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Refrigerants and Global Warming Potential

Understanding Global Warming Potential

Refrigerants are used in air conditioners (ACs) and heat pumps to transfer heat from one area to another during the cooling or heating process. Regulations have evolved over time to require more sustainable refrigerants. Refrigerants are now limited in the United States based on their global warming potential (GWP). Refrigerants that are ozone-depleting substances (ODS), like R-22, have been banned in the U.S.

A refrigerant’s GWP is determined by comparing its global warming impact relative to the amount of carbon dioxide that would cause an equivalent global warming impact. Refer to the table above for the GWP of various refrigerants. The higher the GWP, the greater the climate impact. 

How GWP Values are Calculated

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 4th AR. The GWP is based on the intensity of radiative forcing or climate impact of each gas and how long harmful emissions remain in the atmosphere. The United States Environmental Protection Agency (EPA) also uses 100-year GWP from AR4 in its regulations.

The Impact of Refrigerants on Global Warming

AC refrigerants are inherently greenhouse gases (GHGs). 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.

Common types of past and current refrigerants can include:

  • Chlorofluorocarbons (CFCs) (e.g., R-11) phased out very high ODSs with very high GWPs 
  • Hydrochlorofluorocarbons (HCFCs) (e.g., R-22) phased out ODSs with high GWPs
  • Hydrofluorocarbons (HFCs) (e.g., R-410A) high GWP phased down under the American Innovation and Manufacturing (AIM) Act
  • Hydrofluoroolefins (HFOs) – ultra-low GWP refrigerants enabling GWP phasedown 

Comparison of different refrigerants and their global warming potential

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.

Why Are We Transitioning to Environmentally Friendly Refrigerants?

Transition to these more sustainable refrigerants is in the beginning stages. Based on EPA mandates, HVAC manufacturers will begin phasing out equipment production using R-410A and transition to production of equipment that uses HFO refrigerants and blends. 

We are transitioning to low-GWP refrigerants 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.  

Low GWP Refrigerants

There are 2 new refrigerants 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: 

  • R-32, GWP 675, 68% lower than R-410A (GWP 2088) 
  • R-454B, GWP 466, 78% lower than R-410A 

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. 

Challenges and Considerations in Transitioning to 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 months and years, Trane will be transitioning to R-454B refrigerant for many of its new products. 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 tonnes 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? Check out our resources guide, or contact a local technician.

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