Global warming potential (GWP) is a measure of how much heat a greenhouse gas (GHG) will trap in the Earth’s atmosphere over a set period. The higher the GWP, the more heat the GHG traps, leading to a warming planet.
The GWP formula was developed to allow scientists to compare the global warming impact of different gases.
Refrigerants are used in air conditioners and heat pumps to transfer heat from one area to another during the cooling or heating process. Regulations have evolved to require more sustainable refrigerants.
That’s because AC refrigerants are inherently greenhouse gases. Greenhouse gases absorb and trap the heat in the atmosphere creating the same heating effect found in a greenhouse. But instead of warming plants in a greenhouse, GHGs trap the sun’s heat in the Earth’s atmosphere.
Some GHGs are essential for life, like water, which occurs naturally in the atmosphere. But releases of refrigerants used in air conditioning our homes and carbon dioxide from the burning of fossil fuels to produce electricity across the globe can lead to additional greenhouse gases.
The result is a changing climate, with shifts in snow and rainfall patterns, rising average temperatures, and more extreme climate events such as hurricanes, heat waves, and floods.
A refrigerant’s GWP is determined by comparing its global warming impact relative to the amount of carbon dioxide (CO²) that would cause an equivalent global warming impact. The higher the GWP, the greater the climate impact.
The Intergovernmental Panel on Climate Change (IPCC) periodically summarizes the latest GWP estimates in their Assessment Reports (ARs), The United Nations Montreal Protocol Kigali Amendment that mandated the phase-down of high GWP refrigerants uses the 100-year GWP in the IPCC Fourth Assessment Report (AR4).
The GWP is based on the intensity of radiative forcing or climate impact of each gas and how long harmful greenhouse gas emissions remain in the atmosphere. The United States Environmental Protection Agency (EPA) also uses 100-year GWP from AR4 in its regulations.
CFC refrigerants have the highest ozone depletion levels and very high GWPs and have already been phased out. HCFC refrigerants, such as R-22 (HCFC-22) or Freon™, shown in the chart above, have also been phased out in new equipment by the Environmental Protection Agency (EPA) because of their ozone depletion potential (ODP).
R-410A refrigerant is a blend of hydrofluorocarbon (HFC) refrigerants R-32 and R-125 that replaced R-22. But the global warming potential of R-410A is 2088. The EPA set a limit of 700 GWP for chillers, air conditioning, and heat pumps in 2025 under the American Innovation and Manufacturing (AIM) Act.
HFO refrigerants are very short-lived chemicals in the atmosphere, having lifetimes as short as several days. HFOs have carbon double bonds (unsaturated). HFCs do not contain a carbon-carbon double bond. HFOs have a zero ODP and ultra-low GWP. This makes them more sustainable refrigerants.
The transition to these more sustainable refrigerants is still in the beginning stages. Based on EPA mandates, Trane Residential HVAC began phasing out equipment production using R-410A and transitioning in 2025 to the production of heat pumps and air conditioners that use HFO refrigerants and blends.
We’re making the transition to using a low-GWP refrigerant because it’s the right thing to do for the planet, but also because of federal regulations.
HVAC technicians can still service your air conditioner or heat pump that utilizes an older refrigerant, so don’t worry that your existing HVAC system is obsolete. Just know that when it comes time to replace your units, they will utilize a more sustainable refrigerant with a lower GWP.
Two new refrigerants are being adopted by the industry that meet the AIM Act 700 GWP limit for air conditioning and heating systems. Some of the new low-GWP refrigerants include:
Replacing R-22 or R-410A with these low-GWP refrigerants will greatly reduce global warming contribution from the refrigerant, but the bigger climate impact will be the improved energy efficiency of the new equipment, which will reduce carbon dioxide emissions from energy as a result. Less greenhouse gases will be emitted from new air conditioners and heat pumps utilizing new refrigerants.
Big transitions like this don’t happen overnight. HVAC manufacturers such as Trane have been researching refrigerants and energy efficiency to develop innovative new heating and cooling products
In addition to changes in manufacturing and product design, we will strive to fully educate our team of Trane dealers, sales force, and homeowners like you. We hope to fully explain the need for the transition and how it may impact you as well as the planet.
Over the next few years, Trane will be transitioning to R-454B refrigerant for all of our new heat pumps and air conditioners. R-454B is an HFO mixture with the best in-case GWP refrigerants with the benefit of higher efficiency than R-410A with zero ODP. Sold under the trademarked names of Opteon™ XL41, Puron Advance™, and Solstice® 454B, this refrigerant has a GWP of 466, which is 78% lower than that of R-410A.
These more sustainable refrigerants that will reduce GHG emissions also support our Gigaton Challenge goal of reducing one billion tons of carbon emissions from our consumers’ carbon footprint by 2030. That’s the total amount of carbon produced by Italy, France, and the U.K. combined each year!
Most HVAC manufacturers are transitioning to R-454B as well, making it the new industry standard.
Questions about the transition to low-GWP refrigerants and what it means for your HVAC system? Read our Complete Guide to HVAC Refrigerants or contact your local Trane dealer.
Anne Fonda, Content Writer
A Content Writer with Trane Technologies, Anne Fonda researches topics and writes for Trane® and associated residential HVAC brands. She works in collaboration with Trane Technologies subject matter experts, offering easy-to-understand, informative content on complex topics. Her goal is to help consumers make informed decisions on the products and services they need.
She has written for HVAC and other service provider websites for over 16 years. Before transitioning to web content writing, Anne had a 14-year stint as an award-winning journalist. She graduated cum laude from the University of Missouri-Columbia School of Journalism.
When she’s not working, Anne enjoys playing word games, reading, gardening, spending time with family, and visiting gardens and museums.
Expert review by Helen Walter-Terrinoni, Global Director, Climate Policy
Refrigerant is a chemical cooling compound that absorbs and releases heat at different points in the heat exchange cycle as it runs throughout an HVAC system.
R-410A is the refrigerant that replaced R-22 (Freon®) in air conditioning and heat pump systems manufactured after 2009.
R-454B is a blend of R-32, a hydrofluorocarbon (HFC), and R-1234yf a hydrofluoroolefin (HFO). R-454B has a lower GWP than previous refrigerants.
R-22 is a chemical cooling compound used in older air conditioners and heat pumps. It is currently being phased out of production and use due to its harmful environmental impact.
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