The approved refrigerant you’ll find in most new household refrigerators sold in the United States is R-600a, also known as isobutane. As of January 1, 2025, new household refrigerators and freezers manufactured or imported into the U.S. must use a refrigerant with a global warming potential (GWP) of 150 or less, which effectively eliminates the older refrigerant R-134a that dominated for decades. R-600a, with a GWP of just 3, is the clear frontrunner and the standard choice for major manufacturers.
Why R-600a Replaced R-134a
For most of the last 30 years, the workhorse refrigerant in household refrigerators was R-134a, a hydrofluorocarbon (HFC) with a GWP of 1,430. That means every kilogram of R-134a released into the atmosphere traps as much heat as 1,430 kilograms of carbon dioxide over a century. R-600a, by comparison, has a GWP of just 3, making it nearly climate-neutral.
The shift wasn’t only about environmental impact. A Department of Energy project found that refrigerators using R-600a can achieve roughly 30% higher energy efficiency compared to R-134a systems. Isobutane has favorable thermodynamic properties: it moves heat effectively at the temperatures household refrigerators operate at, which translates to lower electricity bills. European manufacturers made this switch years ago, and the vast majority of refrigerators sold worldwide already use R-600a.
The Law Behind the Switch
The legal foundation is the American Innovation and Manufacturing (AIM) Act, signed into law in December 2020. The AIM Act requires an 85% reduction in HFC production and consumption from historic baseline levels by 2036, following a stepwise schedule: a 10% cut starting in 2022, dropping to 60% of baseline by 2024, then 30% by 2029, and down to just 15% by 2036.
Under this authority, the EPA finalized rules setting a GWP limit of 150 for household refrigerators and freezers. The manufacture and import compliance date was January 1, 2025. Sale, distribution, and export of non-compliant products is prohibited three years after that date, meaning existing stock of R-134a refrigerators can still be sold through the end of 2027, but no new ones can be made.
Other Approved Refrigerants
While R-600a is the dominant choice, it isn’t the only option on the EPA’s approved list for household refrigerators. The EPA’s Significant New Alternatives Policy (SNAP) program lists several acceptable substitutes, though most are either outdated, niche, or impractical for modern home units.
R-290 (propane) is also approved with a GWP of 3.3, but it’s used primarily in commercial equipment like beverage coolers, display cases, and ice machines rather than home refrigerators. R-441A, a hydrocarbon blend with a GWP below 5, is another approved option. HFC-152a, with a GWP of 124, technically falls under the new 150 GWP limit and has been on the approved list since 1994, though it hasn’t gained significant market share in home refrigerators.
Several older blends containing HCFCs (like R-401A and R-409A) remain listed as acceptable for retrofit purposes in existing equipment, but their GWP values are well above 150, so they cannot be used in newly manufactured units. The practical reality is that if you’re buying a new refrigerator today, it almost certainly runs on R-600a.
Safety and Charge Limits
R-600a is classified as an A3 refrigerant, meaning it has low toxicity but is flammable. This is the most common concern people have when they learn their refrigerator runs on a hydrocarbon. In practice, the amount used is tiny. New household refrigerators typically contain around 100 grams or less of isobutane, roughly the weight of a small bar of soap. Safety standards limit the charge to a formula based on the refrigerant’s lower flammability limit, keeping the amount well below what could create a hazardous concentration even if the entire charge leaked into a small kitchen.
Billions of refrigerators worldwide have used R-600a safely for years. The systems are factory-sealed and factory-charged, meaning the refrigerant circulates in a closed loop that you never interact with during normal use. The safety record across Europe and Asia, where isobutane refrigerators have been standard since the early 2000s, is comparable to that of older R-134a models.
What This Means if You’re Buying a Refrigerator
If you’re shopping for a new refrigerator in 2025 or later, you don’t need to do anything special to find one with an approved refrigerant. Every new model on the market will comply with the GWP limit. The refrigerant type is printed on the unit’s rating plate, usually on the inside wall or back of the appliance, and you’ll see “R-600a” listed there on most models.
If you still own an older refrigerator running R-134a, it remains legal to use and service. The new rules apply to manufacturing and importing new units, not to keeping your existing appliance running. However, as R-134a production is phased down, servicing costs for older units will gradually increase over the coming years as supply tightens. When the time comes to replace your refrigerator, the transition to R-600a happens automatically with your purchase.