3-i

CHAPTER 3. MARKET AND TECHNOLOGY ASSESSMENT

TABLE OF CONTENTS

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

3.2 PRODUCT DEFINITION ............................................................................................... 3-1

3.3 PRODUCT CLASSES..................................................................................................... 3-3

3.4 PRODUCT TEST PROCEDURES ................................................................................. 3-4

3.5 MANUFACTURER TRADE GROUPS ......................................................................... 3-5

3.6 MANUFACTURER INFORMATION ........................................................................... 3-5

3.6.1 Manufacturers and Market Shares................................................................................... 3-6

3.6.2 Mergers and Acquisitions................................................................................................ 3-7

3.6.3 Small Business Impacts ................................................................................................... 3-7

3.6.4 Distribution Channels ...................................................................................................... 3-8

3.7 REGULATORY PROGRAMS ....................................................................................... 3-8

3.7.1 California’s Regulations .................................................................................................. 3-8

3.7.3 Canada’s Proposed Energy Conservation Standards....................................................... 3-9

3.7.4 Australia and New Zealand Minimum Energy Performance Standards.......................... 3-9

3.8 SHIPMENTS ................................................................................................................. 3-10

3.9 PRODUCT RETAIL PRICES ....................................................................................... 3-10

3.10 INDUSTRY COST STRUCTURE................................................................................ 3-12

3.11 INVENTORY LEVELS AND CAPACITY UTILIZATION RATES.......................... 3-14

3.12 TECHNOLOGY ASSESSMENT.................................................................................. 3-15

3.12.1 Portable AC Operations and Components..................................................................... 3-15

3.12.2 Portable AC Technology Options.................................................................................. 3-17

3.12.3 Energy Efficiency .......................................................................................................... 3-24

LIST OF TABLES

Table 3.6.1 Portable AC Original Equipment Manufacturers and Importers* ............................ 3-6

Table 3.10.1 Air-Conditioning and Warm Air Heating Equipment Manufacturing 

Industry Employment and Earnings................................................................... 3-12

Table 3.10.2 Air-Conditioning and Warm Air Heating Equipment Manufacturing 

Industry Materials and Wages Cost ................................................................... 3-13

Table 3.10.3 Industry Cost Structure Using SEC Data, Average 2006–2012 ........................... 3-13

Table 3.11.1 Air-Conditioning and Warm Air Heating Equipment Manufacturing 

Industry Inventory Levels.................................................................................. 3-14

Table 3.11.2 Full Production Capacity Utilization Rate for Ventilation, Heating, AirConditioning, and Commercial Refrigeration Equipment, 

................................ 3-15

Table 3.12.1 Technology Options for Portable ACs.................................................................. 3-18
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LIST OF FIGURES

Figure 3.9.1 Retail Price versus Capacity for Single-Duct Portable ACs ................................. 3-11

Figure 3.9.2 Retail Price versus Capacity for Dual-Duct Portable ACs.................................... 3-11

Figure 3.12.1 Single-Duct Portable Air Conditioner Operation Schematic .............................. 3-17

Figure 3.12.2 CEC Energy Efficiency and Capacity Data......................................................... 3-24

Figure 3.12.3 Distribution of the Capacities of Units in the CEC Database ............................. 3-25
3-1

CHAPTER 3. MARKET AND TECHNOLOGY ASSESSMENT

3.1 INTRODUCTION

This chapter provides a preliminary assessment of the portable air conditioner (AC)

industry 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 product 

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 PRODUCT DEFINITION

There currently is no definition of portable ACs included in the Energy Policy and 

Conservation Act (EPCA), Pub. L. 94-163, 42 United States Code (U.S.C.) 6291 et seq. or in the 

Code of Federal Regulations. In July 2013, DOE issued a notice of proposed determination 

(NOPD) (hereinafter the “July 2013 NOPD”), in which DOE proposed to define a portable AC 

as “a consumer product, other than a packaged terminal air conditioner, which is powered by a 

single phase electric current and which is an encased assembly designed as a portable unit that 

may rest on the floor or other elevated surface for the purpose of providing delivery of 

conditioned air to an enclosed space. It includes a prime source of refrigeration and may include 

means for ventilating and heating.” DOE also noted that this proposed definition is mutually 

exclusive to the definition for a room AC, which is “designed as a unit for mounting in a window 

or through the wall.” 79 FR 40403, 40404 (Jul. 5, 2013).

As discussed in chapter 2 of this preliminary technical support document (TSD), DOE 

received multiple stakeholder comments regarding the proposed product definition and resulting 

scope of coverage. Accordingly, DOE conducted further research into the different types of 

portable ACs and their typical characteristics.

Portable ACs typically range in cooling capacity from 5,000 to 14,000 British thermal 

units per hour (Btu/h) when measured according to existing industry test methods, and are most 

commonly of single-duct or dual-duct configuration. Portable ACs are also available on the 

market in a spot-cooler configuration (i.e., with no ducting attached to the condenser air stream). 

According to sizing charts provided by vendors, portable ACs are intended to cool rooms of up 

to approximately 525 square feet in area. Portable ACs are often heavier than 50 pounds, so are 

designed with wheels to provide mobility from room to room. 
3-2

In a test procedure notice of proposed rulemaking (NOPR) issued on February 12, 2015

(hereinafter the “February 2015 Test Procedure NOPR”)a, DOE did not propose any methods to 

characterize the performance of spot coolers. For this reason, DOE’s preliminary analysis 

focuses on single-duct and dual-duct portable ACs, and not spot coolers.

DOE also recognizes that certain portable ACs include options for operating as a 

dehumidifier and/or heater, with heating means provided by either an electric resistance heater or 

by modifying internal refrigerant flow to operate the unit as a heat pump. The dehumidification 

function may be achieved in some units by removing the condenser duct(s), and for certain units, 

disabling the self-evaporative feature by draining the condensate before it reaches the condenser 

coils or deactivating the condensate slinger fan when the controls are set to dehumidification 

mode. In all of these cases, the air flow pattern and psychrometrics differ fundamentally from 

those of a residential dehumidifier, resulting in different energy efficiencies, even though both 

products may use a refrigeration system to remove moisture from the air.

DOE also recognizes that although room ACs and portable ACs share many of the same 

components that operate similarly to provide cooled air to a conditioned space, a portable AC, 

unlike a room AC, may be entirely located within the conditioned space so that some or all of the 

condenser air may be drawn from that space, and heat from the refrigeration system and ducting 

is transferred to the conditioned space as well. These differences lead to differing energy 

efficiencies between room ACs and portable ACs, even if the products were to incorporate the 

same components. In addition, operation of the portable AC without activation of the 

refrigeration system may be more accurately characterized as “air circulation” rather than 

“ventilation”, because the portable AC may be operated without drawing air from outside the 

conditioned space. Thus, DOE proposed in the February 2015 Test Procedure NOPR to clarify in 

the definition of “portable air conditioner” that the primary function of the product is to provide 

cooled conditioned air to the space in addition to other functions such as air circulation or 

heating, and that it is a product other than a room AC or dehumidifier. DOE also proposed a 

definition for portable AC that would align with the dehumidifier and room AC definitions. In 

sum, DOE proposed in the February 2015 Test Procedure NOPR to add to 10 CFR 430.2 the 

following definition for “portable air conditioner”:

An encased assembly, other than a “packaged terminal air conditioner,” “room air 

conditioner,” or “dehumidifier,” designed as a portable unit for delivering cooled, conditioned air 

to an enclosed space, that is powered by single-phase electric current, which may rest on the 

floor or other elevated surface. It includes a source of refrigeration and may include additional

means for air circulation and heating.

DOE conducted this preliminary analysis according to this proposed definition for a 

portable AC.

 

a The test procedure is available at:

http://www1.eere.energy.gov/buildings/appliance_standards/product.aspx/productid/79.
3-3

3.3 PRODUCT CLASSES

When evaluating and establishing energy conservation standards, DOE generally divides 

covered products into product classes by the type of energy used or by capacity or other 

performance-related features that affect efficiency. Different energy conservation standards may 

apply to different product classes. (42 U.S.C. 6295(q)) Because portable ACs are not currently 

covered by EPCA, there are not current product classes within this product type. For this 

preliminary analysis, DOE considered whether it should separate portable ACs into separate 

product classes based on two characteristics: duct configuration and capacity. 

Portable ACs are typically available with three types of duct configurations that affect 

product performance: single-duct, dual-duct, and spot cooler. As mentioned in section 3.2, DOE 

did not consider spot coolers for this preliminary analysis. Single-duct units draw all of the 

condenser inlet air from the conditioned space without the means of a duct, and discharge the hot 

condenser outlet air to the unconditioned space through a duct. Dual-duct units draw some or all 

of the condenser inlet air from the unconditioned space through a duct, and may draw additional 

condenser inlet air from the conditioned space. The condenser outlet air is discharged to the 

unconditioned space by means of a separate duct. Single-duct units typically create more net 

negative pressure within the conditioned space than dual-duct units, leading to more infiltration 

airflow from outside the conditioned space. This typically leads to lower single-duct unit 

efficiencies than for comparable dual-duct units when measured according to the method 

proposed in the February 2015 Test Procedure NOPR. 

DOE evaluated whether there is any consumer utility associated with the different duct 

configurations. DOE considered whether all installation locations would be able to accommodate 

both single-duct and dual-duct units. Based on discussions with manufacturers and a review of 

the market and the range of possible window connections, DOE tentatively concludes that no

installation location would preclude the use of either duct configuration. In particular, all 

window fixtures are of sufficient width to accommodate connections to two ducts. DOE also 

investigated whether duct configuration may affect noise performance of a portable AC. Based 

on a review of published noise data, DOE did not find a correlation between noise levels and 

duct configuration. Therefore, DOE tentatively concludes that duct configuration does not 

warrant separate product classes because it is not aware of any unique consumer utility 

associated with either configuration. However, because duct configuration does impact portable 

AC performance, DOE considered ducting configurations in its identification of technology 

options.

Although DOE did not separate portable ACs into product classes based on duct 

configuration for this preliminary analysis, DOE proposed in the February 2015 Test Procedure 

NOPR the following definitions for the different product configurations to account for their 

different testing requirements: 

“Single-duct portable air conditioner” means a portable air conditioner that draws all of 

the condenser inlet air from the conditioned space without the means of a duct, and discharges 

the condenser outlet air outside the conditioned space through a single duct.
3-4

“Dual-duct portable air conditioner” means a portable air conditioner that draws some or 

all of the condenser inlet air from outside the conditioned space through a duct, and may draw 

additional condenser inlet air from the conditioned space. The condenser outlet air is discharged 

outside the conditioned space by means of a separate duct. Id. 

“Spot cooler” means a portable air conditioner that draws condenser inlet air from and 

discharges condenser outlet air to the conditioned space, and draws evaporator inlet air from and 

discharges evaporator outlet air to a localized zone within the conditioned space. DOE proposed 

the spot cooler definition to clarify that testing these products would not be required at this time.

Id.

Additionally, portable AC efficiencies are a function of product capacity. Higher-capacity 

units typically achieve higher efficiencies than lower-capacity units when measured according to 

the method proposed in the February 2015 Test Procedure NOPR. As discussed in the February 

2015 Test Procedure NOPR, DOE observed from its test data that this relationship between 

efficiency and capacity is consistent across the range of measured capacities for products that 

implement the same technologies. DOE did not identify any inherent differences in efficiency for 

different ranges of capacity that would produce a different efficiency-capacity relationship. 

Therefore, DOE is not proposing separate portable AC product classes based on capacity. 

Instead, DOE is proposing to evaluate potential energy conservation standards based on 

equations that relate efficiency to capacity.

As a result, DOE is considering a single portable AC product class for this preliminary 

analysis.

3.4 PRODUCT TEST PROCEDURES

DOE does not currently specify a test procedure for portable ACs, but such a test 

procedure has been proposed in a separate rulemaking. DOE initiated the test procedure 

rulemaking by publishing a notice of data availability (NODA) on May 9, 2014 (hereinafter the 

“May 2014 NODA”), to request feedback on potential testing options. 79 FR 26639. In the May 

2014 NODA, DOE presented data from investigative testing according to the Association of 

Home Appliance Manufacturers (AHAM) PAC-1-2009, “Portable Air Conditioners” (AHAM 

PAC-1-2009) and ANSI/American Society of Heating, Refrigerating, and Air-Conditioning 

Engineers (ASHRAE) Standard 16-1983 (RA 99), “Method of Testing for Rating Room Air 

Conditioners and Packaged Terminal Air Conditioners” (ANSI/ASHRAE Standard 16-1983 ), 

with certain modifications to allow testing of portable ACs. DOE also presented an alternate test 

approach, in which testing would be conducted according to ANSI/AHAM PAC-1-2009, but the 

calculations for capacity and energy efficiency ratio (EER) would account for any heat 

transferred to or from the conditioned space due to infiltration air or a warm or cold product case.
3-5

Based on feedback received in response to the May 2014 NODA and further investigative 

testing, DOE proposed a test procedure for portable ACs in the February 2015 Test Procedure 

NOPR. The proposed test procedure is consistent with the alternate approach described in the 

May 2014 NODA; however the February 2015 Test Procedure NOPR references the recently

updated version of the PAC-1 standard, AHAM PAC-1-2014 “Portable Air Conditioners” 

(AHAM PAC-1-2014). The 2014 version of the standard includes minor revisions to the indoor 

and outdoor conditions from the 2009 version to fully harmonize with CSA’s test procedure. 

After careful review of both versions of PAC-1, DOE does not expect the revisions to that test 

procedure to have a significant impact on test results.

In the February 2015 Test Procedure NOPR, DOE proposed a combined energy 

efficiency ratio (CEER) that would account for portable AC performance in each available 

operating mode; however, DOE conducted this preliminary analysis based solely on portable AC 

performance in cooling mode, in terms of cooling capacity and cooling energy efficiency ratio 

(EERcm), as determined by the method proposed in the February 2015 Test Procedure NOPR.

DOE focused on cooling mode for this analysis because cooling is the primary function of 

portable ACs. DOE expects that its proposals in future stages of this standards rulemaking would 

be based on CEER after finalizing the calculation of that metric in the test procedure rulemaking.

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 portable AC

industry, DOE researched various associations available to manufacturers, suppliers, and users of 

such equipment.

AHAMb, formed in 1967, aims to enhance the value of the home appliance industry 

through leadership, public education and advocacy. AHAM provides services to its members 

including government relations; certification programs for room ACs, dehumidifiers and room 

air cleaners; an active communications program; and technical services and research. In addition, 

AHAM conducts other market and consumer research studies. AHAM also develops and 

maintains technical standards for various appliances to provide uniform, repeatable procedures 

for measuring specific product characteristics and performance features.

3.6 MANUFACTURER INFORMATION

The following section details information regarding domestic manufacturers of portable 

ACs, including estimated market shares (section 3.6.1), industry mergers and acquisitions 

(section 3.6.2), potential small business impacts (section 3.6.3), and product distribution 

channels (section 3.6.4).

 

b For more information, please visit www.aham.org.
3-6

3.6.1 Manufacturers and Market Shares

The majority of single-duct and dual-duct portable ACs are manufactured overseas by 

three major manufacturers. These products are then imported to the United States and sold under 

a variety of brands belonging to both appliance manufacturers and importers. Additionally, some 

foreign original equipment manufacturers (OEM) engage in the direct sale of portable ACs into 

the U.S. market under their own brands. 

DOE estimates that there are approximately 29 entities selling single-duct and dual-duct 

portable ACs in the United States. Table 3.6.1 lists these manufacturers and importers. 

Table 3.6.1 Portable AC Original Equipment Manufacturers and Importers*

American Comfort Worldwide**

Bigwall Enterprises Inc.**

Danby**

DeLonghi America Inc.

Electrolux**

Friedrich**

GD Midea Air Conditioning Equipment Co. Ltd.

Grainger**

Gree Electric Appliances Inc., of Zhuhai

Haier America Trading LLC**

Hisense Kelon Electrical Holdings Co. Ltd.

Honeywell International Inc.**

R.E. Hansen Industries Inc.**

LG Electronics Inc.**

Living Direct**

Luzerne Trading Company Inc.**

Mestek Inc.**

Motors and Armatures Inc.**

New Widetech Electric Co. Ltd.

NewAir**

Ningbo Bole Electric Appliance Co. Ltd.

Royal Sovereign International, Inc.**

Sealed Unit Parts Co (SUPCO)**

Sears Holding Corporation**

Sharp Electronics

Sunpentown International Inc.**

Toyotomi Co. Ltd.

Whynter LLC**

Zhejiang Aoli Electric Appliance Co. Ltd.
3-7

*These manufacturers and importers represent the entities DOE has identified that would be regulated under any 

energy conservation standards resulting from this rulemaking.

**These companies do not manufacture the products covered by this rulemaking; instead they source products from 

OEMs and rebrand them.

Using publicly available data, DOE estimated the market shares of entities responsible 

for the sale of single-duct and dual-duct portable ACs in the United States. DOE estimates that

Haier Americacand LG each comprise more than 20 percent of the portable AC market, while

De'Longhi America,

d American Comfort Worldwide, and Danby each hold approximately a 10 

percent share of the market. Other players in the portable AC industry have 5 percent market 

share or less. 

3.6.2 Mergers and Acquisitions

Recent merger and acquisition activities relating to the U.S. portable AC market include 

the joint venture formed between Chinese manufacturer Gree and U.S.-based SoleusAir in 2011, 

which led to the creation of Gree USA, headquartered in City of Industry, CA. Gree USA 

manufactures its own brands of heating, ventilation, and air conditioning (HVAC) products and 

OEM private labels, and sells directly to wholesalers. This collaboration has facilitated Gree’s

presence in the United States.

e Also in 2011, LG Electronics acquired LS Mtron’s AirConditioning unit, and in November 2012, Corinthian Capital Group acquired Friedrich Air 

Conditioning Co. from U.S. Natural Resources Inc. According to one source, Texas-based 

Friedrich supported the sale so that it could “aggressively expand.”f

 

In 2013, Motors and Armatures (d.b.a. MARS), a commercial and residential 

HVAC/refrigeration motors and components supplier acquired Heat Controller, Inc., a 

commercial and residential HVAC equipment (including portable ACs) supplier.g Also in 2013, 

Haier America became a wholly owned subsidiary of Haier Group, which, for Haier, “signifies a 

continued focus and commitment to serving [its] customers in the Americas.”h

3.6.3 Small Business Impacts

DOE considers the possible impact of energy conservation standards on small businesses. 

The products covered by this rulemaking are classified under the North American Industry 

 

c A wholly-owned subsidiary of Haier Group (China).

d A subsidiary of De’Longhi S.p.A. (Italy).

e

“SoleusAir, Gree Electronic Appliances Merge,” Air Conditioning, Heating & Refrigeration News Weekly, April 4, 

2011. 

f

“Corinthian Chills Out With Acquisition of Friedrich Air Conditioning,” Dow Jones LBO Wire, November 29, 

2012.

g

“MARS Acquires Heat Controller, Inc.,” Business Wire, May 25, 2013.

h

“Haier America Becomes Wholly Owned Subsidiary of Haier Group,” Globe Newswire, August 15, 2013.
3-8

Classification System (NAICS) code 333415: Air-Conditioning and Warm Air Heating 

Equipment and Commercial and Industrial Refrigeration Equipment Manufacturing. The Small 

Business Association defines a small business as a company that has fewer than 750 employees 

for both NAICS codes. The 750-employee threshold includes all employees in a business’s 

parent company and any other subsidiaries. 

Using this classification in conjunction with information from industry databases, the 

SBA member directory, and reports from vendors such as Dun & Bradstreet, DOE has not 

identified any small, U.S.-based manufacturers of single-duct and dual-duct portable ACs 

products addressed by this rulemaking. DOE will continue investigate whether there are any 

small manufacturers of single-duct and dual-duct portable ACs based in the U.S. 

3.6.4 Distribution Channels

Understanding the distribution channels through which portable ACs are sold is an 

important facet of the market assessment because it helps to define the constraints or motivators 

manufacturers face from their customer base. DOE gathered information regarding the 

distribution channels for portable ACs from publicly available sources, as well as from 

preliminary interviews with manufacturers.

Because major OEMs of single-duct and dual-duct portable ACs are based overseas, the 

distribution channel for these products is often multi-tiered. In one arrangement, foreign OEMs 

sell their products to a sourcing company with a greater U.S. presence, which in turn sells the 

products directly to retailers or, to a lesser extent, distributors. Alternatively, OEMs sell their 

products under their own brands either to distributors or directly to retailers. In either 

arrangement, these retailers include large discount stores, home improvement stores, and 

department stores. 

3.7 REGULATORY PROGRAMS

The following sections detail current or proposed regulatory initiatives for portable ACs. 

3.7.1 California’s Regulations

The California Energy Commission (CEC) regulates “spot air conditioners”, which it

defines as “an air conditioner that discharges cool air into a space and discharges rejected heat 

back into that space, where there is no physical boundary separating the discharges.” The metric 

used for spot ACs is the cooling efficiency ratio (CER), obtained by dividing the sum of the 

cooling capacity and the fan electrical input in Btu/h by the electrical input power in watts, using 

ANSI/ASHRAE 128-2001.i California currently requires only reporting of CER, cooling 

 

i California Code of Regulations, Title 20, Division 2, Chapter 4, Article 4, Sections 1602(d) and 1604(d).
3-9

capacity, input power, and fan input power in its product database, and does not have energy 

efficiency regulations for spot ACs.

3.7.3 Canada’s Proposed Energy Conservation Standards

Canada’s energy efficiency regulations proposed to establish energy conservation 

standards for portable ACs in 2009, based on a minimum energy efficiency that would be a 

function of cooling capacity.j These proposed standards, based on testing according to Canadian 

Standards Association (CSA) C370 “Cooling Performance of Portable Air Conditioners” (CSA 

C370)

k

, which have not been adopted, were defined in terms of a minimum spot cooling 

efficiency (SCE, equivalent to EER) for air-cooled portable ACs with cooling capacities less 

than 36,000 Btu/h according to the following equation:

SCE = 7.76 + 0.0164 x C/1000 

where C is the cooling capacity in Btu/h.

Natural Resources Canada (NRCan) estimated that at the time of the proposal, 

approximately 90 percent of portable ACs on the market would have met the minimum SCE 

requirement included in the proposal.

3.7.4 Australia and New Zealand Minimum Energy Performance Standards

Australia and New Zealand have established energy efficiency regulations, Minimum 

Energy Performance Standards (MEPS), for single-phase and three-phase air conditioners in 

ducted or non-ducted configurations. Labeling requirements only specify single-phase air 

conditioners in a non-ducted configuration, but manufacturers can choose to label three-phase 

and ducted air conditioners. MEPS requirements were introduced in Australia in April 2010, and

were further modified in April and October 2010. MEPS requirements in New Zealand were 

revised and implemented in June 2011. The Australia requirements are found in Standards 

Australia/Standards New Zealand (AS/NZS) 3832.2:2011 and apply to all products imported 

after October 2011. The New Zealand requirements are found in AS/NZS 3823.2:2009 and apply 

to all products imported after June 2011.l The test procedures used for compliance with these 

standards are AZ/NZS 3832.1.1:1988 for non-ducted units and AZ/NZS 3823.1.2:2001 for 

ducted units.m

 

j Natural Resources Canada – Office of Energy Efficiency, Bulletin on Developing Standards for Portable ACs, 

2009. Available online at: http://oee.nrcan.gc.ca/regulations/bulletins/9205.

k CSA standards are available for purchase online at: http://shop.csa.ca/.

l Additional information can be found at: www.energyrating.gov.au/for-industry/regulation-information-forindustry/product-standards/overview/asnzs3823/

m Additional test procedure information can be found at: www.energyrating.gov.au/for-industry/regulationinformation-for-industry/product-standards/overview/
3-10

3.8 SHIPMENTS

In the July 2014 NOPD, DOE estimated that 973.7 thousand units were shipped in North 

America in 2012, with a projected growth to 1743.7 thousand units by 2018, representing nearly 

80-percent growth in 6 years.n

3.9 PRODUCT RETAIL PRICES

DOE used the CEC Appliance Efficiency Database,

o

supplemented with web based 

research, to compile a database of portable AC products. DOE identified a total of 251 models of 

portable ACs, which encompass 36 different brands. Of these, DOE was able to collect consumer 

retail price data for 118 single-duct units and 26 dual-duct units using the websites of five types 

of retailers: “big box” stores, discount department stores, wholesale clubs, manufacturer 

websites, and online appliance retailers (e.g., AJ Madison). 

Figure 3.9.1 and Figure 3.9.2 summarize the data collected by DOE. These figures 

generally suggest that retail price is positively related to capacity for both single-duct and dualduct portable ACs. The consumer retail prices for single-duct portable ACs ranged from $150 to 

$998, with a model-weighted average of $446. Single-duct portable ACs are available with 

manufacturer-rated capacities ranging from 1,000 Btu/h to 14,000 Btu/h, with a model-weighted

average capacity of 9,400 Btu/h.

 

n Transparency Media Research, Air Conditioning Systems Market - Global Scenario, Trends, Industry Analysis, 

Size, Share and Forecast, 2012 – 2018, January 2013.

o The California Energy Commission Appliance Efficiency Database reports data for “spot ACs”: 

www.appliances.energy.ca.gov/AdvancedSearch.aspx
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Figure 3.9.1 Retail Price versus Capacity for Single-Duct Portable ACs

The consumer retail prices for dual-duct portable ACs ranged from $351 to $799, with a

model-weighted average of $497. Dual-duct units range in manufacturer-rated capacity from 

9,000 Btu/h to 14,000 Btu/h, with a model-weighted average capacity of 11,500 Btu/h.

Figure 3.9.2 Retail Price versus Capacity for Dual-Duct Portable ACs
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3.10 INDUSTRY COST STRUCTURE

DOE developed the cost structure for the industry classification associated with the 

portable AC industry from publicly available information from the U.S. Census Bureau’s Annual 

Survey of Manufactures (ASM) and Economic Census, and the U.S. Securities and Exchange 

Commission (SEC) 10-K reports filed by publicly-owned manufacturers. 

Table 3.10.1 presents the employments levels and payroll for NAICS code 333415 for 

air-conditioning and warm air heating equipment and commercial and industrial refrigeration 

equipment manufacturing. DOE converted the payroll data to constant 2013 dollars using the 

Gross Domestic Product Implicit Price Deflator published by the U.S. Bureau of Economic 

Analysis.p Both employment and earnings for the industry decline between 2007 and 2009 with 

levels remaining largely flat thereafter through 2011. The percent change in production and total 

industry employees tracks relatively closely with the percent change in payroll for all employees.

Table 3.10.1 Air-Conditioning and Warm Air Heating Equipment Manufacturing Industry 

Employment and Earnings1

Year Production 

Workers

All 

Employees

Total 

Payroll

(2013 $ Mil)

2011 62,009 83,969 $3,887

2010 61,380 83,054 $3,974

2009 60,041 86,454 $3,908

2008 70,787 96,610 $4,319

2007 74,728 101,485 $4,418

2006 74,909 102,354 $4,519

2005 76,011 98,097 $4,568

Table 3.10.2 shows the cost of materials and industry payroll as a percentage of value of 

shipments for the air-conditioning and warm air heating equipment and commercial and 

industrial refrigeration equipment manufacturing industry from 2005–2011. Material prices as a 

percentage of value of shipments have increased slightly over the 7-year period, with small 

fluctuations from year to year. The cost of payroll for production workers as a percentage of 

value of shipments has decreased slightly since 2005. Finally, over the 7-year period, the cost of 

non-production payroll has remained relatively constant, with fluctuations from year to year. 

DOE notes that, overall, wages and cost of materials combined represent approximately the same 

percentage of the total shipments value in 2005 and 2011 (68 percent).

 

p Available online at www.bea.gov/iTable/iTable.cfm?ReqID=9&step=1#reqid=9&step=1&isuri=1
3-13

Table 3.10.2 Air-Conditioning and Warm Air Heating Equipment Manufacturing Industry 

Materials and Wages Cost2

Cost as a Percentage of Value of 

Shipments (%)

Year Materials

Payroll for 

Production 

Workers

Payroll for 

All Other 

Employees 

2011 55.1% 7.5% 5.2%

2010 52.9% 7.8% 5.7%

2009 55.1% 7.9% 6.0%

2008 54.6% 8.1% 5.4%

2007 55.6% 8.2% 5.3%

2006 53.2% 8.9% 4.9%

2005 53.8% 8.5% 5.3%

Table 3.10.3 presents the portable AC industry cost structure derived from SEC 10-K 

reports of publicly-owned manufacturers. DOE averaged the financial data from 2006–2012 of 

U.S.-based appliance manufacturers to obtain an industry average. Each financial statement entry 

is presented as a percentage of total revenues.

Table 3.10.3 Industry Cost Structure Using SEC Dataq, Average 2006–2012

Financial Statement Entry Percent of 

Revenues

Cost of sales 72.1%

EBIT 9.1%

Selling, general and administrative 19.0%

Capital expenditure 2.8%

Research and development 1.5%

Depreciation 2.7%

Net plant, property and equipment 13.5%

Working capital 19.4%

A detailed financial analysis is presented in the manufacturer impact analysis (MIA, 

chapter 12 of this preliminary TSD). This analysis identifies key financial inputs including cost 

of capital, working capital, depreciation, capital expenditures, etc.

 

q SEC 10-K filings are available at: www.sec.gov/edgar/searchedgar/companysearch.html
3-14

3.11 INVENTORY LEVELS AND CAPACITY UTILIZATION RATES

Table 3.11.1 shows the year-end inventory for the air-conditioning and warm air heating 

industries, according to the ASM. The value of the end-of-year (EOY) inventories increased from 

2005 to 2007 and decreased overall from 2007 to 2011. As a percentage of the value of 

shipments, value of inventories data shows a slight upward trend from 2005 to 2007 and a 

decreasing trend from 2009 to 2011 (likely a reaction to over-supply during the recession).

Table 3.11.1 Air-Conditioning and Warm Air Heating Equipment Manufacturing Industry 

Inventory Levels3

Year

End-ofYear 

Inventory 

(2013 $ 

Mil)

EOY 

inventory 

as % of 

Shipments 

Value

2011 2,755 9.0%

2010 2,718 9.3%

2009 2,807 10.0%

2008 3,127 9.7%

2007 3,325 10.1%

2006 3,246 9.9%

2005 3,114 9.4%

DOE obtained full production capacity utilization rates from the U.S. Census Bureau’s 

Survey of Plant Capacity from 2004–2006. After 2006, the Census Bureau discontinued this 

survey, and began a new Quarterly Survey of Plant Capacity Utilization. However, this survey 

does not collect utilization data beyond the 4 digit NAICS codes for the ventilation, heating, airconditioning, and commercial refrigeration equipmentr

industry. Table 3.11.2 presents utilization 

rates for this umbrella industry. 

 

r “Ventilation, heating, air-conditioning, and commercial refrigeration equipment” is the umbrella NAICS category 

3334 that includes NAICS code 333415 for “air-conditioning and warm air heating equipment and commercial and 

industrial refrigeration equipment.”
3-15

Table 3.11.2 Full Production Capacity Utilization Rate for Ventilation, Heating, AirConditioning, and Commercial Refrigeration Equipment4, 5

Year

Plant Capacity 

Utilization Rate 

(%)

2013 55%

2012 55%

2011 60%

2010 60%

2009 60%

2008 67%

2007 66%

2006 62%

2005 66%

2004 61%

Full production capacity is defined as the maximum level of production an establishment

could attain under normal operating conditions.sIn the Survey of Plant Capacity reports, the full 

production utilization rate is a ratio of the actual level of operations to the full production 

capacity. The full production utilization rate for ventilation, heating, air-conditioning, and 

commercial refrigeration manufacturers reached a peak in 2008, at 67 percent, and hit a low of 

55 percent in 2012 and 2013. Decreased capacity utilization in the industry may reflect the 

impact of the 2007–2009 recession.

3.12 TECHNOLOGY ASSESSMENT

This section provides a technology assessment for portable ACs. Contained in this 

technology assessment are details about product characteristics and operation (section 3.12.1)

and an examination of possible technological improvements (section 3.12.2).

3.12.1 Portable AC Operations and Components

Single-duct and dual-duct portable ACs are self-contained, refrigeration-based products

that provide cool air to a conditioned space and reject heat outside of the conditioned space. 

Similar to room ACs, these products remove both latent and sensible heat from the ambient air;

however, unlike room ACs, they are not permanently installed through a wall or in a window. 

 

s See: www.census.gov/manufacturing/capacity/definitions/index.html
3-16

Portable ACs are typically designed with wheels to allow for moving the units from room to 

room, weigh in the range of 50 to 90 pounds, and are generally 28 to 36 inches tall. 

Portable ACs operate with a similar refrigeration circuit as for room ACs or 

dehumidifiers, but with a different air flow pattern. Components of the refrigeration system 

include an evaporator, expansion valve or capillary tube, a condenser, and a compressor. Singleduct and dual-duct portable ACs typically operate as follows:

1. A circulating blower draws air from the conditioned space via an intake grille;

2. The air is pulled across an evaporator heat exchanger that is cooled by the electricallypowered vapor compression refrigeration system;

3. The evaporator cools the air, and moisture from the air condenses on the evaporator and 

drips down across the hot condenser heat exchanger, where some or all of it evaporates 

and the excess is collected in a drip pan below the condenser;

4. The cooled, drier evaporator air is exhausted to the conditioned space;

5. At the same time, a blower draws air in a separate flow stream across the hot condenser 

heat exchanger;

a. Single-duct units draw condenser inlet air from the conditioned space;

b. Dual-duct units draw some or all of the condenser inlet air from the unconditioned 

space through a duct, and may draw additional condenser inlet air directly from 

the conditioned space;

6. Certain units with an “auto evaporative” feature deliver any accumulated condensate 

back onto the condenser heat exchanger by means of a slinger wheel or pump to 

evaporate as much of it as possible; and

7. The warm, moist condenser outlet air containing evaporated condensate from the 

conditioned air stream is discharged to the unconditioned space by means of a duct.
3-17

Source: Adapted from kingersons.com6

Figure 3.12.1 Single-Duct Portable Air Conditioner Operation Schematic

The intake of condenser air from the conditioned space and its exhaust to the 

unconditioned space results in a net negative pressure in the conditioned space. In turn, this 

results in air infiltration to the conditioned space from other locations. Because all of their 

condenser air is drawn from the conditioned space, single-duct units typically create more net 

negative pressure within the conditioned space than dual-duct units, leading to more infiltration 

airflow from outside the conditioned space.

3.12.2 Portable AC Technology Options

DOE identified several possible technologies that manufacturers may use to improve the 

efficiency or performance of portable ACs. These technology options were initially identified 

during the residential dehumidifier and room AC energy conservation standards rulemakings 

because of their similarities to portable ACs. The technology options for portable ACs are listed 

in Table 3.12.1 and described in greater detail later in this section.

Conditioned Air from 

Evaporator Outlet

Return Air to 

Evaporator Inlet

Condenser Inlet Air from 

Conditioned Space

Condenser Outlet Air to 

Unconditioned Space
3-18

Table 3.12.1 Technology Options for Portable ACs

Increased Heat Transfer Surface Area

Improving the overall heat transfer surface area of the condenser and evaporator coils 

would result in improved efficiency of the refrigeration system. With a larger surface area, a coil 

can transfer the same amount of heat as a smaller coil while using a higher (in the case of an 

evaporator) or lower (in the case of a condenser) refrigerant temperature. This decreases the 

pressure difference between the two sides of the refrigerant cycle, lowering the necessary 

compressor power input.

Manufacturers have multiple options to increase the heat transfer surface area, including 

increasing cross-sectional area, heat exchanger depth, and fin density. While these heat 

exchanger changes improve coil performance, there are some additional tradeoffs. Operating the 

evaporator coil at a higher temperature in cooling mode may limit the unit’s ability to 

dehumidify the cool air stream, a significant component to increasing comfort in the conditioned 

space. Increasing cross-sectional area and heat exchanger depth will increase unit weight and 

possibly case size, thereby increasing the unit manufacturing and shipping cost and reducing 

consumer portability. Increasing heat exchanger depth and fin density both require increasing 

blower capacity to offset the greater pressure drop for the airstream passing over the heat 

exchanger. Additionally, a greater fin density could result in more water retention in the 

evaporator, or accumulation of dust and dirt leading to decreased heat transfer over time.

Increased Heat-Transfer Surface Area

1. Increased frontal coil area 

2. Increased depth of coil (add tube rows) 

3. Increased fin density 

4. Add subcooler to condenser coil

Increased Heat-Transfer Coefficients 

5. Improved fin design 

6. Improved tube design 

7. Spray condensate onto condenser coil 

8. Microchannel heat exchangers 

Component Improvements 

9. Improved compressor efficiency

10. Improved blower/fan efficiency 

11. Low-standby-power electronic controls

12. Ducting insulation

13. Improved duct connections

14. Case insulation

Part-Load Technology Improvements 

15. Variable-speed compressors 

16. Thermostatic or electronic expansion valves 
3-19

Subcoolers are added between the condenser coil outlet and the capillary tube inlet and 

are either submerged near the condenser in the condensate produced by the evaporator or sent 

through a heat exchanger with the cooler refrigerant gas coming off of the evaporator. Adding a 

subcooler effectively increases the size of the condenser coil as it further cools the refrigerant 

coming out of the condenser. However, it may be difficult to incorporate subcoolers within the 

portable AC case, and they may have limited efficiency improvements.

Increased Heat-Transfer Coefficients

Manufacturers may make further improvements to the evaporator or condenser beyond 

increasing surface area to improve the heat transfer capability of the heat exchangers. Different 

fin designs, including louvered or slit-type fins, result in more turbulent air flow through the heat 

exchanger, increasing the air-side heat-transfer coefficient. Similar to increasing fin density, as 

described above, adjusting fin design may result in water retention in the evaporator or fouling 

due to dirt and dust collection. To improve refrigerant-side heat-transfer coefficients, 

manufacturers may incorporate refrigerant tubes with a grooved interior surface. This 

significantly increases the refrigerant-side heat-transfer coefficient compared to a typical 

smooth-surface refrigerant tube. Manufacturers may also improve the condenser heat-transfer 

coefficient by spraying or dripping condensate from the evaporator over the condenser. The 

condensate evaporating off of the warm condenser surface enhances the heat transfer compared 

to a condenser rejecting heat only to an air stream.

Microchannel heat exchangers may also increase heat transfer coefficients compared to 

typical tube-and-fin heat exchangers. Microchannel heat exchangers use many small rectangular 

channels with aluminum fins brazed between the rectangular tubes to increase heat transfer while 

reducing pressure drop compared to conventional coils. However, DOE is not aware of any 

portable ACs that incorporate microchannel heat exchangers, likely due to the much higher 

investment cost required for the equipment needed to fabricate these heat exchangers (i.e., 

brazing ovens) as compared with equipment used for fabrication of conventional heat 

exchangers.

Research has compared the performance of a window-mounted room air conditioner with 

microchannel condensers to a baseline system with a conventional tube-and-fin condenser. The 

results showed the heat transfer rates per unit core volume of the microchannel heat exchangers 

were 14 to 331 percent higher than the conventional heat exchangers. However, the overall 

efficiencies of two systems using the microchannel condenser heat exchanger were 1 to 3 percent 

lower than the baseline system. The lower efficiencies attained by this work were believed to be 

due, in part, to the un-optimized condensate slinger ring and decreased subcooling of the 

microchannel systems. The results did show reductions in refrigerant charge, condenser core 

volume, and weight of 35, 55, and 35 percent, respectively, using microchannel condensers.7

More recent research performed in 2006 indicated that a microchannel condenser with the 

same area as a fin-and-tube configuration requires 49-percent less internal refrigerant flow 

volume and 10-percent lower refrigerant charge, and results in a 6 to 10-percent increase in the 

steady–state coefficient of performance (COP), defined as the cooling capacity divided by the 
3-20

power consumption. This COP increase is due to a decrease in the compressor power 

consumption rather than an increase in the cooling capacity. The research also indicated that a 

microchannel condenser system with the same frontal area as a traditional fin-and-tube 

configuration results in a greater than 7-percent increase in seasonal efficiency.8

Additional research performed in 2009 for mobile air conditioning indicated that 

microchannel heat exchangers provide volume benefits (17.2-percent and 15.1- percent volume 

reduction for evaporator and condenser, respectively) and weight benefits (2.8-percent and 14.9-

percent weight reduction for evaporator and condenser, respectively) when compared with finand-tube heat exchangers. The overall cooling capacity and COP of the microchannel heat 

exchanger system were increased by about 5 percent and 8 percent, respectively, under ideal 

conditions.9

Improved Compressor Efficiency

Portable ACs typically use rotary R-410A compressors. Rotary R-410A compressors are 

available in a range of efficiencies, from an EER of 9 Btu per watt-hour (Btu/Wh) up to roughly 

10.5 Btu/Wh, where EER represents the cooling capacity of the compressor divided by its power 

input. “Inertia” compressors and scroll compressors have higher efficiencies than the traditional 

rotary compressors. However, manufacturer interviews and DOE’s market research indicated 

that finding a suitable high-efficiency compressor at the capacities and price points needed for a 

portable AC is a challenge.

The inertia compressor is a technology that allows reciprocating compressors to approach 

an energy efficiency ratio EER of 12.0 Btu/Wh. “Inertia” compressors utilize lightweight, 

responsive valve technology and an innovative refrigerant flow path to reduce losses and 

improve cylinder volumetric efficiency. 

Scroll compressors require high precision to produce their internal components and are 

typically found in higher-efficiency central air-conditioning systems. Scroll compressors 

compress gas in a fundamentally different manner from traditional compressors — between two 

spirals, one fixed and one nutating. Scroll compression is inherently more efficient than 

traditional compression methods.

Both inertia and scroll compressors are, however, substantially larger, heavier, and 

sometimes noisier than their rotary counterparts, and, as such, are not well-suited for use in 

portable ACs.

Improved Blower/Fan Efficiency

The air-circulation system of a portable AC usually consists of permanent split capacitor 

(PSC) fan motors that drive the evaporator and condenser blowers.

Fans and blowers for portable ACs are generally molded plastic parts with fairly 

advanced geometries. The housings for the fans and heat exchangers are also molded plastic 
3-21

parts designed for each particular unit. Air system efficiency could possibly be improved through 

more advanced fan and blower design; however, this would likely be a relatively costly design 

option for a manufacturer in relation to the minimal efficiency benefit. The air system efficiency 

could also be improved by reducing restrictions to air flow; however, improving the efficiencies 

of the heat exchangers often corresponds to restricting air flow, as discussed in the sections 

addressing heat exchangers above.

Given the limited opportunity to improve air system efficiency, manufacturers would 

likely consider efficiency improvements to the fan motor only.

In a PSC motor, the start-up winding is electrically connected in parallel with the main 

winding and in series with a capacitor. At start-up, the interactions between the magnetic field 

generated by the start-up winding and that generated by the main winding induce rotation. As the 

capacitor charges, the current flowing through the start-up winding decreases and the start-up 

winding becomes an auxiliary winding after the motor reaches running speed. Consequently, the 

current to the start-up winding is cut off once the capacitor is fully charged and the motor 

reaches steady-state speed. Because of this, PSC motors are substantially more efficient than 

their shaded-pole counterparts, with motor efficiencies ranging from 60 to 65 percent. Like 

shaded-pole motors, PSC motors are produced in large quantities and are relatively 

inexpensive.10 

Electric motors with even higher efficiencies can be implemented by switching to 

permanent-magnet motors, which come in many varieties. The most widely-known variety is the 

electronically-commutated motor (ECM), though DC motors can also be used. Permanent 

magnet motors are less noisy and substantially more efficient than either shaded-pole or PSC 

motors. ECM motors convert single-phase AC input power into three-phase power, and have 

motor efficiencies approaching 80 percent.11 However, ECM motors can weigh twice as much as 

equivalent PSC motors, potentially necessitating a redesign of the portable AC chassis. In 

addition, ECM motors are complex, are not currently produced in large volumes, and can cost 

roughly twice as much as a PSC motor.12

Low-Standby-Power Electronic Controls

Electronic controls may consume power even when the portable AC is not performing its 

intended function. Depending on the implementation of the controller, standby power is required 

to enable the electronic controls to detect user input without the user first having to turn on a 

mechanical power switch or to enable displays, illuminate switches, etc. Reducing the standby 

power consumption of electronic controls will reduce the annual energy consumption of the 

portable AC, but will not impact the energy consumption of the unit during operation in cooling 

mode.

Ducting Insulation

In the February 2015 Test Procedure NOPR, DOE proposed a portable AC test method 

that would account for any heat lost to the conditioned space from the duct(s). Under the 
3-22

proposed test conditions in cooling mode, DOE testing demonstrated that the condenser exhaust 

duct carries air that is on average 40 degrees Fahrenheit (°F) warmer than the 80 °F temperature 

of the indoor side test chamber. Accordingly, the warm exhaust duct transfers heat to the 

conditioned space. For dual-duct units, the condenser inlet duct also has a net heating effect, 

although not as significant because it carries air at 95 °F, only 15 °F warmer than the indoor side 

test chamber. Manufacturers may choose to insulate ducts to minimize heat lost to the 

conditioned space. However, DOE notes that it is not aware of any portable ACs that utilize 

insulated ducting. DOE observed that manufacturers use accordion-style plastic ducts that ship in 

a compacted state, and thus insulation opportunities would be limited. 

Improved Duct Connections

DOE is aware that the duct connections at the window mounting bracket or portable AC 

are often not well sealed. Air leaking through these duct connections may be up to 40 °F warmer 

than the ambient temperature, and may leak from the condenser exhaust stream to the

conditioned space. DOE, therefore, acknowledges the overall cooling performance benefit of

tightly-sealed duct connections. However, DOE did not observe any units in the test sample that 

provided additional sealing in the duct connections. DOE also did not observe any significant 

gaps in any of the duct connections (either at the portable AC or the window mounting bracket) 

for units in its test sample. DOE lacks detailed information regarding the heat impacts of air 

leakage at the duct connections.

Case Insulation

The February 2015 Test Procedure NOPR would also account for any heat lost to the 

conditioned space through the product case. Portable AC product cases house internal 

components that may operate at high temperatures, such as the compressor, which may result in 

locally high case surface temperatures and heat transferred to the conditioned space. 

Manufacturers could potentially limit this heat loss using insulated cases. Although DOE is 

aware that certain portable ACs incorporate insulation to seal the air flow between the heat 

exchanger compartments, DOE is not aware of any portable ACs that use additional insulation 

on the external product case to limit heat transfer to the room. Therefore, DOE does not have 

information regarding the performance and reliability effects of restricting the heat rejection 

from the internal components.

Variable-Speed Compressors

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. Variablespeed compressors enable modulation of the refrigeration-system cooling power beyond simple 

on/off control, allowing the portable AC to better match the compressor power to the load, 

increasing compression efficiency. DOE is not aware of variable-speed compressor technology 

implemented in portable ACs to date, and it is therefore difficult to predict the energy efficiency 

improvements that could be achieved through its use. However, DOE expects that a variablespeed compressor in a portable AC could provide more precise control of the evaporator coil 
3-23

temperature to ensure more efficient heat removal, especially at low temperatures where ice 

buildup may occur.

The greatest benefit of variable speed systems is to save energy under varying operating 

conditions. However, the test procedures proposed in the February 2015 Test Procedure NOPR 

would require testing under constant steady-state conditions. Accordingly, the test procedure 

would not reflect efficiency improvements at different operating conditions. DOE notes that in 

central air conditioning systems, research shows that variable-speed compressors may produce 

energy savings from 15 to 40 percent.13, 14, 15

Thermostatic or Electronic Expansion Valves

Nearly all portable ACs use capillary-tubes for flow control. The capillary-tube 

expansion valve is a pressure-reducing device that consists of a small-diameter line that connects 

the outlet of the condenser to the inlet of the evaporator. It is designed to provide optimum 

energy characteristics at one design point. If sized properly, the capillary-tube expansion valve 

compensates automatically for load and system variations and gives acceptable performance over 

a wide range of operating conditions. Because ambient temperature and humidity vary, however, 

portable ACs sometimes operate under conditions outside of the target conditions, leading to 

reduced efficiency.

The thermostatic expansion valve (TXV) — a flow-control alternative to the capillary 

tube — is commonly used in higher-efficiency central air-conditioning systems. TXVs regulate 

the flow of liquid refrigerant entering the evaporator in response to the superheat of the 

refrigerant leaving it. TXVs can adapt better to changes in operating conditions such as those due 

to variations in ambient temperature, which affect the condensing temperature. As a result, TXVs 

can lead to a somewhat increased seasonal operating efficiency.

Electronic expansion valves (EEVs) are similar to TXVs, but unlike TXVs, they can be 

actively controlled. While a TXV relies on a single temperature sensor for feedback, digital 

controllers can use multiple sensors for feedback control and respond using multiple approaches. 

For example, besides modulating the refrigerant flow, the controller may also vary the fan speed 

to optimize efficiency under varying conditions. As with TXVs, EEVs can use the superheat 

control method to regulate refrigerant flow. Other methods, such as controlling compressor 

discharge temperature, can also be used. 

During the reverse-engineering analysis, DOE did not observe any units with either 

TXVs or EEVs. Given the cost of TXVs and EEVs, it is unlikely that manufacturers would 

implement them in portable ACs. Additionally, because DOE proposed testing under constant 

ambient conditions, the test procedure may not capture efficiency gains associated with these 

technologies.
3-24

3.12.3 Energy Efficiency

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

energy efficiency of residential portable ACs currently available in the marketplace. These data 

are taken from the CEC Appliance Efficiency database. While this section is not intended to 

provide a complete characterization of the energy efficiency of all portable ACs currently 

available and in use, it does provide a general overview of the energy efficiency of these 

products. Figure 3.12.2 and Figure 3.12.3 display a scatter plot of the energy efficiency data and 

a distribution of the capacities, respectively, of portable ACs currently listed in the CEC product 

database.

Figure 3.12.2 CEC Energy Efficiency and Capacity Data

0

2

4

6

8

10

12

14

16

18

0 5000 10000 15000

EER (Btu/Wh)

Capacity (Btu/h)
3-25

Figure 3.12.3 Distribution of the Capacities of Units in the CEC Database

0

10

20

30

40

50

60

70

80

90

100

<= 6,000 6,001 - 8,000 8,001 -

10,000

10,001 -

12,000

12,001 -

14,000

Number of Models

Capacity Bins (Btu/h)
3-26

REFERENCES

 

1 U.S. Census Bureau. 2005–2011. “Annual Survey of Manufactures: General Statistics: 

Statistics for Industry Groups and Industries,” ASM. Available online at: 

http://factfinder2.census.gov/faces/tableservices/jsf/pages/productview.xhtml?pid=ASM_

2011_31GS101&prodType=table.

2

Ibid.

3

Ibid.

4 U.S. Census Bureau, Survey of Plant Capacity, 2004 to 2006.

5 U.S. Census Bureau, Quarterly Survey of Plant Capacity Utilization, 2007 to 2012.

6 www.kingersons.com/how_it_works.html

7 M.H. Kim and C.W. Bullard. 2002. “Performance Evaluation of a Window Room Air 

Conditioner with Microchannel Condensers.” Journal of Energy Resources Technology.

Vol. 124, Issue 1, pp. 47–55.

8 R. Yun, Y. Hwang, R. Radermacher, and R. Zecirovic. 2006. “Comparison of 

Performance of Residential Air-Conditioning System Using Microchannel and Fin-andTube Heat Exchanger.” International Refrigeration and Air Conditioning Conference at 

Purdue, July 17-20, 2006.

9 Z. Qi, Y. Zhao, J. Chen. 2009. “Performance enhancement study of mobile air 

conditioning system using microchannel heat exchangers.” International Journal of 

Refrigeration. Issue 33, pp. 301-312.

10 U.S. DOE. 1997. Op. cit.

11 Simmons. 2003. Op. cit.

12 Ibid.

13

 H.I. Henderson, Jr. 1990. “A Side-by-Side Field Test of Variable-Speed and ConstantSpeed Air Conditioners.” ASHRAE Transactions. 96(1): pp 683–692.

14 V. Bahel and S.M. Zubair. 1989. “An Assessment of Inverter-Driven Variable-Speed Air 

Conditioners: Sample Performance Comparison with a Conventional System. ASHRAE 

Transactions. 95(1): pp 455–464.
3-27

 

15 M. Hori, I. Akamine, and T. Sakai. 1985. “1985. “Seasonal Efficiencies of Residential 

Heat Pump Air Conditioners with Inverter-Driven Compressors.” ASHRAE Transactions. 

91(2B): pp 1585–1595.