 V) product classes) to evaluate the impact of changes in initial RMC on measured EF, 

supplementing the RMC data AHAM submitted. The units were each tested at three different 

initial RMC levels: (1) nominally 70 percent, representing the conditions specified in the current 

DOE test procedure; (2) nominally 56 percent, to compare directly with the AHAM data 

submittal; and (3) nominally 39 percent, which was selected to be close to the weighted-average 

RMC of front-loading residential clothes washers currently on the market. 

Results of these tests, with EF calculated according to the formula provided in the DOE 

test procedure, are shown in Figure 5.6.7. In general, reducing initial RMC produced a decrease 

in measured EF for all product classes. Average percentage reductions in EF as a function of 

initial RMC are summarized in Table 5.6.7. 

5-50 

 

 

 

 

 

 

 

 

 

3.20
 

3.00 

2.80 

2.60 

Measured EF 

2.40 

2.20 

2.00 

Initial RMC 

Figure 5.6.7 Impact of Initial RMC on Clothes Dryer EF (Calculated According to the 


Existing DOE Test Procedure)
 

However, as discussed in section 5.6.1.1, the scaling factor of 66 in the current DOE test 

procedure is intended to normalize the calculated EF, for which initial and ending RMCs can 

vary slightly within allowable tolerances, to a reduction in RMC over the course of the test from 

70 percent to 4 percent. For tests in which the nominal starting RMC is no longer 70, DOE 

believes that the scaling factor may not be meaningful. Therefore, DOE subsequently calculated 

the EFs for the test units using scaling factors at each starting RMC that reflected a change from 

that RMC to 4 percent. For example, for a starting RMC of 56 percent, the scaling factor would 

be 52 (56 percent initial RMC minus 4 percent ending RMC). The results using adjusted scaling 

factors are presented in Figure 5.6.8. 

Vented Electric Standard 

Vented Electric Compact 

Vented Gas 

Vent-less Electric Compact 

20% 30% 40% 50% 60% 70% 80%
 

5-51 

 

 

 

 

 

 

 

 

 

6.00
 

Measured EF 

5.50 

5.00 

4.50 

4.00 

3.50 

3.00 

2.50 

Vented Electric Standard 

Vented Electric Compact 

Vented Gas 

Vent-less Electric Compact 

2.00 

20% 30% 40% 50% 60% 70% 80% 

Initial RMC 

Figure 5.6.8 Impact of Initial RMC on Clothes Dryer EF (Calculated Using Adjusted
 

Scaling Factors)
 

Using the revised scaling factor methodology, DOE determined that reducing the initial 

RMC increased EF significantly, as shown in Table 5.6.7. 

Table 5.6.7 Average Change in Clothes Dryer Energy Factor as a Function of Initial RMC 

as Compared to Initial RMC of 70 Percent 

Initial RMC % 

Change in EF using Existing Scaling Factor 

(%) 

Change in EF using Adjusted Scaling Factor 

(%) 

DOE Results AHAM Results DOE Results AHAM Results 

56 -3 -4 23 22 

39 -10 70 

At the time of the preliminary analysis, DOE was considering amendments to its clothes 

dryer test procedure to revise the initial RMC to reflect the performance of residential clothes 

washers currently on the market, but had not yet published a NOPR proposing active mode test 

procedure amendments. Therefore, in the preliminary analysis, DOE did not analyze energy 

conservation standards based on initial RMCs lower than the existing 70 percent. 

Maximum-Available Vented Gas Clothes Dryer Testing 

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After the framework document was published, DOE determined several models of vented 

gas clothes dryers were listed in the CEC product database with an EF (based on the previous 

DOE test procedure) above the maximum-available efficiency level proposed in the framework 

document. As discussed in section 5.6.1.5, multiple manufacturers stated during interviews that 

the current maximum efficiency that is listed for vented gas clothes dryers in the CEC product 

database is not achievable. Therefore, DOE tested the model that was rated as the maximumavailable efficiency vented gas clothes dryer to help determine an appropriate max-tech level 

value for the preliminary analysis. DOE purchased three identical units of this model and tested 

each three times according to the previous DOE clothes dryer test procedure. Table 5.6.8 shows 

the results from this testing, which indicate that the maximum-available model was measured as 

having an EF significantly lower than its rated value. Therefore, DOE did not consider this EF 

value for the max-tech level analysis. 

Table 5.6.8 Results from DOE Testing of Maximum-Available Vented Gas Clothes Dryers 

Unit 

Measured Average 

EF (lb/kWh) 

% Difference from CEC 

Product Database Value 

(3.44 EF) 

1 2.83 -17.7 

2 2.75 -20.1 

3 2.82 -18.0 

5.6.1.3 Product Teardown 

As part of its reverse-engineering process, DOE tore down clothes dryers to identify 

design features, and corresponding manufacturing costs, that are associated with successively 

higher efficiency levels. The clothes dryer teardown analysis performed for this engineering 

analysis included the 12 teardown units total for four of the five product classes selected for the 

preliminary analysis, excluding only vented electric compact (120 V) clothes dryers due to lack 

of availability. For the other vented product classes, DOE selected products such that within that 

class, the chosen models span the range of EF from baseline to max-available. 

DOE first notes that all of the clothes dryers it examined are constructed with an outer 

sheet metal assembly comprising panels that had been formed by stamping, joined, and painted. 

This assembly houses the cylindrical drum, drive motors, heater systems, and the associated 

ducting. Details of these components and sub-assemblies are as follows. 

Baseline Construction

 For the baseline vented units, the bottom base plate of the cavity holds a single 1/4–1/3 

horsepower (hp) induction motor which drives both the drum and the blower. For gas clothes 

dryers, the bottom base plate also holds the gas burner system, which consists of a single stage 

gas valve, venturi, and gas inlet pipe. A conical duct then directs the hot air generated from the 

gas burner towards the back of the cabinet, where it flows through a duct to the rear of drum. For 

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the baseline electric standard clothes dryers, the heating system consists of an electrical 

resistance heater which is contained in a duct which covers the back wall of the drum. 

For the baseline unit construction, the laundry basket consists of a metal cylinder which 

has a circular plate attached on the rear to form a drum. The drum is driven by the single 

induction motor (installed on the bottom base plate) and a drive belt. The drum rotates about a 

shaft mounted on the plate on the rear of the drum. On the front edge of the drum, the drum spins 

on smooth plastic strips mounted to the front face of the cavity. 

The hot air from both gas and electric heating systems enters from behind the drum, 

passes through the clothes load, and exits the drum near the front door. The moist air is then 

pulled through the lint filter and through the blower fan, which is driven by the same single 

induction motor that rotates the drum. Subsequently, the moist flue air exits through the exhaust 

pipe leading out the rear of the exterior sheet metal assembly. 

The baseline clothes dryer is also equipped with electromechanical controls which allow 

the user to select specific cycle settings. DOE also noted in its teardown of baseline units and 

through surveys of products available on the market that baseline clothes dryers feature 

automatic cycle termination using temperature switches and timer controls. All baseline clothes 

dryers torn down feature temperature switches in the heater duct and blower/exhaust duct 

sections. 

The baseline ventless electric compact (240 V) clothes dryer has a similar construction to 

the baseline vented electric clothes dryer, with the following differences. A baseline ventless 

clothes dryer is equipped with a permanent split capacitor (PSC) motor which drives both the 

drum and the blower fan. The drum rotates about a shaft mounted on the plate on the rear of the 

drum; however, the front edge of the drum spins on two roller wheels mounted to the front face 

of the cavity. DOE also noted in its teardown that a baseline unit features electronic controls as 

well as automatic cycle termination using temperature sensors. 

The baseline ventless electric compact (240 V) electrical resistance heater is in a 

dedicated duct mounted behind the rear of the drum. The hot air from the heating system enters 

from behind the drum, passes through the clothes load, and exits the drum near the front door. 

The moist air is then pulled through the lint filter and through the blower fan, whereupon the air 

flows through a duct mounted to the base of the cabinet containing an air-to-air cross-flow heat 

exchanger. Moisture in the warm, moist air condenses as the air flows past the heat exchanger 

towards the back of the cabinet, where it again enters the dedicated electric heater duct and 

repeats the airflow cycle. As part of the heat exchanger system, an additional blower fan is 

mounted to the single PSC motor, which pulls ambient air from the surroundings and blows it 

past the air-to-air heat exchanger in a direction perpendicular to the dry cycle air flow. The heat 

exchanger duct also houses a drain pump, which pumps the condensed moisture from the heat 

exchanger out of the cabinet. 

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The construction of the baseline combination washer/dryer is more complex than that of a 

conventional clothes dryer since it is able to run both washing and drying cycles in a single 

cabinet using a single drum. The wash basket is contained in a tub, which prevents water from 

escaping into the cabinet. The tub is mounted on four shock absorbers, which in turn are 

mounted to the base of the cabinet. Mounted to the bottom of the tub is a large cement block, 

which dampens vibrations from the wash and spin cycles. An induction motor spins a drive 

wheel mounted on the back of the tub via a belt. This induction motor is capable of the high 

rotational speeds required for spin cycles. The wash basket, comprising a metal cylinder which 

has a circular plate attached on the rear, rotates about a shaft mounted to the rear of the drum. 

The drive system also uses two large ball bearings for the drive wheel and the rear drum shaft. 

A PSC motor is also mounted to the bottom of the tub, which drives a blower fan 

contained in a dedicated duct mounted to the rear of the tub via a drive belt. The air is blown 

from this duct to a duct mounted to the top of the tub, which contains the electrical resistance 

heater. The hot air flows from the heater duct into the front of the tub, passes through the clothes 

load, and exits through the rear of the tub into a space between the wash basket and the tub. The 

air is then pulled back through the dedicated blower fan duct and the airflow cycle repeats. 

The combination washer/dryer is also different from a conventional dryer in that it does 

not use a lint filter. DOE also noted in its teardown that the baseline unit features electronic 

controls, but that it does not have an automatic termination feature. 

Based upon product teardowns, DOE developed the following baseline production cost 

distributions and materials costs distributions, shown in Figure 5.6.9 through Figure 5.6.18. 

Depending on the manufacturer and the production volume, the depreciation costs may vary 

from those shown in the figures, which assume a “green-field” site. For product classes such as 

vented electric compact (120 V and 240 V), ventless electric compact (240 V) and ventless 

combination washer/dryers, DOE assumed much smaller production volumes than for vented 

electric standard and vented gas dryers. 

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Figure 5.6.9 Baseline Vented Electric Standard Clothes Dryer Full Production Cost
 

Distribution
 

5-56 

 

Figure 5.6.10 Baseline Vented Electric Standard Clothes Dryer Materials Cost Distribution 

5-57 

 

Figure 5.6.11 Baseline Vented Electric Compact (240V) Clothes Dryer Full Production
 

Cost Distribution
 

5-58 

 

Figure 5.6.12 Baseline Vented Electric Compact (240V) Clothes Dryer Materials Cost
 

Distribution
 

5-59 

 

Figure 5.6.13 Baseline Vented Gas Clothes Dryer Full Production Cost Distribution 

5-60 

 

Figure 5.6.14 Baseline Vented Gas Clothes Dryer Materials Cost Distribution 

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Figure 5.6.15 Baseline Ventless Electric Compact (240V) Clothes Dryer Full Production
 

Cost Distribution
 

5-62 

 

Figure 5.6.16 Baseline Ventless Electric Compact (240V) Clothes Dryer Materials Cost
 

Distribution
 

5-63 

 

Figure 5.6.17 Baseline Ventless Combination Washer/Dryer Full Production Cost 


Distribution
 

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Figure 5.6.18 Baseline Ventless Combination Washer/Dryer Materials Cost Distribution 

Construction at Higher Efficiency Levels 

Based on the design options retained from the screening analysis (see chapter 4 of this 

preliminary TSD), the reverse engineering analysis, and discussions with manufacturers, 

summarized in section 5.6.1.5 and 5.6.1.6, DOE developed manufacturing costs associated with 

various design features necessary to achieve higher efficiencies. 

The following are the design changes DOE believes would be necessary to meet each 

efficiency level, which were subsequently modeled to obtain incremental manufacturing cost 

estimates. 

Vented Electric Clothes Dryers

 Efficiency Level 1 

Based on characteristics of units selected for teardown and based on discussions with 

manufacturers, DOE research suggests that EL 1 is achieved in vented electric clothes dryers 

through three changes: 

1. Switching to Open Cylinder Drum 

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This design change can allow better air flow through the drum. The drum suspension 

system is also changed to a roller wheel design with wheels at the front and back edges of the 

drum as the bearing system in order minimize frictional losses and decrease the load on the 

motor. 

2.	 Dedicated Heater Duct 

The hot air flow duct that directs the air into the drum through the back would be 

changed from the baseline duct to a dedicated duct which directs air flow more directly into the 

drum and reduces heat losses. 

3.	 Change in Air Flow Patterns 

The air flow through the drum would change from a baseline back to front air flow, to 

flowing in through one side of the back and exiting on the other. This design change requires an 

outlet duct from the drum that attaches to the rear of the drum, which then leads to the blower 

duct and the exhaust duct. DOE notes that the costs associated with these design options will 

differ for standard-size and compact-size dryers because of the different amounts of materials 

required for structural design changes.

 Efficiency Level 2 

For the preliminary analysis, DOE stated that it believed that for EL2, manufacturers 

would apply the same design changes as used for EL 1 and additionally incorporate inlet air 

preheating, which requires better airflow and moisture control. However, based on further 

research and more recent discussions with manufacturers, DOE believes that for EL2, 

manufacturers would apply the same design changes as used for EL1, but additionally 

incorporate 2-stage modulating heat, which would require moisture sensing and multi-speed 

airflow 

1.	 2-Stage Modulating Heat 

For this design change, the conventional single electric resistance heater would be 

replaced by two smaller-sized electric resistance heaters to allow for 2-stage control of the heat 

output. The resistance heaters would be controlled by the control board that also reads the 

moisture (discussed below), and would require and additional relay to control the additional 

heater. 

2.	 Moisture Sensing and Multi-Speed Airflow 

Moisture sensing requires a separate measurement and control board, which can be used 

in conjunction with electromechanical controls. Since baseline motors drive both the drum and 

the fan, variable airflow requires the adoption of dedicated drum and fan blower motors. Both 

motors would likely be PSC-style motors, with the drum motor featuring single-speed and the 

blower motor triple-speed operation to match the heat output of the 2-stage heater. The speed of 

the blower motor would be controlled by the control board that also reads the moisture.

 Efficiency Level 3 

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For the preliminary analyses, DOE stated that manufacturers would likely add fully 

modulating heat to the platform described for EL 2 to achieve EL 3, without inlet air-preheating. 

Because DOE is not aware of any gas clothes dryers with fully modulating burner systems 

currently on the market, DOE did not consider this technology further in developing the 

standards set forth in today’s direct final rule. DOE does include this technology as a longer-term 

means to achieve energy efficiency improvements in a sensitivity analysis described in chapter 

16 of this TSD. Based on further research and more recent discussions with manufacturers, DOE 

believes that for EL 3, manufacturers would apply the same design changes as used for EL 2 and 

additionally incorporate inlet air preheating, which requires better airflow and more advanced 

control systems. 

1.	 Inlet air pre-heating 

Inlet air pre-heating requires an air-to-air heat exchanger (with added ducting) in order to 

recover exhaust heat energy with which to preheat inlet air. To prevent condensation, moisture 

sensors and variable-speed blowers are required to adjust airflow rates and to allow for more 

accurate control of the drying cycle. The control system would have to be upgraded to electronic 

controls to allow for more accurate control of the airflow, heaters, and sensors. 

2.	 Variable Airflow 

A variable-speed fan motor is likely required to seamlessly match the heat output of the 

heater coil and the rate of heat recovery from the inlet air pre-heating to prevent condensation. 

Typically, manufacturers incorporate electronically-commutated motors or equivalent motor 

designs for such applications. Such a motor is also more efficient than the standard induction 

motor of PSC motor, which results in a slight increase of the overall efficiency of the clothes 

dryer.

 Efficiency Level 4 

DOE research suggests that EL 4 would require the use of heat pump technology. As a 

starting point, this level would incorporate most features described for EL 2. Two features would 

likely be omitted, however: the airflow rerouting described in EL 1 as well as the pre-heater 

described in EL 2. Other required design features would be a more sophisticated control system, 

an upgraded air flow system, a booster heater, and a condensate removal system. 

1.	 Heat Pump System 

The heat pump system would be made up of a reciprocating compressor, evaporator, 

condenser, and sealed system components. Existing heat pump clothes dryer design schematics 

suggest the use of tube and fin heater exchangers with wide evaporator fin spacing to prevent lint 

foiling. In order to handle the variation in heating load throughout the drying cycle, a 

thermostatic expansion valve is used to control the refrigerant flow. Standard-size and compactsize dryers would require different material costs for this design option because of the different 

sizes of the heat exchangers and shipping packaging. 

2.	 Electronic Controller, Thermal and Moisture Sensing 

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A heat pump dryer would likely require sophisticated moisture, airflow, and temperature 

control to maximize the energy savings. Thus, an electronic controller, moisture sensors, and 

multiple thermal sensors are incorporated into this efficiency level. 

3.	 Upgraded Airflow System 

A heat pump dryer is expected to require dedicated fan and drum motors, as described in 

EL 2. However, the additional pressure drop imposed by ducting, heat exchangers, etc. will 

likely double the shaft power requirements of the fan motor. The size and wire density of the lint 

filter would also need to be increased to prevent lint migration past the filter to the heat 

exchanger. 

4.	 Booster Heater 

Because of the long warm-up times associated with a heat pump system, and the 

consumer demand for shorter dry cycles, DOE believes that manufacturers could incorporate a 

booster heating element. This heating element would be undersized compared to the 

conventional heating element and would run only during the warm-up phase. 

5.	 Condensate Removal 

Since a heat pump dryer produces condensate, a condensate removal system is expected 

to be standard feature in a heat pump dryer, just as it is in condensing dryers. 

Gas Clothes Dryers 

DOE believes that the same fundamental design changes described above for vented 

electric standard dryers for EL 1 through EL 3 would be applied to vented gas clothes dryers. 

Because of inherent differences in the designs between gas and electric clothes dryers (e.g., 

different ducting, heat sources, etc.), the costs at each efficiency level are not identical. Most 

notably for EL 2, the 2-stage modulation of gas heat requires significantly different component 

changes as compared to 2-stage modulating electric heat. 

For EL 2, DOE believes that manufacturers would switch from the baseline single-stage 

gas valve to a 2-stage modulating gas valve. DOE notes that gas-fired clothes dryers with 2-stage 

modulating gas valves are available on the market today. Additional controls would be required 

to control the gas valve modulation. As with the EL 2 design changes for electric standard 

dryers, the same disaggregated motor design (with additional controls) would also be 

incorporated into this level. 

Ventless Electric Compact (240 V) Clothes Dryers 

DOE believes that essentially the same changes described above for vented electric 

clothes dryers for EL 1, EL 2, and EL 4 would be applied to ventless electric compact (240 V) 

clothes dryers. However, because the baseline unit already contains a dedicated heat duct, only 

the remaining design options for vented electric clothes dryer EL 1 would need to be applied to 

EL 1 for this product class. Also, because the EL 3 design changes applied to vented electric 

clothes dryers were based upon inlet air preheating, these design changes would not be applied to 

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a ventless electric compact (240 V) clothes dryer because it already recirculates the air back 

through the system. For this reason, the EL 2 and EL 4 design changes for vented electric clothes 

dryers are applied as EL 2 and EL 3, respectively, for this product class. DOE also notes that the 

baseline ventless electric compact (240 V) clothes dryer already contains electronic controls; 

therefore, certain design options such as moisture sensing and variable speed motor control will 

require a smaller incremental manufacturing cost. 

Ventless Electric Combination Washer Dryer 

Because the baseline unit in this product class does not have automatic cycle termination, 

DOE believes that EL 1 would be achieved by incorporating such a feature. Because the baseline 

unit already has a number of temperature sensors as well as electric controls, the changes 

required to implement an automatic cycle termination feature would likely be minimal, 

consisting primarily of an additional temperature sensor in the exhaust air as well as control logic 

reprogramming. 

Because of the complex construction of the baseline combination washer/dryer, DOE 

believes that the design changes for EL 2 for vented electric clothes dryers (i.e., inlet air 

preheating) could not be applied to this product class. Further, for the reasons described above 

for ventless electric compact (240 V) clothes dryers, DOE believes that the EL 2 and EL 4 design 

changes for vented electric clothes dryers would be applied to EL 2 and EL 3, respectively, for 

this product class. Again, because the baseline unit already incorporates a two motor design, as 

well as electronic controls, the incremental manufacturing costs will be smaller for this product 

class as compared to vented electric clothes dryers. 

Standby Mode Construction 

As part of the reverse engineering analysis, DOE investigated the design options and 

incremental manufacturing costs for decreasing standby power consumption. DOE developed the 

following design pathways for the standby levels identified in section 5.4.2.2. 

DOE’s analysis suggests that SL 1 can be achieved by implementing a switch-mode 

power supply in place of a conventional linear regulated control board power supply. DOE 

observed a number of clothes dryers which incorporated switching power supplies. DOE’s 

teardown analysis also suggests that SL 2 can be achieved by implementing a transformerless 

power supply along with a conventional power supply. Such a power supply design, incorporated 

with a “soft” power pushbutton and electromechanical relay, would provide just enough power 

through the transformerless power supply to maintain the microcontroller chip while the clothes 

dryer is not powered on. When the power button is pressed, the control logic enables a Triode for 

Alternating Current (Triac) to enable power to the transformer of linear power supply. Hence, the 

Triac isolates the linear power supply from the mains until it is needed to power relays, the user 

interface, etc. Through this means, the standby power issues typically associated with linear 

power supplies can be eliminated. 

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5.6.1.4 Cost-Efficiency Curves 

Active Mode 

Based upon product teardowns and cost modeling, DOE developed the following costefficiency relationships for each product class, shown in 

Figure 5.6.19 through Figure 5.6.24 and Table 5.6.9 through Table 5.6.14. DOE updated the 

manufacturing cost model data developed for the preliminary analysis based on the revisions to 

the design options at each efficiency level. In addition, DOE updated raw material and purchased 

parts costs based on the latest available data, as well as updating costs for manufacturing 

equipment, labor, and depreciation. For product classes for which AHAM provided data, the 

corresponding cost-efficiency curves are plotted as well. The EF values (for both DOE and 

AHAM data) shown below are adjusted using the percentage increases to account for the 

amendments to the DOE clothes dryer test procedure (10 CFR part 430, subpart B, appendix 

D1), as discussed above in section 5.4.1.1. 

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Figure 5.6.19 Vented Electric Standard Clothes Dryer Cost-Efficiency Curves 

Table 5.6.9 Vented Electric Standard Clothes Dryer Incremental Manufacturing Costs 

Efficiency Level (EF, 

lb/kWh) 

Incremental 

Cost 

Baseline (3.62) $0 

1 (3.74) $7.92 

2 (3.81) $49.85 

3 (4.08) $87.79 

4 (5.43) $279.43 

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Figure 5.6.20 Vented Electric Compact (120V) Clothes Dryer Cost-Efficiency Curve 

Table 5.6.10 Vented Electric Compact (120V) Clothes Dryer Incremental Manufacturing 

Costs 

Efficiency Level (EF, 

lb/kWh) 

Incremental 

Cost 

Baseline (3.62) $0 

1 (3.72) $20.64 

2 (3.80) $61.94 

3 (4.09) $108.21 

4 (5.44) $266.37 

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Figure 5.6.21 Vented Electric Compact (240V) Clothes Dryer Cost-Efficiency Curve 

Table 5.6.11 Vented Electric Compact (240V) Clothes Dryer Incremental Manufacturing 

Cost 

Efficiency Level (EF, 

lb/kWh) 

Incremental 

Cost 

Baseline (3.27) $0 

1 (3.36) $20.64 

2 (3.49) $61.94 

3 (3.61) $108.21 

4 (4.91) $266.37 

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Figure 5.6.22 Vented Gas Clothes Dryer Cost-Efficiency Curves 

Table 5.6.12 Vented Gas Clothes Dryer Incremental Manufacturing Cost 

Efficiency Level (EF, 

lb/kWh) 

Incremental 

Cost 

Baseline (3.20) $0 

1 (3.31) $8.30 

2 (3.41) $71.50 

3 (3.62) $108.87 

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Figure 5.6.23 Ventless Electric Compact (240V) Clothes Dryer Cost-Efficiency Curve 

Table 5.6.13 Ventless Electric Compact (240V) Clothes Dryer Incremental Manufacturing 

Cost 

Efficiency Level (EF, 

lb/kWh) 

Incremental 

Cost 

Baseline (2.69) $0 

1 (2.72) $25.31 

2 (2.81) $56.69 

3 (4.04) $241.25 

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Figure 5.6.24 Ventless Electric Combination Washer/Dryer Cost-Efficiency Curves 

Table 5.6.14 Ventless Electric Combination Washer/Dryer Incremental Manufacturing 

Cost 

Efficiency Level (EF, 

lb/kWh) 

Incremental 

Cost 

Baseline (2.17) $0 

1 (2.46) $1.51 

2 (2.56) $30.58 

3 (3.70) $296.43 

Standby Mode 

Based upon the product teardowns and cost modeling, DOE developed the incremental 

costs associated with decreasing standby power consumption, shown in Table 5.6.15. As 

discussed above for the active mode incremental manufacturing costs, DOE updated the 

incremental costs for standby power design changes based on the latest available electronics 

components pricing. 

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Table 5.6.15 Standby Power Incremental Manufacturing Cost 

Standby Power Level 

(W) 

Incremental 

Cost 

Baseline (2.0) $0 

1 (1.5) $0.93 

2 (0.08) $1.11 

Incremental Costs by CEF 

As discussed in section 5.4, the clothes dryer analysis for this rulemaking is based on the 

integrated metric, CEF. DOE analyzed the improvement in CEF associated both with design 

options that improve EF and design options that reduce standby power. DOE developed overall 

cost-efficiency relationships for the CEF efficiency levels presented in section 5.4.2.3. As noted 

above in section 5.4.2.3, DOE incorporated incremental standby power levels into CEF 

efficiency levels where DOE determined them to be most cost effective. In addition, as discussed 

above in section 5.4.2.3, DOE analyzed baseline efficiency products available on the market, and 

weighted the efficiency improvement and incremental manufacturing cost associated with 

standby power based on the percentage of baseline efficiency products that have electronic 

controls. For the integrated efficiency levels for which electronic controls would be required as 

part of the active mode design changes, DOE assumed that the standby power levels and 

incremental manufacturing costs affected 100 percent of clothes dryer models. Table 5.6.16 

through Table 5.6.21 present DOE’s estimates of incremental manufacturing cost for 

improvement of clothes dryer CEF above the baseline. 

Table 5.6.16 Cost-Efficiency Relationship for Vented Electric Standard Clothes Dryers 

Integrated Efficiency 

Level (CEF, lb/kWh) 

Incremental 

Manufacturing Cost 

Baseline (3.55) $0 

1 (3.56) $0.68 

2 (3.61) $0.82 

3 (3.73) $8.74 

4 (3.81) $50.67 

5 (4.08) $88.89 

6 (5.42) $280.54 

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Table 5.6.17 Cost-Efficiency Relationship for Vented Electric Compact (120V) Clothes 

Dryers 

Integrated Efficiency 

Level (CEF, lb/kWh) 

Incremental 

Manufacturing Cost 

Baseline (3.43) $0 

1 (3.48) $0.68 

2 (3.61) $0.82 

3 (3.72) $21.46 

4 (3.80) $62.76 

5 (4.08) $109.31 

6 (5.41) $267.48 

Table 5.6.18 Cost-Efficiency Relationship for Vented Electric Compact (240V) Clothes 

Dryers 

Integrated Efficiency 

Level (CEF, lb/kWh) 

Incremental 

Manufacturing Cost 

Baseline (3.12) $0 

1 (3.16) $0.68 

2 (3.27) $0.82 

3 (3.36) $21.46 

4 (3.48) $62.76 

5 (3.60) $109.31 

6 (4.89) $267.48 

Table 5.6.19 Cost-Efficiency Relationship for Vented Gas Clothes Dryers 

Integrated Efficiency 

Level (CEF, lb/kWh) 

Incremental 

Manufacturing Cost 

Baseline (3.14) $0 

1 (3.16) $0.68 

2 (3.20) $0.82 

3 (3.30) $9.12 

4 (3.41) $72.32 

5 (3.61) $109.98 

Table 5.6.20 Cost-Efficiency Relationship for Ventless Electric Compact (240V) Clothes 

Dryers 

Integrated Efficiency 

Level (CEF, lb/kWh) 

Incremental 

Manufacturing Cost 

Baseline (2.55) $0 

1 (2.59) $0.93 

2 (2.69) $1.11 

3 (2.71) $26.42 

4 (2.80) $57.80 

5 (4.03) $242.36 

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Table 5.6.21 Cost-Efficiency Relationship for Ventless Electric Combination 

Washer/Dryers 

Integrated Efficiency 

Level (CEF, lb/kWh) 

Incremental 

Manufacturing Cost 

Baseline (2.08) $0 

1 (2.35) $1.51 

2 (2.38) $2.44 

3 (2.46) $2.62 

4 (2.56) $31.69 

5 (3.69) $297.54 

5.6.1.5 Manufacturer Interviews – Preliminary Analysis 

DOE conducted interviews with residential clothes dryer manufacturers to determine 

appropriate efficiency levels for the preliminary analysis and to develop a better understanding 

of the technologies used to improve energy efficiency. During these interviews, DOE asked 

manufacturers what max-tech efficiency levels would be appropriate for each clothes dryer 

product class. DOE also asked manufacturers what groupings of design options are used in 

baseline designs and what would be implemented to increase the energy efficiency in order to 

meet the efficiency levels proposed in section 0 for residential clothes dryers. The discussion 

helped DOE understand what proposed design options have already been implemented and what 

additional design options DOE should consider. In addition, DOE conducted discussions 

regarding issues with the DOE test procedure for clothes dryers. The discussion below represents 

a consolidation of the responses. DOE subsequently conducted another series of interviews with 

manufacturers to solicit feedback on preliminary manufacturing cost estimates DOE developed 

through the reverse engineering analysis. 

Max-Tech Efficiency Levels 

Manufacturers indicated that the current maximum-available EF for vented gas clothes 

dryers listed in the CEC product database is not achievable. Multiple manufacturers stated that 

the CEC product database has had errors in the values listed in the past for other products, and at 

least one manufacturer suggested that DOE test the maximum-available model to determine an 

appropriate max-tech level. As discussed in section 0, DOE tested the maximum-available gas 

clothes dryer and determined that it did not achieve the rated EF. 

Multiple manufacturers indicated that an EF of approximately 3.0 would be an 

appropriate max-tech value. In addition, AHAM submitted incremental manufacturing cost data, 

aggregated from manufacturer inputs, for the max-tech active mode efficiency level for vented 

gas clothes dryers proposed in the framework document (3.02 EF). 

Components That Influence Energy Efficiency 

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Manufacturers identified components that influence energy efficiency in residential 

clothes dryers that are related to baseline designs. DOE also identified components and design 

options that it believed could potentially influence energy efficiency in residential clothes dryers. 

DOE requested comment on each of these design options and their potential for increasing 

energy efficiency. 

Manufacturers indicated that they use a single 4-pole induction motor to drive both the 

drum and the blower in their baseline clothes dryer. Manufacturers also use a single-element 

electric resistance heater for electric clothes dryers and a single-stage gas valve for gas clothes 

dryers. In addition, manufacturers generally incorporate electromechanical controls into their 

baseline units along with some form of automatic termination control by temperature sensing. 

A number of manufacturers indicated that improvements to energy efficiency can be 

made by implementing more efficient fan motors in place of the standard 4-pole induction motor. 

Manufacturers believed that 1 to 5 percent improvement can be achieved using more efficient fan 

motors, such as electronically-commutated motors (ECM), however the costs are high. 

Manufacturers also indicated that all of their units incorporate some form of automatic 

termination sensing control. Manufacturers stated that thermostatically controlled automatic 

termination control with electromechanical controls is generally the least accurate form of 

automatic termination sensing. Using moisture sensors along with the thermostat controlled 

automatic termination sensing can improve the accuracy of these systems. To increase the 

accuracy further, manufacturers indicated that they would use moisture sensing controls with 

thermistors, which give continuous feedback, along with electronic controls. 

At least one manufacturer indicated that adding insulation could improve efficiency 

minimally. However, most manufacturers believed that there is no significant efficiency 

improvement with insulation. 

A number of manufacturers indicated that modifying the air flow can improve efficiency. 

For example, multiple manufacturers indicated that switching the drum air flow design from 

front to back to a design flowing in through one side of the drum on the back and out through the 

other side of the back can improve efficiency 1 to 3 percent. 

Manufacturers also indicated that preheating inlet air, either through the use of an air-toair heat exchanger or recirculation of process air, can improve energy efficiency. Manufacturers 

indicated varying degrees of potential improvements to energy efficiency associated with this 

design option, ranging from 1 to 12 percent. 

With regards to modulating heat, manufacturers indicated that they would incorporate a 

modulating heater to reach different efficiency levels. They also indicated that modulating gas 

valves are significantly more expensive than single-stage gas valves. 

A number of manufacturers have indicated that they manufacture heat pump dryers for 

international markets. Most manufacturers stated that 30 to 50 percent efficiency improvement is 

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possible using heat pump technology. Manufacturers indicated that they would generally 

consider using a R-134a compressor along with tube and fin heat exchangers. 

Strategies to Increase Energy Efficiency 

Manufacturers generally supported the proposed efficiency levels for the vented dryer 

product classes. However, a number of manufacturers indicated that the max-available gas 

efficiency level above 3.44 EF (proposed in the first set of preliminary manufacturer interviews) 

may be difficult to achieve. Manufacturers generally indicated that the max-available efficiency 

level for vented gas dryers should be between 3.0 and 3.06 EF (90 percent of the max-available 

level for vented electric standard). DOE subsequently adjusted the max-available gas dryer 

efficiency level based on updates to the CEC database. For the vented electric compact 120V 

product class, at least one manufacturer was in agreement with the method used to develop the 

efficiency levels. However, other manufacturers indicated that meeting even the baseline 

efficiency would be difficult. 

For the ventless electric compact 240V product class, at least one manufacturer indicated 

that it believed the proposed efficiency levels were appropriate. However, a few manufacturers 

also indicated that the proposed efficiency levels were low compared to the efficiencies achieved 

by the units that they manufacture. 

Although manufacturers cited different design pathways for meeting the proposed 

efficiency levels, in general they cited the following strategies to increase energy efficiency: (1) 

air flow system improvements, (2) modulating heat design, (3) inlet air preheating, (4) higherefficiency motor designs, and (5) heat pump technology for electric dryers. 

Manufacturers indicated that air flow system changes would be included in design 

changes to meet the proposed efficiency levels. Some manufacturers cited such changes as using 

direct duct heaters to provide better heating and minimize heat losses. Other manufacturers 

indicated that better air flow sealing or insulation could also be used to meet efficiency levels. 

Manufacturers generally indicated that air flow system changes would be incorporated as part of 

design changes to meet EL 1 or EL 2 for vented dryers. 

Manufacturers cited modulating heat designs as a strategy to improve energy efficiency. 

Some manufacturers indicated that the costs for this design change would be 3 to 4 times higher 

for a gas dryer, which would require a modulating gas valve and additional controls, as 

compared to an electric dryer, which would use either a multi-element resistance heater or a 

single element with modulating current. Various manufacturers indicated that they would use 

modulating heat as part of the design changes to meet EL 1 through EL 3 for vented dryers. 

Manufacturers also indicated that when adopting a modulating heater, they would additionally 

implement improved moisture sensing and more complicated controls systems. 

Manufacturers also indicated that preheating inlet air is important to consider for 

achieving efficiency improvements. Some manufacturers indicated that this could be achieved by 

partial recirculation of the process air through the burner or heater system for all or part of the 

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cycle. Manufacturers indicated that if they were to recirculate the process air, they would add or 

modify lint screens to prevent lint migration into the heater system. Other manufacturers 

believed that inlet air could be pre-heated by using a heat exchanger. Manufacturers that 

commented they would incorporate this design option, believed that it would be used as part of 

the design changes to meet either EL 2 or EL 3 for vented dryers. 

Manufacturers cited improved motor efficiency as a strategy for meeting the proposed 

efficiency levels. Most manufacturers that commented that they would incorporate improved 

motor efficiency stated that they would likely incorporate this into the design changes for EL 3. 

Manufacturers indicated that they would likely use a separate ECM motor for the fan. 

Manufacturers indicated that heat pump technology would provide the largest 

improvement to efficiency. Most manufacturers indicated that 30 to 50 percent improvement in 

efficiency can be achieved with heat pump dryers. However, manufacturers that produce 

compact-size heat pump clothes dryers for international markets indicated that the very long 

cycle times would be a consumer utility issue for U.S. consumers as well as the much higher 

initial cost of the unit. 

A few manufacturers indicated that they would need to incorporate heat pump technology 

to reach EL 3 for vented electric standard dryers, which would be a 13 percent improvement over 

the baseline EF. DOE notes that there are currently units available on the market which meet EL 

3 which do not incorporate heat pump technology and DOE believes that using heat pump 

technology can improve the efficiency beyond this point to the proposed EL 4. DOE also notes 

that some manufacturers indicated design changes to meet EL 3 that did not include switching to 

a heat pump design. 

Manufacturers also noted that a number of the above mentioned design changes would 

require improved control systems using moisture sensing and electronic controls. 

Manufacturers indicated that for ventless electric compact (240V) dryers, they would 

apply the same design changes as were used for vented electric dryers. In addition, they would 

consider modifications to the heat exchanger as a potential source for improving energy 

efficiency. 

With regards to the proposed standby power levels for clothes dryers, at least one 

manufacturer commented in agreement with the proposed design changes for decreasing standby 

power in clothes dryers. They indicated that both incorporating a switching power supply and a 

transformerless power supply with a Triac to control power through the transformer are 

reasonable approaches to achieving standby levels 1 (1.5W) and 2 (0.08W). Again at least one 

manufacturer agreed that the incremental manufacturing costs associated with standby levels 1 

and 2 that DOE developed through its reverse engineering analysis are appropriate. 

Incremental Manufacturing Cost 

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In the initial set of preliminary manufacturing interviews, DOE requested feedback on 

whether the aggregated costs submitted by AHAM were representative of the manufacturing 

costs developed by each manufacturer. Most manufacturers indicated that the aggregated costs 

submitted by AHAM were representative of their costs for each efficiency level. 

After DOE conducted the first round of preliminary manufacturer interviews, DOE 

developed incremental manufacturing cost-efficiency curves based on manufacturer inputs and 

reverse engineering analysis. DOE subsequently requested feedback from manufacturers on 

these incremental manufacturing cost-efficiency curves in order to refine its analysis. 

Manufacturers indicated that although they were not always in agreement with the design 

changes used to meet each efficiency level, they were generally in agreement with the 

incremental manufacturing cost-efficiency curves, indicating that values developed by DOE 

were generally within 20 percent of the values submitted by these manufacturers. Manufacturers 

also provided indications of the appropriateness of component pricing estimates used in DOE’s 

cost model. DOE used information learned during these discussions to revise its reverse 

engineering analysis and incremental manufacturing costs. 

Test Procedure Issues 

DOE requested comment on a number of issues regarding the DOE test procedure for 

clothes dryers. Manufacturers indicated that they have observed test to test variation from 0.03 to 

0.1 EF points for a single unit tested multiple times. At least one manufacturer indicated that 

latest test cloth may have some problems, showing variations in measured EF as the test cloth is 

used for multiple test runs. A number of manufacturers also indicated that variation in results can 

be seen within the allowable range ambient humidity and temperatures. Manufacturers stated that 

variations in ambient humidity had more of an effect on results than temperature. However, at 

least one manufacturer indicated that the ambient conditions are difficult to maintain and it 

would be hard to justify tighter tolerances given the requirements of increased control. 

5.6.1.6 Manufacturer Interviews – Final Rule 

DOE conducted additional interviews with residential clothes dryer manufacturers to 

discuss the efficiency levels and incremental manufacturing costs proposed in the preliminary 

analysis and to develop a better understanding of the challenges that manufacturers face in order 

to improve energy efficiency. During these interviews, DOE asked manufacturers what 

groupings of design options are used in baseline designs and what would be implemented to 

increase the energy efficiency in order to meet higher efficiency levels for residential clothes 

dryers. DOE also asked manufacturers about repair and maintenance costs for residential clothes 

dryers at higher efficiencies, as well as the manufacturing costs associated with complying with 

the Underwriters Laboratory (UL) Standard 2158 “Electric Clothes Dryers” (UL 2158) fire 

containment requirements. In addition, DOE conducted discussions regarding issues with the 

DOE test procedure for clothes dryers. The discussion below represents a consolidation of the 

responses. 

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Strategies to Increase Energy Efficiency 

Manufacturers generally supported the design changes and efficiency levels analyzed by 

DOE for the preliminary analysis. However, a number of manufacturers indicated that they 

would likely incorporate 2-stage modulating heat as part of the design changes to meet active 

mode EL2 for vented clothes dryer product classes, and that inlet-air preheating would be 

incorporated to the design changes used for active mode EL2 to achieve active mode EL3. 

Manufacturers also indicated that inlet-air preheating would theoretically result in a 5 to 

15 percent improvement in efficiency. Manufacturers noted that in real-world situations, the 

potential efficiency improvement would be limited the necessary fin spacing for heat exchangers 

to prevent lint fouling. In addition, manufacturers indicated that improvements in efficiency 

would be limited by issues with condensation 

Repair and Maintenance Costs 

DOE requested information on how repair and maintenance costs would be impacted by 

more stringent energy conservation standards. A number of manufacturers indicated that repair 

and maintenance costs and frequency of repairs would likely increase with increased complexity 

and number of parts. Manufacturers also indicated that heat pump technology would 

significantly increase time and cost of repair and maintenance due to the addition of more 

complex refrigeration systems. 

Underwriters Laboratory Standard 2158 - Electric Clothes Dryers 

DOE requested information from clothes dryer manufacturers on the manufacturing costs 

and design changes required to comply with the UL 2158 fire containment requirements. 

Manufacturers indicated that, among other changes, a number of plastic components would have 

to be changed to metal, in particular for airflow ducting. However, DOE did not receive 

sufficient data to determine the incremental manufacturing costs to baseline clothes dryers to 

comply with the fire containment requirements of UL 2158. In addition, DOE did not receive 

sufficient information to indicate that the cost associated with complying with UL 2158 would 

vary at efficiency levels above the baseline. As a result, DOE did not include additional cost to 

comply with UL 2158 in the baseline manufacturing production cost. As discussed in chapter 13 

of this TSD, DOE has investigated the costs of complying with the fire containment 

requirements in UL 2158 in the cumulative regulatory burden for the manufacturer impact 

analysis (MIA). 

Test Procedure Issues 

DOE requested comment on a number of issues regarding the DOE test procedure for 

clothes dryers. Multiple manufacturers stated that if DOE were to change the 50 percent 

cotton/50 percent polyester mix test cloth to a 100 percent cotton test cloth would increase the 

test-to-test variation. Multiple manufacturers also indicated that increasing the clothes dryer load 

size would increase the measured efficiency. 

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With regards to test load preparation, a number of manufacturers indicated that changing 

the water temperature for clothes dryer test load preparation from 100 °F ± 5 °F to 60 °F ± 5 °F 

would be more representative of consumer usage. Manufacturers also stated that such a change 

would result in a reduction in the measured efficiency because of the additional energy required 

to heat the clothes load from a lower starting temperature. 

5.6.2 Room Air Conditioners 

DOE considered cost and efficiency information obtained from multiple sources for the 

room air conditioner engineering analysis. During the preliminary analysis, DOE conducted 

room air conditioner teardown assessments and developed a manufacturing cost model to 

calculate the manufacturing costs for designs of varying efficiency levels. The preliminary 

analysis reverse engineering work was primarily based on the HCFC-22 refrigerant products 

available at that time. During the final rule analysis, DOE supplemented this information with 

room air conditioner teardowns for selected products using R-410A refrigerant. DOE also carried 

out energy modeling supported by manufacturing cost analysis to determine the incremental cost 

associated with efficiency improvements for products using R-410A. DOE also conducted 

interviews with room air conditioner manufacturers to obtain greater insight into design 

strategies and their associated costs to improve efficiency. DOE conducted preliminary 

manufacturer interviews after the framework comment period. DOE also conducted additional 

manufacturer interviews after the preliminary analysis. DOE did not receive aggregated industry 

data from AHAM for the incremental costs to achieve higher efficiency levels, because too few 

manufacturers reported data to allow aggregation and reporting of the data. 

5.6.2.1 AHAM Data 

In support of the room air conditioner rulemaking, AHAM requested incremental 

manufacturing cost data from its member companies. As mentioned above, not enough responses 

were obtained to allow reporting to DOE. Table 5.6.22 and Table 5.6.23 describe market share 

by product class from 2005 to 2007. A large majority of the shipped products are from product 

classes 1 through 5, products without reverse cycle and with louvered sides. 

Table 5.6.22 AHAM Room Air Conditioner Product Class Market Share Data Submittal: 

Product Classes 1 Through 5 

Without Reverse Cycle (RC) and With Louvered Sides (LS) 

Product Class 1 2 3 4 5 

<6k 6–8k 8–14k 14–20k >20k 

2005 37% 19% 30% 3% 2% 

2006 23% 19% 34% 5.5% 3.9% 

2007 32% 16% 36% 6% 2.6% 

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Table 5.6.23 AHAM Room Air Conditioner Product Class Market Share Data Submittal: 

Product Classes 6 through 16 

Without 

Reverse 

Cycle and 

Without 

With Reverse Cycle and 

With Louvered Sides 

With Reverse Cycle and 

Without Louvered Sides 

Casement 

Only 

Casement 

Slider 

Louvered 

Sides 

<20k >20k <14k >14k 

Product Class 6 - 10 11 13 12 14 15 16 

2005 7% 0.7% 0.1% 0.4% 0.4% 

2006 12% 1.0% 0.6% 0.6% 

2007 7% **   **  0.4% 

**Insufficient responses were received by AHAM to allow reporting for these product classes. 

Table 5.6.24 and Table 5.6.25 detail the shipment-weighted average energy efficiency of 

room air conditioner shipments from 2005 to 2007 by product class. AHAM did not provide data 

for product classes 6, 7, 10, 13, 14, and 15. The efficiency trends for presented in the tables are 

mixed, with EER increasing for some product classes and decreasing for others. 

Table 5.6.24 AHAM Room Air Conditioner Shipment Weighted Efficiency Data (EER) 

Submittal: Product Classes 1 through 5 

Without Reverse Cycle (RC) and With Louvered Sides (LS) 

Product Class 1 2 3 4 5 

<6k 6–8k 8–14k 14–20k >20k 

2005 9.5 10.2 10.3 10.3 9 

2006 9.8 10.4 10.4 10.5 9.2 

2007 9.8 9.9 10.1 10.3 9.1 

Table 5.6.25 AHAM Room Air Conditioner Shipment Weighted Efficiency Data (EER) 

Submittal: Product Classes 6 through 16 

Without Reverse Cycle 

and Without Louvered 

Sides 

With Reverse 

Cycle and With 

Louvered Sides 

With Reverse Cycle 

and Without 

Louvered Sides 

Casement 

Slider 

8–14k 14–20k <20k <14k 

Product Class 8 9 11 12 16 

2005 9.5 ** 10.6 9.6 9.9 

2006 9.5 ** 10.5 9.6 ** 

2007 9.5 9.0 ** 9.5 

**Insufficient responses were received by AHAM to allow reporting for these product classes. 

In addition to market share by product class and shipment-weighted average energy 

efficiency for room air conditioners, AHAM also submitted data disclosing market share by 

efficiency level and year. These data are tabulated in appendix 5B of this TSD. 

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5.6.2.2 Manufacturer Interviews 

During the preliminary analysis in 2008, DOE conducted interviews with room air 

conditioner manufacturers to develop a better understanding of the technologies used to improve 

energy efficiency. These interviews took place as manufacturers were developing R-410A 

designs for 2010 but before ramp-up of manufacturing of these units. During these interviews, 

DOE asked manufacturers what groupings of design options would be required to increase the 

energy efficiency to meet the efficiency levels proposed in section 5.4.2 for room air 

conditioners. The discussions helped DOE understand which design options have already been 

implemented and which additional design options DOE should consider. The discussion below 

represents a consolidation of the responses. 

DOE also conducted interviews with room air conditioner manufacturers during the final 

rule analysis, in 2010. These interviews took place after manufacturers’ initial experience of fullline production of products using R-410A refrigerant. During these interviews, DOE asked 

manufacturers what groupings of design options are used in baseline designs and what would be 

implemented to increase the energy efficiency in order to meet higher efficiency levels for room 

air conditioners. DOE asked about the state of the R-410A transition and the technical challenges 

still facing manufacturers to meet higher efficiencies. 

Components That Influence Energy Efficiency 

Manufacturers identified the components that influence energy efficiency in room air 

conditioners as fans, blowers, fan motors, heat exchanger coils, and compressors. Most 

manufacturers use PSC fan motors. Some manufacturers have considered electronicallycommutated motors (ECM), which use less energy than PSC fan motors, but generally have not 

pursued using them because of cost.

 Manufacturers currently use rotary compressors in their room air conditioners, and the 

efficiency range of compressors available today varies by product class. Manufacturers were 

required to stop using HCFC-22 refrigerant starting in 2010, so manufacturers now use R-410A 

refrigerant. Compressor vendors were still developing their lines of R-410A compressors during 

the course of the analysis, so some of the information about them has been changing. 

Manufacturers mentioned during the preliminary analysis phase that the EER range for R-410A 

compressors currently available tops out at 10.0, as compared to 11.0 for HCFC-22 compressors. 

Manufacturers expected to be able to make up for much but not all of the difference as a result of 

the better heat transfer performance of R-410A. Manufacturers have not implemented variablespeed compressors because of the higher cost and because the steady conditions of the DOE test 

procedure do not capture the actual-use benefits of such compressors. Other compressor 

technologies, such as scroll or reciprocating compressors, are available only for higher capacity 

room air conditioners but are generally not used due to size, weight, and/or vibration issues. 

Strategies to Increase Energy Efficiency 

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Manufacturers consider material cost, shipping cost, and weight as key design 

parameters. Manufacturers cited the following strategies to increase energy efficiency: (1) heat 

exchanger coil improvements or face area increase, (2) air system design improvement to 

increase air flow, (3) use of higher-efficiency fan motors, (4) higher-efficiency compressors, and 

(5) subcooler coils. 

Manufacturers cited compressors as a key strategy to increase energy efficiency. 

However, as mentioned above, compressors vendors were not initially offering as full a range of 

compressor EER levels with R-410A compressors as have been available for HCFC-22. This is 

expected to change over the next few years, but initial R-410A designs were constrained by 

limitations in compressor availability. 

Manufacturers are emphasizing heat exchanger coil improvements to increase energy 

efficiency, since this design option offers the most potential for improvement. Further increases 

in efficiency are typically only possible via increasing the coil area. Larger coils require more 

material, which manufacturers cited as a concern due to high material prices. Also, as coils grow, 

the chassis may have to grow as well. If the unit size and weight increase past a certain point, 

consumer utility is impacted. For larger capacity products, window sizes won’t allow further size 

increases. Fewer products can fit in a shipping container, which results in higher per-unit 

shipping costs. 

Manufacturers mentioned that maximizing air flow is also an important consideration in 

achieving efficiency improvements. This may involve reducing fin density or coil depth, using 

more powerful fans and/or blowers, and paying closer attention to minimizing losses in the air 

flow passages. However, more powerful fans can have a detrimental impact on consumer utility 

by making the room air conditioner noisier. Finally, while both higher efficiency PSC motors 

and subcooling coils were cited as having the potential to improve efficiency, the overall impact 

of these design options is relatively small. 

Final Rule Analysis Interviews 

Manufacturers in 2010 had experience with R-410A designs. However, because 

compressor vendors’ product lines were not fully developed and because only one year of 

products had been produced, not all issues associated with the new refrigerant had been resolved. 

All manufacturers stated that R-410A compressors were available, but choices were 

limited. Manufacturers reported that there were less compressor choices, in terms of efficiency 

and capacity. The maximum R-410A rotary compressor efficiency available for use in most 

products was still 10 EER, according to most manufacturers interviewed. However, testing and 

development of higher efficiency compressors was on-going. 

The majority of manufacturers continued to concentrate on heat exchanger 

improvements, mainly through increases in product size. Some manufacturers reported limits in 

the potential size of heat exchangers, due to the impacts from excess refrigerant charge and 

possible impacts on dehumidification performance. Some manufacturers have had to increase the 

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number of tube rows (i.e., the depth) of the heat exchangers in their units. The increase of heat 

exchanger size often is accompanied by use of compressors with lower nominal capacity, 

because the operating capacity of the compressor increases when evaporating temperature is 

raised and condensing temperature lowered, as occurs with larger heat exchangers. 

To implement new R-410A designs, some manufacturers reported that they had to grow 

their units to accommodate the larger heat exchangers, either by developing new product sizes or 

by using the next chassis size available (e.g., using last year’s 10,000 Btu/h product chassis for 

this year’s 8,000 Btu/h product). All manufacturers are very sensitive to the cost of increasing 

the size of units, as larger sizes mean more material and more costs. Many times, the additional 

product costs have been borne by the manufacturers themselves, because the market is extremely 

competitive. However, manufacturers realize that they are reaching the limit of current box sizes. 

Through-the-wall units (products with non-louvered sides) of higher capacity have faced 

an extreme challenge, because product size cannot be increased for these products. Some 

manufacturers reported that larger capacity products may be unable to meet efficiency standards, 

and may disappear from the market. 

5.6.2.3 Product Teardowns 

During the preliminary analysis, DOE conducted reverse engineering for 21 room air 

conditioners across 6 product classes to identify design options, and their associated costs, that 

can be used to raise EER. To the extent possible, DOE selected reverse engineering products of 

similar nominal capacity but varying efficiencies. Figure 5.6.25 shows the efficiency ranges of 

the selected products. The efficiency ranges for the products selected from product classes 1, 3, 

and 5 cover the range of efficiency levels of available products. For product classes 3 and 8, 

products were selected at capacity levels of both 8,000 Btu/h and 12,000 Btu/h. 

DOE notes that all the room air conditioners torn down in the preliminary analysis used 

HCFC-22 as their refrigerant. DOE identified only one commercially available R-410A room air 

conditioner when this analysis was conducted. DOE purchased this unit and conducted reverse 

engineering, but did not conduct a full teardown of this unit. Nevertheless, DOE was able to 

obtain sufficient information about this unit to allow development of both an energy model and 

manufacturing cost model for it. The reverse engineering included close examination of all heat 

exchanger details, identification of the compressor and fan motor model number, and 

measurement of fan power input, among other things. 

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Note: The product class 2 unit did not undergo full teardown and uses R-410A refrigerant. All other products use 

HCFC-22 refrigerant. The 12,000 Btu/h 9.5 EER product class 3 product was advertised as being a through-the-wall 

product (product class 8). 

Figure 5.6.25 Efficiency Range of Room Air Conditioner Teardowns 

During the final rule phase, DOE conducted teardown analysis of commercialized R410A products. This allowed confirmation and validation of information developed in the 

preliminary analysis. DOE tore down four R-410A room air conditioners, listed in Table 5.6.26. 

Table 5.6.26 R-410A Teardown Products selected for validation of analysis 

Teardown 

Unit 

Product 

Class 

Capacity 

(Btu/hr) 

EER 

1 1 5000 9.7 

2 2 6,000 12.0 

3 3 12,000 10.8 

4 5B 28,500 8.5 

During teardown analysis, DOE groups costs into key materials categories. Figure 5.6.26 

shows the breakdown of material costs for a typical HCFC-22 baseline product class 3 room air 

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conditioner, as generated from DOE’s BOM, developed during the preliminary analysis. Note 

that the refrigeration system, heat exchangers, and fan components (components that largely 

determine energy consumption) make up 63 percent of the material costs. Figure 5.6.27 shows 

the various costs comprising a typical baseline product class 3 room air conditioner’s full 

production cost. Depending on the manufacturer and the production volume, the depreciation 

costs may vary from those shown in the figure, which assumes a “green-field” site. Figure 

5.6.28 and Figure 5.6.29 show the same breakdown for an R-410A ENERGY-STAR product 

class 3 room air conditioner. Note that the refrigeration system, heat exchangers, and fan 

components make up 73 percent of the material costs for this product. 

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Figure 5.6.26 Baseline HCFC-22 Product Class 3 (12,000 Btu/h) Room Air Conditioner 


Material Cost Distribution ($157 total)
 

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Figure 5.6.27 Baseline HCFC-22 Product Class 3 12,000 Btu/h Room Air Conditioner Full
 

Production Cost Distribution ($195 total)
 

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Interior Frame, 

4.4% Outer Chassis, 4.1% 

Packaging, 5.8%
 

Installation Kit,
 Compressor, 29.3% 2.1%
 

Tubing, 5.6%
 

Controls, 10.2% 

Motor, 7.6% 

Evap, 12.6% 

Cond, 18.3% 

Figure 5.6.28 ENERGY-STAR R-410A Product Class 3 (12,000 Btu/h) Room Air 


Conditioner Material Cost Distribution ($150 total)
 

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19% 

4% 

Building Dep. Cost Indirect Process Costs 

Tooling Dep. Cost 0% 1%
 

11%
 

Equipment Dep. Cost
 

1%
 

Raw Material Costs 

Indirect Labor Cost 

Supervision Cost 

1% 

Fab Labor Cost
 

6%
 

Assy Labor Cost 

4% 

Purchased Parts 

Material Costs 

53% 

Figure 5.6.29 ENERGY-STAR R-410A Product Class 3 12,000 Btu/h Room Air 

Conditioner Full Production Cost Distribution ($211 total) 

The manufacturing cost model was used in subsequent analysis to determine the cost of 

room air conditioner designs incorporating series of design options to increase efficiency. The 

results of these analyses are discussed in section 5.6.2.9. 

Teardown of Max-Tech 6,000 Btu/h Units 

During the preliminary analysis public meeting, General Electric (GE) noted that the 

6000 Btu/h, 12.0 EER R-410A product DOE had identified during its preliminary analysis had 

been mentioned in a Consumer Reports article indicating that a sample tested by Consumer 

Union did not meet the 12.0 EER ratingg

. GE recommend that DOE should consider another 

heavier 6,000 Btu/h, 12.0 EER R-410A unit as more representative for its analysis. A 

comparison of these two units is presented in Table 5.6.27. 

g

 Consumer Reports. October 2008. Pg. 24 Vol. 73 No. 10. Copyright 2008 Consumers Union of U.S., Inc. 

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Table 5.6.27 R-410A Characteristics of Selected R-410A 6,000 Btu/h 12.0 EER Units 

Brand Haier Friedrich 

Model ESA4066 XQ06M10 

Product Dimensions 

(W×H×D) 

13.63” × 19.75” × 17.75” 14” × 19.75” × 21.38” 

Product Volume 

(cubic feet) 2.75 3.5 

Weight (lb) 57 72 

DOE considered the Consumer Reports article regarding this product, which was initially 

considered to represent 12.0 EER using R-410A. Matching this performance level with the 

energy model required making some input assumptions at the optimistic end of reasonable 

expectations, particularly for the condenser air flow rate. Given the information now available, 

DOE has revised its analysis, using the Friedrich 12.0 EER product to represent the highestefficiency available for low-capacity room air conditioners with louvered sides. The revised 

analysis for product class 1 is based on calibration of the energy model to match the performance 

of the Friedrich product. DOE conducted a teardown of this product to verify its design details. 

The Friedrich unit has a capacity of 6,000 Btu/h, just above the capacity range for product class 

1. Section 5.6.2.7 describes the adjustments to the product class 1 engineering analysis in greater 

detail. 

DOE conducted energy modeling in order to determine what design options are required 

to achieve increased efficiency levels in room air conditioners using R-410A refrigerant. DOE 

upgraded the energy model developed as part of the previous room air conditioner energy 

conservation standard rulemaking for this purpose. The original room air conditioner energy 

model was an adaptation of the Oak Ridge National Laboratory Mark III Heat Pump program for 

modeling of room air conditioner cooling performance and is described in the 1997 TSD from 

the previous room air conditioner energy conservation standards rulemaking.5

 Additional 

modifications made during this rulemaking to upgrade the program for modern room air 

conditioners include the following. 

Revision of the heat exchanger performance models to reflect more recent correlations for 

airside heat transfer and pressure drop performance. This includes correlations for the slit fins 

typically used in today’s room air conditioners as well as for microchannel heat exchangers. 

Incorporation of property routines for other refrigerants, including R-410A. 

Development of a platform to allow running the program in the Microsoft Windows 

operating system. 

The modified program is called MarkN. Because MarkN does not incorporate calculation of the 

performance of fans or blowers or the air pressure drops associated with components other than 

the heat exchangers, DOE conducted some modeling external to the program to properly account 

for system changes that impact air flows. DOE developed airside models that calculated the 

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pressure losses within the room air conditioner of air passages, flow transitions, inlets, and 

outlets, and that incorporated heat exchanger pressure drop results from MarkN for both the 

evaporator and condenser. The airside models also included models of the fan or blower 

performance. With the airside model used in conjunction with MarkN, DOE was able to properly 

account for the impacts on air flow and fan motor shaft power associated with the analyzed 

design modifications. 

Fan performance information was generally not available for the fans and blowers of the 

teardown models that were analyzed. DOE obtained performance data for similar fans and 

blowers from vendors. DOE adjusted the available fan and blower performance information 

using the fan laws from the 2008 ASHRAE Handbook, HVAC Systems and Equipment6

, to 

approximate the performance of the components in the products that were analyzed. Further 

information on the airside models is available in appendix 5D of this TSD. 

DOE modeled the energy use for each of the teardown units and compared to the rated 

performance for these units to verify the validity of the upgraded energy model. DOE based 

inputs for the individual models on the design details determined during teardown of the 

products. DOE determined some of the system operating parameters using energy testing, as 

discussed in section 5.6.2.4. DOE set evaporator air flow equal to the rated evaporator air flow. 

DOE also made hot wire anemometer measurements of condenser air flow and fan motor power 

input measurements prior to teardown to provide model input for these parameters. DOE used 

data obtained from compressor vendors to represent compressor performance. 

Comparisons of energy model results and rated performance of the teardown units are 

shown in Figure 5.6.30 below. The figure shows that both capacity and efficiency of the products 

were well predicted by the energy model. Of these products, only the 6,000 Btu/h 12.0 EER 

room air conditioner used R-410A refrigerant. All other units used HCFC-22 refrigerant. 

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Figure 5.6.30 Comparison of Energy Modeling Results with Rated Air Conditioner 


Performance
 

After calibration of the energy models by comparison with rated performance data as 

discussed above, DOE used the energy model to determine the energy impact of conversion to R410A refrigerant. DOE conducted this analysis for all of the teardown products using HCFC-22 

refrigerant, assuming only drop-in of an R-410A compressor with no other adjustments for the 

new refrigerant. DOE obtained performance data of the R-410A compressors from compressor 

vendors. The R-410A drop-in analyses are compared with the baseline HCFC-22 analyses in 

Figure 5.6.31 below. The models generally show a reduction in EER in the range of 0 to 15 

percent. 

Figure 5.6.31 Energy Modeling Results for R-410A Drop-In 

DOE conducted further energy analysis on designs modified by a series of design options 

in order to determine the energy efficiency improvement possible with each of these design 

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options. For the final rule analysis, DOE performed this analysis for the seven baselineefficiency products of product classes 1, 3, 5A, 5B, 8A, and 8B (DOE conducted analysis for 

product class 3 designs at 8,000 Btu/h and 12,000 Btu/h capacities). For all of these products, 

some improvement was required for the initial R-410A design in order to achieve EER levels 

meeting the current DOE energy standards. Additional improvements allowed examination of the 

incremental cost for efficiency improvements for R-410A room air conditioners. The results of 

the design option energy modeling analyses are discussed in section 5.6.2.9 below. 

5.6.2.4 Energy Testing 

During the preliminary analysis, DOE tested four units prior to teardown. DOE used the 

energy test results to verify performance of some of the higher-efficiency products. The 

comparison between rated and tested performance is shown in Figure 5.6.32 below. Test results 

for three of the units were close to the rated performance, while the results of the fourth were not. 

*This product was advertised as being for through-the-wall installations (i.e. product class 8), 

but it had louvered sides. 

Figure 5.6.32 Room Air Conditioner Energy Test Results 

The energy testing conducted with additional instrumentation to allow recording of 

system temperatures. These measurements were used during energy modeling to help in 

calibration of the models with test results. Refrigerant temperatures were approximated by 

measurement of tube surface temperatures with thermocouples adhered to the tubes and 

externally insulated. The additional system measurements included: 

� compressor discharge; 

� condenser mid (a return bend roughly halfway between the condenser inlet and outlet, a 

location where the refrigerant is expected to be at saturated conditions); 

� condenser outlet or subcooler outlet (for those units having a subcooler); 

� evaporator inlet; 

� evaporator outlet; and 

� suction. 

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5.6.2.5 R-410A Conversion Costs 

DOE determined, from manufacturer and vendor interviews, that there were intrinsic 

costs associated with the conversion from HFC-22 to R-410A. From these interviews, DOE 

determined that these cost increases include increased compressor costs, increased costs of the 

switch to polyolester (POE) oil, and increased refrigerant cost. DOE considered the impacts of 

each effect when calculating the cost of manufacturing for each room air conditioner. 

Compressor Costs 

From interviews with manufacturers and compressor vendors, DOE determined that 

rotary compressors designed for use with R-410A carried a higher price than compressors for 

HCFC-22 refrigerant. R-410A compressors require a thicker shell due to the higher pressures of 

R-410A, which is a key factor in the cost increase. Using the feedback from a variety of 

interviews, DOE used a compressor cost premium of 10 percent for R-410A compressors. This 

cost is for an R-410A compressor matching the capacity of the R-22 compressor it replaces. 

Compressor Oil Switch 

Due to miscibility issues, HFC refrigerants generally cannot be used in compressors 

lubricated with mineral oils, which have been used with HCFC-22. POE oils are being used in R410A rotary compressors. DOE calculated the additional cost of oil based on the price difference 

between mineral oil and POE oils. The cost of the compressor oil switch was added separately, 

because the 10 percent compressor cost increase mentioned above is based on purchasing 

compressors without oil. The prices of mineral oil and POE oil were based on manufacturer and 

oil vendor inputs. 

Refrigerant Switch 

During interviews, manufacturers mentioned that R-410A costs more than HFC-22. DOE 

calculated the cost increase associated with the refrigerant based on the HCFC-22 charge of the 

teardown units. The costs of R-410A and HFC-22 refrigerants were based on inputs from 

manufacturers and retail sources of refrigerant. 

DOE added the impacts of these three factors to calculate the total cost increase of the R410 drop-in conversion. Table 5.6.28 below summarizes these costs for each analyzed product 

class. Note that the designs associated with these costs have lower EER than the baseline, and 

hence additional costs need to be added to represent the cost increase to maintain the baseline 

efficiency with an R-410A product. These additional costs were determined as the first step in 

the analysis of design options for improvement of efficiency, and they are discussed in section 

5.6.2.5. 

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Table 5.6.28 Manufacturing Cost Increase for Drop-In Conversion to R-410A 

Product Class Total Costs Due to 

Refrigerant Switch 

1 (5,000 Btu/h Capacity) $3.29 

3 (8,000 Btu/h Capacity) $4.48 

3 (12,000 Btu/h Capacity) $6.27 

5 (24,000 Btu/h Capacity) $11.43 

5B (28,000 Btu/h Capacity) $ 11.43 

8A (8,000 Btu/h Capacity) $4.78 

8B (12,000 Btu/h Capacity) $6.73 

5.6.2.6 Analysis Treatment of Design Options 

To generate cost-efficiency curves, DOE examined both design options that influence 

EER and design options that influence standby or off mode energy use. 

After the screening analysis and further elimination of design options discussed in section 

5.2.2, DOE retained the design options listed in Table 5.6.29 below for improvement of 

efficiency. 

Table 5.6.29 Retained Design Options for Room Air Conditioners 

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. Microchannel heat exchangers 

Component Improvements 

6. Improved blower/fan motor efficiency 

7. Improved compressor efficiency 

Standby Power Improvements 

8. Switching Power Supply 

DOE determined the energy savings associated with each of these design options using 

energy modeling. DOE determined the cost impact per option using the manufacturing cost 

model established during the teardown analysis, obtaining additional input on component costs 

from vendor inquiries and manufacturer interviews. Details regarding the approach to savings 

and cost calculations for each of the design options are discussed below in greater detail. 

Increased Frontal Coil Area 

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The energy and manufacturing cost models directly calculate the benefit and cost of 

increasing frontal coil area. DOE considered a number of variants on this design option, 

depending on the details of the baseline product under consideration. 

Increases in Evaporator Width 

In some of the baseline products, the evaporator width was limited unnecessarily by 

placement of the electronic control board next to the evaporator, preventing its expansion along 

the face of the unit. In many cases, there was sufficient space in alternative locations for the 

controls, such as above the evaporator adjacent to the vent. One variant of this design option that 

DOE examined was placing the controls above the evaporator, rather than beside it, thus freeing 

space to expand the evaporator. Some teardown units already incorporated the placement of the 

controls above the evaporator, especially the high-efficiency units. It did not appear to have an 

impact on utility. 

Bending of the Condenser Coil 

For some products, it may be possible to add a bend to the condenser coil in order to fit 

more coil frontal area within an existing chassis size. DOE examined this approach for the 

product class 1 unit and for both product class 8 units (products without louvered sides). DOE 

observed that some of the teardown units had bent condensers. 

Increasing Physical Size of Product 

DOE believes that larger coil frontal area (and larger package size to allow it) are key 

factors in maximizing EER in the max-tech products of product classes 1, 3, and 5 (products with 

louvered sides). The sizes and weights of these units are shown in Table 5.6.30 below. This table 

includes both the HCFC-22 units of the preliminary analysis, and the R-410A teardown units of 

the final rule analysis. Each analyzed product class group (1, 3, 5A, 5B) contains a baseline 

efficiency product that was analyzed, all but product class 5B contains an ENERGY-STAR rated 

unit, and analyzed product classes 1 and 3 contain max-tech units. Product class 2 was included 

because DOE tore down the max-tech 6,000 Btu/h 12 EER unit. 

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Table 5.6.30 Sizes and Weights of Product Class 1, 3, 5A, and 5B Teardown Units 

Design Description 

Refrigerant Width 

(in) 

Height 

(in) 

Depth 

(in) 

Weight 

(lb) 

Product Class 1 

Baseline 1, 9.7 EER 

Baseline 2, 9.7 EER 

Baseline 3, 9.7 EER 

10.7 EER

 11 EER* 

HCFC-22 

HCFC-22 

R-410A 

HCFC-22 

HCFC-22 

15.5 

17.28 

17.28 

18.91 

18.5 

11.75 

11.16 

12.84 

12.46 

12.5 

12 

7.28 

11.16 

14.69 

14 

38.6 

36.5 

38 

48.2 

44.4 

Product Class 2, 6,000 Btu/h

 12.0 EER* R-410A 19.75 14 20.25 72 

Product Class 3, 8,000 Btu/h 

Baseline, 9.8 EER 

10.8 EER

 11.4 EER 

HCFC-22 

HCFC-22 

HCFC-22 

18.5 

18.59 

25.94 

12.5 

12.75 

15.94 

15.5 

16.34 

27.38 

49.4 

49.4 

108 

Product Class 3, 12,000 Btu/h 

Baseline, 9.8 EER 

10.8 EER 

11.8 EER*

 10.8 EER 

HCFC-22 

HCFC-22 

HCFC-22 

R-410A 

19.58 

23.63 

25.94 

19 

13.75 

15 

22.25 

14.5 

19.63 

22.25 

27.38 

21.25 

73 

78.6 

108.8 

67 

Product Class 5A, 24,000 Btu/h 

Baseline, 8.5 EER

 9.4 EER 

HCFC-22 

HCFC-22 

26 

26.5 

17.69 

18.63 

28.41 

25 

132 

135.2 

Product Class 5B, 28,500 Btu/h

 Baseline, 8.5 EER R-410A 26.5 18.75 25.5 138 

* Max-tech Unit 

In the preliminary analysis, DOE considered increase of the physical size of the room air 

conditioner for product classes 1, 3, and 5. For product class 8, size increase was not 

considered—since much of the market for room air conditioners without louvered sides involves 

installation in existing wall sleeves, size increase for product classes 6 through 10 (including 8) 

(products without reverse cycle without louvered sides), 12, and 14 (products with reverse cycle 

without louvered sides) are not possible. The sizes of the product class 1, 3, and 5 that DOE used 

to represent baseline and higher efficiency products in DOE’s preliminary analysis are compared 

in Figure 5.6.33 with a distribution of product sizes of baseline-efficiency room air conditioners 

from the database developed by DOE from the CEC, ENERGY STAR, and AHAM databases 

described in chapter 3. The comparisons show that the sizes of the analyzed products could be 

increased without exceeding the size of other current baseline-efficiency products. DOE drew a 

similar conclusion when comparing weights of the analyzed product designs with the weights of 

other baseline products in the database. With an overall unit size increase, the frontal areas of 

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both the evaporator and condenser can be increased. The sizes DOE used in the analysis are 

summarized in Table 5.6.33 below. 

Figure 5.6.33 Size Distributions of Baseline-Efficiency Room Air Conditioners – HCFC 

Products on the Market 

During the final rule analysis, DOE again compared the preliminary analysis product 

sizes against products on the market, in this case R-410A units. The results are shown in Figure 

5.6.34 below. This assessment shows that the distribution of sizes of commercially available 

HCFC-22 room air conditioners examined during the preliminary analysis did not differ 

significantly from the size distribution of currently available R-410A products. 

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0 1 2 3 4 5 6 7 8 9 10 11 12 

R-410A Products Volume of Chassis (cuft) 

Baseline Product Sizes 

Investigated Larger Sizes 

R-410A Models 

Product Class 3, 8,000 Btu/hr 

Product Class 3, 12,000 Btu/hr 

Product Class 5 

Product Class 4 

Product Class 2 

Product Class 3, 10,000 Btu/hr 

Product Class 1 

Figure 5.6.34 Size Distributions of Baseline-Efficiency Room Air Conditioners – R-410A 

Products on the Market 

DOE observed that the physical sizes chosen for the analyzed baseline products matched 

the sizes of the smallest available baseline products well, except for the product class 3 unit of 

12,000 Btu/h capacity. To adjust, DOE revised its analysis for this product class and capacity, 

using the 12,000 Btu/h R-410A baseline teardown product as a basis for the new analysis. The 

size data for this product is presented in Table 5.6.31 below. 

Table 5.6.31 Adjusted Baseline Size for Product Class 3 – 12,000 Btu/h Analysis 

Width 

(in) 

Height 

(in) 

Depth 

(in) 

Volume 

(cf) 

Baseline PC3-12k Unit 19 14.5 21.25 3.39 

Because of the split of product class 5, DOE also reviewed chassis sizes for the new 

product classes 5A (capacity between 20,000 and 27,999 Btu/h) and 5B (capacity larger than 

27,999 Btu/h). DOE selected products of capacities 24,000 Btu/h 28,000 Btu/h room air 

conditioner to represent the analysis for these new product classes. DOE observed that no 

products on the market within the capacity range of the new product class 5A had chassis size 

near the roughly 12 cubic feet volume used as the maximum size in the DOE analysis. However, 

for products on the market with capacities within the range of the new product class 5B, this size 

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level is required to achieve better than baseline efficiency, as shown in Table 5.6.32 below. 

Product 1 of this list is not within the product class 5B capacity range, but nevertheless, the 

largest chassis size is required for this product to achieve ENERGY STAR efficiency level. 

Table 5.6.32 Product Class 5B – R-410A Product Sizes 

Capacity 

(Btu/h) 

EER Product volume 

(cf) 

Product 1 27,800 9.7 11.6 

Product 2 28,500 8.5 7.6 

Product 3 36,000 8.5 11.6 

DOE adopted the following approach for size selection of these product classes: 

For Product Class 5A, DOE did not consider growth to a volume near 12 cubic feet. 

For Product Class 5B, DOE did allow growth to this size. 

The examined size increases in the final rule analysis are summarized in Table 5.6.33 

below. 

Table 5.6.33 Size Increases Examined During Room Air Conditioner Design Option 

Analysis 

Design Description 

Width 

(inches (in)) 

Height 

(in) 

Depth 

(in) 

Weight 

(lb) 

Product Class 1 

Baseline 

First Size Increase

 Second Size Increase 

15.5 

18.5 

19.69 

11.75 

12.5 

13.63 

12 

14 

17.72 

38.6 

42.7 

46.8 

Product Class 3, 8,000 Btu/h 

Baseline 

First Size Increase

 Second Size Increase 

18.5 

19.3 

22.5 

12.5 

15.63 

15.63 

15.5 

18 

23.6 

49.4 

55.7 

63.6 

Product Class 3, 12,000 Btu/h 

Baseline 

First Size Increase

 Second Size Increase 

19 

23.5 

26 

14.5 

15.63 

15.63 

21.25 

23.6 

28.4 

76.5 

81.2 

87.6 

Product Class 5A 

Baseline 

First Size Increase

 Second Size Increase 

26 

27.75 

-

17.69 

17.94 

-

28.41 

30.94 

-

129.2 

136.4 

-

Product Class 5B 

Baseline 

First Size Increase

 Second Size Increase 

26 

27.75 

29.81 

17.69 

17.94 

22.38 

28.41 

30.94 

30.94 

129.2 

136.4 

156.5 

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DOE is aware that product size has a significant impact on efficiency, and requested 

comment during the preliminary analysis phase on acceptable maximum product sizes for 

louvered room air conditioners. 

DOE received the following comments from stakeholders, on maximum product sizes: 

AHAM noted that smaller products (especially those in product classes 1 (room air 

conditioners without reverse cycle, with louvered sides, and capacities less than 6,000 

Btu/h) and 2 (room air conditioners without reverse cycle, with louvered sides, and 

capacities 6,000 to 7,999 Btu/h)) would be most negatively impacted by an increase in 

weight. AHAM indicated that the Occupational Safety and Health Administration 

(OSHA) recommends an additional person for lifting and installing products weighing 

over 50 lbs. AHAM stated that the 50 lbs. limit is expected to influence consumer 

acceptance of these products. 

NPCC recommended that DOE compare the maximum unit dimensions in each 

preliminary analysis to the dimensions of the highest efficiency model available on the 

market. NPCC recommended that, if these two product dimensions are similar, that DOE 

assume that all units can be equally as large. NPCC also recommended that, if the market 

unit is smaller than the unit proposed by DOE, that DOE determine whether a redesign of 

the proposed unit would eliminate the size constraint. 

DOE implemented the following changes in its analysis based on the comments 

submitted by stakeholders: 

DOE limited the maximum weight for product class 1 unit to 50 lbs., based on the 

Occupational Safety and Health Administration (OSHA) and National Institute of 

Occupational Safety and Health (NIOSH) suggested weight limits. 

DOE adopted maximum product heights and widths consistent with max-tech 

products. 

Further details of each analysis are detailed in the sections below. 

50 lbs Weight Limit 

NIOSH lists among its hazard evaluation checklist the handling of loads exceeding 50 lbs 

as a risk factor used to identify potential problems.h

 OSHA, in its Ergonomics eTool: Solutions 

for Electrical Contractors, states that lifting loads heavier than 50 lbs will increase the risk of 

injury, and recommends use of more than one person to lift weights greater than 50 lbs.i

 These 

h

 http://www.cdc.gov/niosh/docs/2007-131/ 

i

 http://www.osha.gov/SLTC/etools/electricalcontractors/materials/heavy.html 

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guidelines calling for additional personnel for product lifting represent distinct changes in 

consumer utility for products that currently weigh less than 50 lbs. 

DOE notes that all but the smallest room air conditioners weigh more than 50 lbs, a trend 

illustrated by the weights of the teardowns in Table 5.6.34 above. A summary of the baseline 

weights for each analyzed product class is included in Table 5.6.34 below. 

Table 5.6.34 Baseline Product Weights of the Units for the Analyzed Product Classes 

Product 

Class 

Capacity (Btu/h) Baseline CEER 

Analyzed Weight 

(lb.)* 

1 5,200 40.0 

3 8,000 50.1 

3 12,000 68.03 

5A 24,000 132.5 

5B 28,000 140.3 

8A 8,000 61.7 

8B 12,000 67.4 

*Product weights for the analyzed design options are calculated using the manufacturing cost model 

DOE limited the total weight of the product class 1 baseline unit with integrated design 

options to 50 lbs, to avoid exceeding OSHA and NIOSH guidelines for single-person lifting. 

DOE did not consider limiting the weight of the other analyzed product classes, since they 

already exceeded this limit. 

Maximum Chassis Sizes on the Market 

DOE based the maximum chassis width and height of each analyzed product class on the 

dimensions of the largest R-410A room air conditioners in each product class on the market. 

DOE’s maximum chassis sizes were based on HCFC-22 and R-410A products. Table 5.6.35 

below compares DOE’s max-tech design dimensions with the largest available products, for each 

product class. For each of these product classes, the physically largest product on the market also 

has the maximum available efficiency. 

Table 5.6.35 Comparison of DOE Analysis Chassis Size and Market Chassis Size 

Product Class Large Chassis Size in DOE 

Analysis 

(w x h x d) 

R-410A Max-Tech 

Unit on the Market 

(w x h x d) 

1 19.69 × 13.63 × 17.72 19.75 × 14.0 × 21.38 

3 (8000 Btu/h) 22.5 × 15.63 × 23.6 25.94 × 15.94 × 29 

3 (12,000 Btu/h) 26 × 15.63 × 23.6 25.94 × 15.94 × 29 

5A 27.75 × 17.84 × 30.94 26 × 17.5 × 29.75 

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5B 29.81 × 22.38 × 30.94 28 × 20.19 × 35.5 

DOE chose maximum product heights and widths consistent with the largest products on 

the market. These dimensions set the face areas available for heat exchangers. However, DOE 

observed that the depths of the max-tech available products are significantly larger than 

expected—these depths are out of proportion when considering the relationship between depth 

and width or height of other products. DOE’s analysis indicated that depths consistent with the 

proportions observed in most other products are sufficient to provide max-tech performance. 

Hence, DOE analysis selected max-tech design depths less than those observed in the max-tech 

available products. DOE used this approach for product classes 3 (room air conditioners without 

reverse cycle, with louvered sides, and capacities 8,000 to 13,999 Btu/h), 5A (room air 

conditioners without reverse cycle, with louvered sides, and capacities 20,000 to 27,999 Btu/h), 

and 5B (room air conditioners without reverse cycle, with louvered sides, and capacities 28,000 

Btu/h or more). This limitation did not apply to product class 1 (room air conditioners without 

reverse cycle, with louvered sides, and capacities 5,999 Btu/h or less), for which growth was 

limited by consideration of the 50 lbs maximum weight. 

Added Shipping Costs for Chassis Size Increases 

The room air conditioner reverse-engineering included documentation of the packaging 

used for shipping the product, and additional accessories (remote control, window installation 

kit, bracing). As the chassis expands, the surrounding packaging also increases in size. The costs 

associated with all of these increases are part of the calculated incremental cost for the efficiency 

improvements. Most of the shipping material packaging cost is the cost of the surrounding 

cardboard box. 

Most room air conditioners are shipped from overseas, and manufacturers mentioned 

during interviews the added shipping costs associated with larger chassis sizes. DOE calculated 

the cost of shipping to a U.S. distribution facility based on the size of the room air conditioner 

being shipped; the cost is determined based on the volume of the unit. This cost was reported 

separately from the manufacturing production cost (MPC). DOE expects that the manufacturer 

markup does not apply to this cost because manufacturers indicated that many room air 

conditioners are shipped by retailers. Hence, in determining the incremental cost associated with 

efficiency improvements, the shipping cost increase would be added to the incremental 

manufacturer sales price (MSP). 

The shipping cost was determined as follows. DOE estimated the total shipping costs for 

a standard shipping container, based on interviews with manufacturers and quotes from shipping 

companies. The costs include shipping from the factory to a U.S. distribution facility. The 

number of units per container was calculated by volume, and divided by the cost of shipping to 

determine the cost of shipping per unit. For design options that involved increase in chassis size, 

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DOE calculated incremental shipping costs to account for the larger size. The cost estimate 

including distribution within the U.S. is considered to be conservative, because part of this cost 

may already be included in the typical retailer markup, which has not be reduced to account for 

separate consideration of part of the shipping cost. 

Increased Depth of Coil 

DOE examined increasing the depth of the evaporator and/or condenser. Energy impacts 

were determined using the energy model, and cost impacts were determined using the 

manufacturing cost model. DOE determined that increasing coil depth beyond two tube rows 

generally is not effective in increasing EER. Most room air conditioners use heat exchangers 

with two tube rows, although some have more rows. However, the DOE analysis shows that the 

airflow reduction or fan power increase associated with increases in coil depth often negates the 

benefits of the additional heat exchanger surface area. 

Increased Fin Density 

DOE examined increases in fin density for all of the products. Energy impacts were 

determined using the energy model, and cost impacts were determined using the manufacturing 

cost model. DOE considered a maximum fin density of 22 fins per inch (FPI). In some cases, 

increasing fin density improves performance. For many cases, the airflow resistance of the 

additional fins leads to reduced airflow and/or higher fan power which negates the benefit of the 

increased heat exchanger surface area. Many units already use high fin densities, so increased fin 

density often results in minimal or no gains. Lastly, high fin densities have been mentioned by 

manufacturers as having potential detrimental effects on long-term unit efficiency, since cleaning 

coils with high fin densities is very difficult. 

Add Subcooler to Condenser Coil 

DOE examined the use of subcoolers for all room air conditioners. Energy impacts were 

determined using the energy model, and cost impacts were determined using the manufacturing 

cost model. DOE used a subcooler exit temperature of 95 °F, based on information provided by 

manufacturers.5 In all cases, the subcooler made a small improvement in efficiency, but was 

highly cost-effective. Inspection of the teardown units revealed that many high-efficiency units 

placed the subcooler within the condenser plenum. DOE determined that the addition of a 

subcooler to a unit would not require any chassis size increase. 

In selecting the appropriate subcooler length for each product class, DOE considered the 

subcoolers from the teardown units. In each product class, the highest-efficiency unit contains a 

subcooler. The length of this subcooler provided the basis for the length of the subcooler added 

for a product of the same capacity. In some cases DOE determined that the chosen subcooler 

length was excessive for the baseline chassis size. DOE reduced the selected length and 

performance of the subcooler in these cases. DOE maintained a fixed subcooler length with 

subsequent chassis size increases. 

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Microchannel Heat Exchangers 

DOE analyzed microchannel condensers as a design option during the preliminary 

analysis. Performance modeling of microchannel heat exchangers is included in the upgraded 

room air conditioner energy model. Information provided from vendors indicates that, in most 

cases, this technology is not suitable for evaporators because (1) the geometry is not suitable for 

quick drainage of condensate from the heat exchanger surface; and (2) uniform refrigerant 

distribution into the many parallel tubes is not assured. Therefore, microchannel heat exchangers 

were considered only for condensers. Use of this technology resulted in a small efficiency 

improvement in most of the analysis. DOE determined microchannel condenser incremental 

manufacturing costs based on prices provided by a vendor for two representative sizes, one 

suitable for a 5,000 Btu/h room air conditioner and the other suitable for a 24,000 Btu/h unit, 

assuming high-volume production. In addition to purchase price, the costs also incorporate the 

cost of brazing two pieces of copper tubing to the all-aluminum microchannel heat exchanger, 

since many purchasers do not have the capability of brazing copper to aluminum and such 

fabrication would represent an additional step in the manufacturing process. 

The sizes and cost estimates of the microchannel heat exchanger designs considered in 

the analysis are presented in Table 5.6.36 below. For the most part, the costs are an order of 

magnitude greater than that of any of the other design options considered. The table also shows 

the modeled efficiency improvements calculated for this design option. The improvements were 

low or zero. 

Table 5.6.36 Microchannel Condenser Costs - Preliminary Analysis 

Room Air 

Conditioner Capacity 

(Btu/h) 

Condenser Core 

Dimensions 

(Height x Length, in) 

Condenser 

Core Depth 

(in) Cost 

EER Increase 

Benefit from 

Baseline 

5,000 11.25 × 15.25 1 $75 0.3 

8,000 12.75 × 17.25 1 $85 -

12,000 16 × 21.63 1 $110 -

24,000 16.37 × 22 1 $115 0.1 

Improved Fan/Blower Motor Efficiency 

Room air conditioners almost exclusively use double-shafted PSC motors to power the 

condenser fan and evaporator blower. DOE considered improved motor efficiency as a design 

option, in the form of high efficiency PSC motors and brushless DC (BLDC) motors. DOE 

considered the cost of the motors as a function of motor type, shaft power, and efficiency, 

although only one efficiency level was considered for BLDC motors. DOE obtained cost data 

from vendors, both for room air conditioner motors and for single-shaft motors with similar 

power output and speed used in other applications. DOE selected a typical range of motor shaft 

power rating for each product class it analyzed, based on the motors used in the teardown units, 

and sought information about similar motors at higher efficiencies. The selected shaft power 

levels are shown in Table 5.6.37 below. 

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Table 5.6.37 Motor Power Rating by Product Capacity 

Room air conditioner capacity (Btu/h) Fan Motor Shaft Power Rating (W) 

<6,000 25-35 

8,000 to 13,999 60-75 

>20,000 150-200 

DOE selected a motor efficiency of 50 percent for the PSC motors of baseline room air 

conditioner. This was consistent with the motors in the teardown units, as well as the information 

obtained during manufacturer interviews. DOE selected a peak PSC motor efficiency of 70 

percent for the analysis. 

BLDC motors are a more efficient alternative to PSC motors, and BLDC motors are used 

in similar applications, such as packaged terminal air conditioners (PTACs). DOE obtained 

information about BLDC motors from motor vendors, motor catalogs, and discussions with room 

air conditioner manufacturers. Reported BLDC motor efficiencies were in the range 75 percent 

to 90 percent. DOE selected an efficiency level of 80 percent for the analysis. 

DOE examined PSC motor prices from a wide variety of motor vendors. DOE conducted 

analysis on this motor data to establish a robust correlation for motor cost based on motor 

characteristics including efficiency, shaft power, weight, current, and voltage. The assessment 

included single-shafted and double-shafted PSC motors intended for HVAC applications. DOE 

found the strongest correlation between motor price and weight, and used this relationship as the 

basis for calculating the incremental costs for PSC motor efficiency improvements. Figure 5.6.35 

below shows the calculated cost of increasing the efficiency of a PSC motor from 50 percent to 

70 percent as a function of motor shaft power output, for shaft outputs from 20 W to 100 W. This 

range included motors for product classes 1, 3 and 8. For the product class 5 baseline motor, with 

a rated shaft output of 200 W, DOE extrapolated the cost of the motor from the smaller motor 

sizes. Further information on the assessment of PSC motor costs is available in appendix 5D of 

this TSD. 

5-112 

 

 

 

 

 

 

Figure 5.6.35 Cost Differential for Increasing PSC Motor Efficiency from 50% to 70% 

DOE also compiled pricing and size information on BLDC motors from motor vendors 

and catalogs. DOE found prices for BLDC motors with the same motor shaft output as the PSC 

motors found in the reverse engineering units, and calculated the cost of replacing the baseline 

PSC motors with the BLDC motors. Figure 5.6.36 below shows the calculated cost of replacing a 

baseline PSC motor with a BLDC motor. 

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Figure 5.6.36. Cost Differential for Replacing a Baseline PSC Motor with a BLDC Motor. 

Some manufacturers raised concerns regarding the use of BLDC motors, stating that they 

are physically much larger than PSC motors and thus may not fit into the small space allowed in 

a room air conditioner. Table 5.6.38 shows the characteristics of a typical 70 W PSC motor, and 

the characteristics of a typical 70 W BLDC motor observed by DOE. These ranges are derived 

from motor vendor catalog data. The data show that the BLDC motor has greater weight and 

length than the comparable double-shafted PSC motor. However, DOE did not conclude that the 

size increase of these motors would prevent their use in room air conditioners. 

Table 5.6.38 Comparison of a typical range of sizes for a 70W PSC Double-Shafted Motor 

and a 70W BLDC Motor 

Typical Characteristics Double-Shafted PSC BLDC 

Typical Efficiency 50% 80% 

Weight 8–10 lbs. 12 lbs. 

Outer Diameter 3.75–5.0 in 1.73–2.63 in 

Motor Length (w/o Shaft) 3.0–4.25 in 4.5–6.39 in 

Improved compressor efficiency 

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DOE conducted the engineering analysis based on use of R-410A refrigerant, since this is 

the refrigerant currently used by all new room air conditioners 

During the preliminary analysis, DOE sought information on the performance of R-410A 

rotary compressors of varying efficiency levels for all of the products under analysis. In many 

cases, the range of efficiency for which vendors were willing to provide performance data was 

limited. Conducting the analysis generally required knowledge not just of design point capacity 

and EER—DOE requested performance data for a representative range of evaporating and 

condensing conditions, as required for input into the energy model. In some cases, the trends of 

compressor performance as a function of operating conditions were extrapolated from the trends 

exhibited by a compressor of the same refrigerant of nearly the same capacity. For product class 

5, DOE also analyzed scroll compressors as a design option. The EER and capacity of the 

compressors for which DOE obtained performance data are illustrated in Figure 5.6.37 below. As 

can be seen, there were data for many more HCFC-22 compressors than for R-410A rotary 

compressors. The EER ratings of the R-410A compressors were not only generally lower than 

those of HCFC-22 rotary compressors of similar capacity, but exhibited a much more limited 

EER range (i.e., HCFC-22 compressor EER levels ranged from 9.0 to 11.2 near 5,000 Btu/h 

nominal capacity, whereas the R-410A compressor EER range was roughly 9.0 to 10.0). The 

chart shows that reduction in the EER when switching to R-410A compressors was greater for 

lower capacities than for higher capacities. The chart also shows that the use of scroll 

compressors does not improve efficiency for most of the capacity range of interest for room air 

conditioners. 

5-115 

 

 

 

 

 

Figure 5.6.37 Compressor Performance Specifications – Preliminary Analysis 

During the final rule analysis, DOE again reviewed R-410A compressors, checking 

vendor websites and speaking with vendor representatives about performance of commercially 

available, developmental, and future compressors. Website data for R-410A compressors are 

illustrated in Figure 5.6.38 below. 

5-116 

 

 

 

 

 

 

 

 

 

 

8.6 

8.8 

9 

9.2 

9.4 

9.6 

9.8 

10 

10.2 

10.4 

0 5000 10000 15000 20000 25000 30000 35000 

Compressor EER (Btu/h/W) 

Compressor Capacity (Btu/h) 

Figure 5.6.38 R-410A Compressor Performance Characteristics – Final Rule Analysis 

Based on DOE’s research and manufacturer interviews (see above), DOE decided to 

consider maximum compressor-rating EER of 10.0 for lower-capacity compressors, and EER of 

10.3 for higher-capacity compressors. The data clearly showed availability of R-410A 

compressors spanning a range of EER, so DOE added “high efficiency compressor” as a design 

option in the analysis. The maximum EERs considered for the analyzed product classes are listed 

in Table 5.6.39 below. 

Table 5.6.39 Maximum Compressor EER Levels 

Product Class Maximum Compressor EER 

in Final Rule Analysis 

1,3,8A,8B 10.0 

5A,5B 10.3 

DOE used detailed performance maps data (capacity and EER as a function of suction 

and discharge pressures) to model many of the compressors. However, in some cases, where 

such detailed data was not available from vendors, DOE used maps of compressors with nearly 

the same capacity or EER, adjusted for the modeled compressor’s design-point performance. 

5-117
 
 

 

 

 

 

 

 

 

 

 

 

The relationship between R-410A compressor cost and baseline-efficiency room air 

conditioner capacity that DOE used in the analysis is illustrated in Figure 5.6.39 below. This 

relationship was developed based on information collected during past rulemakings, discussions 

with manufacturers, and cost information provided by compressor vendors. It includes the 10 

percent cost premium for R-410A compressors discussed in section 5.6.2.5. The figure is based 

on room air conditioner capacity, and not compressor rating point capacity. 

Figure 5.6.39 R-410A Compressor Cost 

Scroll Compressors 

During the preliminary analysis phase, DOE considered scroll compressors as a design 

option for product class 5. However, scroll compressors do not provide additional efficiency 

above the 10.3 maximum EER considered in the analysis for rotary compressors. They are also 

heavier and more costly. Thus, for the final rule analysis, DOE did not consider scroll 

compressors as a cost-effective design option in room air conditioners. 

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Standby Mode and Off Mode 

DOE identified and analyzed only one option for reducing standby and off mode energy 

use–changing from a transformer-based power supply to a switching power supply. DOE 

conducted energy measurements of electronic boards, and determined that the total standby 

mode power for a typical baseline control board is roughly 1.4 W, and that the transformer 

consumes about 75 percent of this power. DOE concluded that the main source of power 

consumption in standby mode for a room air conditioner is the power supply, as shown in Table 

5.6.40. The measurements reported in this table were made by disconnecting more loads for the 

successive measurements, thus showing that nearly 1 W of the 1.32 W associated with the 

standby mode for this unit represents the transformer loss (the transformer loss could actually be 

a larger portion of the 1.32 W, since disconnecting the loads as indicated reduces power supplied 

by the transformer, and thus could also be reducing the its loss in the successive measurements). 

Table 5.6.40 Standby Energy Consumption by Component 

Example Stand-by Energy Breakdown for Electronic Board 

Components Energized Power Consumption (W) 

User Interface Board + Control Board 1.32 

Control Board 1.28 

Transformer 0.96 

Two of the teardown units with electronic control boards used switch-mode power 

supplies, an alternate technology to the traditional linear regulated power supply. The switching 

power supply replaces the traditional power supply with a more complex circuit board and a 

much smaller transformer. The two switching power supply units consumed roughly 0.7 W. 

DOE obtained conversion cost information for switching power supplies for cell phone 

technology, based on similar production volumes and power levels as for room air conditioner 

control board power supplies. During the preliminary analysis, the increase in direct material 

costs for converting to a switch-mode power supply based on this information was estimated at 

approximately $1.00. DOE updated its cost-model, reviewed additional teardown information for 

these units and reviewed the incremental costs of this technology for similar household 

appliances, and adjusted its estimate to $0.75 for the final analysis. 

5.6.2.7 Summary of Analysis Adjustments 

During the final rule analysis, DOE revised its preliminary analysis based on new 

information collected in 2010, based on investigation of the room air conditioner market after the 

R-410A conversion. Key changes in the analysis are listed in Table 5.6.31 below. 

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Table 5.6.41 Summary of Key Adjustments to the Engineering Analysis during Final Rule 

Analysis 

Topic Preliminary Analysis Changes made in the final rule analysis 

Product Classes Full analysis of 

existing product 

classes 1,3,5,8 

Full analysis of product classes 1,3, 5A, 

5B, 8A, 8B 

Compressor 

Efficiency 

Used available R410A compressor data, 

which was limited 

Maximum compressor nominal EER of 

10.0 for product classes 1, 3, 8A, and 

8B; and 10.3 for product classes 5A and 

5B 

Size Limits for Based on the range of 50 lbs weight limit for product class 1 

Products with 

Louvered Sides 

sizes of available 

products 

Maximum height and width consistent 

with available max-tech products, 

maximum depth consistent with typical 

depth/height/width ratios. 

Chassis Design Based on baseline 

units analyzed 

Chassis thicknesses were adjusted based 

on the calculated weight of each unit, in 

accordance with teardown analysis. 

Chassis design was also adjusted from 

simple basepan design to welded box 

design as needed. 

Scroll Compressors Considered for product 

class 5 

Not considered. 

Cost-Model Material 

and Labor Costs 

Costs updated as of 

2008 

Costs updated as of 2010 

As part of the analysis of product class 1 for this final rule, DOE made adjustments to the 

product design of the 6,000 Btu/h 12.0 EER unit used as the max-tech model for the product 

class 1 cost-efficiency curve. These adjustments reflected an adjustment in the capacity of the 

unit from 6,000 Btu/h to 5,000 Btu/h. DOE adjusted the cost-efficiency curve for product class 1 

based on this analysis, and then applied the 50 lbs product limit suggested by stakeholders. DOE 

noted that the 12.0 EER product that was reverse-engineered did not incorporate all of DOE’s 

analyzed design options, and so the calibration did not only apply to the max-tech of the costefficiency curve, but to some intermediate steps as well. The product 1 max-tech level of 11.8 is 

a product of both this calibration and the 50 lbs product limit. 

5.6.2.8 Active Mode Analysis 

The cost-efficiency curves based on the active mode metric (EER) are shown in Figure 

5.6.40 through Figure 5.6.46 below. The cost axis of these charts represents MSP plus shipping 

cost. Note that AHAM did not receive a sufficient number of responses regarding costs from 

manufactures to allow aggregation of this data for submission to DOE. Hence, there is no 

AHAM data to allow comparisons. The figures do, however, compare preliminary-analysis and 

5-120 

 

 

 

 

 

 

final rule analysis results. Each separate point in the plots represents a different design 

configuration, rather than a specific efficiency level. 

Most of the final rule analysis curves are shifted to a higher cost as compared with the 

preliminary analysis results. The key exception is the 12,000 Btu/h product class 3 analysis, for 

which DOE decreased the baseline chassis size, using information from the teardown of a 12,000 

Btu/h R-410 product. 

5-121 

 

5-122 

Figure 5.6.40 Product Class 1 Cost-Efficiency Curve 

$150.00 

$170.00 

$190.00 

$210.00 

$230.00 

$250.00 

$270.00 

$290.00 

$310.00 

8.5 9 9.5 10 10.5 11 11.5 12 12.5 13 

MSP + Shipping Costs 

EER (Btu/hr/W) 

RAC Final Rule Analysis 

RAC Preliminary Analysis 
 

5-123 

Figure 5.6.41 Product Class 3 - 8,000 Btu/h Capacity Cost-Efficiency Curve 

$200.00 

$220.00 

$240.00 

$260.00 

$280.00 

$300.00 

$320.00 

$340.00 

$360.00 

$380.00 

$400.00 

8.5 9 9.5 10 10.5 11 11.5 12 12.5 13 

MSP + Shipping Costs 

EER (Btu/hr/W) 

RAC Final Rule Analysis 

RAC Preliminary Analysis 
 

5-124 

Figure 5.6.42 Product Class 3 - 12,000 Btu/h Capacity Cost-Efficiency Curve 

$260.00 

$280.00 

$300.00 

$320.00 

$340.00 

$360.00 

$380.00 

$400.00 

$420.00 

$440.00 

$460.00 

$480.00 

8.5 9 9.5 10 10.5 11 11.5 12 12.5 13 

MSP + Shipping Costs 

EER (Btu/hr/W) 

RAC Final Rule Analysis 

RAC Preliminary Analysis 
 

 

MSP + Shipping Costs
 

$1,000.00 

$900.00 

$800.00 

$700.00 

$600.00 

$500.00 

$400.00 

RAC Final Rule Analysis 

RAC Preliminary Analysis 

7.5 8 8.5 9 9.5 10 10.5 11 

EER (Btu/hr/W) 

Figure 5.6.43 Product Class 5A – 24,000 Btu/h Cost-Efficiency Curve 

5-125 

 

 

$830.00 

$480.00 

$530.00 

$580.00 

$630.00 

$680.00 

$730.00 

$780.00 

MSP + Shipping Costs 

RAC Final Rule 

Analysis 

7 7.5 8 8.5 9 9.5 

EER (Btu/hr/W) 

Figure 5.6.44 Product Class 5B – 28,000 Btu/h Cost-Efficiency Curve 

5-126 


10 
 MSP + Shipping Costs
 

$410.00 

$390.00 

$370.00 

$350.00 

$330.00 

$310.00 

$290.00 

$270.00 

RAC Final Rule Analysis 

RAC Preliminary Analysis 

8 8.5 9 9.5 10 10.5 

EER (Btu/hr/W) 

Figure 5.6.45 Product Class 8A - 8,000 Btu/h Capacity Cost-Efficiency Curve 

5-127 


11 
 

 

 

 

 

 

 

 

 MSP + Shipping Costs
 

$460.00 

$440.00 

$420.00 

$400.00 

$380.00 

$360.00 

$340.00 

$320.00 

RAC Final Rule Analysis 

RAC Preliminary Analysis 

$300.00 

8 8.5 9 9.5 10 10.5 

EER (Btu/hr/W) 

Figure 5.6.46 Product Class 8B - 12,000 Btu/h Capacity Cost-Efficiency Curve 

5.6.2.9 Incremental Costs by CEER 

The previous section discusses costs associated with increase of the active mode 

efficiency, measured in EER. As discussed in section 5.4, the analysis for this rulemaking is 

based on the integrated metric, CEER. DOE analyzed the improvement in CEER associated both 

with design options that improve EER and design options that reduce standby power. DOE 

developed overall cost-efficiency relationships for CEER by combining these analysis. In this 

overall analysis, DOE chose to implement the design options in order of decreasing costeffectiveness. The reduction in standby power had cost-effectiveness between that of the best and 

worst active mode design options. This is illustrated for the product class 1 analysis in Figure 

5.6.47 below. The plot shows the incremental CEER improvement of the design option divided 

5-128 

 

 

 

 

 

 

 

by incremental manufacturing production cost (MPC) associated with the design option, for the 

final analysis. 

0 

0.05 

0.1 

0.15 

0.2 

0.25 

0.3 

0.35 

CEER Improvement per Manufacturing

Cost Increase (Btu/h-W-$) 

Figure 5.6.47 Comparison of the Cost-Effectiveness of Active and Standby Mode Design 

Options 

As discussed above, DOE determined that the incremental cost for reducing standby 

mode power consumption from 1.4 W to 0.7 W is $0.75. Table 5.6.42 below summarizes this 

incremental cost. 

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Table 5.6.42 Room Air Conditioner Cost-Standby/Off Mode Power Relationship 

Standby Level Power (W) Incremental Cost 

Baseline 1.4 $0 

1 0.7 $0.75 

Table 5.6.43 through Table 5.6.49 present DOE’s estimates of incremental cost in terms 

of MPC for improvement of room air conditioner CEER above the baseline. DOE updated this 

analysis from the preliminary analysis based on information collected during the final rule 

analysis phase. For the final rule analysis, DOE calculated the incremental costs for product 

classes 1, 3 (8,000Btu/h and 12,000Btu/h), 5A, 5B, 8A, and 8B. The incremental costs start at 

zero additional cost for the baseline R-410A unit. 

The tables also present the calculated shipping cost at each efficiency level, based on the 

shipping package size. The first level of each table reflects the calculated CEER of a unit with a 

baseline EER rating and a standby power consumption of 1.4 W. The cost for this level 

represents the estimated cost associated with regaining the current standard EER level with the 

new refrigerant. DOE calculated the costs for each CEER level based on appropriate selection of 

active mode and standby mode design options. In cases where the CEER efficiency level does 

not coincide with the CEER determined for the design configuration directly analyzed with 

energy and manufacturing cost modeling, DOE took the following approach. If the next design 

option could be partially applied, DOE interpolated between costs and CEER levels calculated 

for the nearest design configurations. This approach applied to heat exchanger or chassis size 

increases, PSC motor efficiency improvement, and addition of a subcooler. In cases where the 

next design option could not be partially applied, the full cost of the design option was applied. 

This approach applied to increase in the number of heat exchanger circuits, change in heat 

exchanger tube size, and switch to BLDC motor technology. 

Table 5.6.43 Room Air Conditioner Cost-Efficiency Relationships for Product Classes 1 

Product Class 1: Without Reverse Cycle, With Louvered Sides, < 6,000 Btu/h 

Efficiency 

Level 

CEER MPC Increase Shipping Costs 

Baseline 9.52 $0.00 $3.86 

1 10.1 $6.31 $4.68 

2 10.6 $13.53 $7.22 

3 11.1 $22.72 $8.39 

4 11.4 $32.32 $8.39 

5 12.7 $75.82 $8.39 

5-130 

 

 

 

 

Table 5.6.44 Room Air Conditioner Cost-Efficiency Relationship for Product Class 3 – 

8,000 Btu/h Capacity Unit 

Product Class 3 – 8,000 Btu/h: Without Reverse Cycle, With Louvered Sides, 

8,000 - 13,999 Btu/h 

Efficiency 

Level 

CEER MPC Increase Shipping Costs 

Baseline 9.69 $0.00 $6.32 

1 10.2 $5.30 $6.76 

2 10.7 $12.30 $9.11 

3 10.9 $15.95 $9.58 

4 11.5 $30.92 $10.91 

5 12.0 $103.87 $14.63 

Table 5.6.45 Room Air Conditioner Cost-Efficiency Relationship for Product Class 3 – 

12,000 Btu/h Capacity Unit 

Product Class 3 – 12,000 Btu/h: Without Reverse Cycle, With Louvered Sides, 

8,000 - 13,999 Btu/h 

Efficiency 

Level 

CEER MPC Increase Shipping Costs 

Baseline 9.72 $0.00 $10.33 

1 10.2 $2.00 $10.33 

2 10.7 $7.42 $10.33 

3 10.95 $9.33 $10.33 

4 11.5 $29.43 $10.33 

5 12.0 $47.81 $16.08 

Table 5.6.46 Room Air Conditioner Cost-Efficiency Relationships for Product Class 5A – 

24,000 Btu/h 

Product Class 5A: Without Reverse Cycle, With Louvered Sides,

 20,000 to 27,999 Btu/h 

Efficiency 

Level 

CEER MPC Increase Shipping Costs 

Baseline 8.47 $0.00 $24.79 

1 9.0 $8.85 $27.22 

2 9.4 $19.04 $27.22 

3 9.8 $50.66 $27.22 

4 10.15 $204.62 $27.22 

5-131 

 

 

 

 

 

 

Table 5.6.47 Room Air Conditioner Cost-Efficiency Relationships for Product Class 5B – 

28,000 Btu/h 

Product Class 5B: Without Reverse Cycle, With Louvered Sides, 

≥ 28,000 Btu/h 

Efficiency 

Level 

CEER MPC Increase Shipping Costs 

Baseline 8.48 $0.00 $29.75 

1 9.0 $23.52 $36.15 

2 9.4 $50.27 $36.46 

3 9.8 $229.01 $36.46 

Table 5.6.48 Room Air Conditioner Cost-Efficiency Relationship for Product Class 8A – 

8,000 Btu/h 

Product Class 8A – 8,000 Btu/h: Without Reverse Cycle, Without 

Louvered Sides, 8,000 – 10,999 Btu/h 

Efficiency 

Level 

CEER MPC Increase Shipping Costs 

Baseline 8.41 $0.00 $12.26 

1 9.3 $4.61 $12.26 

2 9.6 $6.68 $12.26 

3 10.0 $16.63 $12.26 

4 10.4 $88.45 $12.26 

Table 5.6.49 Room Air Conditioner Cost-Efficiency Relationship for Product Class 8B – 

12,000 Btu/h 

Product Class 8B – 12,000 Btu/h: Without Reverse Cycle, Without Louvered 

Sides, 

11,000 – 13,999 Btu/h 

Efficiency 

Level 

CEER MPC Increase Shipping Costs 

Baseline 8.44 $0.00 $12.26 

1 9.3 $11.72 $12.26 

2 9.5 $15.39 $12.26 

3 9.8 $26.06 $12.26 

4 10.0 $93.36 $12.26 

DOE used consolidated product class 3 results in the downstream analysis. The 

consolidated results are the average of results of the two product capacities examined. The 

incremental cost averages for product class 3 are shown in Table 5.6.50 below. 

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Table 5.6.50 Room Air Conditioner Cost-Efficiency Relationship for Product Class 3 – 

Average 

Product Class 3 – Average: Without Reverse Cycle, With Louvered Sides, 

8,000 – 13,999 Btu/h 

Efficiency 

Level 

CEER MPC Increase Shipping Costs 

Baseline 9.71 $1.25 $8.33 

1 10.2 $4.90 $8.55 

2 10.7 $11.11 $9.72 

3 10.9 $13.89 $9.95 

4 11.5 $31.43 $10.62 

5 12.0 $77.09 $15.36 

The incremental cost data for active mode design options are detailed further in appendix 

5D of this TSD. The appendix also provides incremental cost data for both the integrated metric 

(CEER) and non-integrated metric (EER). 

5.6.2.10 Product Class Modifications 

As discussed above, DOE is making changes to the existing product class structure for room air 

conditioners. During the preliminary phase, DOE proposed no changes to the existing product 

class structure. DOE received one comment addressing product classes during the preliminary 

analysis comment period from AHAM, and one comment after the end of the comment period 

titled, “Agreement on Minimum Federal Efficiency Standards, Smart Appliances, Federal 

Incentives and Related Matters for Specified Appliances” from a group of joint petitioners 

representing manufacturers, industry representatives, and efficiency and consumer advocates. 

This latter group is referred to as the Joint Petitioners. The comments were as follows: 

AHAM recommended that product class 5 be split into two product classes based on 

product cooling capacity, the first class including products with capacity from 20,000 

Btu/h to 24,999 Btu/h, and the second with capacity greater than 25,000 Btu/h. AHAM 

also recommended that product class 8 be split into two product classes, the first with 

capacity from 8,000 Btu/h to 10,999 Btu/h, and the second with capacity from 11,000 

Btu/h to 13,999 Btu/h. 

The Joint Petitioners also proposed splitting both product classes 5 and 8, but 

recommended splitting product class 5 at a different capacity than suggested by AHAM. 

This comment recommended a split at 28,000 Btu/h. 

Product Class 5 Modifications 

DOE based its considerations regarding the product class 5 split (room air conditioners 

without reverse cycle, with louvered sides, and capacity 20,000 Btu/h or more) on the following 

inputs: 

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Individual discussions with manufacturers
 

Research on available product sizes and available product efficiencies.
 

Reverse engineering of three product class 5 units, including a 28,500 Btu/h unit and two 

24,000 Btu/h units 

Engineering analysis of R-410A product class 5 baseline products at the 24,000 Btu/h and 

28,000 Btu/h capacity levels. 

DOE’s research indicates that efficiency drops off monotonically as capacity increases.. 

For current product class 5, the current standard requires a minimum energy efficiency ratio 

(EER)j

 of 8.5 Btu/h-W. DOE’s research found that no 2010 product of this class with a capacity 

higher than 28,000 Btu/h has an EER exceeding this minimum level, whereas products with 

lower capacity do exceed the minimum efficiency level. The trend for all room air conditioners 

with louvered sides without reverse cycle (current product classes 1, 2, 3, 4, and 5) is illustrated 

in Figure 5.6.48 below. 

8 

8.5 

9 

9.5 

10 

10.5 

11 

11.5 

12 

12.5 

0 5000 10000 15000 20000 25000 30000 35000 40000 

EER (Btu/hr/W) 

Capacity (Btu/hr) 

R-410A Louvered Units 

Max-Tech Trend Line 

Figure 5.6.48 R-410A Louvered Products – Efficiency versus Capacity 

DOE produced cost-efficiency curves for product class 5 products at both 24,000 Btu/h 

and 28,000 Btu/h capacity levels. Additional information of this analysis is available in chapter 5 

j

 Energy Efficiency Ratio (EER) is equal to the product’s cooling capacity, expressed in Btu/h, divided by the power 

input, in Watts (W). 

5-134 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

of this TSD. Table 5.6.51 shows the results of these analyses, which clearly show (1) much 

steeper increase in cost as the CEER increases and (2) significantly lower max tech for the larger 

capacity. 

Table 5.6.51 Comparison of 24,000 Btu/h and 28,000 Btu/h Incremental Costs 

Efficiency 

Level 

PC5A – 24,000 Btu/h PC5B – 28,000 Btu/h 

CEER Incremental Cost CEER Incremental Cost 

1 8.47 $0.00 8.48 $0.00 

2 9.0 $8.85 9.0 $23.52 

3 9.4 $19.04 9.4 $50.27 

4 9.8 $50.66 9.8 $229.01 

5 10.15 $204.62 - -

In addition, DOE’s analysis of the 28,000 Btu/h size shows that two growths in product size are 

needed to reach these efficiency levels, including one to a very large size; for the 24,000 Btu/h, 

only one growth was required to achieve the same level of efficiency. Despite the additional 

product growth, the 28,000 Btu/h product did not reach the same max-tech efficiency level as the 

24,000 Btu/h product. Additional information of this analysis is available in chapter 5 of this 

TSD. Table 5.6.52 shows the product sizes analyzed. 

Table 5.6.52 Size Increases Examined During Room Air Conditioner Design Option 

Analysis – Product Classes 5A and 5B 

Design Description 

Width 

(inches (in)) 

Height 

(in) 

Depth 

(in) 

Volume 

(cubic feet (cf)) 

Weight 

(lb) 

Product Class 5A 

Baseline 

First Size Increase

 Second Size Increase 

26 

27.75 

-

17.69 

17.94 

-

28.41 

30.94 

-

7.56 

8.91 

-

129.2 

136.4 

-

Product Class 5B 

Baseline 

First Size Increase

 Second Size Increase 

26 

27.75 

29.81 

17.69 

17.94 

22.38 

28.41 

30.94 

30.94 

7.56 

8.91 

11.94 

129.2 

136.4 

156.5 

This analysis demonstrates the much greater potential for efficiency improvement in products 

lower than 28,000 Btu/h. DOE’s decision to establish the new product classes 5A and 5B that 

take the place of the previous product class 5 is based on the stakeholder comments and DOE’s 

analysis. DOE believes that the new product classes are needed to ensure establishment of 

meaningful efficiency levels over the full range of capacities. 

Product Class 8 Modifications 

DOE considered the following inputs when considering whether to split product class 8 

(Non-louvered, non-reverse-cycle, capacity of 8,000 to 13,999 Btu/h): 

Individual discussions with manufacturers 

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Research on available product sizes and available product efficiencies. 

Reverse engineering of six product class 8 units, including three 8,000 Btu/h units and 

three 12,000 Btu/h units 

Engineering analysis of R-410A product class 8 baseline products at the 8,000 Btu/h and 

12,000 Btu/h capacity levels. 

The max tech EERs of available room air conditioners without louvered sides using R410A refrigerant are very dependent on capacity range. These products are designed to fit in 

sleeves installed in the building wall. Due to the heavy dependence of this market on 

replacement sales, as reported by manufacturers during interviews for the final rule analysis, 

there is little opportunity to adjust the physical size of the product. This is in distinct contrast to 

products with louvered sides, which are designed to fit in windows; this design allows more 

flexibility for size increase to improve efficiency. The max tech levels of non-louvered products 

are very dependent on the individual product’s capacity. Products with capacity greater than 

12,600 Btu/h are unable to meet the current ENERGY-STAR EER level. See Figure 5.6.49 for 

the results of DOE’s survey of non-louvered, non-reverse-cycle R-410 products, completed in 

May 2010. DOE further notes that ENERGY STAR products in the capacity range 11,500 to 

12,600 Btu/h require oversized sleeves. At a slightly higher capacity level, products cannot be 

designed to meet the DOE energy standard—the available data show that there are currently no 

available products having greater than 13,999 Btu/h capacity. During interviews, manufacturers 

reported that there is great technical difficulty in producing non-louvered products greater than 

15,000 Btu/h that would meet the DOE’s current efficiency standards. 

5-136
 
 

 

 

 

 

 

 

 

8 

8.2 

8.4 

8.6 

8.8 

9 

9.2 

9.4 

9.6 

9.8 

10 

5000 7000 9000 11000 13000 15000 

EER (Btu/h/W) 

Capacity (Btu/hr) 

R-410A Units 

DOE Minimum Federal Standard 

ENERGY-STAR Standard 

Figure 5.6.49 R-410A Products from DOE Survey of Non-louvered, Non-reverse-cycle 


Products
 

DOE produced cost-efficiency curves for non-louvered R-410A room air conditioners at 

8,000 Btu/h and 12,000 Btu/h capacities, shown in Table 5.6.53 below. Additional information 

of this analysis is available in chapter 5 of this TSD. As with the product class 5 analyses, the 

results of the analysis of product class 8 show the significantly steeper increase in cost as 

efficiency level is raised above the baseline and the reduced max tech level for the highercapacity product. 

Table 5.6.53 Comparison of 8,000 Btu/h and 12,000 Btu/h Incremental Costs 

Efficiency 

Level 

PC8A – 8,000 Btu/h PC8B – 12,000 Btu/h 

CEER Incremental Cost CEER Incremental Cost 

1 8.41 $0.00 8.44 $0.00 

2 9.3 $4.61 9.3 $11.72 

3 9.6 $6.68 9.5 $15.39 

4 10.0 $16.63 9.8 $26.06 

5 10.4 $88.45 10.0 $93.36 

This analysis demonstrates the much greater potential for efficiency improvement for the 

lower-capacity products. DOE’s decision to establish the new product classes 8A and 8B that 

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take the place of the current product class 8 is based on the stakeholder comments and DOE’s 

analysis. DOE believes that the new product classes are needed to ensure establishment of 

meaningful efficiency levels over the full range of capacities. 

5.6.2.11 Analysis Extension to All Product Classes 

The process of extending incremental cost data for room air conditioner product classes 

not directly analyzed is discussed in this section. The methodology for estimating the 

incremental costs associated with efficiency increases for these product classes is described 

below. 

During the preliminary analysis, DOE used interpolation and extrapolation methods, 

based on the IEER/CEER levels of the analyzed product classes, to estimate efficiency levels and 

incremental costs for the remaining product classes. DOE’s downstream analysis were 

constructed just for the directly analyzed product classes. The other product classes have been 

assigned to each of the full analysis, based on determination of which of the fully-analyzed 

classes provided the best representation of life cycle costs. DOE used the criteria described in 

Table 5.6.54 below to establish the final product groupings. 

Table 5.6.54 Product Class Grouping Criteria 

Criterion Description 

Energy Use Grouping of product classes with similar capacity and estimated operating 

hours. Table 5.6.55 provides a summary of representative capacities and 

operating hours by product class. 

Ability to reach 

high efficiencies 

Some product classes have limited potential for efficiency increase. Product 

classes without louvered sides, high-capacity products, and casement-slider 

or casement-only have limited potential for physical size increase, thus they 

also have reduced potential for efficiency improvement. 

Extrapolated costefficiency curve During the preliminary analysis, DOE estimated cost-efficiency curves for 

the non-analyzed product classes (see the preliminary TSD, chapter 5, 

section 5.6.2.7) DOE compared these extrapolated curves to the final rule 

results for the fully analyzed product classes to assist in selecting product 

class groups. DOE ranked each analyzed product class, in order of cost 

efficiency, to assist in this analysis. 

Capacity and energy use characteristics for each product class are listed in Table 5.6.55 

below. DOE used this information to assist in the grouping of product classes. 

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Table 5.6.55 Room Air Conditioner Representative Capacities and Operating Hours 

Product 

Class 

Description Representative 

Capacity 

(Btu/h) 

Estimated 

Operating 

Hours 

With Louvers, Without Reverse Cycle 

1 < 6,000 Btu/h 5000 1281 

2 6,000 to 7,999 Btu/h 6000 913 

3 8,000 to 13,999 Btu/h 10,000 545 

4 14,000 to 19,999 Btu/h 18,000 438 

5A 20,000 to 27,999 Btu/h 24,000 331 

5B > 28,000 Btu/h 28,000 331 

Without Louvers, Without Reverse Cycle 

6 < 6,000 Btu/h 5,000 1281 

7 6,000 to 7,999 Btu/h 6,000 913 

8A 8,000 to 10,999 Btu/h 8,000 545 

8B 11,000 to 13,999 Btu/h 12,000 545 

9 14,000 to 20,000 Btu/h 14,000 438 

10 > 20,000 Btu/h 20,000 331 

With Louvers, With Reverse Cycle 

11 < 20,000 Btu/h 12,000 545 

13 > 20,000 Btu/h 14,000 331 

Without Louvers, With Reverse Cycle 

12 < 14,000 Btu/h 10,000 545 

14 > 14,000 Btu/h 14,000 438 

Casement 

15 Casement-only 10,000 545 

16 Casement-slider 10,000 545 

The final product class groupings are presented in Table 5.6.56 below. These groupings 

were used in the subsequent LCC analysis. 

Table 5.6.56 Room Air Conditioner Product Class Groupings 

Group Analyzed Product 

Class 

Extrapolated Product 

Classes 

1 1 -

2 3 2,4,11 

3 5A 12 

4 5B 10 

5 8A 6,7,13,15,16 

6 8B 9,14 

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REFERENCES 

1 T Richter. 2005. Op. cit. 

2 D.R. Tree, V.W. Goldschmidt, R.W. Garrett, and E. Kach. 1978. “Effect of Water Sprays on 

Heat Transfer of a Fin and Tube Heat Exchanger.” Sixth International Heat Transfer 

Conference. Vol. 4, pp. 339–44. 

3 Kao, J. “Energy Test Results of a Conventional Clothes Dryer and a Condenser Clothes 

Dryer,” National Institute of Standards and Technology, Gaithersburg, MD, 1998. 

4 For information on American Metals Market, please visit: www.amm.com. 

5 U.S. Department of Energy–Office of Energy Efficiency and Renewable Energy. Technical 

Support Document for Energy Conservation Standards for Room Air Conditioners: 

September 1997. Washington, D.C. Available at: 

www.eere.energy.gov/buildings/appliance_standards/residential/room_ac.html 

6 2008 ASHRAE Handbook: Fundamentals. ASHRAE, Atlanta, GA 2008. 

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