TRANSITIONING TO LOW-GWP ALTERNATIVES 

in Residential and Commercial Air Conditioning 

and Chillers

Background

This fact sheet provides current information on low global 

warming potential (GWP)1 alternative refrigerants to high-GWP

hydrofluorocarbons (HFCs) for use in residential and commercial 

air conditioning (AC) equipment, including chillers. HFCs are 

powerful greenhouse gases (GHGs) with GWPs hundreds to 

thousands of times more potent per pound than carbon dioxide 

(CO2); however, more low-GWP alternatives are becoming 

available. 

Globally, approximately 80% of HFCs are emitted in the 

refrigeration, AC, and motor vehicle AC (MVAC) sectors, with 

the remainder accounted for by the foam-blowing, aerosols, 

fire suppression, and solvents sectors. While developed 

nations have historically accounted for the majority of global 

HFC emissions, total HFC emissions in developing nations are 

projected to quadruple by 2030. This rapidly increasing rate of 

HFC emissions is largely driven by the increased demand for 

refrigeration and AC, particularly in the tropical climates of 

much of the developing world, and the transition away from 

ozone depleting substances (ODS). 

HFC refrigerant emissions from AC applications are released 

to the atmosphere throughout the lifecycle of equipment—i.e., 

during equipment manufacture, installation, operation, 

maintenance, and at end-of-life.

Figure 1. Global HFC Emissions in 2020 by Sector

Source: Estimates based on U.S. EPA (2013). 

AC Equipment

Residential and commercial AC equipment used in households 

and commercial buildings contain one or more factory-made 

assemblies that normally include an evaporator or cooling coil(s), 

compressor(s), and condenser(s). These include small AC systems 

(self-contained AC and split AC), large AC systems (single 

split and multi-split, variable refrigerant flow, and ducted and 

packaged rooftop units), as well as chillers. Descriptions of each 

of these AC equipment categories are provided below, followed 

by Table 1, which lists the typical capacity, refrigerant charge, and 

annual operational leak rate for each equipment type.

1 GWP is a measure of a substance’s climate warming impact compared to CO2.

Commercial

Ref

26%

Aerosols, 

Solvents, 

Foams, 

and Fire Ext.

21%

AC

28%

Other Ref

12%

MVAC

13%

Global HFC Emissions: 1,084 MMT CO2 Eq. 

Global HFC Emissions in AC: 306 MMT CO2 Eq.
TRANSITIONING TO LOW-GWP ALTERNATIVES in Residential and Commercial Air Conditioning and Chillers

Small AC Systems 

Small Self-Contained AC

• Small hermetically sealed AC units

are used for cooling small rooms

in residential and commercial

buildings

• The compressor, evaporator, and

condenser are all housed within

a single unit

• Includes portable units, window-mounted units, through-thewall units, and packaged terminal air conditioning

(PTAC) units

• Portable units utilize flexible ductwork to supply outside air

to the condenser and return heated air to outside of

the room

• PTAC units are often used in the hospitality industry

(e.g., inside hotel rooms)

• Packaged terminal heat pumps (PTHPs) are similar to

PTACs and also provide heating

Source: U.S. EPA (2015d)

Small Split AC 

• Small split AC units are used

for cooling single rooms in

residential and commercial

buildings

• Systems contain two factorybuilt units interconnected by a

refrigerant line; the indoor unit includes the evaporator,

installed inside conditioned room on the wall, ceiling,

or floor; the outdoor unit includes a compressor and a

condenser

• Some systems can operate in reverse and provide heating

in cold weather

Source: UNEP (2015c)

Large AC Systems

Large Single Split and Multi-Split AC 

• Larger versions of the

small split system

described above

• Multi-split systems have

several indoor units connected

to a single outdoor unit

• Some models are designed to

provide both heating and cooling

Source: UNEP (2015d)

Variable Refrigerant Flow 

(VRF) Systems 

• More complex multi-split

systems

• One or more air source

outdoor compressor units

serving multiple indoor fan

coil refrigerant evaporator units

• Heated or cooled refrigerant moves throughout building

in small diameter pipes and passes through coils in each

conditioned room

• Systems can deliver heating and/or cooling to different

rooms of the same building simultaneously through

various units

Ducted and Packaged Rooftop Systems

• In ducted systems, the

evaporator is located in an air

handling unit to cool air

• In packaged rooftop systems,

the compressor, evaporator,

and condenser are all housed

within a single unit

• Air is circulated throughout the

building via a ducted air ventilation system

Source: U.S. EPA (2015d)

Source: Pacific Northwest National 

Laboratory (2012)
TRANSITIONING TO LOW-GWP ALTERNATIVES in Residential and Commercial Air Conditioning and Chillers

Chillers

Comfort Cooling

• Large buildings are often cooled 

by a central chiller that pumps 

chilled water to heat exchangers 

in air handling or fan-coil units 

that deliver conditioned air 

• Often located in a machinery 

room (large buildings) or 

outdoors (small buildings)

• Small and medium-sized chillers typically use a vapor 

compression cycle with positive displacement compressors 

(i.e., reciprocating, rotary, scroll, or screw), while large 

chillers typically use screw or centrifugal compressors

Source: UNEP (2015e)

District Cooling

• Uses a centralized cooling 

plant to deliver chilled water 

via underground insulated 

pipes to several buildings 

using a single system

• Provides AC to multiple buildings 

in a central location (e.g., hospitals, universities, 

shopping malls, airports)

• Chillers using vapor compression technology and centrifugal 

compressors often used in cooling plant 

• Increasing in popularity; commonly used in the Middle East; 

some installations in China, the United States, Northern 

Europe, and coastal sites such as Hawaii, Malaysia, and 

Mauritius, with sufficient deep water resources

Source: AEC Online (2007)

Table 1. Typical AC Equipment Characteristics

Equipment Type Capacity

(kW) Refrigerant Charge (kg) Annual Operational Leak Ratea (%)

Small Self-Contained AC 2–7 0.2–2 <1

Small Split AC 2–12 0.5–3 1–4

Single Split and Multi-Split (Large) 10–40 3–10 1–4

VRF Systems (Large) 12–150 5–100 1–5

Ducted Systems (Large) 12–750 5–200 2–6

Small/Medium Chillersb 50–750 40–500 2–4

Large Chillersc 750–21,000 500–36,000 2–4

Sources: UNEP (2015a – e) and Johnson Controls (2014).

a

 Typical annual operational leak rate does not include additional refrigerant leaks that can occur during equipment installation, maintenance, servicing, and disposal. 

b

 Typically use positive displacement compressors (i.e., reciprocating, rotary, scroll, or screw). 

c

 Typically use screw or centrifugal compressors.

HFC Alternatives and Market Trends

Many residential and commercial AC systems in use contain 

ozone-depleting refrigerants CFC-11, CFC-12, and HCFC-22, 

which are being phased out globally under the Montreal 

Protocol. Many new units sold today contain HFCs, or HFC 

blends, namely R-410A and R-407C, with GWP values of 

2,088 and 1,774, respectively. A number of lower-GWP 

alternative refrigerants are available and currently in use or 

under development for use in residential and commercial AC 

systems—including hydrocarbons, carbon dioxide, ammonia, 

water, as well as HFC and HFO2

 blends. These alternatives and 

their potential applications are described on the next page and 

summarized in Table 2. 

2

 HFOs (hydrofluoroolefins) are unsaturated HFCs (i.e., containing a carbon-carbon double bond).
TRANSITIONING TO LOW-GWP ALTERNATIVES in Residential and Commercial Air Conditioning and Chillers

R-290 (Propane) and Hydrocarbon Blends (e.g., R-441A)

• Successfully used in some regions including China and 

India in small AC units that utilize less than 1 kilogram of 

refrigerant

• Used in small self-contained AC and small split AC in Europe, 

Far East, Japan, and India

• Used in small capacities and outdoor applications in 

air-cooled chillers in Indonesia, Malaysia, the Philippines, 

Europe, and New Zealand

• R-290 and R-441A are listed acceptable substitutes 

(subject to use conditions) in room AC units by the U.S. EPA 

Significant New Alternatives Policy (SNAP) program

• Efficiency and performance expected to be equal to or better 

than R-410A, particularly in regions with warmer climates

• Safety concerns for flammable refrigerants require 

technician training and can increase installation costs

Carbon Dioxide (CO2, R-744)

• Can be used in large AC equipment, typically in ducted 

systems

• Air-cooled chillers using R-744 have been introduced in 

northern Europe

Ammonia (R-717) 

• Suitable in chillers for numerous building AC applications 

and district cooling

• Used in medium and large chillers with screw or 

reciprocating compressors

• Central comfort cooling chiller plant installations exist in the 

Middle East, China, Europe, and the United States

• Ammonia is listed as an acceptable substitute by the U.S. 

EPA SNAP program in vapor compression chillers (with a 

secondary loop)

• Ammonia is also used in absorption systems, which are 

listed as acceptable by the U.S. EPA SNAP program for 

chillers and in residential and light commercial AC equipment 

• Safety concerns in comfort cooling applications can increase 

installation costs and require technician training; restrictions 

often apply in some countries due to certain building codes 

or regulations

Water (R-718)

• Developmental chillers demonstrated in the Middle East, 

South Africa, and Europe

• Requires large space and use of complex 

compressor technology

HFC-32

• Small self-contained and split AC systems produced with 

HFC-32 are commercially available in 30 countries, including 

Japan, India, Indonesia, Australia, and soon in China and the 

United States

• HFC-32 is listed as an acceptable substitute (subject to use 

conditions) in room AC units by the U.S. EPA SNAP program

• Efficiency and performance expected to be equal to or better 

than R-410A

Low-GWP Fluorinated Compounds

• HFO-1234yf and HFO-1234ze(E) have similar properties to 

HFC-134a and are under development for ducted and rooftop 

unit systems 

• Use of HFO-1234ze(E) is currently under development in 

large centrifugal chillers and large AC equipment and 

commercially available in small and medium-sized positive 

displacement chillers

• Chillers using HFO-1234ze(E) are available in the 

European market 

• HFO-1234ze(E) is listed as an acceptable substitute in 

centrifugal, reciprocating, and screw chillers by the U.S. EPA 

SNAP program

• SolsticeTM 1233zd(E) is currently used in centrifugal chillers 

in Europe, the Middle East, and Japan

• SolsticeTM 1233zd(E) is listed as an acceptable substitute in 

centrifugal chillers by the U.S. EPA SNAP program

• HFO-1336mzz(Z) is under development for use in low 

pressure centrifugal chillers

• HFO-1336mzz(Z) is listed as an acceptable substitute in 

centrifugal and positive displacement chillers by the U.S. 

EPA SNAP program

HFC/HFO Blends

• Various blends of HFCs and HFOs (i.e., unsaturated HFCs) are 

being developed for all types of AC equipment

• R-450A and R-513A are listed as acceptable substitutes in 

centrifugal, reciprocating, and screw chillers by the U.S. EPA 

SNAP program

• Testing and trials using blends of R-444B, R-446A, and 

R-447A, in both small and large AC systems, are ongoing, 

with manufacturers in Japan, Korea, China, and New 

Zealand developing prototypes

• Safety regulations may be required for lower flammability 

blends (e.g., R-444B, R-446A and R-447A), especially in 

larger AC equipment
TRANSITIONING TO LOW-GWP ALTERNATIVES in Residential and Commercial Air Conditioning and Chillers

Table 2. Lower-GWP Alternatives for Residential and Commercial ACa

Refrigerant GWPb

Small 

Self-Contained 

ACc

Small Split 

ACc

Single & 

Multi- Split AC 

(Large)c

VRF (Large)c

Ducted 

Systems 

(Large)c

Chillersc

HFC-32 675 u+ u u u u o

R-513A 630 u+ 

R-450A 601 u+

HFO-1336mzz(Z) 9 o+

HFO-1234ze(E) 6 o u+

R-441A <5 u+

SolsticeTM 1233zd(E) 4.7 - 7 u+ d

HFO-1234yf 4 o

R-290 3 u+ u u

R-744 (CO2) 1 u u

R-717 (ammonia) 0 u+

Note: R-444B, R-446A, R-447A, and R-718 are currently under development for use in various residential and commercial AC applications.

a

 u = Available now; o = Under Development; + = U.S. EPA SNAP-approved

b

 GWP values are from IPCC Fourth Assessment Report (2007) and U.S. EPA (2015c).

c

 UNEP (2015a – e).

d

 U.S. EPA SNAP-approved for centrifugal chillers only.

Reducing Emissions from Servicing and Disposal

Refrigerant emissions from AC equipment occur during various 

events, including manufacture, operation (i.e., leaks from 

fittings, joints, shaft seals, etc.), servicing (i.e., due to loss 

of refrigerant from fugitive emissions), and end-of-life (i.e., 

equipment disposal). When leaks are fixed during servicing, 

refrigerant recovery is necessary for certain applications. 

During servicing events and end-of-life, the refrigerant 

losses depend on various factors including the existence of 

or compliance with refrigerant recovery laws, the technical 

efficiency of refrigerant recovery equipment, and the technical 

performance of technicians. Improvements in the technologies 

and practices associated with the use of these gases by 

manufacturers and technicians, the introduction of alternative 

gases and technologies, implementation of refrigerant recovery 

laws and standards, and market/policy drivers that provide 

financial incentives for recovery may help to offset most HFC 

refrigerant emissions from residential and commercial 

AC equipment.

Case Study: Hydrocarbon Refrigerants in China

With support from the United Nations Industrial Development Organization (UNIDO) and approval for funding by the Executive Committee 

of the Multilateral Fund for the Implementation of the Montreal Protocol in July 2010, two manufacturers in China—Guangdong Meizhi 

Co. Ltd and Guangdong Midea Refrigeration Equipment Co. Ltd—conducted a demonstration project to convert R-22 compressors and 

split AC units to R-290. The Meizhi production line, which has an annual production capacity of 1.83 million rotary compressors for split AC 

systems, was converted to produce R-290 compressors. The Midea production line was converted to an advanced mechanized line producing 

200,000 R-290 split units annually. After 30 months of factory conversion the project was completed by the end of 2013 and two types 

of compressors (fixed and variable speed) and two types of AC units (split and portable) became available for mass production by these 

manufacturers. The R-290 AC units also meet both national and international performance standard requirements.

In converting the plants, engineering controls and safety measures were implemented into the production lines to address the flammability 

of R-290, including modified products, tools, parts, equipment, installation procedures, leak detection and containment, staff training, and 

technology dissemination. The success of this project and advancement of hydrocarbon-based AC technologies has already influenced other 

Chinese manufacturers to invest in conversion activities. For example, in 2015, nine AC manufacturers in China were designated by the 

Chinese Ministry of Environmental Protection to receive subsidies to convert to R-290. These advancements are expected to encourage other 

manufacturers in other developing countries to invest in alternative AC technologies.
TRANSITIONING TO LOW-GWP ALTERNATIVES in Residential and Commercial Air Conditioning and Chillers

Future Outlook

Together, the suite of known alternative chemicals, new 

technologies, as well as better process and handling practices, 

can significantly reduce HFC use in both the near and long term. 

Many countries are transitioning to lower-GWP alternatives 

in AC applications while satisfying the various international 

energy efficiency, safety, and environmental standards. The 

equipment manufacturers and chemical producers for the AC 

industry are continuing to work on developing new alternatives 

that can be marketed worldwide. Although much work remains 

to fully develop and adopt some of these low-GWP

alternatives, and some unknowns still remain, the affected 

industries have proven through the ODS phaseout that they 

can move quickly to develop low-GWP alternatives that protect 

the environment. 

References

AEC Online. 2007. “Empower and Logstor to build the UAE’s largest preinsulated pipe manufacturing facility.” Available online at: http://www.

aeconline.ae/13/pdcnewsitem/00/98/45/index_13.html

European Parliament and the Council of the European Union (EU). 2014. 

“Regulation (EU) No 517/2014 on fluorinated greenhouse gases and repealing 

Regulation (EC) No 842/2006.” Official Journal of the European Union. 16 

April 2014. Available online at: http://eur-lex.europa.eu/legal-content/EN/

TXT/PDF/?uri=CELEX:32014R0517&from=EN

Intergovernmental Panel on Climate Change (IPCC). 2006. “2006 IPCC 

Guidelines for National Greenhouse Gas Inventories.” The National 

Greenhouse Gas Inventories Programme, The Intergovernmental Panel 

on Climate Change, H.S. Eggleston, L. Buendia, K. Miwa, T. Ngara, and K. 

Tanabe (eds.). Hayama, Kanagawa, Japan.

Intergovernmental 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

Johnson Controls. 2015. “Model YD Dual Centrifugal Compressor Chillers.” 

Available online at: http://cgproducts.johnsoncontrols.com/YorkDoc/160.69-

EG3.pdf

McNeil, M.A. and V.E. Letschert. 2007. “Future air conditioning energy 

consumption in developing countries and what can be done about it: the 

potential of efficiency in the residential sector.” ECEEE 2007 Summer Study. 

Available online at: http://www.eceee.org/library/conference_proceedings/

eceee_Summer_Studies/2007/Panel_6/6.306/paper

Pacific Northwest National Laboratory. 2012. “Variable Refrigerant Flow 

Systems.” Prepared for the General Services Administration by Pacific 

Northwest National Laboratory. December 2012. Available online at: http://

www.gsa.gov/portal/mediaId/169771/fileName/GPG_VRF_Report_-_

FINAL_DRAFT_4-16-13

Shecco. 2016. Manufacturers see openings for natural refrigerants in China. 

Hydrocarbons 21 Industry News. 14 April 2016. Available online at: http://

www.hydrocarbons21.com/news/view/6948.

Schwarz, W., B. Gschrey, A. Leisewitz, A. Herold, S. Gores, I. Papst, J. 

Usinger, D. Oppelt, I. Croiset, P.H. Pedersen, D. Colbourne, M. Kauffeld, K. 

Kaar, and A. Lindborg. 2011. “Preparatory study for a review of Regulation 

(EC) No 842/2006 on certain fluorinated greenhouse gases.” Prepared for the 

European Commission. September 2011. 

Technology and Economic Assessment Panel (TEAP). 2013. “Decision 

XXIV/7 Task Force Report: Additional Information to Alternatives on ODS.” 

September 2013. Available online at: http://ozone.unep.org/Assessment_

Panels/TEAP/Reports/TEAP_Reports/TEAP_TaskForce%20XXIV-7-

September2013.pdf

Technology and Economic Assessment Panel (TEAP). 2014. “Decision 

XXV/5 Task Force Report: Additional Information to Alternatives on ODS 

(Final Report).” October 2014. Available online at: http://ozone.unep.org/

en/Assessment_Panels/TEAP/Reports/TEAP_Reports/TEAP_Task%20

Force%20XXV5-October2014.pdf

Technology and Economic Assessment Panel (TEAP). 2015. “Decision XXVI/9 

Task Force Report: Additional Information to Alternatives to ODS.” June 

2015. Available online at: http://conf.montreal-protocol.org/meeting/oewg/

oewg-36/presession/Background%20Documents%20are%20available%20

in%20English%20only/TEAP_Task-Force-XXVI-9_Report-June-2015.pdf

United Nations Environment Programme (UNEP). 2011. “2010 Report of 

the Refrigeration, Air Conditioning and Heat Pumps Technical Options 

Committee.” February 2011. Available online at: http://ozone.unep.org/

Assessment_Panels/TEAP/Reports/RTOC/RTOC-Assessment-report-2010.

pdf

United Nations Environment Programme (UNEP). 2014. Addendum: Status 

Reports and Compliance. Executive Committee of the Multilateral Fund for 

the Implementation of the Montreal Protocol, Seventy-third Meeting Paris, 

9-13 November 2014. UNEP/OzL.Pro/ExCom/73/17/Add.1. Available online at: 

http://www.multilateralfund.org/73/English/1/7317a1.pdf.

United Nations Environment Programme (UNEP). 2015a. “2014 Report 

of the Refrigeration, Air Conditioning and Heat Pumps Technical Options 

Committee.” February 2015. Available online at: http://conf.montrealprotocol.org/meeting/mop/mop-27/presession/Background%20

Documents%20are%20available%20in%20English%20only/RTOCAssessment-Report-2014.pdf

United Nations Environment Programme (UNEP). 2015b. “Fact Sheet 7: 

Small Self-Contained Air-Conditioning.” UNEP Ozone Secretariat Workshop 

on HFC management: technical issues. Bangkok, 20 and 21 April 2015. 

Available online at: http://conf.montreal-protocol.org/meeting/workshops/

hfc_management-02/presession/English/FS%207%20Small%20self%20

contained%20air-conditioning%20final.pdf

United Nations Environment Programme (UNEP). 2015c. “Fact Sheet 8: 

Small Split Air-Conditioning.” UNEP Ozone Secretariat Workshop on HFC 

management: technical issues. Bangkok, 20 and 21 April 2015. Available 

online at: http://ozone.unep.org/sites/ozone/files/Meeting_Documents/

HFCs/FS_8_Small_split_air-conditioning_Oct_2015.pdf
TRANSITIONING TO LOW-GWP ALTERNATIVES in Residential and Commercial Air Conditioning and Chillers

United Nations Environment Programme (UNEP). 2015d. “Fact Sheet 9: Large 

Air-Conditioning (air-to-air).” UNEP Ozone Secretariat Workshop on HFC 

management: technical issues. Bangkok, 20 and 21 April 2015. Available 

online at: http://ozone.unep.org/sites/ozone/files/Meeting_Documents/HFCs/

FS_9_Large_air_to_air_air-conditioning_Oct_2015.pdf

United Nations Environment Programme (UNEP). 2015e. “Fact Sheet 10: 

Water chillers for air-conditioning.” UNEP Ozone Secretariat Workshop on 

HFC management: technical issues. Bangkok, 20 and 21 April 2015. Available 

online at: http://ozone.unep.org/sites/ozone/files/Meeting_Documents/HFCs/

FS_10_Water_chillers_for_air-conditioning_Oct_2015.pdf

United Nations Industrial Development Organization (UNIDO). Demonstrating 

the Feasibility of R-290 Based AC Manufacturing: China’s Midea and Meizhi 

Case. OzonAction Fact Sheet. Available online at: http://www.unep.org/

ozonaction/Portals/105/documents/events/MOP26/Fact%20Sheet%20

UNIDO%20Meizhi%20Nov%2013.pdf.

United States Environmental Protection Agency (U.S. EPA). 2010a. “Federal 

Register Vol. 75, No. 115.” Available online at: https://www.gpo.gov/fdsys/

pkg/FR-2010-06-16/pdf/2010-14510.pdf

United States Environmental Protection Agency (U.S. EPA). 2010b. “Summary 

of Substitute Refrigerants Listed in SNAP Notice 25.” Available online 

at: http://www2.epa.gov/sites/production/files/2014-11/documents/

notice25substituterefrigerants.pdf

United States Environmental Protection Agency (U.S. EPA). 2011. “Federal 

Register Vol. 76, No. 60.” Available online at: http://www.gpo.gov/fdsys/pkg/

FR-2011-03-29/pdf/2011-6268.pdf

United States Environmental Protection Agency (U.S. EPA). 2012. “Federal 

Register Vol. 77, No. 155.” Available online at: http://www.gpo.gov/fdsys/pkg/

FR-2012-08-10/pdf/2012-19688.pdf

United States Environmental Protection Agency (U.S. EPA). 2013. “Global 

Mitigation of Non-CO2 Greenhouse Gases: 2010-2030.” EPA Report 430-

R-13-011. September 2013. Available online at: https://www3.epa.gov/

climatechange/Downloads/EPAactivities/MAC_Report_2013.pdf

United States Environmental Protection Agency (U.S. EPA). 2014. “Federal 

Register Vol. 79, No. 203.” Available online at: http://www.gpo.gov/fdsys/pkg/

FR-2014-10-21/pdf/2014-24989.pdf

United States Environmental Protection Agency (U.S. EPA). 2015a. “Federal 

Register Vol. 80, No. 136.” Available online at: http://www.gpo.gov/fdsys/pkg/

FR-2015-07-16/pdf/2015-17469.pdf

United States Environmental Protection Agency (U.S. EPA). 2015b. “Federal 

Register Vol. 80 No. 69.” Available online at: http://www.gpo.gov/fdsys/pkg/

FR-2015-04-10/pdf/2015-07895.pdf

United States Environmental Protection Agency (U.S. EPA). 2015c. “Substitutes 

by Sector.” Significant New Alternatives Policy (SNAP) Program. Available 

online at: http://www.epa.gov/snap/substitutes-sector

United States Environmental Protection Agency (U.S. EPA). 2015d. 

“Transitioning to Low-GWP Alternatives in Residential & Light Commercial 

Air Conditioning.” Available online at: http://www.epa.gov/sites/production/

files/2015-09/documents/epa_hfc_residential_light_commercial_ac.pdf 

Velders, G.J.M., D.W. Fahey, J.S. Daniel, S.O. Andersen, and M. McFarland. 

2015. Future atmospheric abundances and climate forcings from scenarios 

of global and regional hydrofluorocarbon (HFC) emissions. Atmospheric 

Environment. Volume 123, Part A. December 2015. Available online at: 

http://dx.doi.org/10.1016/j.atmosenv.2015.10.071.

EPA-430-F-15-028 • www.epa.gov • December 2016