CHAPTER 5. ENGINEERING ANALYSIS 

TABLE OF CONTENTS 

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


5.2	 TECHNOLOGIES UNABLE TO BE INCLUDED IN THE PRELIMINARY 


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 Variable Speed Compressors ......................................................................... 5-4 


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


5.2.2.8 Thermostatic Cyclic Controls ........................................................................ 5-4 


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 ...................................................................... 5-10 


5.4.1.3 Integrated Efficiency .................................................................................... 5-14 


5.4.2 	 Incremental Efficiency and Standby Levels .................................................................. 5-15 


5.4.2.1 Active Mode................................................................................................. 5-15 


5.4.2.2 Standby Mode and Off Mode ...................................................................... 5-18 


5.4.2.3 Integrated Efficiency .................................................................................... 5-19 


5.5	 METHODOLOGY OVERVIEW .................................................................................. 5-21 


5.5.1 	 AHAM Data Request..................................................................................................... 5-22 


5.5.2 	Manufacturer Interviews................................................................................................ 5-22 


5.5.3 	Product Teardowns ........................................................................................................ 5-23 


5.5.3.1 Generation of Bill of Materials .................................................................... 5-23 


5.5.3.2 Cost Structure of the Spreadsheet Models ................................................... 5-24 


5.5.3.3 Cost Model and Definitions......................................................................... 5-25 


5.5.3.4 Cost Model Assumptions............................................................................. 5-26 


5.5.4 	 Review of Previous Technical Support Documents and Models................................... 5-27 


5.5.5 	Product Testing .............................................................................................................. 5-27 


5.6	 ANALYSIS AND RESULTS........................................................................................ 5-27 


5.6.1 	Clothes Dryers ............................................................................................................... 5-27 


5.6.1.1 AHAM Data................................................................................................. 5-27 


5.6.1.2 Product Testing ............................................................................................ 5-32 


5.6.1.3 Product Teardown........................................................................................ 5-44 


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5.6.1.4 Cost-Efficiency Curves ................................................................................ 5-60 


5.6.1.5 Manufacturer Interviews.............................................................................. 5-68 


5.6.2 Room Air Conditioners.................................................................................................. 5-73 


5.6.2.1 AHAM Data................................................................................................. 5-73 


5.6.2.2 Manufacturer Interviews.............................................................................. 5-74 


5.6.2.3 Product Teardowns ...................................................................................... 5-76 


5.6.2.4 Energy Modeling ......................................................................................... 5-79 


5.6.2.5 Energy Testing............................................................................................. 5-82 


5.6.2.6 R-410A Conversion Costs ........................................................................... 5-82 


5.6.2.7 Cost-Efficiency Curves ................................................................................ 5-84 


LIST OF TABLES 

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

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 Room Air Conditioner Baseline Active Mode Unit Efficiencies ........................... 5-10
 

Table 5.4.3 Clothes Dryer Standby and Off Mode Power Input Measurements ....................... 5-13
 

Table 5.4.4 Room Air Conditioner Standby and Off Mode Power Input Measurements ......... 5-14
 

Table 5.4.5 Baseline Clothes Dryer IEF .................................................................................... 5-15
 

Table 5.4.6 Baseline Room Air Conditioner IEER for Analyzed Product Classes ................... 5-15
 

Table 5.4.7 Vented Clothes Dryer Active Mode Efficiency Levels .......................................... 5-16
 

Table 5.4.8 Vent-less Clothes Dryer Active Mode Efficiency Levels ...................................... 5-17
 

Table 5.4.9 Room Air Conditioner Active Mode Efficiency Levels--Product Classes 1 


and 3................................................................................................................... 5-18
 

Table 5.4.10 Room Air Conditioner Active Mode Efficiency Levels--Product Classes 5 


and 8................................................................................................................... 5-18
 

Table 5.4.11 Clothes Dryer Standby Power Levels................................................................... 5-19
 

Table 5.4.12 Room Air Conditioner Standby Power Levels ..................................................... 5-19
 

Table 5.4.13 Clothes Dryer Integrated Efficiency Levels (IEF) – Vented Product Classes...... 5-20
 

Table 5.4.14 Clothes Dryer Integrated Efficiency Levels (IEF) – Vent-less Electric 


Compact (240V)................................................................................................. 5-20
 

Table 5.4.15 Clothes Dryer Integrated Efficiency Levels (IEF) – Vent-less Electric 


Combination Washer/Dryers ............................................................................. 5-20
 

Table 5.4.16 Room Air Conditioner Integrated Efficiency Levels (IEER)--Product 


Classes 1 and 3................................................................................................... 5-21
 

Table 5.4.17 Room Air Conditioner Integrated Efficiency Levels (IEER)--Product 


Classes 5 and 8................................................................................................... 5-21
 

Table 5.5.1 Engineering Analysis Methods............................................................................... 5-22
 

Table 5.5.2 Major Manufacturing Processes ............................................................................. 5-25
 

Table 5.6.1 AHAM Clothes Dryer Market Share Data Submittal............................................. 5-28
 

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


Submittal............................................................................................................ 5-28
 

Table 5.6.3 AHAM Clothes Dryer Incremental Cost Data Submittal ....................................... 5-29
 

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EERE-2007-BT-STD-0010 COMMENT 20.3
Table 5.6.4 AHAM Shipment-Weighted Clothes Washer RMC Data Submittal...................... 5-32
 

Table 5.6.5 Vented Electric Standard Clothes Dryer Test Unit Features .................................. 5-33
 

Table 5.6.6 Vented Electric Compact (240 V), Gas, and Vent-less Clothes Dryer Test 


Unit Features...................................................................................................... 5-34
 

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

Table 5.6.8 Results from DOE Testing of Maximum Available Vented Gas Clothes Dryer.... 5-44
 

Table 5.6.9 Vented Electric Standard Clothes Dryer Incremental Manufacturing Costs.......... 5-61
 

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

Costs................................................................................................................... 5-62
 

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

Cost .................................................................................................................... 5-63
 

Table 5.6.12 Vented Gas Clothes Dryer Incremental Manufacturing Cost............................... 5-64
 

Table 5.6.13 Vent-less Electric Compact (240V) Clothes Dryer Incremental
 

Manufacturing Cost ........................................................................................... 5-65
 

Table 5.6.14 Vent-less Electric Combination Washer/Dryer Incremental Manufacturing
 

Cost .................................................................................................................... 5-66
 

Table 5.6.15 Standby Power Incremental Manufacturing Cost................................................. 5-66
 

Table 5.6.16 Cost-Efficiency Relationship for Vented Electric Standard Clothes Dryers ........ 5-67
 

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


Dryers ................................................................................................................. 5-67
 

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


Dryers ................................................................................................................. 5-67
 

Table 5.6.19 Cost-Efficiency Relationship for Vented Gas Clothes Dryers ............................. 5-68
 

Table 5.6.20 Cost-Efficiency Relationship for Vent-less Electric Compact (240V) 


Clothes Dryers ................................................................................................... 5-68
 

Table 5.6.21 Cost-Efficiency Relationship for Vent-less Electric Combination 


Washer/Dryers ................................................................................................... 5-68
 

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


Product Classes 1 Through 5 ............................................................................. 5-73
 

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


Product Classes 6 through 16............................................................................. 5-73
 

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


Submittal: Product Classes 1 through 5 ............................................................. 5-74
 

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


Submittal: Product Classes 6 through 16 ........................................................... 5-74
 

Table 5.6.26 Manufacturing Cost Increase for Drop-In Conversion to R-410A ....................... 5-84
 

Table 5.6.27 Retained Design Options for Room Air Conditioners.......................................... 5-84
 

Table 5.6.28 Size Increases Examined During Room Air Conditioner Design Option 


Analysis.............................................................................................................. 5-86
 

Table 5.6.29 Sizes and Weights of Teardown Units for Product Classes 1, 3, and 5................ 5-87
 

Table 5.6.30 Microchannel Condenser Costs ............................................................................ 5-89
 

Table 5.6.31 Motor Power Rating by Product Capacity............................................................ 5-90
 

Table 5.6.32 Comparison of a typical range of sizes for a 70W PSC Double-Shafted 


Motor and a 70W BLDC Motor......................................................................... 5-92
 

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Table 5.6.33 Size and Weight of Applicable Rotary and Scroll Compressors for a 24,000 

Btu/h Room Air Conditioner ............................................................................. 5-95
 

Table 5.6.34 Standby Energy Consumption by Component...................................................... 5-96
 

Table 5.6.35 Room Air Conditioner Cost-Standby/Off Mode Power Relationship................ 5-104
 

Table 5.6.36 Room Air Conditioner Cost-Efficiency Relationships for Product Classes 1 .... 5-105
 

Table 5.6.37 Room Air Conditioner Cost-Efficiency Relationship for Product Class 3 –
 

8,000 Btu/h Capacity Unit ............................................................................... 5-105
 

Table 5.6.38 Room Air Conditioner Cost-Efficiency Relationship for Product Class 3 –
 

12,000 Btu/h Capacity Unit ............................................................................. 5-105
 

Table 5.6.39 Room Air Conditioner Cost-Efficiency Relationships for Product Class 5 ....... 5-106
 

Table 5.6.40 Room Air Conditioner Cost-Efficiency Relationship for Product Class 8 –
 

8,000 Btu/h ....................................................................................................... 5-106
 

Table 5.6.41 Room Air Conditioner Cost-Efficiency Relationship for Product Class 8 –
 

12,000 Btu/h ..................................................................................................... 5-106
 

Table 5.6.42 Room Air Conditioner Cost-Efficiency Relationship for Product Class 3 –
 

Average ............................................................................................................ 5-107
 

Table 5.6.43 Room Air Conditioner Cost-Efficiency Relationship for Product Class 8 –
 

Average ............................................................................................................ 5-107
 

Table 5.6.44 EER Efficiency Levels for Product Classes 2, 4, 6, 7 ........................................ 5-108
 

Table 5.6.45 EER Efficiency Levels for Product Classes 9, 10, 11, 13 .................................. 5-108
 

Table 5.6.46 EER Efficiency Levels for Product Classes 12, 14, 15, 16 ................................ 5-108
 

Table 5.6.47 IEER Efficiency Levels for Product Classes 2, 4, 6, 7 ....................................... 5-109
 

Table 5.6.48 IEER Efficiency Levels for Product Classes 9, 10, 11, 13 ................................. 5-109
 

Table 5.6.49 IEER Efficiency Levels for Product Classes 12, 14, 15, 16 ............................... 5-110
 

Table 5.6.50 Representative Capacities for Room Air Conditioner Product Classes .............. 5-110
 

Table 5.6.51 Extrapolated Incremental Cost Data for Product Classes 2, 4, 6, and 7 ............. 5-111
 

Table 5.6.52 Extrapolated Incremental Cost Data for Product Classes 9, 10, 11, 13.............. 5-111
 

Table 5.6.53 Extrapolated Incremental Cost Data for Product Classes 12, 14, 15, 16............ 5-111
 

LIST OF FIGURES 

Figure 5.5.1 Manufacturing Cost Assessment Stages................................................................ 5-24 


Figure 5.6.1 AHAM Clothes Dryer Cost-Efficiency Curves..................................................... 5-30 


Figure 5.6.2 AHAM Data Submittal for Impact of Initial RMC on Clothes Dryer EF ............. 5-31 


Figure 5.6.3 Measured Clothes Dryer Cycle Time versus Rated EF......................................... 5-37 


Figure 5.6.4 Measured Clothes Dryer Energy Consumption versus Rated EF ......................... 5-38 


Figure 5.6.5 Measured versus Rated Clothes Dryer EF............................................................. 5-39 


Figure 5.6.6 Disaggregated Clothes Dryer Power Consumption ............................................... 5-40 


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


Existing DOE Test Procedure)........................................................................... 5-42 


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


Scaling Factors) ................................................................................................. 5-43 


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Figure 5.6.9 Baseline Vented Electric Standard Clothes Dryer Full Production Cost 

Distribution ........................................................................................................ 5-47 


Figure 5.6.10 Baseline Vented Electric Standard Clothes Dryer Materials Cost 


Distribution ........................................................................................................ 5-48 


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


Cost Distribution................................................................................................ 5-49 


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


Distribution ........................................................................................................ 5-50 


Figure 5.6.13 Baseline Vented Gas Clothes Dryer Full Production Cost Distribution ............. 5-51 


Figure 5.6.14 Baseline Vented Gas Clothes Dryer Materials Cost Distribution ....................... 5-52 


Figure 5.6.15 Baseline Vent-less Electric Compact (240V) Clothes Dryer Full Production 


Cost Distribution................................................................................................ 5-53 


Figure 5.6.16 Baseline Vent-less Electric Compact (240V) Clothes Dryer Materials Cost 


Distribution ........................................................................................................ 5-54 


Figure 5.6.17 Baseline Vent-less Combination Washer/Dryer Full Production Cost 


Distribution ........................................................................................................ 5-55 


Figure 5.6.18 Baseline Vent-less Combination Washer/Dryer Materials Cost Distribution..... 5-56 


Figure 5.6.19 Vented Electric Standard Clothes Dryer Cost-Efficiency Curves....................... 5-61 


Figure 5.6.20 Vented Electric Compact (120V) Clothes Dryer Cost-Efficiency Curve ........... 5-62 


Figure 5.6.21 Vented Electric Compact (240V) Clothes Dryer Cost-Efficiency Curve ........... 5-63 


Figure 5.6.22 Vented Gas Clothes Dryer Cost-Efficiency Curves ............................................ 5-64 


Figure 5.6.23 Vent-less Electric Compact (240V) Clothes Dryer Cost-Efficiency Curve........ 5-65 


Figure 5.6.24 Vent-less Electric Combination Washer/Dryer Cost-Efficiency Curves ............ 5-66 


Figure 5.6.25 Efficiency Range of Room Air Conditioner Teardowns..................................... 5-76 


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


Material Cost Distribution ($157 total).............................................................. 5-78 


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


Full Production Cost Distribution ($195 total) .................................................. 5-79 


Figure 5.6.28 Comparison of Energy Modeling Results with Rated Air Conditioner 


Performance ....................................................................................................... 5-81 


Figure 5.6.29 Energy Modeling Results for R-410A Drop-In................................................... 5-81 


Figure 5.6.30 Room Air Conditioner Energy Test Results........................................................ 5-82 


Figure 5.6.31 Size Distributions of Baseline-Efficiency Room Air Conditioners .................... 5-86 


Figure 5.6.32 Cost Differential for Increasing PSC Motor Efficiency from 50% to 70% ........ 5-91 


Figure 5.6.33. Cost Differential for Replacing a Baseline PSC Motor with a BLDC 


Motor.................................................................................................................. 5-92 


Figure 5.6.34 Compressor Performance Data............................................................................ 5-94 


Figure 5.6.35 R-410A Compressor Cost.................................................................................... 5-95 


Figure 5.6.36 Product Class 1 Cost-Efficiency Curve............................................................... 5-98 


Figure 5.6.37 Product Class 3 - 8,000 Btu/h Capacity Cost-Efficiency Curve ......................... 5-99 


Figure 5.6.38 Product Class 3 - 12,000 Btu/h Capacity Cost-Efficiency Curve ..................... 5-100 


Figure 5.6.39 Product Class 5 Cost-Efficiency Curve............................................................. 5-101 


Figure 5.6.40 Product Class 8 - 8,000 Btu/h Capacity Cost-Efficiency Curve ....................... 5-102 


Figure 5.6.41 Product Class 8 - 12,000 Btu/h Capacity Cost-Efficiency Curve ..................... 5-103 


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EERE-2007-BT-STD-0010 COMMENT 20.3
Figure 5.6.42 Comparison of the Cost-Effectiveness of Active and Standby Mode Design
 

Options ............................................................................................................. 5-104 


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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 analyzed for this rulemaking (section 5.2), discusses proposed 

product classes (section 5.3), establishes baseline unit specification (section 5.4.1), discusses 

incremental efficiency levels (section 5.4.1.2), explains the methodology used during data 

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

engineering analysis for residential clothes dryers and room air conditioners. 

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

and technology assessment (Chapter 3 of the preliminary technical support document 

(preliminary TSD)) and technology options from 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 

energy-use and end-use load characterization (Chapter 6) and the life-cycle cost (LCC) and 

payback period (PBP) analyses (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 PRELIMINARY 

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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EERE-2007-BT-STD-0010 COMMENT 20.3
 

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 measured1

. 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 scaling 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 credited by the test procedure. DOE is currently 

conducting a clothes dryer test procedure rulemaking in which this issue, among others, is being 

considered. If test procedure amendments addressing an improved means of addressing cycle 

termination become available in time to be considered in this rulemaking, DOE will do so at that 

time. For this preliminary analysis, however, DOE will not further analyze improved 

termination. 

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EERE-2007-BT-STD-0010 COMMENT 20.3
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 

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. Hence, DOE did not further analyze this technology. 

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EERE-2007-BT-STD-0010 COMMENT 20.3
 

 

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 Variable Speed Compressors 

Variable speed 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, the speed of 

a variable-speed compressor would remain constant during the test. If the compressor maintains 

constant speed, there is no opportunity for the compressor to increase the measured energy 

efficiency ratio (EER) because the power input and work output are constant. In fact, the losses 

associated with the inverter board would decrease the maximum-capacity 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. 

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. 

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EERE-2007-BT-STD-0010 COMMENT 20.3
 

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 vent-less dryers, as shown in Table 5.3.1. This is a new analytical structure 

for clothes dryers, recognizing the unique utility that vent-less clothes dryers offer to consumers. 

(Previously, DOE has described vent-less dryers as condensing dryers. The new designation 

reflects the actual consumer utility (i.e., no external vent required) and the potential market 

availability of vented 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 spaceconstrained environments (e.g., apartments, recreational vehicles), and all products of this type 

appear to utilize vent-less operation. Thus, like other vent-less dryers, such combination 

washer/dryers can be installed in locations where venting dryers would be precluded due to 

venting restrictions. Although the DOE clothes dryer test procedure does not currently contain 

provisions for testing vent-less units, DOE has initiated a separate test procedure rulemaking 

concurrent with this rulemaking to address active mode test procedures for clothes dryers and 

room air conditioners, including potential amendments to allow for the measurement of vent-less 

clothes dryers. As part of this rulemaking, DOE will consider methodology proposed in an 

alternate test procedure for condenser clothes dryers in LG Electronics, Inc.’s (LG’s) Petition for 

Waiver and Denial of the Application for Interim Waiver, as well as other methodologies 

suggested by interested parties (see chapter 3). DOE expects that test procedure amendments to 

incorporate such provisions would be completed in time to be available for this energy 

conservation standards rulemaking, thus allowing consideration of vent-less product classes. 

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 

Vent-less 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 

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EERE-2007-BT-STD-0010 COMMENT 20.3
 

 

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

were applicable to units designed for single- or double-hung window installation or through-thewall 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). 

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

 Table 5.3.2 lists the existing 16 product classes for room air conditioners. 

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. The first three of these product classes span the range of capacities 

of room air conditioners without reverse cycle and with louvered sides. The fourth product class 

is the intermediate-capacity product class for room air-conditioners without reverse cycle and 

without louvered sides. DOE then extended this analysis numerically to the remaining 12 product 

classes. 

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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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 

5. 20,000 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 

8. 8,000 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 life-cycle-cost and 

payback-period analysis. To determine energy savings and changes in price, DOE compared 

each higher-energy-efficiency or lower-energy-efficiency design option with the baseline unit. 

As discussed in chapter 3 of this preliminary TSD, section 310 of the Energy 

Independence and Security Act of 2007 (EISA 2007), Pub. L. 110-140, amended section 325 of 

EPCA to require that the test procedures for clothes dryers and room air conditioners be 

amended to include measurement of standby mode and off mode power, taking into 

consideration the most current versions of Standards 62301 and 62087 of the International 

Electrotechnical Commission (IEC). EPCA, as amended by EISA 2007, also required that any 

final rule establishing or revising a standard for a covered product, adopted after July 1, 2010, 

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EERE-2007-BT-STD-0010 COMMENT 20.3
 

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)) DOE initiated a test 

procedure rulemaking to modify the test procedures for clothes dryers and room air conditioners 

to provide procedures for measurement of standby and off energy use. DOE published a notice of 

proposed rulemaking (NOPR) for this rule on December 9, 2008 (December 2008 NOPR). The 

December 2008 NOPR proposed new integrated metrics for residential clothes dryers and room 

air conditioners, the integrated energy factor (IEF) and the integrated energy efficiency ratio 

(IEER), which integrate standby and off mode energy use with active mode energy use. 72 FR 

74639. DOE has not yet published a final rule for the test procedures, but expects that the energy 

conservation standards for clothes dryers and room air conditioners will be based on integrated 

metrics (IEF and IEER), although the final definition of these metrics is still to be 

determined..For the purpose of the engineering analysis, DOE has analyzed the cost-efficiency 

relationship for IEF and IEER using the alternative definitions for these metrics in the December 

2008 NOPR, which integrate only “inactive mode” energy use with active mode energy use.b 

Subsequent analyses, such as the LCC and PBP analyses, and the national impact analysis (NIA) 

also are based on the integrated metrics. 

Test data based on the integrated metrics IEF and IEER, defined in the December 2008 

NOPR, are not available for any products. As a result, the definition of baseline units using these 

metrics is based on 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 EF in pounds (lb) per kilowatt-hour (kWh), became effective on May 14, 1994. 

Table 5.4.1 sets forth the standards for the four vented clothes dryer product classes. (10 Code of 

Federal Regulations (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 vent-less dryers based upon testing it conducted 

on representative units, using the DOE clothes dryer test procedure without the exhaust 

simulator, as described in section 5.3 (and, in more detail, chapter 3 of this preliminary TSD). 

b DOE proposed in the December 2008 NOPR to define “inactive mode” as a standby mode other than delay start 

mode or cycle finished mode (for clothes dryers) or off-cycle mode (for room air conditioners) that facilitates the 

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

continuous status display. 

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EERE-2007-BT-STD-0010 COMMENT 20.3
 

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 

Vent-less dryers 

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

6. Electric, Combination Washer/Dryer 1.95* 

* Because there are no current energy conservation standards for these product classes, DOE estimated the baseline 

values on results of tests it conducted on representative units. 

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 5.4.2 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. As mentioned in section 5.3, 

DOE analyzed only product classes 1, 3, and 5 (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; and 20,000 

Btu/h or more) and subsequently extended the analysis numerically to the other product classes. 

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Table 5.4.2 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 

5. 20,000 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 

8. 8,000 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 

5.4.1.2 Standby Mode and Off Mode 

In the December 2008 NOPR, DOE proposed clothes dryer and room air conditioner test 

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

“active mode,” “standby mode,” and “off mode” are defined according to the EISA 2007 

amendments to EPCA. 73 FR 74645. 

EPCA defines “active mode” as “the condition in which an energy-using product – 

(I) is connected to a main power source; 

(II) has been activated; and 

(III) provides 1 or more main functions.” 

(42 U.S.C. 6295(gg)(1)(A)(i)) 

EPCA defines “standby mode” as “the condition in which an energy-using product – 

(I) is connected to a main power source; and 

(II) offers 1 or more of the following user-oriented or protective functions: 

(aa) To facilitate the activation or deactivation of other functions (including active 

mode) by remote switch (including remote control), internal sensor, or timer. 

(bb) Continuous functions, including information or status displays (including 

clocks) or sensor-based functions.” 

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EERE-2007-BT-STD-0010 COMMENT 20.3
 

 

 

 

 

(42 U.S.C. 6295(gg)(1)(A)(iii)) 

EPCA defines “off mode” as “the condition in which an energy-using product – 

(I) is connected to a main power source; and 

(II) is not providing any standby mode or active mode function.” c 

(42 U.S.C. 6295(gg)(1)(A)(ii)) 

In addition, DOE proposed that if power consumption drops from a higher-power 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. 73 FR 74645, 74656, 74658. 

DOE determined after the December 2008 NOPR was published that it would continue 

the clothes dryer and room air conditioner test procedure rulemaking to allow for consideration 

of a revised version of IEC Standard 62301, which at that time was expected in July 2009. DOE 

anticipated, based on review of drafts of the updated IEC Standard 62301, that the revisions 

could include different mode definitions. DOE expected to publish a supplemental NOPR 

(SNOPR) for the test procedure rulemaking in which the new mode definitions are considered. 

However, more recently, DOE received information that the revised IEC Standard 62301 would 

not be available until mid-2010. Therefore, these preliminary analyses for the clothes dryer and 

room air conditioner energy conservation standards rulemaking are based on the amendments for 

standby and off mode power measurement that were proposed in the December 2008 NOPR. 

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 5.4.3 below. The compact (240 V) vent-less 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. 

c

 DOE notes that some features that provide consumer utility, such as displays and remote controls, are associated 

with standby mode and not off mode. A clothes dryer or room air conditioner is considered to be in “off mode” if it 

is plugged in to a main power source, is not being used for an active function such as drying clothing or providing 

cooling, and is consuming power for features other than a display, controls (including a remote control), or sensors 

required to reactivate it from a low power state. For example, a clothes dryer with electromechanical controls and no 

display or continuously-energized moisture sensor, but that consumed power for components such as a power supply 

when the unit was not activated, would be considered to be in off mode when not providing an active function. For 

room air conditioners, a unit with electromechanical controls and no display or remote control but with a power 

supply which is consuming energy, for example, could be considered to be in off mode while not providing an active 

function. 

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EERE-2007-BT-STD-0010 COMMENT 20.3
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 

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 5.4.3 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 

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EERE-2007-BT-STD-0010 COMMENT 20.3
 

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 

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 5.4.3 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 

Vent-less 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 5.4.4 below. Note that products with electronic controls were 

capable of operation in inactive mode, as defined in the December 2008 NOPR, 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. 

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Table 5.4.4 Room Air Conditioner Standby and Off Mode Power Input Measurements 

Product 

Class 

Capacity 

(Btu/h) 

EER 

(Btu/h-W) Control Type 

Power Input (W) 

Inactive 

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 

DOE based its preliminary analysis for residential clothes dryers on the IEF metric 

proposed as an alternative option in the December 2008 NOPR. Baseline IEF levels were 

determined from the baseline EF and standby energy use as discussed in sections 5.4.1.1 and 

5.4.1.2. 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 “inactive mode” per-cycle 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 5.4.1.2 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 inactive 

mode. DOE notes that it is considering amendments to the number of clothes dryer cycles in a 

year in a separate concurrent test procedure rulemaking to address active mode test procedures 

for clothes dryers (as distinct from the rulemaking DOE is also currently conducting to consider 

revisions to the clothes dryer and room air conditioner test procedures for measuring standby 

mode and off mode energy use). These amendments would affect the calculated per-cycle energy 

consumption associated with inactive mode and the calculated IEF. If test procedure 

amendments addressing the number of clothes dryer cycles per year become available in time to 

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EERE-2007-BT-STD-0010 COMMENT 20.3
 

be considered in this rulemaking, DOE will do so at that time. Table 5.4.5 shows the baseline 

IEF for each residential clothes dryer product class. 

Table 5.4.5 Baseline Clothes Dryer IEF 

Product Class EF 

(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 

Vent-less 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 

DOE based its preliminary analysis for room air conditioners on the IEER metric 

proposed as an alternative option in the December 2008 NOPR. Baseline IEER levels were 

determined from the baseline EER and standby energy use as discussed in sections 5.4.1.1 and 

5.4.1.2. The IEER is calculated as capacity times active mode hours (equal to 750) divided by the 

sum of active mode annual energy use and inactive mode, as defined above, annual energy use. 

This is the standby mode measured under the discussion in section 5.4.1.2 above. The number of 

hours associated with this standby mode for room air conditioners is 5,115 hours per year. 

Because IEER 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 analyses, the baseline IEERs are as indicated in Table 5.4.6 below. 

Table 5.4.6 Baseline Room Air Conditioner IEER for Analyzed Product Classes 

Product Class Capacity 

(Btu/h) 

EER 

(Btu/h-W) 

Standby Power 

(W) 

IEER 

(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 

5 24,000 8.5 1.4 8.47 

8 8,000 8.5 1.4 8.41 

8 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 5.4.7 through 

Table 5.4.10 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 

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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 vent-less clothes dryers, the maximum levels identified in Table 5.4.7 and 

Table 5.4.8 are based on available research and product literature on heat pump clothes dryers as 

well as discussions with manufacturers. 

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 5.4.7. 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 framework document and for which 

AHAM submitted aggregated incremental manufacturing cost data. 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 5.6.1.2, DOE testing of the “maximum-available” gas clothes dryer 

determined that this unit did not achieve the rated efficiency. For these reasons, DOE is 

proposing 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 maxtech 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. 

Table 5.4.7 Vented Clothes Dryer Active Mode Efficiency Levels 

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 3.4 3.54* 3.2 3.02 (maxtech) 

4 Max-Tech 4.51 4.70* 4.35 

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

For vent-less clothes dryers, DOE considered three efficiency levels above the baseline 

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

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vent-less 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 (240 V) vented clothes dryers (EF = 

2.90) to obtain an EF of 2.39 for electric compact (240 V) vent-less clothes dryers. A gap-fill 

level for EL 2 was derived based upon NIST test data. For vent-less 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 3d for electric standard 

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

max-tech for both vent-less 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. 

Table 5.4.8 Vent-less Clothes Dryer Active Mode Efficiency Levels 

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.2 

For room air conditioners, DOE considered varying numbers of efficiency levels, 

depending on the product class, as indicated in Table 5.4.9 and Table 5.4.10 below. These levels 

were determined 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. 

d

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

combination washer/dryers. 

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Table 5.4.9 Room Air Conditioner Active Mode Efficiency Levels--Product Classes 1 and 3 

Level Efficiency Level 

Description 

EER (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 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. 

Table 5.4.10 Room Air Conditioner Active Mode Efficiency Levels--Product Classes 5 and 

8 

Level Efficiency Level 

Description 

EER (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 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. 

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 5.4.11, are believed to be the same for all clothes dryer product classes. 

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Table 5.4.11 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 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 

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 

5.4.12 below. 

Table 5.4.12 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 

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, multiple 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 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 shown in Table 

5.4.13 through Table 5.4.15. 

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Table 5.4.13 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 

Table 5.4.14 Clothes Dryer Integrated Efficiency Levels (IEF) – Vent-less 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 5.4.15 Clothes Dryer Integrated Efficiency Levels (IEF) – Vent-less 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 

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 discussed in section 5.4.2.1 as 

closely as was feasible. The selected levels are summarized in Table 5.4.16 and Table 5.4.17 

below. 

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Table 5.4.16 Room Air Conditioner Integrated Efficiency Levels (IEER)--Product Classes 1 

and 3 

Level 

IEER (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 10.3 

2 10.6 10.8 

3 11.1 11.3 

4 11.6 11.5 

5 12.0 

Table 5.4.17 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 

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 

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. 

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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 analyses 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 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. 

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 

product efficiency, and their associated manufacturing costs. Sample questions asked during 

interviews are contained in appendix 5C. 

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EERE-2007-BT-STD-0010 COMMENT 20.3
 

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. 

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 

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EERE-2007-BT-STD-0010 COMMENT 20.3
 

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.3

 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 Manufacturing Cost Assessment StagesFigure 5.5.1 

shows the three major steps in generating the manufacturing cost. 

Figure 5.5.1 Manufacturing Cost Assessment Stages 

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EERE-2007-BT-STD-0010 COMMENT 20.3
 

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. For this 

analysis, $24.00 per hour was used as the average fully-burdened labor rate based on typical 

annual wages and benefits of industry employees. 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. 

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: 

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EERE-2007-BT-STD-0010 COMMENT 20.3
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.
 

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 

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EERE-2007-BT-STD-0010 COMMENT 20.3
 

 

 

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 vent-less 

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. 

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 EF ranges for electric standard and gas clothes dryer 

shipments in the years 2005 and 2006. AHAM noted that, in order to maintain confidentiality, 

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EERE-2007-BT-STD-0010 COMMENT 20.3
 

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 vent-less 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. 

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 Vent-less 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, 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 

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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. 

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 0.25 9.02 50.18 0.46 29.83 

Tooling and 

Equipment 5.25 37.68 118.93 2.62 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 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. 

5-29 

EERE-2007-BT-STD-0010 COMMENT 20.3
 

 

 

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 existing test procedure assumes an initial remaining moisture content (RMC) 

of the test cloth load of 70.0 ± 3.5 percent. It is likely, however, that this RMC value is 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. 

5-30 

EERE-2007-BT-STD-0010 COMMENT 20.3
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. 

5-31 

EERE-2007-BT-STD-0010 COMMENT 20.3
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 

5.6.1.2 Product Testing 

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 vent-less 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. 

5-32 

EERE-2007-BT-STD-0010 COMMENT 20.3
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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EERE-2007-BT-STD-0010 COMMENT 20.3
 

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

Features 

Feature 

Clothes Dryer Test Unit Designation 

Vented 

Electric 

Compact 

(120 V) 

Vented Gas 

Vent-less 

Electric 

Compact 

(240 V) 

Vent-less 

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 on the twelve units in the test sample. The test 

results included not only the measurements required to evaluate the performance according to the 

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 DOE test procedure (10 CFR 430 subpart B, 

appendix D). For the vent-less units, the test was run without the use of the exhaust simulator, as 

proposed by DOE in LG’s Petition for Waiver and Denial of the Application for Interim Waiver. 

71 FR 49437, 49439. 

The test procedure consists 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 

5-34 

EERE-2007-BT-STD-0010 COMMENT 20.3
 

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”e

 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) 

3412 = the conversion factor of Btu/kWh 

e “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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EERE-2007-BT-STD-0010 COMMENT 20.3
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 vent-less units, which removes condensate; and 

� water valve for vent-less 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 vent-less clothes dryers have not been rated, the EF 

for these units could only be represented by the value measured during testing. 

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EERE-2007-BT-STD-0010 COMMENT 20.3
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-sized dryers, a 

vent-less 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 vent-less dryer’s heater. Finally, these data show a 

significantly longer drying time associated with the vent-less 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 vent-less). 

5-37 

EERE-2007-BT-STD-0010 COMMENT 20.3
 

 

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 vent-less data plotted 

as a function of measured rather than rated EF. The slope for compact units (which include the 

vent-less 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, which 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 

electric standard and gas clothes dryers had measured EFs that were lower than the certification 

data would indicate. 

5-38 

EERE-2007-BT-STD-0010 COMMENT 20.3
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 degrees Fahrenheit (°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. 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 

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 

5-39 

EERE-2007-BT-STD-0010 COMMENT 20.3
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. 

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 

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: 

5-40 

EERE-2007-BT-STD-0010 COMMENT 20.3
 

� 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. 

� Vent-less 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 

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 vent-less 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 5.4.1.2. 

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 vent-less 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. 

5-41 

EERE-2007-BT-STD-0010 COMMENT 20.3
 

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. 

5-42 

EERE-2007-BT-STD-0010 COMMENT 20.3
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 

DOE is currently 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. 

However, DOE has not yet published a NOPR for potential test procedure amendments. 

Therefore, for this Preliminary-NOPR (Pre-NOPR), DOE did not analyze energy conservation 

standards based on initial RMCs lower than the existing 70 percent. DOE may consider revising 

the IEF efficiency levels in later stages of this rulemaking as warranted by further research and 

comments from interested parties. 

Maximum-Available Vented Gas Clothes Dryer Testing 

5-43 

EERE-2007-BT-STD-0010 COMMENT 20.3
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 above the maximumavailable 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 maximum-available efficiency vented gas clothes 

dryer to help determine an appropriate max-tech level value for the preliminary analyses. DOE 

purchased three identical units of this model and tested each three times according to the 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 in the preliminary 

analyses. 

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 12 teardown units total for four of the five product classes, 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-tech. 

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 

5-44 

EERE-2007-BT-STD-0010 COMMENT 20.3
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 vent-less electric compact (240 V) clothes dryer has a similar construction 

to the baseline vented electric clothes dryer, with the following differences. A baseline vent-less 

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 vent-less 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. 

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 

5-45 

EERE-2007-BT-STD-0010 COMMENT 20.3
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), vent-less electric compact (240 V) and vent-less 

combination washer/dryers, DOE assumed much smaller production volumes than for vented 

electric standard and vented gas dryers. 

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EERE-2007-BT-STD-0010 COMMENT 20.3
Figure 5.6.9 Baseline Vented Electric Standard Clothes Dryer Full Production Cost 


Distribution
 

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EERE-2007-BT-STD-0010 COMMENT 20.3
Figure 5.6.10 Baseline Vented Electric Standard Clothes Dryer Materials Cost Distribution 

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


Cost Distribution
 

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EERE-2007-BT-STD-0010 COMMENT 20.3
Figure 5.6.12 Baseline Vented Electric Compact (240V) Clothes Dryer Materials Cost 


Distribution 


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EERE-2007-BT-STD-0010 COMMENT 20.3
Figure 5.6.13 Baseline Vented Gas Clothes Dryer Full Production Cost Distribution 

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EERE-2007-BT-STD-0010 COMMENT 20.3
Figure 5.6.14 Baseline Vented Gas Clothes Dryer Materials Cost Distribution 

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EERE-2007-BT-STD-0010 COMMENT 20.3
Figure 5.6.15 Baseline Vent-less Electric Compact (240V) Clothes Dryer Full Production 


Cost Distribution
 

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Figure 5.6.16 Baseline Vent-less Electric Compact (240V) Clothes Dryer Materials Cost 


Distribution 


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Figure 5.6.17 Baseline Vent-less Combination Washer/Dryer Full Production Cost 


Distribution 


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EERE-2007-BT-STD-0010 COMMENT 20.3
Figure 5.6.18 Baseline Vent-less 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 analyses, and discussions with manufacturers, 

summarized in section 0, 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 and compact-sized dryers because of the different amounts of materials 

required for structural design changes. 

Efficiency Level 2 

Based on research and discussion with manufacturers, DOE research suggests that for EL 

2, 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. 

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 multi-speed blowers are required to adjust airflow rates and to allow for more 

accurate control of the drying cycle. 

2.	 Moisture Sensing and Variable 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. The speed of the blower motor would be controlled by the 

control board that also reads the moisture. 

Efficiency Level 3 

DOE research suggests that manufacturers would likely add modulating heat to the 

platform described for EL 2 to achieve EL 3. A modulating-heat design is less likely to benefit 

from inlet air preheating (since the exit air temperature can be closely controlled) so the inlet air 

pre-heater described for EL2 would likely be dropped. Therefore, it was not included in the 

design changes for this efficiency level. 

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1.	 Modulating Heat 

For the design change, the control system would have to be upgraded to allow 

modulation. To accurately control the temperature, manufacturers are likely to switch to 

electronic controls that incorporate bidirectional triode thyristors (Triacs) or similar solid-state 

approaches to control the heat output. A variable-speed fan motor is likely required also to 

seamlessly match the heat output of the heater coil. Typically, manufacturers incorporate 

electronically-commutated or equivalent motor designs for such applications. 

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 and compact-size 

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 

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 

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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 3, the modulation of gas heat requires significantly different component changes 

as compared to modulating electric heat. 

For EL 3, DOE believes that manufacturers would switch from the baseline single-stage 

gas valve to a modulating gas valve. DOE is not aware of any gas-fired clothes dryers with 

modulating gas valves on the market today, but notes the availability of modulating gas valves 

for other residential appliance applications. Additional controls would be required to control the 

gas valve modulation. As with the EL 3 design changes for electric standard dryers, the same 

disaggregated motor design (with additional controls) would also be incorporated into this level. 

Vent-less Electric Compact (240 V) Clothes Dryers 

DOE believes that essentially the same changes described above for vented electric 

clothes dryers for EL 1, EL 3, and EL 4 would be applied to vent-less 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 2 design changes applied to vented electric 

clothes dryers were based upon inlet air preheating, these design changes would not be applied to 

a vent-less electric compact (240 V) clothes dryer because it already recirculates the air back 

through the system. For this reason, the EL 3 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 vent-less 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. 

Vent-less 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 from EL 1 to EL 2 for vented electric clothes dryers could not 

be applied to this product class. Further, for the reasons described above for vent-less electric 

compact (240 V) clothes dryers, DOE believes that the EL 3 and EL 4 design changes for vented 

electric clothes dryers would be applied to EL 2 and EL 3, respectively, for this product class. 

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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. 

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. For product classes for which AHAM 

provided data, the corresponding cost-efficiency curves are plotted as well. 

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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 (3.01) $0 

1 (3.10) $11.89 

2 (3.16) $63.56 

3 (3.40) $97.48 

4 (4.52) $258.47 

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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 (3.13) $0 

1 (3.22) $10.95 

2 (3.29) $63.37 

3 (3.54) $96.45 

4 (4.70) $245.69 

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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 (2.90) $0 

1 (2.98) $10.95 

2 (3.09) $63.37 

3 (3.20) $96.45 

4 (4.35) $245.69 

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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 (2.67) $0 

1 (2.75) $14.79 

2 (2.85) $65.36 

3 (3.02) $156.01 

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Figure 5.6.23 Vent-less Electric Compact (240V) Clothes Dryer Cost-Efficiency Curve 

Table 5.6.13 Vent-less Electric Compact (240V) Clothes Dryer Incremental Manufacturing 

Cost 

Efficiency Level (EF, 

lb/kWh) 

Incremental 

Cost 

Baseline (2.37) $0 

1 (2.39) $12.35 

2 (2.59) $68.36 

3 (3.55) $215.71 

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Figure 5.6.24 Vent-less Electric Combination Washer/Dryer Cost-Efficiency Curves 

Table 5.6.14 Vent-less Electric Combination Washer/Dryer Incremental Manufacturing 

Cost 

Efficiency Level (EF, 

lb/kWh) 

Incremental 

Cost 

Baseline (1.95) $0 

1 (2.21) $0.81 

2 (2.42) $54.04 

3 (3.32) $230.17 

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. 

Table 5.6.15 Standby Power Incremental Manufacturing Cost 

Standby Power Level 

(W) 

Incremental 

Cost 

Baseline (2.0) $0 

1 (1.5) $1.30 

2 (0.08) $0.66 

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Incremental Costs by IEF 

As discussed in section 5.4, the clothes dryer analysis for this rulemaking is based on the 

integrated metric, IEF. DOE analyzed the improvement in IEF associated both with design 

options that improve EF and design options that reduce standby power. DOE developed overall 

cost-efficiency relationships for the IEF 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 IEF efficiency 

levels where DOE determined them to be most cost effective. Table 5.6.16 through Table 5.6.21 

present DOE’s estimates of incremental manufacturing cost for improvement of clothes dryer 

IEF above the baseline. 

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

Integrated Efficiency 

Level (IEF, lb/kWh) 

Incremental 

Manufacturing Cost 

Baseline (2.96) $0 

1 (3.04) $11.89 

2 (3.10) $63.56 

3 (3.33) $97.48 

4 (3.35) $98.78 

5 (3.40) $98.14 

6 (4.52) $259.13 

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

Dryers 

Integrated Efficiency 

Level (IEF, lb/kWh) 

Incremental 

Manufacturing Cost 

Baseline (3.00) $0 

1 (3.08) $10.95 

2 (3.15) $63.37 

3 (3.37) $96.45 

4 (3.41) $97.75 

5 (3.53) $97.11 

6 (4.69) $246.35 

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

Dryers 

Integrated Efficiency 

Level (IEF, lb/kWh) 

Incremental 

Manufacturing Cost 

Baseline (2.79) $0 

1 (2.86) $10.95 

2 (2.96) $63.37 

3 (3.06) $96.45 

4 (3.10) $97.75 

5 (3.19) $97.11 

6 (4.34) $246.35 

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Table 5.6.19 Cost-Efficiency Relationship for Vented Gas Clothes Dryers 

Integrated Efficiency 

Level (IEF, lb/kWh) 

Incremental 

Manufacturing Cost 

Baseline (2.63) $0 

1 (2.71) $14.79 

2 (2.80) $65.36 

3 (2.97) $156.01 

4 (2.98) $157.31 

5 (3.02) $156.67 

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

Dryers 

Integrated Efficiency 

Level (IEF, lb/kWh) 

Incremental 

Manufacturing Cost 

Baseline (2.29) $0 

1 (2.31) $1.30 

2 (2.37) $0.66 

3 (2.39) $13.01 

4 (2.59) $69.02 

5 (3.54) $216.37 

Table 5.6.21 Cost-Efficiency Relationship for Vent-less Electric Combination 

Washer/Dryers 

Integrated Efficiency 

Level (IEF, lb/kWh) 

Incremental 

Manufacturing Cost 

Baseline (1.90) $0 

1 (2.15) $0.81 

2 (2.34) $54.04 

3 (2.36) $55.34 

4 (2.42) $54.70 

5 (3.31) $230.83 

5.6.1.5 Manufacturer Interviews

 DOE conducted interviews with residential clothes dryer manufacturers to determine 

appropriate efficiency levels for the preliminary analyses 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 5.4.1.2 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 

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another series of interviews with manufacturers to solicit feedback on preliminary manufacturing 

cost estimates DOE developed through the reverse engineering analyses. 

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 5.6.1.2, 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 

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. 

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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 

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 vent-less 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. 

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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 

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 sized 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 

EL3 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. 

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 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 vent-less 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 

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. 

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5.6.2 Room Air Conditioners 

The room air conditioner engineering analysis was performed by considering cost and 

efficiency information from multiple sources. DOE conducted its own detailed room air 

conditioner teardowns and estimated the manufacturing costs of observed efficiency features for 

current designs using HCFC-22 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 did not receive aggregated industry data from AHAM for the 

incremental costs to achieve higher efficiency levels. 

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% 

Table 5.6.23 AHAM Room Air Conditioner Product Class Market Share Data 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 

Only 

Casement 

Slider 

<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. Data were not provided for 

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product classes 6, 7, 10, 13, 14, and 15. The efficiency trends for these products 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. 

5.6.2.2 Manufacturer Interviews 

DOE conducted interviews with room air conditioner manufacturers to develop a better 

understanding of the technologies used to improve energy efficiency. During these interviews, 

DOE asked manufacturers what groupings of design options would be required to increase the 

energy efficiency in order to meet the efficiency levels proposed in section 5.4.1.2 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. 

Components That Influence Energy Efficiency 

Manufacturers identified the components that influence energy efficiency in room air 

conditioners as fans, blowers, and 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. 

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 Manufacturers currently use rotary compressors in their room air conditioners, and the 

efficiency range of compressors available today varies by product class. Since new products 

cannot use HCFC-22 starting in 2010, manufacturers have been transitioning their room air 

conditioner designs to R-410A refrigerant. The range of compressors for use with R-410A 

refrigerant which have been fully tested and UL-approved is significantly more limited than the 

range of compressors which can use HCFC-22. Manufactures mentioned 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 variable-speed 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 

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 are not currently 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 at this point it is not clear what level of 

compressor performance will be available when the new standards for room air conditioner 

efficiency take effect. 

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 

metal, 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 

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and subcooling coils were cited as having the potential to improve efficiency, the overall impact 

of these design options is relatively small. 

5.6.2.3 Product Teardowns 

DOE tore down 21 room air conditioners across 6 product classes to identify design 

options, and their associated costs, that can be used to raise EER. As best as possible, DOE 

selected 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. 

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 

After the room air conditioner teardowns, DOE grouped 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 conditioner, as generated from DOE’s BOM. Note that the refrigeration 

system, heat exchangers, and fan components (components that largely determine energy 

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EERE-2007-BT-STD-0010 COMMENT 20.3
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. 

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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) 

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 5.6.2.7. 

5.6.2.4 Energy Modeling 

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. The 

energy model developed as part of the previous room air conditioner energy conservation 

standard rulemaking was upgraded 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.4

 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. 

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EERE-2007-BT-STD-0010 COMMENT 20.3
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, and it is explained in greater detail in the MarkN 

manual provided with the program. 

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, some 

modeling external to the program was conducted to properly account for system changes that 

impact air flows. DOE developed airside models that calculated the 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. Performance data for similar fans and blowers were 

obtained from vendors. DOE adjusted the available fan and blower performance information 

using the fan laws from the 2008 ASHARE Handbook, HVAC Systems and Equipment5

, in 

order to approximate the performance of the components in the products that were analyzed. 

Further information on the airside models is available in appendix 5D. 

The energy use for each of the teardown units was modeled and compared to the rated 

performance for these units to verify the validity of the upgraded energy model. Inputs for the 

individual models were based on the design details determined during teardown of the products. 

Some of the system operating parameters were determined from energy testing, as discussed in 

section 5.6.2.5. Evaporator air flow was set equal to the rated evaporator air flow. Hot wire 

anemometer measurements of condenser air flow and fan motor power input measurements were 

made prior to teardown to provide model input for these parameters. Compressor performance 

input data were obtained from compressor vendors. 

The results of this comparison of energy model results and rated performance of the 

teardown units are shown in Figure 5.6.28 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 HCFC22 refrigerant. 

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EERE-2007-BT-STD-0010 COMMENT 20.3
Figure 5.6.28 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. Performance data of the R-410A compressors was obtained from compressor 

vendors. The R-410A drop-in analyses are compared with the baseline HCFC-22 analyses in 

Figure 5.6.29 below. The models generally show a reduction in EER in the range of 0 to 15 

percent. 

Figure 5.6.29 Energy Modeling Results for R-410A Drop-In 

Further energy analysis was conducted on designs modified by a series of design options 

in order to determine the energy efficiency improvement possible with each of these design 

options. This analysis was performed for the six baseline-efficiency products of product classes 

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EERE-2007-BT-STD-0010 COMMENT 20.3
1, 3, 5, and 8. For most 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 R410A room air conditioners. The results of the design option energy modeling analyses are 

discussed in section 5.6.2.7 below. 

5.6.2.5 Energy Testing 

Four of the teardown units were energy tested prior to teardown. The energy test results 

were used to verify performance of some of the higher-efficiency products. The comparison 

between rated and tested performance is shown in Figure 5.6.30 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 5.6.30 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. 

5.6.2.6 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 

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EERE-2007-BT-STD-0010 COMMENT 20.3
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 and EER 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 5.6.26 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 

5.6.2.6. 

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Table 5.6.26 Manufacturing Cost Increase for Drop-In Conversion to R-410A 

Product Class Total Costs Due to 

Refrigerant Switch 

PC 1 $3.92 

PC 3 (8,000 Btu/h Capacity) $5.47 

PC 3 (12,000 Btu/h Capacity) $7.49 

PC 5 $13.70 

PC 8 (8,000 Btu/h Capacity) $5.77 

PC 8 (12,000 Btu/h Capacity) $7.95 

5.6.2.7 Cost-Efficiency Curves 

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 5.6.27 below for improvement of 

efficiency. 

Table 5.6.27 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. 

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. 

Increasing the physical size of the room air conditioner was considered 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), 12, and 

14 are not possible. The sizes of the product class 1, 3, and 5 baseline products in DOE’s 

test sample are compared in Figure 5.6.31 with a distribution of product sizes of baselineefficiency 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 analyzed products can be made larger 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 both the evaporator and 

condenser can be increased. The examined size increases are summarized in Table 5.6.28 

below. 

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. The condenser coil bend was a 

feature observed in some teardown units. 

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Figure 5.6.31 Size Distributions of Baseline-Efficiency Room Air Conditioners 

Table 5.6.28 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 

15.3 

15.3 

14 

18 

23.6 

49.4 

55.7 

63.6 

Product Class 3, 12,000 Btu/h 

Baseline 

First Size Increase

 Second Size Increase 

19.63 

24.63 

26.38 

13.75 

17.5 

17.5 

19.63 

22.25 

26.75 

76.5 

81.2 

87.6 

Product Class 5 

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 believes increases in coil frontal area and package size are among the primary 

factors contributing to EER improvements in the higher-efficiency teardown units for product 

classes 1, 3, and 5. The sizes and weights of these units are shown in Table 5.6.29 below. 

Table 5.6.29 Sizes and Weights of Teardown Units for Product Classes 1, 3, and 5 

Design Description 

Width 

(in) 

Height 

(in) 

Depth 

(in) 

Weight 

(lb) 

Product Class 1 

Baseline 1, 9.7 EER 

Baseline 2, 9.7 EER 

10.7 EER

 11 EER 

15.5 

17.28 

18.91 

18.5 

11.75 

11.16 

12.46 

12.5 

12 

7.28 

14.69 

14 

38.6 

36.5 

48.2 

44.4 

Product Class 3, 8,000 Btu/h 

Baseline, 9.8 EER 

10.8 EER

 11.4 EER 

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 

19.58 

23.63 

25.94 

13.75 

15 

22.25 

19.63 

22.25 

27.38 

73 

78.6 

108.8 

Product Class 5 

Baseline, 8.5 EER

 9.4 EER 

26 

26.5 

17.69 

18.63 

28.41 

25 

132 

135.2 

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 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 

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determine the cost of shipping per unit. For design options that involved increase in chassis size, 

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 a subcooler 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 feedback provided by 

manufacturers.4 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 

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 analyses. Microchannel condenser incremental manufacturing costs 

were calculated 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 5.6.30 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 5.6.30 Microchannel Condenser Costs 

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 5.6.31 below. 

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Table 5.6.31 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 5.6.32 

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. 

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Figure 5.6.32 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 5.6.33 below shows the calculated cost of replacing a 

baseline PSC motor with a BLDC motor. 

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Figure 5.6.33. 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 5.6.32 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. 

Table 5.6.32 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 all 

room air conditioners will require use of this new refrigerant before any new energy conservation 

standard becomes effective. 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 5.6.34 below. As can be seen, there are data for many more HCFC-22 

compressors than for R-410A rotary compressors. The EER ratings of the R-410A compressors 

are not only generally lower than that of an HCFC-22 rotary compressor with a similar capacity, 

but exhibit a much more limited EER range (i.e., HCFC-22 compressor EER levels range from 

9.0 to 11.2 near 5,000 Btu/h nominal capacity, whereas the R-410A compressor EER range is 

roughly 9.0 to 10.0). The chart shows that reduction in the EER when switching to R-410A 

compressors is greater for lower capacities than for higher capacities. The chart also shows that 

the use of scroll compressors does not improve efficiency for the capacities of interest for room 

air conditioners. 

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Figure 5.6.34 Compressor Performance Data 

The relationship between R-410A compressor cost and baseline-efficiency room air 

conditioner capacity that DOE used in the analysis is illustrated in 

Figure 5.6.35 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 

5.6.2.6. The figure is based on room air conditioner capacity, and not compressor rating point 

capacity. 

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Figure 5.6.35 R-410A Compressor Cost 

Concerns about the potential size and weight increase, and higher cost, exists in 

considering the use of a scroll compressor in a 24,000 Btu/h room air conditioner. The baseline 

HCFC-22 compressor and R-410A scroll compressors that could be considered for product class 

5 are compared in Table 5.6.33 below. The smaller-capacity scroll compressor is relevant 

because it provides sufficient capacity for the room air conditioner after energy-savings changes 

such as improvement in condenser and evaporator performance are implemented. The heights of 

the scroll compressors are close to 3 inches less than the heights of the product class 5 units 

which were part of the teardown work (see section 5.6.2.3 above). The size and weight data show 

that design of a high efficiency product using the smaller scroll compressor would be acceptable. 

Table 5.6.33 Size and Weight of Applicable Rotary and Scroll Compressors for a 24,000 

Btu/h Room Air Conditioner 

24,000 Btu/h 

HCFC-22 Rotary 

Compressor 

24,000 Btu/h 

R-410A Scroll 

Compressor 

21,000 Btu/h 

R-410A Scroll 

Compressor 

Shell Height (in) 13 15.14 15.28 

Shell Diameter (in) 5.5 5.5 5.5 

Weight (lb) 44 63 47 

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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 inactive 

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 inactive mode for a room air conditioner is the power supply, as shown in Table 

5.6.34. 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 5.6.34 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. The increase in direct material costs for converting to a switchmode power supply based on this information is approximately $1.00. 

Cost-Efficiency Curves based on EER 

DOE developed two sets of cost-efficiency curves for each product class/capacity 

combination analyzed fully: 

A curve based on the HCFC-22 teardown products. This curve was generally incomplete, 

since a full range of EER was not purchased for each product class. For one of the 

product classes, two sets of HCFC-22 curves were developed, since two sets of products 

(i.e., products at two efficiency levels made by each of two manufacturers) were 

purchased. 

A curve based on the analysis of R-410A designs that is described in detail in this 

chapter. 

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The cost-efficiency curves based on EER are shown in Figure 5.6.36 through Figure 

5.6.41 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. All of these curves are based on design configuration, i.e. each separate point in the 

plot represents a different design configuration. Note that the plots show the reduction in EER 

and the cost impact of the conversion to R-410A, including the drop in EER for initial “drop-in” 

of the new refrigerant. The data in all of these plots are for products with a “baseline” standby 

power level of 1.4 W. 

Each cost-efficiency curves developed for R-410A is plotted next to a cost-efficiency 

curve for HCFC-22. The efficiency levels on the R-410A curves were calculated using the 

energy model, while the efficiency levels on the HCFC-22 curves represent the efficiency levels 

of the products selected for reverse engineering. The manufacturing costs for both sets of curves 

are based on the cost model developed from DOE’s reverse engineering work. 

The charts show that, although the HCFC-22 curves are shifted to a lower cost and higher 

initial EER, there is generally good agreement in slope between curves for the HCFC-22 

products and the modeled R-410A curves. The slope of the HCFC-22 curve for the product class 

8 12,000 Btu/h product is in reverse because of some of the design details associated with the 

baseline product of this group. This baseline was one of the few teardown products observed 

which had heat exchangers with four rows of tubes (most of the products, even the higher EER 

models, had heat exchangers with two rows of tubes). The use of deeper heat exchangers resulted 

in unusually high costs for this product. 

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Figure 5.6.36 Product Class 1 Cost-Efficiency Curve 

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Figure 5.6.37 Product Class 3 - 8,000 Btu/h Capacity Cost-Efficiency Curve 

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Figure 5.6.38 Product Class 3 - 12,000 Btu/h Capacity Cost-Efficiency Curve 

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Figure 5.6.39 Product Class 5 Cost-Efficiency Curve 

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Figure 5.6.40 Product Class 8 - 8,000 Btu/h Capacity Cost-Efficiency Curve 

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Figure 5.6.41 Product Class 8 - 12,000 Btu/h Capacity Cost-Efficiency Curve 

Incremental Costs by IEER 

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, IEER. DOE analyzed the improvement in IEER associated both 

with design options that improve EER and design options that reduce standby power. DOE 

developed overall cost-efficiency relationships for IEER by combining these analyses. 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 

5.6.42 below. The plot shows the incremental IEER improvement of the design option divided 

by incremental manufacturing production cost (MPC) associated with the design option. 

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Figure 5.6.42 Comparison of the Cost-Effectiveness of Active and Standby Mode Design 

Options 

As discussed above, DOE determined that the incremental cost for reducing inactive 

mode power consumption from 1.4 W to 0.7 W is $1.00. Table 5.6.35 below summarizes this 

incremental cost. 

Table 5.6.35 Room Air Conditioner Cost-Standby/Off Mode Power Relationship 

Standby Level Power (W) Incremental Cost 

Baseline 1.4 $0 

1 0.7 $1.00 

Table 5.6.36 through Table 5.6.41 present DOE’s estimates of incremental cost in terms 

of MPC for improvement of room air conditioner IEER above the baseline. 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 IEER 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 IEER level based on appropriate selection of active mode and 

standby mode design options. In cases where the IEER efficiency level does not coincide with 

the IEER 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 IEER 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 

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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 5.6.36 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 

IEER MPC Increase Shipping Costs 

Baseline 9.52 $7.65 $4.18 

1 10.1 $12.18. $5.31 

2 10.6 $18,22 $6.25 

3 11.1 $27.19 $7.64 

4 11.6 $37.30 $8.39 

5 12.0 $44.10 $8.39 

Table 5.6.37 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 

IEER MPC Increase Shipping Costs 

Baseline 9.69 $9.58 $6.32 

1 10.3 $18.65 $8.61 

2 10.8 $27.12 $11.65 

3 11.3 $38.38 $14.63 

4 11.5 $43.12 $14.63 

Table 5.6.38 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 

IEER MPC Increase Shipping Costs 

Baseline 9.72 $11.20 $14.46 

1 10.3 $17.57 $15.89 

2 10.8 $24.25 $17.64 

3 11.3 $42.64 $21.79 

4 11.5 $114.06 $21.79 

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Table 5.6.39 Room Air Conditioner Cost-Efficiency Relationships for Product Class 5 

Product Class 5: Without Reverse Cycle, With Louvered Sides, 

≥ 20,000 Btu/h 

Efficiency 

Level 

IEER MPC Increase Shipping Costs 

Baseline 8.47 $23.78 $24.79 

1 9.0 $37.47 $27.88 

2 9.4 $52.84 $32.66 

3 9.8 $75.30 $36.46 

4 10.0 $104.34 $36.46 

Table 5.6.40 Room Air Conditioner Cost-Efficiency Relationship for Product Class 8 –

8,000 Btu/h 

Product Class 8 – 8,000 Btu/h: Without Reverse Cycle, Without 

Louvered Sides, 8,000 – 13,999 Btu/h 

Efficiency 

Level 

IEER MPC Increase Shipping Costs 

Baseline 8.41 $6.14 $12.26 

1 8.9 $8.62 $12.26 

2 9.3 $10.51 $12.26 

3 9.8 $21.70 $12.26 

Table 5.6.41 Room Air Conditioner Cost-Efficiency Relationship for Product Class 8 –

12,000 Btu/h 

Product Class 8 – 12,000 Btu/h: Without Reverse Cycle, Without Louvered Sides, 

8,000 – 13,999 Btu/h 

Efficiency 

Level 

IEER MPC Increase Shipping Costs 

Baseline 8.44 $8.77 $12.26 

1 8.9 $13.28 $12.26 

2 9.3 $20.21 $12.26 

3 9.8 $35.94 $12.26 

DOE consolidated product classes 3 and 8 by averaging the results of the 8,000 Btu/h 

costs and the 12,000 Btu/h costs. These averages were used in the subsequent LCC analysis. The 

final averages for product classes 3 and 8 are shown in Table 5.6.42 and Table 5.6.43. below. 

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Table 5.6.42 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 

IEER MPC Increase Shipping Costs 

Baseline 9.71 $10.39 $10.39 

1 10.3 $18.11 $12.25 

2 10.8 $25.68 $14.65 

3 11.3 $40.51 $18.21 

4 11.5 $78.59 $18.21 

Table 5.6.43 Room Air Conditioner Cost-Efficiency Relationship for Product Class 8 –

Average 

Product Class 8 – Average: Without Reverse Cycle, Without Louvered Sides, 

8,000 – 13,999 Btu/h 

Efficiency 

Level 

IEER MPC Increase Shipping Costs 

Baseline 8.44 $7.45 $12.26 

1 8.9 $10.95 $12.26 

2 9.3 $15.36 $12.26 

3 9.8 $28.82 $12.26 

Extrapolation of Additional Product Classes 

The 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. 

DOE first established efficiency levels based on the EER metric for the product classes 

that were not directly analyzed. These efficiency levels were determined based on information 

about existing room air conditioners of these product classes, and extrapolation from efficiency 

levels of the product classes that were directly analyzed. The active mode efficiency levels are 

presented in Table 5.6.44 through Table 5.6.46. 

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Table 5.6.44 EER Efficiency Levels for Product Classes 2, 4, 6, 7 

Product 

Class 

2: Without Reverse 

Cycle, With 

Louvered Sides, 

6,000-7,999 Btu/h 

4: Without Reverse 

Cycle, With 

Louvered Sides, 

14,000-19,999 Btu/h 

6: Without Reverse 

Cycle, Without 

Louvered Sides, 

<6,000 Btu/h 

7: Without Reverse 

Cycle, Without 

Louvered Sides, 

6,000-7,999 Btu/h 

Efficiency 

Level 

Description 

Level EER Level EER Level EER Level EER 

DOE 

Standard 1 9.7 1 9.7 1 9.0 1 9.0 

Gap Fill 2 10.2 2 10.2 2 9.5 2 9.5 

Energy Star 3 10.7 3 10.7 3 9.9 

CEE Tier 1 4 11.2 

CEE Tier 2 5 11.6 

Gap Fill 4 10.4 

Maximum 

Available 6 12.0 4 11.0 3 9.7 5 10.8 

Table 5.6.45 EER Efficiency Levels for Product Classes 9, 10, 11, 13 

Product 

Class 

9: Without Reverse 

Cycle, Without 

Louvered Sides, 

14,000-19,999 Btu/h 

10: Without Reverse 

Cycle, Without 

Louvered Sides, 

>=20,000 Btu/h 

11: With Reverse 

Cycle, With 

Louvered Sides, 

<20,000 Btu/h 

13: With Reverse 

Cycle, With 

Louvered Sides, 

>=20,000 Btu/hr 

Efficiency 

Level 

Description 

Level EER Level EER Level EER Level EER 

DOE 

Standard 1 8.5 1 8.5 1 9.0 1 8.5 

Gap Fill 2 9.0 2 9.0 2 9.5 2 9.0 

Energy Star 3 9.4 3 9.9 3 9.4 

Gap Fill 4 10.0 

Maximum 

Available* 5 10.5 3 9.1 4 10.2 * 

*No products of this product class from the databases were found for sale. Maximum database EER was 9.4 

Table 5.6.46 EER Efficiency Levels for Product Classes 12, 14, 15, 16 

Product 

Class 

12: With Reverse 

Cycle, Without 

Louvered Sides, 

<14,000 Btu/h 

14: With Reverse 

Cycle, Without 

Louvered Sides, 

>=14,000 Btu/h 

15: Casement Only 16: Casement-Slider 

Efficiency 

Level 

Description 

Level EER Level EER Level EER Level EER 

DOE 

Standard 1 8.5 1 8.0 1 8.7 1 9.5 

Gap Fill 2 9.0 2 8.4 2 9.2 2 10.0 

Energy Star 3 9.4 3 8.8 3 9.6 3 10.5 

Maximum 

Available 4 9.5 4 9.1 9.5 10.5 

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DOE conducted its analysis on the basis of the integrated IEER metric, so DOE next 

established efficiency levels based on IEER for these product classes. DOE selected efficiency 

levels 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 discussed in the tables above 

as closely as was feasible. DOE calculated these IEER efficiency levels by first selecting a 

representative capacity for each product class (shown in Table 5.6.50, and derived from the 

average capacity of representative identified units) and an appropriate stand-by power level for 

each efficiency level. At baseline efficiency level, DOE assumed baseline standby power. DOE 

adjusted the standby power to SL 1 at EL 2 based on results that were determined for product 

classes that were directly analyzed. DOE then calculated the IEER efficiency levels using the 

EER efficiency levels presented above using the method described in section 5.4.2.3. DOE 

adjusted the max-tech IEER in certain cases to maintain the appropriate IEER differentials 

between baseline and max-tech levels. For product classes for which cost increments were 

interpolated, DOE adjusted the max-tech IEER to match the lower of the two values for the 

product classes from which it was interpolated. For product classes for which cost increments 

were extrapolated, DOE adjusted the max-tech IEER to maintain the differential of the product 

class from which it was extrapolated. In certain cases, the max-tech IEER was further adjusted to 

account for different sets of design options and capacities. The selected levels are summarized in 

Table 5.6.47 through Table 5.6.49 below. 

Table 5.6.47 IEER Efficiency Levels for Product Classes 2, 4, 6, 7 

Level 

IEER (Btu/h-W) 

2: Without Reverse 

Cycle, 

With Louvered 

Sides, 

6,000-7,999 Btu/h 

4:Without Reverse 

Cycle, 

With Louvered Sides, 

14,000 - 19,999 Btu/h 

6: Without Reverse 

Cycle, Without 

Louvered Sides, 

<6,000 Btu/h 

7: Without Reverse 

Cycle, Without 

Louvered Sides, 

6,000-7,999 Btu/h 

Baseline 9.56 9.65 8.85 8.88 

1 10.1 10.2 9.4 9.4 

2 10.6 10.7 9.9 9.9 

3 11.1 11.2 10.3 10.3 

4 11.4 

Table 5.6.48 IEER Efficiency Levels for Product Classes 9, 10, 11, 13 

Level 

IEER (Btu/h-W) 

9: Without Reverse 

Cycle, Without 

Louvered Sides, 

14,000-19,999 Btu/h 

10: Without Reverse 

Cycle, Without 

Louvered Sides, 

>=20,000 Btu/h 

11: With Reverse 

Cycle, With 

Louvered Sides, 

<20,000 Btu/h 

13: With Reverse 

Cycle, With 

Louvered Sides, 

>=20,000 Btu/hr 

Baseline 8.46 8.47 8.94 8.47 

1 9.0 9.0 9.5 9.0 

2 9.5 9.5 10.0 9.4 

3 10.5 9.8 

4 10 

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Table 5.6.49 IEER Efficiency Levels for Product Classes 12, 14, 15, 16 

Level 

IEER (Btu/h-W) 

12: With Reverse 

Cycle, Without 

Louvered Sides, 

<14,000 Btu/h 

14: With Reverse Cycle, 

Without Louvered Sides, 

>=14,000 Btu/h 

15: Casement Only 16: Casement-Slider 

Baseline 8.43 7.97 8.62 9.41 

1 9.0 8.5 9.2 10.0 

2 9.4 9.0 9.7 10.5 

3 9.8 10.2 11.0 

Methodology 

DOE used interpolation and extrapolation methods, based on the IEER levels of the 

analyzed product classes, to calculate incremental costs for the remaining product classes. The 

methodology used to calculate incremental costs for each remaining product class is detailed 

below. 

For product classes 2 and 4, DOE calculated incremental costs by interpolating data for 

the neighboring product classes, i.e. the data for product classes 1 and 3 were used to calculate 

the incremental costs for product class 2. DOE carried out this interpolation based on 

representative capacities for the product classes, which were calculated based on the average 

capacity of products in the assembled database of room air conditioners described in Chapter 3. 

The representative capacities are presented in Table 5.6.50 below. The interpolation for 

incremental cost was two-dimensional, based on both capacity and IEER increase as compared 

with the IEER of the initial R-410A design. 

Table 5.6.50 Representative Capacities for Room Air Conditioner Product Classes 

Product 

Class 

Capacity 

(Btu/h) 

Product 

Class 

Capacity 

(Btu/h) 

1 5,100 9 16,300 

2 6,400 10 25,900 

3 10,200 11 13,200 

4 16,900 12 9,600 

5 25,100 13 25,100* 

6 5,100 14 21,800 

7 6,500 15 9,300 

8 10,300 16 9,700 

Sources: CEC, ENERGY STAR, and AHAM databases as of August 2008, with review of manufacturer and retailer 

websites to remove products no longer active. 

*No active products were identified for this product class. Representative capacity is set equal to the same 

representative capacity for product class 5 (the difference between these product classes is reverse cycle for product 

class 13). 

For product classes 6, and 7, DOE extrapolated the incremental costs for product class 8 

to the higher and lower capacity product classes based on the variation of incremental cost with 

capacity exhibited by product classes 1 and 3. For product classes 9 and 10, DOE carried out an 

extrapolation based on the variation of incremental cost with capacity of product classes 3 and 5, 

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but DOE limited the extent of the possible increase in IEER based on room air conditioner size, 

since the through-the-wall products of product classes 6 through 10 cannot increase is size. 

For product classes 11 and 13, DOE carried out an interpolation based on results for 

product classes 1 through 5. DOE assumed for this calculation that the use of reverse cycle for 

these product classes does not affect the cost of improving cooling mode efficiency. DOE carried 

out a similar interpolation for product classes 12 and 14 based on the results for product classes 6 

through 10. 

Finally, for product classes 15 and 16, DOE carried out an interpolation based on the 

results for product class 3, with a limitation on extent of the possible IEER increase based on 

room air conditioner size, due to the limited potential for growth of these product classes. 

The results of the extrapolations are tabulated in Table 5.6.51 through Table 5.6.53. Table 

5.6.36 through Table 5.6.43 shows the incremental cost data from which the extrapolated 

incremental costs were developed. 

Table 5.6.51 Extrapolated Incremental Cost Data for Product Classes 2, 4, 6, and 7 

Product Class 2 Product Class 4 Product Class 6 Product Class 7 

IEER Cost IEER Cost IEER Cost IEER Cost 

9.56 $8.34 9.65 $16.41 8.85 $5.48 8.88 $5.98 

10.1 $12.99 10.2 $26.81 9.4 $7.54 9.4 $8.33 

10.6 $19.14 10.7 $37.89 9.9 $10.91 9.9 $14.70 

11.1 $28.99 11.2 $69.21 10.3 $20.02 10.3 $22.00 

11.4 $43.66 

Table 5.6.52 Extrapolated Incremental Cost Data for Product Classes 9, 10, 11, 13 

Product Class 9 Product Class 10 Product Class 11 Product Class 13 

IEER Cost IEER Cost IEER Cost IEER Cost 

8.46 $13.72 8.47 $23.75 8.94 $13.09 8.47 $23.78 

9.0 $44.99 9.0 $99.45 9.5 $22.01 9.0 $37.47 

9.5 $155.27 9.5 $373.52 10.0 $32.52 9.4 $52.84 

10.5 $53.36 9.8 $75.30 

10 $104.34 

Table 5.6.53 Extrapolated Incremental Cost Data for Product Classes 12, 14, 15, 16 

Product Class 12 Product Class 14 Product Class 15 Product Class 16 

IEER Cost IEER Cost EER Cost EER Cost 

8.43 $7.18 7.97 $19.47 8.62 $10.39 9.41 $10.39 

9.0 $11.83 8.5 $76.19 9.2 $18.11 10.0 $18.11 

9.4 $18.09 9.0 $280.31 9.7 $26.34 10.5 $26.34 

9.8 $27.57 10.2 $103.57 11.0 $103.57 

Further Information. 

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The incremental cost data for active mode design options are detailed further in appendix 

5D. The appendix also provides incremental cost data for both the integrated metric (IEER) and 

non-integrated metric (EER). 

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REFERENCES 

1	 T Richter. 2005. Op. cit. 

2	 Kao, J. “Energy Test Results of a Conventional Clothes Dryer and a Condenser Clothes 

Dryer,” National Institute of Standards and Technology, Gaithersburg, MD, 1998. 

3	 For information on American Metals Market, please visit: www.amm.com. 

4	 2005 ASHRAE Handbook: Fundamentals. ASHRAE, Atlanta, GA 2005. 

4	 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 

5	 2008 ASHRAE Handbook: Fundamentals. ASHRAE, Atlanta, GA 2008. 

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