TRANSITIONING TO LOW-GWP 

ALTERNATIVES IN UNITARY AIR CONDITIONING

Background

This fact sheet1 provides current information on low-Global Warming Potential (GWP) alternatives for new equipment in unitary air conditioning (AC) 

relevant to the Montreal Protocol on Substances that Deplete the Ozone Layer. The unitary AC sector consists of systems that cool enclosed spaces ranging 

from single rooms to large exhibition halls. These systems have a typical lifetime of 15 years and generally fall into four categories:

Small, Self-Contained Air Conditioners 

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Window-mounted, portable, and through-the-wall

Capacities of 1–10.5 kW 

Average charge size of 0.7 kg 

Non-Ducted (or Duct-Free) Split Residential 

and Commercial Air Conditioners

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Compressor/heat exchanger units installed outside the 

space to be cooled/heated

Capacities of 2–20 kW for a mini-split (single 

evaporater), 4.5–135 kW for a multisplit system

Charge sizes of 0.5–90 kg

Ducted, Split Residential Air Conditioners

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m

Duct supplies cooled/heated air to each room or zone

Used primarily in developed countries, especially in North 

America 

Capacities of 5–17.5 kW

Charge sizes of 1–6 kg

Ducted, Commercial, Split and Packaged Air 

Conditioners

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Mounted on roofs or on the ground adjacent to buildings

Capacities typically range from 5–420 kW

Unitary AC equipment accounts for an estimated 91 million 

metric tons of carbon dioxide equivalent (MMTCO2eq.) or 8% of global HFC consumption 

in 2010. In the refrigeration/AC sector, unitary AC accounts for 11% of consumption. 

This percentage is expected to increase as the transition from HCFCs to HFCs matures. 

An estimated 38% of HFC consumption in the unitary AC sector (35 MMTCO2

eq.) is in 

developing countries.

HFC Alternatives and Market Trends

Today, most unitary AC systems use HCFC-22. Since 2000, developed countries have 

been transitioning to R-410A and, to some extent, R-407C. Most developing countries 

continue to rely on R-22. Currently, R-22 represents approximately 85% (1.2 million tons) 

of refrigerant stocks in existing unitary AC systems worldwide. Of the units sold today, 

R-22 accounts for approximately 60%, while R-410A and R-407C account for most of the 

remainder; propane (R-290) accounts for less than 1%.

Carbon Dioxide (R-744)

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Research to improve efficiency is underway

Custom-built applications and demonstration units are available 

Increased use is expected in cool to moderately warm climates

China’s Experience

China manufactures half of the world’s 50 million mini-split AC systems 

annually. It’s the largest manufacturer of AC equipment in the developing 

world. A significant portion of production is for the export market—China 

supplies nearly 85% of the window, wall, and mini-split AC imports to the 

United States. While R-22 continues to dominate unitary AC domestically, 

China manufactures both R-22 and R-410A units. The R-410A units are in 

high demand as exports to developed countries. China has commercialized 

room ACs with R-290 and is researching unitary AC products with R-32. 

2010 HFC Consumption

(Estimates Presented in MMTCO2eq.)

Refrigeration/

AC (79%)

Foams 

(11%)

Aerosols

(5%)

Fire Extinguishing

(4%)

Solvents

(1%) Other 

Refrigeration/AC

(89%)

Unitary AC

Developed

Countries

(7%)

Unitary AC

Developing 

Countries

(4%)

Global HFC Consumption Total: 1,087 MMTCO2eq.

Global Refrigeration/AC Sector Total: 858 MMTCO2

eq.

Global HFC Consumption Unitary AC: 91 MMTCO2

eq.

Refrigerant GWP ODPa

R-410A 2,088 0

R-22 1,810 0.055

R-407C 1,774 0

HFO Blends <1,032b 0

R-32 675 0

R-1234ze 6 0

R-1234yf 4 0

R-290 (propane) 3.3 0

R-744 (CO2

) 1 0

aODP = ozone depletion potential

bValue shown is based on a blend that mirrors the composition of R-407C, 

substituting R-1234yf for R-134a
R-290

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m

m

Performs very similarly to R-22

Charge size is about 40% of an R-22 unit

Refrigerant costs less than R-22

Successfully used in small units with <1 kg of refrigerant:

Largest Chinese AC manufacturer has commercialized room AC 

units using R-290

Portable units have been sold in Europe for years

Use in low-charge units expected to increase globally, but use in more 

common applications (e.g., ducted split systems, non-ducted mini- and 

multi-splits) will require more time

HFC-32

• A major component of blend R-410A

• Higher capacity and efficiency than R-410A 

• Investigated as a replacement for R-22, especially in Japan, 

China, and Indonesia

HFO-1234yf and HFO-1234ze2

• If used to replace R-410A, would require system redesign due to lower 

pressure

• Could be used in small and medium AC units

• Research is underway to identify lower GWP blends using these agents

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Refrigerant Transition in the Unitary AC End-Use*

R-22

R-410A

R-407C

R-744

R-290

HFOs

R-32

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*Solid arrows represent alternatives already available in 

the market for these systems; dashed arrows indicate 

those likely to be available in the future.

Challenges to Market Entry and Potential Solutions

Some climate-friendly alternatives in the unitary AC sector face technical challenges, such as flammability and toxicity. Additional research is needed to 

identify appropriate substitutes for unitary AC equipment, particularly given the relatively recent and gradual transition from R-22 to HFCs.

Alternative Challenges to Market Entry Potential Solutions

R-290 High Flammability – Challenges for Use in 

Equipment with a High Refrigerant Charge

Safety Code Restrictions

Liability Concerns

Safety Devices

Secondary Refrigerant Loop for Larger Systems, if Performance Penalties 

Can Be Avoided

Leak Testing and Pump Down Circuits 

Standards, Service Procedures, Training, and Education

Engineering Design, Research, and Development

R-744 Acute Toxicity/Safety Risks

High Operating Pressure

Low Critical Temperature; Can Lead to Low 

Efficiency

Engineering Design

Training and Education

Research Is Being Conducted to Overcome Safety and Efficiency Barriers

R-32 Low Flammability

High Pressure

Has Not Been Submitted to EPA’s Significant New 

Alternatives Policy (SNAP) Program

Engineering Design – Limited Technical Challenges

Research and Development

Regulatory Approval

R-1234yf, 

R-1234ze

Low Flammability

Relatively Low Pressure That Would Require 

Significant System Redesign

Engineering Design

Use in a Blend with HFCs to More Closely Match the Performance of R-22 

and R-410A

Research and Development

Future Outlook

Together, the suite of known alternative chemicals, new technologies, and better process and handling practices can significantly reduce HFC consumption 

in both the near and long term, while simultaneously completing the HCFC phaseout. Although much work remains to fully adopt these chemicals, 

technologies, and practices, and some unknowns still remain, the industries currently using HCFCs and HFCs have proven through the ODS phaseout that 

they can move quickly to protect the environment.
References

GTZ-Proklima International. 2009. “Showcase Production of Hydrocarbon Room Air-Conditioning Systems in China.” 

GTZ-Proklima International. 2009. “Gree Electric R290 Air Conditioner.” Presented on behalf of Gree by Dr. Volkmar Hasse, GTZ-Proklima International, at the Joint 

West Asia and South Asia Network Meeting. May 10, 2009. Available online at: http://www.hydrocarbons21.com/files/papers/Gree-presenattion.ppt. 

Accessed September 30, 2010.

ICF International. 2007. “Assessment of HCFC-Based Air Conditioning Equipment and Emerging Alternative Technologies.” Final Report prepared for the 

World Bank. September 2007.

International Panel on Climate Change (IPCC). 2007. “Climate Change 2007: The Physical Science Basis.” Contribution of Working Group I to the 

Fourth Assessment Report of the Intergovernmental Panel on Climate Change. Solomon, S., D. Qin, M. Manning, Z. Chen, M. Marquis, K.B. Averyt, M. 

Tignor, and H.L. Miller (Eds.). Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA. September 2007. Available online at: 

http://www.ipcc.ch/publications_and_data/ar4/wg1/en/contents.html. Accessed September 30, 2010.

International Panel on Climate Change (IPCC)/Technology and Economic Assessment Panel (TEAP). 2005. “Safeguarding the Ozone Layer and the 

Global Climate System: Issues Related to Hydrofluorocarbons and Perfluorocarbons.” Metz, B., K. Lambert, S. Solomon, S.O. Andersen, O. Davidson, 

J. Pons, D.d. Jager, T. Kestin, M. Manning, and L. Meyer (Eds.). Cambridge University Press, United Kingdom. Available online at: 

http://www.ipcc.ch/publications_and_data/publications_and_data_reports_safeguarding_the_ozone_layer.htm. Accessed September 30, 2010.

Technology and Economic Assessment Panel (TEAP). 2010. “TEAP 2010 Progress Report, Volume 1: Assessment of HCFCs and Environmentally Sound 

Alternatives, Scoping Study on Alternatives to HCFC Refrigerants under High Ambient Temperature Conditions.” May 2010. Available online at: 

http://www.unep.ch/ozone/Assessment_Panels/TEAP/Reports/TEAP_Reports/teap-2010-progress-report-volume1-May2010.pdf. Accessed September 

30, 2010.

Technology and Economic Assessment Panel (TEAP). 2009. “Task Force Decision XX/8 Report, Assessment of Alternatives to HCFCs and HFCs and 

Update of the TEAP 2005 Supplement Report Data.” May 2009. Available online at: http://www.unep.ch/ozone/Assessment_Panels/TEAP/Reports/

TEAP_Reports/teap-may-2009-decisionXX-8-task-force-report.pdf. Accessed September 30, 2010.

United Nations Environment Programme (UNEP). 2007. “Study on the Strategy for the Long Term Management of HCFCs in China (Presented by 

Germany).” February 19, 2007. Available online at: http://www.multilateralfund.org/files/51/51inf3.pdf. Accessed September 30, 2010.

United Nations Environment Programme (UNEP). 2003. “2002 Report of the Refrigeration, Air Conditioning and Heat Pumps Technical Options 

Committee.” January 2003. Available online at: http://ozone.unep.org/teap/Reports/RTOC/RTOC2002.pdf. Accessed September 30, 2010.

United Nations Environment Programme (UNEP). 2010. “Alternatives to HCFCs in the Refrigeration and Air Conditioning Sector, Practical Guidelines 

and Case Studies for Equipment Retrofit and Replacement.” Available online at: http://www.unep.fr/ozonaction/ebooks/alternatives-to-hcfcs/. Accessed 

September 20, 2010.

1

 The four fact sheets in this series (October 2010) cover domestic refrigeration, commercial refrigeration, motor vehicle air conditioning, 

and unitary air conditioning. These four end-uses represent about 85% of HFC consumption in the refrigeration/AC sector. The remaining 

HFC consumption in the refrigeration/AC sector comes from other end-uses including chillers, cold storage, industrial process refrigeration, 

and refrigerated transport. Any service-related consumption is attributed to the specific end-use.

2

 HFOs (hydrofluoro-olefins) are unsaturated HFCs. HFO-1234yf refrigerant is also commonly referred to as HFC-1234yf or R-1234yf, as it is 

referred to in the remainder of this fact sheet. HFO-1234ze is also commonly referred to as HFC-1234ze or R-1234ze.

U.S. Environmental Protection Agency

EPA-430-F-10-044 • www.epa.gov • October 2010

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