CHAPTER 3. MARKET AND TECHNOLOGY ASSESSMENT

TABLE OF CONTENTS

3.1 INTRODUCTION ........................................................................................................... 3-1

3.2 EQUIPMENT DEFINITIONS......................................................................................... 3-1

3.3 EQUIPMENT CLASSES ................................................................................................ 3-1

3.4 EQUIPMENT TEST PROCEDURES AND ENERGY USE METRIC ......................... 3-2

3.5 MANUFACTURER TRADE GROUPS ......................................................................... 3-3

3.6 MANUFACTURER INFORMATION ........................................................................... 3-4

3.6.1 Manufacturers and Market Shares ....................................................................... 3-4

3.6.2 Small Business Impacts ....................................................................................... 3-4

3.7 REGULATORY PROGRAMS ....................................................................................... 3-5

3.7.1 Federal Energy Conservation Standards .............................................................. 3-5

3.7.2 Foreign Power Regulatory Programs ................................................................... 3-6

3.8 VOLUNTARY PROGRAMS .......................................................................................... 3-7

3.8.1 ENERGY STAR .................................................................................................. 3-7

3.8.2 Federal Energy Management Program ................................................................ 3-8

3.8.3 ASHRAE Standard 90.1 ...................................................................................... 3-8

3.8.4 ASHRAE Standard 189.1 .................................................................................. 3-10

3.8.5 Consortium for Energy Efficiency ..................................................................... 3-11

3.8.6 Commercial Building Energy Alliance’s High Performance Rooftop Unit 

Challenge ........................................................................................................... 3-12

3.9 HISTORICAL SHIPMENTS......................................................................................... 3-13

3.9.1 Census Bureau Data ........................................................................................... 3-13

3.10 TECHNOLOGY ASSESSMENT .................................................................................. 3-13

3.10.1 Equipment Operations and Components ........................................................... 3-14

3.10.2 Technology Options ........................................................................................... 3-14

3.10.2.1 Compressor ............................................................................................... 3-15

3.10.2.2 Heat Exchangers ....................................................................................... 3-16

3.10.2.3 Condenser Fans and Fan Motors .............................................................. 3-17

3.10.2.4 Evaporator Fans and Fan Motors ............................................................. 3-18

3.1.1.1 Expansion Valves ..................................................................................... 3-19

3.10.3 Energy Efficiency .............................................................................................. 3-20

REFERENCES .......................................................................................................................... 3-24

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LIST OF TABLES

Table 3.3.1 Current Equipment Classes for Commercial Unitary Air Conditioner 

Market ............................................................................................................ 3-2

Table 3.7.1 Minimum Cooling and Heating Efficiency Levels for Air-Cooled 

Commercial Air Conditioners and Heat Pumps, ≥65,000 Btu/h and 

<760,000 Btu/h .............................................................................................. 3-6

Table 3.7.2 NRCan Minimum Performance Levels for Large Air Conditioners and 

Heat Pumps .................................................................................................... 3-7

Table 3.8.1 ENERGY STAR Criteria for Qualified Light Commercial Air 

Conditioners ................................................................................................... 3-8

Table 3.8.2 ASHRAE Standard 90.1–2010 Minimum Efficiency Requirements for 

Air-Cooled Electronically Operated Unitary Air Conditioners and Heat 

Pumps ............................................................................................................. 3-9

Table 3.8.3 Draft Addendum CL Proposed Minimum Efficiency Requirements for 

Air-Cooled Electronically Operated Unitary Air Conditioners and Heat 

Pumps ........................................................................................................... 3-10

Table 3.8.4 ASHRAE Standard 189.1–2011 Prescriptive Efficiency Requirements for 

Air-Cooled Electronically Operated Unitary Air Conditioners and Heat 

Pumps ........................................................................................................... 3-11

Table 3.8.5 CEE Specifications for Unitary Air Conditioning and Unitary Heat Pump ........... 3-12

Table 3.9.1 Shipments for Unitary Air Conditioners and Air Source Heat Pumps 

(excluding room air conditioners) ................................................................ 3-13

LIST OF FIGURES

Figure 3.10.1 Distribution of EER Levels for all CUAC considered by DOE .................. 3-21

Figure 3.10.2 Distribution of EER Levels for all CUHP considered by DOE ................... 3-21

Figure 3.10.3 Distribution of IEER Levels for all CUAC considered by DOE......................... 3-22

Figure 3.10.4 Distribution of IEER Levels for all CUHP considered by DOE ................. 3-22

Figure 3.10.5 Distribution of COP Levels for all CUHP considered by DOE................... 3-23

3-ii
CHAPTER 3. MARKET AND TECHNOLOGY ASSESSMENT

3.1 INTRODUCTION

This chapter provides a profile of small, large, and very large air-cooled commercial 

package air conditioning and heating equipment (also referred to in this notice as small, large, 

and very large air-cooled commercial unitary air conditioners (CUAC) and commercial unitary 

heat pumps (CUHP)) in the United States. The U.S. Department of Energy (DOE) developed the 

market and technology assessment presented in this chapter primarily from publicly available 

information. This assessment is helpful in identifying the major manufacturers and their 

equipment characteristics, which form the basis for the engineering and the life-cycle cost (LCC) 

analyses. Present and past industry structure and industry financial information help DOE in the 

process of conducting the manufacturer impact analysis. 

3.2 EQUIPMENT DEFINITIONS

DOE defines “Commercial package air-conditioning and heating equipment” under the 

Energy Policy and Conservation Act (EPCA) of 1975, Pub. L. 94-163, as air-cooled, watercooled, evaporatively-cooled, or water-source (not including groundwater-source) electricallyoperated, unitary central air conditioners and central air-conditioning heat pumps for commercial 

application. (42 United States Code (U.S.C.) 6311(8)(A)) This equipment is designed to heat and 

cool commercial buildings and is typically located on the building’s rooftop. This category of 

equipment has a rated capacity between 64,000 Btu/h and 760,000 Btu/h. 

This rulemaking is limited to air-cooled CUAC and CUHP rated at or greater than 64,000 

Btu/h, but less than 760,000 Btu/h. It does not cover water-cooled, evaporatively-cooled, or 

water-source equipment, nor does it cover equipment with cooling capacities of less than 64,000 

Btu/h. There are single package and split system air conditioners and heat pumps within these 

equipment types.

In the case of single-package units, which house all of the components (i.e., compressor, 

condenser and evaporator coils and fans, and associated operating and control devices) within a 

single cabinet, this package unit is typically located on the building’s rooftop. In the case of splitsystem units, the compressor and condenser coil and fan (or in the case of CUHP, the outdoor 

coil and fan) are housed in a cabinet typically located on the outside of the building, and the 

evaporator coil and fan (or in the case of CUHP, the indoor coil and fan) are housed in a cabinet 

typically located inside the building. 

3.3 EQUIPMENT CLASSES

When evaluating and establishing energy conservation standards, DOE divides covered 

equipment into equipment classes by the type of energy used or by capacity or other 

performance-related features that justifies a different standard. In making a determination 

whether a performance-related feature justifies a different standard, DOE considers such factors 

as the utility to the consumer of the feature and other factors DOE determines are appropriate.

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The current equipment classes as established in the Energy Policy Act of 2005, Pub. L. 

No. 109-58 (Aug. 8, 2005) (EPAct 2005) for small, large, and very large air-cooled CUAC and 

CUHP divide this equipment into twelve equipment classes characterized by rated cooling 

capacity, equipment type (air conditioner versus heat pump), and heating type. Table 3.3.1 shows 

the current equipment class structure. 

Table 3.3.1 Current Equipment Classes for Commercial Unitary Air Conditioner 

Market

Equipment 

Class Equipment Type Cooling Capacity SubCategory Heating Type

1 

Small Commercial Packaged 

Air-Conditioning and Heating 

Equipment (Air-Cooled)

≥65,000 Btu/h and 

<135,000 Btu/h

AC

Electric Resistance Heating or 

No Heating

2 All Other Types of Heating

3 

HP

Electric Resistance Heating or 

No Heating

4 All Other Types of Heating

5 

Large Commercial Packaged 

Air-Conditioning and Heating 

Equipment (Air-Cooled)

≥135,000 Btu/h and 

<240,000 Btu/h

AC

Electric Resistance Heating or 

No Heating

6 All Other Types of Heating

7 

HP

Electric Resistance Heating or 

No Heating

8 All Other Types of Heating

9 

Very Large Commercial 

Packaged Air-Conditioning 

and Heating Equipment (AirCooled)

≥240,000 Btu/h and 

<760,000 Btu/h

AC

Electric Resistance Heating or 

No Heating

10 All Other Types of Heating

11

HP

Electric Resistance Heating or 

No Heating

12 All Other Types of Heating

AC=Air conditioner; HP=Heat pump

3.4 EQUIPMENT TEST PROCEDURES AND ENERGY USE METRIC

DOE’s test procedures for small, large, and very large, air-cooled CUAC and CUHP 

appear at 10 CFR 431.96. The May 2012 Test Procedure Final Rule amended the test procedures 

for small, large, and very large, air-cooled CUAC and CUHP to incorporate by reference AirConditioning, Heating and Refrigeration Institute (AHRI) Standard 340/360–2007, “Performance 

Rating of Commercial and Industrial Unitary Air-Conditioning and Heat Pump Equipment,” 

including Addendum 1 in December 2010 and Addendum 2 in June 2011 (AHRI Standard 

340/360–2007). 77 FR 28928 (May 16, 2012). AHRI Standard 340/360–2007 includes methods 

and procedures for testing and rating equipment cooling efficiency with both an energy 

efficiency ratio (EER) and integrated energy efficiency ratio (IEER) metric. EER is the ratio of 

the cooling capacity (in Btu/h) to the power input (in watts), and provides a measure of the 

efficiency of equipment operating at full load (i.e., 100 percent cooling capacity). IEER is a 

single number figure of merit expressing cooling part-load EER efficiency on the basis of 

weighted operation at various load capacities for the equipment. The IEER metric factors in the 

efficiency of operating at part-loads of 75 percent, 50 percent, and 25 percent of capacity as well 

as the efficiency at full load. This is accomplished by weighting the full- and part-load 

efficiencies with the average amount of time operating at each loading point. The IEER metric 

3-2 
incorporates part load efficiencies measured with outside temperatures appropriate for the load 

levels, i.e. at lower temperatures for lower load levels. 

AHRI Standard 340/360–2007 also specifies methods and procedures for testing and 

rating equipment heating efficiency for air-cooled CUHP based on the COP metric. The heating 

efficiency COP is the ratio of the heating capacity (in watts) to the power input (in watts).a AHRI 

Standard 340/360–2007 provides methods to rate the COP at both high-temperature steady-state 

heating conditions (47 degrees Fahrenheit (°F) dry bulb and 43 °F wet bulb) and lowtemperature steady-state heating conditions (17 °F dry bulb and 15 °F wet bulb). 

The current energy conservation standards for small, large, and very large air-cooled 

CUAC and CUHP cooling efficiency are based on the EER metric. For CUHP, the current 

heating efficiency standards for this equipment are based on the COP metric, rated at the hightemperature steady-state heating rating conditions. (10 CFR 431.97) As discussed in chapter 5 of 

this TSD, DOE is proposing energy conservation standards for small, large, and very large, aircooled CUAC and CUHP based on the IEER metric for cooling efficiency and (in the case of 

CUHP) the COP metric (at the high-temperature steady-state heating rating conditions) for 

heating efficiency.

3.5 MANUFACTURER TRADE GROUPS

DOE recognizes the importance of trade groups in disseminating information and 

promoting the interests of the industry that they support. To gain insight into the CUAC and 

CUHP industry, DOE researched various associations available to manufacturers, suppliers, and 

users of such equipment. DOE also used the member lists of these groups in the construction of 

an exhaustive database containing domestic manufacturers. DOE identified AHRI as the most 

prominent trade association for CUAC and CUHP manufacturers. AHRI coordinates with 

member manufacturers to establish the Unitary Large Equipment Section within AHRI. This

section serves to develop standards and implement a certification program for small, large, and 

very large air-cooled CUAC and CUHP. 

The Unitary Large Equipment section applies to: 

• One piece or matched split-system air conditioners and air-source heat pumps with 

cooling capacities of 65,000 Btu/h and above, 

• Condensing units for air conditioning applications with cooling capacities of 65,000 

Btu/h and above, and 

• Evaporator coils with or without blowers intended for use as a part of a matched split 

system.

The technical activities of AHRI include: 

• working to harmonize international equipment standards; 

• developing industry performance standards for CUAC and CUHP; 

a Any supplementary resistance heat is excluded from the test. 

3-3 

 
• updating industry guidelines for operation and installation of CUAC and CUHP

equipment; 

• communicating with refrigerant suppliers and government agencies about 

environmentally acceptable refrigerants; and 

• providing input to government agencies concerning regulations affecting the industry. 

3.6 MANUFACTURER INFORMATION

The following section details information regarding domestic manufacturers of CUAC 

and CUHP, including estimated market shares (section 3.6.1) and potential small business 

impacts (section 3.6.2). 

3.6.1 Manufacturers and Market Shares

Current members of AHRI’s Unitary Large Equipment division are listed below; parent 

companies are shown in parentheses if applicable.1

• Aaon, Inc.

• Allied Air Enterprises (Lennox International, Inc.)

• Carrier Corporation (United Technologies Corporation) 

• Daikin Industries

• Goodman Manufacturing Company, LP (Daikin Industries)

• IntelliChoice Energy

• Johnson Controls, Inc. 

• Lennox International, Inc.

• Magic Aire (United Electric Company)

• NORDYNE (Nortek, Inc.)

• Rheem Sales Company (Paloma Co.) 

• Trane (Ingersoll-Rand)

• United CoolAir Corp. 

Six of the major companies listed above, Carrier, Trane, Lennox, York, Goodman, and 

Aaon, hold the majority of the market. Of these six companies, the first five manufacture 

equipment in all four of the major equipment categories that this rulemaking covers (both singlepackage and split-system air conditioners and heat pumps). Aaon manufactures high-efficiency 

year-round, air-cooled, single-package air conditioners (SPY-A) equipment for sale almost 

exclusively to large corporate accounts. 

3.6.2 Small Business Impacts

DOE considered the possibility that energy conservation standards for small, large, and 

very large air-cooled CUAC and CUHP would adversely affect small businesses. For

manufacturers of small, large, and very large air-cooled CUAC and CUHP, the Small Business 

Administration (SBA) has set a size threshold, which defines those entities classified as “small 

businesses.” DOE used the SBA’s small business size standards to determine whether any small 

entities would be subject to the requirements of the rule. 65 FR 30836, 30848 (May 15, 2000), as 

amended at 65 FR 53533, 53544 (Sept. 5, 2000) and codified at 13 CFR part 121. The size 

3-4 
standards are listed by North American Industry Classification System (NAICS) code and 

industry description and are available at http://www.sba.gov/category/navigationstructure/contracting/contracting-officials/small-business-size-standards. Manufacturing of 

small, large, and very large air-cooled CUAC and CUHP is classified under NAICS 333415, 

“Air-Conditioning and Warm Air Heating Equipment and Commercial and Industrial 

Refrigeration Equipment Manufacturing.” The SBA sets a threshold of 750 employees or less for 

an entity to be considered as a small business for this category. 

DOE studied the potential impacts on these small businesses in detail during the 

manufacturer impact analysis, which was conducted as a part of the notice of proposed 

rulemaking (NOPR) analysis. DOE initially identified at least 12 potential manufacturers of 

commercial packaged air conditioners sold in the U.S. DOE then determined that 10 were large 

manufacturers, manufacturers that are foreign owned and operated, or manufacturers that do not 

produce equipment covered by this rulemaking. DOE was able to determine that 2 

manufacturers meet the SBA’s definition of a “small business” and manufacture equipment 

covered by this rulemaking. For more details, please consult chapter 12 of the NOPR TSD. 

3.7 REGULATORY PROGRAMS

The following section details current regulatory programs mandating energy conservation 

standards for commercial unitary air conditioners and heat pumps. Section 3.7.1 discusses 

Federal energy conservation standards. In addition, section 3.7.2 reviews foreign regulatory 

programs that may impact the companies servicing the North American market. 

3.7.1 Federal Energy Conservation Standards 

For small, large, and very large air-cooled CUAC and CUHP, the last final rule issued by 

DOE was on October 18, 2005, which codified both the amended standards for small and large 

equipment and the new standards for very large equipment set by the EPAct 2005. 70 FR 60407. 

The current standards are shown in Table 3.7.1

. 

3-5 
Table 3.7.1 Minimum Cooling and Heating Efficiency Levels for Air-Cooled Commercial 

Air Conditioners and Heat Pumps, ≥65,000 Btu/h and <760,000 Btu/h

Equipment Type Cooling Capacity SubCategory Heating Type Efficiency 

Level

Compliance 

Date

Small Commercial Packaged 

Air-Conditioning and Heating 

Equipment (Air-Cooled)

≥65,000 Btu/h and 

<135,000 Btu/h

AC

Electric Resistance 

Heating or No Heating EER = 11.2 1/1/2010

All Other Types of 

Heating EER = 11.0 1/1/2010

HP

Electric Resistance 

Heating or No Heating

EER = 11.0

COP = 3.3 1/1/2010

All Other Types of 

Heating

EER = 10.8

COP = 3.3 1/1/2010

Large Commercial Packaged 

Air-Conditioning and Heating 

Equipment (Air-Cooled)

≥135,000 Btu/h and 

<240,000 Btu/h

AC

Electric Resistance 

Heating or No Heating EER = 11.0 1/1/2010

All Other Types of 

Heating EER = 10.8 1/1/2010

HP

Electric Resistance 

Heating or No Heating

EER = 10.6

COP = 3.2 1/1/2010

All Other Types of 

Heating

EER = 10.4

COP = 3.2 1/1/2010

Very Large Commercial 

Packaged Air-Conditioning 

and Heating Equipment (AirCooled)

≥240,000 Btu/h and 

<760,000 Btu/h

AC

Electric Resistance 

Heating or No Heating EER = 10.0 1/1/2010

All Other Types of 

Heating EER = 9.8 1/1/2010

HP

Electric Resistance 

Heating or No Heating

EER = 9.5

COP = 3.2 1/1/2010

All Other Types of 

Heating

EER = 9.3

COP = 3.2 1/1/2010

3.7.2 Foreign Power Regulatory Programs 

The Natural Resources Canada (NRCan) Office of Energy Efficiency has established new 

energy efficiency standards for commercial unitary air conditioners as of April 12, 2012. The 

NRCan standard covers all CUAC and CUHP equipment with cooling capacities between 65,000 

Btu/h to 760,000 Btu/h. The latest change harmonized the minimum efficiency requirements 

with the American Society of Heating, Refrigerating, and Air-Conditioning Engineers 

(ASHRAE) Standard 90.1–2007, “Energy Standard for Buildings Except Low-Rise Residential 

Buildings” (ASHRAE Standard 90.1–2007). 

The test method for evaluating the energy performance of large air conditioners and heat 

pumps is CSA-C746–2006: Performance Standard for Rating Large and Single Package Vertical 

Air Conditioners and Heat Pumps.

Table 3.7.2 contains a summary of the minimum efficiency standards set by NRCan.

3-6 
Table 3.7.2 NRCan Minimum Performance Levels for Large Air Conditioners and Heat 

Pumps

Equipment Type Cooling Capacity SubCategory Heating Type EER IEER COP

Small Commercial 

Packaged AirConditioning and Heating 

Equipment (Air-Cooled)

≥65,000 Btu/h and 

<135,000 Btu/h

AC

Electric Resistance Heating 

or No Heating 11.2 11.4 NA

All Other Types of Heating 11.0 11.2 NA

HP

Electric Resistance Heating 

or No Heating 11.0 11.2 3.3/2.25

All Other Types of Heating 10.8 11.0

Large Commercial 

Packaged AirConditioning and Heating 

Equipment (Air-Cooled)

≥135,000 Btu/h and 

<240,000 Btu/h

AC

Electric Resistance Heating 

or No Heating 11.0 11.2 NA

All Other Types of Heating 10.8 11.0 NA

HP

Electric Resistance Heating 

or No Heating 10.6 10.7 3.2/2.05

All Other Types of Heating 10.4 10.5

Very Large Commercial 

Packaged AirConditioning and Heating 

Equipment (Air-Cooled)

≥240,000 Btu/h and 

<760,000 Btu/h

AC

Electric Resistance Heating 

or No Heating 10.0 9.8 NA

All Other Types of Heating 10.1 9.9 NA

HP

Electric Resistance Heating 

or No Heating 9.5 9.6 3.2/2.05

All Other Types of Heating 9.3 9.4

Source: http://oee.nrcan.gc.ca/regulations/bulletins/1230

3.8 VOLUNTARY PROGRAMS

DOE reviewed voluntary programs promoting energy efficient CUAC and CUHP in the 

United States. DOE noted that ENERGY STAR, the Federal Energy Management Program 

(FEMP), ASHRAE and the Consortium for Energy Efficiency (CEE) establish voluntary energy 

conservation standards for this equipment. 

3.8.1 ENERGY STAR

The ENERGY STAR standards issued by the EPA have been effective since May 2010. 

ENERGY STAR sets cooling and (for heat pumps) heating efficiency levels for air-source 

central air conditioners and heat pumps with cooling capacity of ≥65,000 to <135,000 Btu/h (i.e., 

small air-cooled CUAC and CUHP). Table 3.8.1 contains the ENERGY STAR criteria for the 

equipment covered under this rulemaking. 

3-7 
Table 3.8.1 ENERGY STAR Criteria for Qualified Light Commercial Air Conditioners

Equipment Type Size Category Heating Section 

Type EER IEER COP

Air-Source Central Air 

Conditioner

≥65,000 Btu/h -

<135,000 Btu/h

Electric Resistance 

(or None) 11.7 11.8

≥65,000 Btu/h -

<135,000 Btu/h All Other 11.5 11.6

Air-Source Central Air 

Conditioner

≥135,000 Btu/h -

<240,000 Btu/h

Electric Resistance 

(or None) 11.7 11.8

≥135,000 Btu/h -

<240,000 Btu/h All Other 11.5 11.6

Air-Source Heat Pump ≥65,000 Btu/h -

<135,000 Btu/h

Electric Resistance 

(or None) 11.3 11.4 3.35

Air Source Heat Pump ≥65,000 Btu/h -

<135,000 Btu/h

Electric Resistance 

(or None) 10.9 11 3.25

Source: ENERGY STAR (http://www.energystar.gov/index.cfm?c=lchvac.pr_crit_lchvac) 

3.8.2 Federal Energy Management Program 

DOE’s FEMPb works to reduce the cost and environmental impact of the Federal 

government by advancing energy efficiency and water conservation, promoting the use of 

distributed and renewable energy, and improving utility management decisions at Federal sites. 

FEMP helps Federal buyers identify and purchase energy efficient equipment, including small, 

large, and very large air-cooled CUAC and CUHP. 

FEMP uses the ENERGY STAR standards described in Section 3.8.1 as the energy 

efficiency requirements for federal agencies.

3.8.3 ASHRAE Standard 90.1 

The American Society of Heating, Refrigerating, and Air-Conditioning Engineers 

(ASHRAE) releases ASHRAE Standard 90.1 every three years. At the time of publication, the 

latest version is ASHRAE Standard 90.1–2010. Table 3.8.2 shows the energy efficiency 

requirements specified in ASHRAE Standard 90.1–2010 for each equipment class covered by 

this rulemaking. 

b For more information visit http://www.eere.energy.gov/femp. 

3-8 

 
Table 3.8.2 ASHRAE Standard 90.1–2010 Minimum Efficiency Requirements for AirCooled Electronically Operated Unitary Air Conditioners and Heat Pumps

Equipment Type Heating Type IEER EER COP*

Small Commercial 

Packaged AC and HP 

(Air-Cooled) – ≥65,000 

Btu/h and <135,000 

Btu/h Cooling Capacity

AC

Electric Resistance 

Heating or No 

Heating

11.4 11.2

All Other Types of 

Heating 11.2 11.0 3.3 / 2.25

HP

Electric Resistance 

Heating or No 

Heating

11.2 11.0

All Other Types of 

Heating 11.0 10.8 3.3 / 2.25

Large Commercial 

Packaged AC and HP 

(Air-Cooled) – 

≥135,000 Btu/h and 

<240,000 Btu/h Cooling 

Capacity

AC

Electric Resistance 

Heating or No 

Heating

11.2 11.0

All Other Types of 

Heating 11.0 10.8 3.2 / 2.05

HP

Electric Resistance 

Heating or No 

Heating

10.7 10.6

All Other Types of 

Heating 10.5 10.4 3.2 / 2.05 

Very Large Commercial 

Packaged AC and HP 

(Air-Cooled) – ≥240,000 

Btu/h and <760,000 

Btu/h Cooling Capacity

AC

Electric Resistance 

Heating or No 

Heating

10.1 10.0

All Other Types of 

Heating 9.9 9.8 3.2 / 2.05

HP

Electric Resistance 

Heating or No 

Heating

9.6 9.5

All Other Types of 

Heating 9.4 9.3 3.2 / 2.05

* COP is regulated at two points: at 1) 47  ̊F dry bulb (db) / 43  ̊F wet bulb (wb) outdoor air and 2) 17  ̊F db / 15  ̊F 

wb outdoor air

ASHRAE periodically updates the specifications in its Standard 90.1 through a public 

review process. The latest of these proposed changes is contained in the draft of addendum CL to 

ASHRAE Standard 90.1–2010 (Draft Addendum CL), which was made available for public 

review in October 2012. Table 3.8.3 shows the energy efficiency requirements proposed in 

Addendum CL for each equipment class covered by this rulemaking. The proposed IEER 

requirements are 6.5 percent to 15.2 percent higher than the levels specified in the current 

ASHRAE Standard 90.1–2010. The proposed EER and COP requirements did not change from 

the current ASHRAE Standard 90.1–2010. 

3-9 
Table 3.8.3 Draft Addendum CL Proposed Minimum Efficiency Requirements for AirCooled Electronically Operated Unitary Air Conditioners and Heat Pumps

Equipment Type Heating Type IEER EER COP*

Small Commercial 

Packaged AC and HP 

(Air-Cooled) – ≥65,000 

Btu/h and <135,000 Btu/h 

Cooling Capacity

AC

Electric Resistance 

Heating or No 

Heating

12.9 11.2

All Other Types of 

Heating 12.7 11.0

HP

Electric Resistance 

Heating or No 

Heating

12.2 11.0 3.3 / 2.25 

All Other Types of 

Heating 12.0 10.8 3.3 / 2.25

Large Commercial 

Packaged AC and HP 

(Air-Cooled) – ≥135,000 

Btu/h and <240,000 Btu/h 

Cooling Capacity

AC

Electric Resistance 

Heating or No 

Heating

12.2 11.0

All Other Types of 

Heating 12.0 10.8

HP

Electric Resistance 

Heating or No 

Heating

11.4 10.6 3.2 / 2.05

All Other Types of 

Heating 11.2 10.4 3.2 / 2.05

Very Large Commercial 

Packaged AC and HP 

(Air-Cooled) – ≥240,000 

Btu/h and <760,000 Btu/h 

Cooling Capacity

AC

Electric Resistance 

Heating or No 

Heating

11.6 10.0

All Other Types of 

Heating 11.4 9.8

HP

Electric Resistance 

Heating or No 

Heating

10.6 9.5 3.2 / 2.05

All Other Types of 

Heating 10.4 9.3 3.2 / 2.05

* COP is regulated at two points: at 1) 47  ̊F db / 43  ̊F wb outdoor air and 2) 17  ̊F db / 15  ̊F wb outdoor air

3.8.4 ASHRAE Standard 189.1 

ASHRAE Standard 189.1–2011, “Standard for the Design of High-Performance Green 

Buildings,” (ASHRAE Standard 189.1–2011) provides minimum requirements for the siting, 

design, construction, and plan for operation of high-performance green buildings.c Table 3.8.4

presents the prescriptive efficiency requirements for small, large, and very large air-cooled 

CUAC and CUHP specified in ASHRAE Standard 189.1–2011. 

c ASHRAE Standard 189.1–2011 is available online at: https://www.ashrae.org/resources--

publications/bookstore/standard-189-1. 

3-10 

 
Table 3.8.4 ASHRAE Standard 189.1–2011 Prescriptive Efficiency Requirements for AirCooled Electronically Operated Unitary Air Conditioners and Heat Pumps

Equipment Type Heating Type IEER EER COP*

Small Commercial 

Packaged AC and HP 

(Air-Cooled) – ≥65,000 

Btu/h and <135,000 Btu/h 

Cooling Capacity

AC

Electric Resistance 

Heating or No 

Heating

12.0 11.5

All Other Types of 

Heating 11.8 11.3

HP

Electric Resistance 

Heating or No 

Heating

11.8 11.3 3.3 / 2.2

All Other Types of 

Heating 11.6 11.1 3.3 / 2.2

Large Commercial 

Packaged AC and HP 

(Air-Cooled) – ≥135,000 

Btu/h and <240,000 Btu/h 

Cooling Capacity

AC

Electric Resistance 

Heating or No 

Heating

12.0 11.5

All Other Types of 

Heating 11.8 11.3

HP

Electric Resistance 

Heating or No 

Heating

11.8 11.3 3.2 / 2.0

All Other Types of 

Heating 11.6 11.1 3.2 / 2.0

Very Large Commercial 

Packaged AC and HP 

(Air-Cooled) – ≥240,000 

Btu/h and <760,000 Btu/h 

Cooling Capacity

AC

Electric Resistance 

Heating or No 

Heating

10.5 10.0

All Other Types of 

Heating 10.3 9.8

HP

Electric Resistance 

Heating or No 

Heating

9.8 9.8 3.2 / 2.0

All Other Types of 

Heating 9.6 9.6 3.2 / 2.0

* COP is regulated at two points: at 1) 47  ̊F db / 43  ̊F wb outdoor air and 2) 17  ̊F db / 15  ̊F wb outdoor air

3.8.5 Consortium for Energy Efficiency 

CEE released new specifications for CUAC and CUHP effective on January 6, 2012. 

Table 3.8.5 contains the CEE specifications for the covered equipment in this rulemaking. 

3-11 
Table 3.8.5 CEE Specifications for Unitary Air Conditioning and Unitary Heat Pump 

Equipment Size Size 

Category Heating Section Type CEE Tier 0 CEE tier 1 CEE Tier 2

Small Commercial 

Packaged AC and HP 

(Air-Cooled) – 

≥65,000 Btu/h and 

<135,000 Btu/h 

Cooling Capacity

AC

Electric Resistance 

Heating or No Heating

11.7 EER

11.8 IEER

11.7 EER

13.0 IEER

12.2 EER

14.0 IEER

All Other Types of 

Heating

11.5 EER

11.6 IEER

11.5 EER

12.8 IEER

3.4/2.4 COP

12.0 EER

13.8 IEER

HP

Electric Resistance 

Heating or No Heating

11.3 EER

11.4 IEER

11.3 EER

12.3 IEER NA*

All Other Types of 

Heating

11.1 EER

11.2 IEER

11.1 EER

12.1 IEER

3.4/2.4 COP

NA*

Large Commercial 

Packaged AC and HP 

(Air-Cooled) – 

≥135,000 Btu/h and 

<240,000 Btu/h 

Cooling Capacity

AC

Electric Resistance 

Heating or No Heating

11.7 EER

11.8 IEER

11.7 EER

12.5 IEER

12.2 EER

13.2 IEER

All Other Types of 

Heating

11.5 EER

11.6 IEER

11.5 EER

12.3 IEER

3.2/2.1 COP

12.0 EER

13.0 IEER

HP

Electric Resistance 

Heating or No Heating

10.9 EER

11.0 IEER

10.9 EER

11.9 IEER NA*

All Other Types of 

Heating

10.7 EER

10.8 IEER

10.7 EER

11.7 IEER

3.2/2.1 COP

NA*

Very Large 

Commercial Packaged 

AC and HP (AirCooled) – ≥240,000 

Btu/h and <760,000 

Btu/h Cooling 

Capacity

AC

Electric Resistance 

Heating or No Heating

10.5 EER

10.6 IEER

10.5 EER

11.3 IEER

10.8 EER

12.3 IEER

All Other Types of 

Heating

10.3 EER

10.4 IEER

10.3 EER

11.1 IEER

10.6 EER

12.1 IEER

HP

Electric Resistance 

Heating or No Heating

10.3 EER

10.4 IEER

10.3 EER

10.9 IEER NA*

All Other Types of 

Heating

10.1 EER

10.2 IEER

10.1 EER

10.7 IEER NA*

* For some equipment classes, CEE is not establishing higher tier levels due to limited availability. 

Source: Consortium for Energy Efficiency. CEE Commercial Unitary AC and HP Specification. 

http://www.cee1.org/files/CEE_CommHVAC_UnitarySpec2012.pdf

3.8.6 Commercial Building Energy Alliance’s High Performance Rooftop Unit Challenge

The Commercial Building Energy Alliance (CBEA) technology transfer program 

sponsors the High Performance Rooftop Unit Challenge (RTU Challenge).d

 This program 

provides a market mechanism that reduces barriers for manufacturers to procure greater than 18-

IEER 10-tone

 equipment and encourages the private sector to commit to adopt energy-efficient 

equipment. A number of manufacturers are currently participating in the RTU Challenge, 

including Lennox, 7AC Technologies, Rheem, Carrier, and McQuay. Of these participants, both 

d Additional information is available online at: http://www4.eere.energy.gov/alliance/activities/technologysolutions-teams/space-conditioning/rtu. e Air conditioning cooling capacity may be denoted in tons. An air conditioning ton is equivalent to 12,000 Btu/h of 

cooling capacity (or 3.5 kilowatts of cooling capacity).

3-12 

 
Carrier and McQuay have already begun producing AHRI-certified equipment meeting or 

exceeding 18 IEER. In conjunction with manufacturer support, fourteen CBEA-member private 

entities, such as Target Corp., Macy’s, Inc., McDonald’s Corp., and others, have also signaled 

their support and indicated their strong interest in potentially purchasing high-efficiency rooftop 

units, a sign of their confidence in the RTU Challenge and its ability to use IEER to accurately 

portray the energy use of air-cooled CUAC and CUHP in the field. 

3.9 HISTORICAL SHIPMENTS

Awareness of annual equipment shipment trends is an important aspect of the market 

assessment and in the development of the standards rulemaking. DOE reviewed data collected by 

the U.S. Census Bureau to evaluate equipment shipment trends and the value of these shipments, 

which were used during the shipments analysis (chapter 9 of this NOPR TSD.) 

3.9.1 Census Bureau Data

The U.S. Census Bureau’s Current Industrial Report (CIR) series publishes statistics on 

the quantity and value of shipments based on a survey of manufacturers. The CIR has been 

published since 1904, and DOE collected CIR data for purposes of evaluating prices and 

shipments. The Census has not updated its statistics since the publication of the preliminary 

analysis.

Table 3.9.1 shows shipment data for unitary air conditioners and air source heat pumps. 

Table 3.9.1 Shipments for Unitary Air Conditioners and Air Source Heat Pumps 

(excluding room air conditioners)

Equipment Descriptions Year Quantity Value Companies

Unitary air-conditioners, 

excluding air source heat pumps 

2010 6,252 6,251,785 10

2009 6,022 6,022,027 -

Air source heat pumps, 

excluding room air-conditioners 

2010 2,155 2,155,119 10

2009 2,138 2,137,858 -

Source: U.S. Census Bureau, Current Industrial Reports, MA333M – Refrigeration, Air Conditioning and Warm Air 

Heating Equipment Data Tables, http://www.census.gov/manufacturing/cir/historical_data/ma333m/

3.10 TECHNOLOGY ASSESSMENT 

This section provides a technology assessment for air-cooled CUAC and CUHP. The 

purpose of the technology assessment is to develop a preliminary list of technologies that could 

potentially be used to improve the efficiency of air-cooled CUAC and CUHP. The following 

assessment provides descriptions of technologies and designs that apply to subsystems within all 

equipment classes of air-cooled CUAC and CUHP. 

Contained in this technology assessment are details about equipment characteristics and 

operation (section 3.10.1), an examination of possible technological improvements (section 

3.10.2), and a characterization of the equipment efficiency levels currently commercially

available (section 3.10.3).

3-13 
3.10.1 Equipment Operations and Components

In preparation for the screening and engineering analyses, DOE prepared a brief 

description of the characteristics and operation of air-cooled CUAC and CUHP. This description 

provides a basis for understanding the technologies used to improve equipment efficiency.

CUAC and CUHP are refrigeration-based equipment that enable users to cool or warm an 

enclosed space, zone, or building. In addition to the primary cooling or warming function, 

CUAC also reduce the relative humidity (RH) of the conditioned space. RH is defined as the 

amount of water vapor present in the air compared to the maximum amount of water vapor the 

air can hold at that temperature, these amounts being expressed as partial pressures of the water 

vapor. CUAC are designed for permanent installation, typically on a building’s rooftop. CUAC

are classified according to the amount of heat that can be removed from the room air during a 

given time period, called the capacity, expressed in Btu/h. 

CUAC and CUHP contain refrigeration systems that remove both sensible and latent heat 

(i.e. thermal load associated with water vapor in the air) from indoor air. The key refrigerant-side 

components include the evaporator(s) (indoor conditioning coil(s)), the compressor(s), the 

condenser(s) (outdoor coil(s)), and an expansion valve (capillary tube(s), thermostatic expansion 

valve(s) (TXV), or electronic expansion valves (EEV)). These components are all connected 

with refrigerant tubing. The air-side components consist of the evaporator (or indoor coil) fan 

motor(s)and blower(s), and the condenser (or outdoor coil) fan motor(s) and fan(s). 

Single-package units, which house all of the components (i.e., compressor(s), condenser 

and evaporator coils, fans, and associated operating and control devices) within a single cabinet, 

are typically installed on the building’s rooftop. The single cabinet containing both refrigerantside and air-side components is split into an indoor and outdoor side. An insulated divider wall 

separates the two sides and reduces the heat transfer between sides. The indoor components for 

an air conditioner are the evaporator(s) and evaporator blower(s). The outdoor components for an 

air conditioner are the compressor(s), condenser(s), expansion valve(s), fan motor(s), and 

condenser fan(s). For heat pumps, the indoor heat exchanger serves as the evaporator during 

cooling mode and the condenser during heating mode—vice versa for the outdoor heat 

exchanger. Hence, for heat pumps, the heat exchangers and their fans are referred to as indoor or 

outdoor components, e.g. indoor coil and indoor fan. In addition, heat pumps have reversing 

valves that allow the system to switch from cooling mode to heating mode. In split-system units, 

the compressor(s), condenser coil(s), and fan(s) (or in the case of heat pumps, the compressor(s), 

outdoor coil(s), and outdoor fan(s)) are housed in a cabinet typically located on the outside of the 

building, and the evaporator coil(s) and fan(s) (or in the case of heat pumps, the indoor coil(s)

and fan(s)) are housed in a cabinet typically located inside the building. 

3.10.2 Technology Options 

In order to gain a deeper understanding of the technological improvements used to 

increase the efficiency of commercial unitary air conditioners and heat pumps, DOE identified 

several possible technologies and examined the most common improvements used in today’s 

market. 

3-14 
3.10.2.1 Compressor

The compressor is the primary energy consuming component in CUAC and CUHP. Most 

equipment use hermetic compressors in which the entire motor-compressor assembly is 

hermetically sealed in the welded steel shell. Scroll compressors are the most commonly used 

compressors in this application. Scroll compressors compress gas in a fundamentally different 

manner from traditional compressors—between two spirals, one fixed and one rotating. 

High-Efficiency Compressors

Conversion to high-efficiency compressors is fairly straightforward for manufacturers to 

implement as long as compressors of a suitable capacity are commercially available and they do 

not present additional challenges such as larger physical size or greater noise power levels. 

However, for scroll compressors generally used for commercial air conditioning equipment, 

there are few or no commercially available options with improved efficiency. 

Variable-Capacity or Multiple-Tandem Compressors

Most conventional single speed compressors run at a constant speed and equipment using 

such compressors vary their capacity by cycling the compressor(s) on and off in response to the 

thermostat. Variable-speed compressors are typically implemented through the use of an 

electronic control that varies the input frequency of the power supply for the compressor motor. 

Variable-speed compressors enable modulation of the refrigeration-system cooling capacity, 

allowing the air conditioner to match the cooling load. The effectiveness of the heat exchangers 

is greater during operation with reduced mass flow at part load, thus reducing the condensing 

temperature and increasing the evaporating temperature required to transfer the load—this in turn 

reduces the compressor’s operating pressure ratio and its power input. There are non-energy 

advantages to variable-speed control, including quieter operation at low speeds, enhanced 

comfort by eliminating temperature fluctuations in the room, and potential for improved 

dehumidification. 

The control of variable-speed compressors is accomplished through the use of electronic 

adjustable-speed drives (ASDs) at the motor. Because electronic ASDs require no drive-train in 

order to be coupled to the motor, they can be used with the sealed refrigeration systems used in 

commercial unitary air conditioners. ASDs can be designed for use with induction motors or 

with permanent-magnet brushless motors. There are two inverter types that are applicable to 

induction motors typically used in scroll compressors: voltage source (VSI) and pulse-width 

modulated voltage source (PWM) inverters. In either case, the input AC power supply is first 

converted to DC by using a solid-state rectifier. This DC signal is then converted to a variablefrequency AC waveform by the inverter and supplied to the motor. The speed of the motor is 

roughly proportional to the frequency. 

A recently-developed method for modulating capacity in scroll compressors is 

intermittent discharge. This technology utilizes a pressure control system in which a solenoid 

valve opens, relieving the pressure on the back side of a piston. This spring-loaded piston is 

connected to the rotating scroll, and the scroll-piston system is then displaced once the 

backpressure is removed. This displacement disengages the scrolls, leaving the driveshaft free to 

rotate without any compression taking place. Modulating the time in which the scrolls are 

3-15 
engaged allows capacity to be varied from 10 to 100 percent of maximum. Intermittent discharge 

technology, however, is only applicable to scroll compressors, and is a proprietary approach. 

Moreover, such compressors are only available in capacities up to 6 tons, though overall capacity 

can be increased by using these compressors in tandem with other fixed-capacity compressors. 

Most CUAC and CUHP units use more than one compressor. Hence, some reduction of 

capacity is incorporated into most designs by staging of the multiple compressors. However, 

most CUAC and CUHP units with multiple compressors use separate refrigerant circuits for the 

separate compressors. Use of multiple compressors to achieve the efficiency gains associated 

with improved heat exchanger effectiveness resulting from reduction of mas flow at part load 

requires that the staged compressors operate in parallel in the same refrigerant circuit. This 

multiple tandem compressor arrangement is an alternative to use of variable speed or intermittent 

discharge compressors to improve part-load efficiency using multiple compressors. 

3.10.2.2 Heat Exchangers

The covered equipment in this rulemaking use air-cooled heat exchangers to transfer heat 

to and from the refrigerant system. These CUACs and CUHPs use either fin-and-tube or 

microchannel heat exchangers. Fin-and-tube heat exchangers are generally made using copper 

tubes and aluminum fins, while microchannel heat exchangers are generally entirely aluminum. 

Larger Heat Exchangers 

Increasing the heat transfer surface area of the heat exchangers can be achieved by 

increasing their width, height, or depth. These measures can improve heat transfer effectiveness, 

which can reduce the condensing temperature and increase the evaporating temperature needed 

to transfer the cooling (or heating) load. Such temperature adjustments reduce the compressor’s 

compression ratio and hence its required power input. However, size increases can be limited by 

the geometry of the equipment. Also, even if size increase is possible, or the equipment size is 

increased to accommodate larger heat exchangers, the added refrigerant-side or air-side pressure 

drop can reduce the overall potential for efficiency gains. Excessive increase in evaporating 

temperature in cooling mode can also reduce the equipment’s ability to remove moisture from 

the air, which is a key function of CUAC and CUHP equipment. Nevertheless, increase in heat 

exchanger size is a key option for efficiency improvement of this equipment 

Microchannel Heat Exchangers

Microchannel heat exchangers are fabricated entirely of aluminum using flat tubes with 

multiple small channels (typically less than 1mm across) through which refrigerant passes. 

Aluminum fins are brazed between the rectangular tubes. Headers at the ends of the heat 

exchangers distribute the refrigerant flow into the multiple tubes and recollect the refrigerant 

exiting the tubes. Microchannel heat exchangers can increase heat transfer while reducing 

pressure drop as compared with conventional coils. Microchannel heat exchangers generally 

weigh less and hold significantly less refrigerant than a comparable conventional heat exchanger. 

3-16 
Electro-Hydrodynamic Enhancement

Electro-hydrodynamic enhancement (EHD) of heat transfer is the result of applying a 

high-voltage electrostatic potential field across a heat transfer fluid, such as a refrigerant or 

refrigerant mixture. The applied field destabilizes the thermal boundary layer, thereby producing 

better mixing of the bulk fluid flow and increasing the net heat transfer coefficient. EHD is 

achieved by applying an electrical voltage to the heat transfer device. However, because the heat 

transfer fluids are typically dielectric (of low electrical conductivity), even high voltages produce 

very little current. This low current helps keep the power and the associated energy penalty low. 

Although the technique has been shown to improve heat transfer in laboratory testing, it has not 

been implemented in commercially-available equipment.2

Subcoolers 

Subcoolers provide additional cooling of the refrigerant after it leaves the condenser and 

prior to the expansion device; the additional cooling can increase the cooling/heating capacity of 

the system. Subcoolers can consist of either a passively cooled refrigerant tube or of a secondary 

vapor-compression system that actively cools the refrigerant. However, mechanical cooling of 

the refrigerant has not been used or tested in commercial air conditioning equipment or in CUAC 

and CUHP prototypes. 

3.10.2.3 Condenser Fans and Fan Motors

Condenser (or outdoor heat exchanger) fans move cooling air through the air-cooled 

condenser. Condenser fan assemblies used in CUAC and CUHP almost exclusively are axial 

design (propeller fans) that are direct-driven by the condenser fan motors. 

Larger Fan Diameter

Increasing condenser fan diameter reduces the discharge velocity of the air leaving the 

condenser fan. The energy associated with the discharge velocity is dissipated and cannot be 

recovered, hence lower discharge velocity reduces this loss and reduces fan power input. 

Increasing fan diameter requires finding space for these larger fan units within the cabinet. 

More-Efficient Fan Blades 

One option for reducing outdoor fan energy use is the use of more efficient fan blades, 

such as cast or molded blades or twisted sheet metal blades rather than simply curved or angled 

stamped sheet metal designs. 

High-Efficiency Motors

Most condenser fan motors used in equipment today have permanent split-capacitor 

(PSC) designs, which reach efficiencies of 50 to 70 percent. Brushless DC motors can achieve

efficiencies of up to 80 percent, thus representing an option for efficiency improvement. 

PSC motors are produced in large quantities and are relatively inexpensive with motor 

efficiencies ranging from 50 to 70 percent. Electronically commutated motors (ECM) are 

3-17 
brushless permanent magnet motors with motor efficiencies between 70 and 80 percent, making 

them more energy efficient than PSC motors. While PSC motors operate most efficiently at a 

single speed with significantly diminishing operating efficiency at others, ECMs are capable of 

maintaining a high operating efficiency at multiple speeds. However, ECMs can weigh twice as 

much as equivalent PSC motors. In addition, ECMs contain complex electronic circuitry, and can 

be significantly more expensive than PSC motors. 

Variable Speed Fans/Motors 

Inverter technology can improve air conditioner and heat pumps efficiency by varying 

fan speed to reduce air flow rate at part load. If the outdoor heat exchanger or condenser of a 

unit is served by a variable-capacity compressor or by a tandem compressor set, less outdoor air 

flow is needed to transfer the load. Overall system efficiency can be improved by reducing the 

outdoor air flow. While this is often achieved through the use of staging of multiple single-speed 

fans, efficiency can be also improved by using fan speed reduction instead. This is because (a) 

using speed reduction reduces the energy loss associated with the fan discharge velocity, and (b) 

when staging, some of the air flow simply recirculates through the orifice(s) of the non-operating 

fan(s). 

3.10.2.4 Evaporator Fans and Fan Motors 

The fans and fan motors move air through the evaporator (or indoor heat exchanger). 

Evaporator fan assemblies are generally centrifugal fans either direct-driven or connected by a 

belt/sheave system to the evaporator motor. 

Larger Fan Diameter

Larger fans often can provide the same air flow performance as smaller fans at greater 

efficiency, due to the lower air velocities associated with their larger flow passages. Generally, 

the challenge to implementing this option is to find space for these larger fans within the cabinet

without creating more inefficiency by reducing space for transition in and out of the fan. 

More-Efficient Fan Blades

Air-foil, backward-curved, or backward-inclined centrifugal fans are two options that can 

potentially increase efficiency. 

Air-foil centrifugal fans have blades shaped like air foils that are inclined such that the 

blade trailing edge is angled away from the rotation direction. The best airfoil fans can operate at 

efficiencies near 90 percent. However, the backward inclination of the trailing edge means that 

these fans must rotate at higher speeds and/or have larger diameters to deliver the same flow and 

pressure as conventional forward curved centrifugal fans. The higher speed can increase noise 

while the larger size requires more space within a unit’s cabinet. 

Backward-curved or backward-inclined centrifugal fans are similar to airfoil fans, but 

they have simpler blades and cannot attain comparable efficiencies. 

3-18 
High-Efficiency Motors 

Most evaporator fan motors used in equipment today have permanent split capacitor 

(PSC) designs, which reach efficiencies of 50 to 70 percent. Brushless DC motors represent an 

option for further efficiency improvement, as they have efficiencies up to 80 percent.

Variable Speed Fans/Motors 

Inverter technology can improve air conditioner and heat pumps efficiency by varying 

fan speed to reduce air flow rate at part load. If the indoor heat exchanger or evaporator of a unit 

is served by a variable-capacity compressor or by a tandem compressor set, less indoor air flow 

is needed to transfer the load. Overall system efficiency can be improved by reducing the indoor 

air flow and reducing indoor fan power. This can be achieved through the use of variable speed 

fans. 

Operation at reduced flow rate also saves energy when the unit is not cooling or heating 

but simply providing ventilation. Building codes generally require provision of outdoor air 

ventilation at all times that the building is occupied, not just when the CUAC or CUHP is 

providing cooling or heating. While reduced energy use during periods of occupancy with no 

active conditioning would not show up in the IEER, it was considered in the energy use analysis 

(see chapter 7). 

Synchronous (toothed belts) 

Synchronous belts (also called timing, positive-drive, or high-torque drive belts) are 

toothed, require the installation of engaging toothed-drive sprockets, and can be applied to 

supply-air fan drives. Synchronous belts offer about 98 percent efficiency and maintain that high 

efficiency over a wide load range.3 

Direct-Drive Fans

In a direct-drive fan, the fan impeller connects directly to the motor shaft. Direct-drive 

fans eliminate drive belt energy loss. However, unless used with variable-speed fan motors, the 

fixed motor speed significantly limits the flexibility to achieve the needed air flow and pressure 

rise needed for varying field applications. CUAC and CUHP that use direct-drive fans are 

available on the market. 

3.1.1.1 Expansion Valves 

The most common types of expansion valves are thermostatic expansion valves (TXVs), 

and electronic expansion valves (EEVs). Some CUAC and CUHP equipment use fixed-orifice 

designs (a fixed-orifice expansion device is simply a small-diameter flow restriction). While 

such devices can provide optimized flow control for a fixed operating conditions, such as for a 

full-capacity EER test, they clearly do not adapt to varying conditions associated with field 

operation or testing to measure IEER. 

3-19 
Thermostatic Expansion Valve 

The thermostatic expansion valve (TXV) is commonly used in higher-efficiency 

equipment. TXVs regulate the flow of liquid refrigerant entering the evaporator in response to 

the superheat of the refrigerant leaving it using a thermostatic bulb affixed to the suction line. 

TXVs can adapt to changes in operating conditions, such as variations temperature, humidity, 

and compressor staging. As a result, TXVs can control for optimum system operating parameters 

over a wide range of operating conditions, and can thus improve seasonal efficiency. 

Electronic Expansion Valve 

Electronic expansion valves (EEVs) are similar to TXVs, but they operate using 

electronic (microprocessor) control and sensors that measure suction line temperature and 

pressure. The EEV uses a pulse motor, which rotates based on an electronic signal from the 

microprocessor determining the desired valve position. EEVs can maintain more precise control 

of superheat over a wide range of conditions than TXVs. As the case for TXVs, the main benefit 

of electronic expansion valves is to improve efficiency on a seasonal basis. 

3.10.3 Energy Efficiency

In preparation for the screening and engineering analyses, DOE gathered data on the 

energy efficiency of commercial unitary air conditioners currently available in the marketplace. 

These data were taken from databases maintained by AHRI.

f

 While this section is not intended to 

provide a complete characterization of the energy efficiency of all appliances currently available 

and in use, it does provide an overview of the energy efficiency of commercial unitary air 

conditioners covered by this rulemaking. 

Figure 3.10.1 and Figure 3.10.2 show the distribution of EER levels for all CUAC and 

CUHP examined, Figure 3.10.3 and Figure 3.10.4 show the distribution of IEER levels for all 

CUAC and CUHP examined, and Figure 3.10.5 shows the distribution of COP levels for all 

CUHP examined. 

f Additional information is available online at: http://www.ahridirectory.org/ahridirectory/pages/home.aspx. 

3-20 

 
Figure 3.10.1 Distribution of EER Levels for all CUAC considered by DOE

Figure 3.10.2 Distribution of EER Levels for all CUHP considered by DOE

3-21 
Figure 3.10.3 Distribution of IEER Levels for all CUAC considered by DOE

Figure 3.10.4 Distribution of IEER Levels for all CUHP considered by DOE

3-22 
Figure 3.10.5 Distribution of COP Levels for all CUHP considered by DOE

3-23 
REFERENCES

1

 Air-Conditioning, Heating, and Refrigeration Institute. Unitary Large Equipment Section, 

Member Manufacturers. (Last accessed August 19, 2013.) < 

http://www.ahrinet.org/unitary+large+equipment+section.aspx> 

2

 M.M. Ohadi, S. Dessiatoun, A. Singh, M.A. Fanni. 1993. “EHD Enhancement of Pool and 

In-Tube Boiling of Alternate Refrigerants.” Report Prepared for the Air-Conditioning and 

Refrigeration Technology Institute, August 1993.

3

 United States Department of Energy. June 3, 2002. Energy Tips: Replace V-Belts with 

Cogged or Synchronous Belt Drives. Office of Industrial Technologies [Online Report]. 

Available URL: 

http://www1.eere.energy.gov/manufacturing/tech_assistance/pdfs/replace_vbelts_motor_syst

emts5.pdf. DOE documented this report in the rulemaking docket as docket ID EERE–2013–

BT–STD–0007-0019. 

3-24