R-454B (brand name Opteon XL41, manufactured by Chemours) is the primary low-GWP refrigerant replacing R-410A in new residential air conditioners and heat pumps in the United States as of 2025.
R-454B has a GWP of 467 — about 78% lower than R-410A. It provides similar cooling performance and operates at similar pressures to R-410A, making equipment transition manageable for manufacturers.
Importantly, R-454B is classified A2L (mildly flammable), which requires updated installation practices, equipment design, and technician training. It is NOT a drop-in replacement for R-410A — equipment must be specifically designed for R-454B. EPA 608 certification is required to handle it.