Central AC System GuideRefrigerant is the fluid that moves heat out of a home, and the type used is now shaped by federal climate rules. The EPA is phasing down hydrofluorocarbons by 85 percent from baseline levels by 2036, and its Technology Transitions rule sets a 700 global warming potential limit for new residential air conditioning and heat pump systems beginning January 1, 2025. That pushes new equipment away from R-410A toward lower-GWP refrigerants such as R-32 and R-454B.
What refrigerant does and why GWP matters
Refrigerant carries heat from indoors to the outdoor unit and back, cycling between liquid and gas. The concern is not the cooling but what happens if the fluid escapes, because many refrigerants are potent greenhouse gases.
The EPA explains that hydrofluorocarbons have climate impacts hundreds to thousands of times greater than the same amount of carbon dioxide. Global warming potential, or GWP, measures that impact: the EPA notes that one kilogram of a gas with a GWP of 700 has 700 times the climate impact of one kilogram of carbon dioxide.
The HFC phasedown
The transition is driven by the AIM Act. The EPA reports that the Act mandates a phasedown of HFCs by 85 percent from historic baseline levels by 2036.
The reduction happens in steps rather than all at once. The EPA's published schedule moves from 90 percent of baseline in 2022 and 2023, to 60 percent for 2024 through 2028, then 30 percent, 20 percent, and finally 15 percent from 2036 onward. Over that period the EPA projects emission reductions equal to 4.6 billion metric tons of carbon dioxide from 2022 through 2050.
R-410A versus R-32 and R-454B by the numbers
The refrigerants differ sharply in GWP. The EPA's Technology Transitions GWP reference table lists R-410A at 2,088, well above the new limit for residential systems.
The replacements sit far lower. The same EPA table lists HFC-32, marketed as R-32, at 675 and R-454B at 698, both under the 700 threshold that new residential air conditioning must meet. For comparison, the table lists HFC-134a at 1,430. The lower-GWP options deliver similar cooling with a much smaller climate footprint if they leak.
The 700 GWP limit for new systems
The Technology Transitions rule sets the line for new equipment. The EPA establishes a 700 GWP limit for residential and light commercial air conditioning and heat pump systems, with manufacture and import restrictions taking effect January 1, 2025. That is why R-410A, at a GWP of 2,088, is no longer used in newly manufactured residential systems, while R-32 and R-454B qualify.
Existing equipment is treated separately. The EPA has proposed preserving flexibilities for residential and light commercial air conditioning and heat pumps manufactured or imported before January 1, 2025, allowing that equipment to continue being installed. In short, the rule targets what manufacturers build going forward rather than forcing homeowners to replace working systems.
What it means for homeowners
For most homeowners the change appears only at replacement time. A new central system installed now uses a lower-GWP refrigerant such as R-32 or R-454B rather than R-410A, and the two refrigerants are not interchangeable in the same equipment.
Refrigerant work stays with professionals regardless of type. The Department of Energy advises that a trained technician repair any refrigerant leak and properly recharge the system rather than simply adding refrigerant, because federal rules govern handling and the underlying leak still needs a fix.