What SEER2 rating is required for new residential AC units in 2024?

For 2024 installations, the Department of Energy requires residential central air conditioners to meet a minimum of 13.4 SEER2 in the North region and 14.3 SEER2 in the Southeast and Southwest regions.

The Department of Energy (DOE) enforcement updates established the updated M1 testing procedure. This testing protocol increases external static pressure requirements by a factor of five, lowering calculated efficiency ratings by roughly 4.5% to 5% compared to legacy SEER standards and creating strict regional installation thresholds for contractors and property owners.

If you only do one thing: Verify that split-system AC equipment matches your regional threshold—13.4 SEER2 for the North, 14.3 SEER2 for the South (<45,000 BTU/h), or 13.8 SEER2 for the South (≥45,000 BTU/h)—before pulling permits or purchasing equipment.

• Northern Region Standards: Central split-system air conditioners installed in northern states must deliver at least 13.4 SEER2 (equivalent to the older 14.0 SEER standard), allowing homeowners to satisfy regional building codes with standard single-stage cooling equipment.
• Southern Region Standards (<45k BTU/h): In the Southeast and Southwest, split-system AC units rated under 45,000 BTU/h (under 3.75 tons) must achieve a minimum of 14.3 SEER2 (legacy 15.0 SEER) and 11.7 EER2 (Energy Efficiency Ratio 2).
• Southern Region Standards (≥45k BTU/h): In the Southeast and Southwest, larger residential systems rated at or above 45,000 BTU/h must meet at least 13.8 SEER2 (legacy 14.5 SEER) and 11.2 EER2 to account for the electrical requirements of larger compressors.
• Single-Package AC Minimums: Packaged air conditioning units nationwide must hit a baseline of 13.4 SEER2 and 10.6 EER2, establishing a single federal standard for rooftop or slab-mounted all-in-one residential units.
• Heat Pump Consistency: Split-system heat pumps carry a nationwide baseline of 14.3 SEER2 and 7.5 HSPF2 (Heating Seasonal Performance Factor 2), removing regional variations for dual-fuel and all-electric heating and cooling projects.

• Watch out for: Date-of-installation enforcement in the Southeast and Southwest, where installing non-compliant inventory manufactured before the rule change is a code violation, unlike the North where sell-through is based on the date of manufacture.
• Watch out for: Mismatched indoor evaporator coils and outdoor condensing units that fail to achieve the required AHRI (Air-Conditioning, Heating, and Refrigeration Institute) certified SEER2 combination rating on paper.
• Watch out for: Static pressure drops across existing undersized ductwork that degrade actual field performance below the lab-tested 0.5 in. w.c. (inches of water column) M1 testing standard.

Check the AHRI directory for the certified system rating of your proposed condenser-and-coil combination to confirm regional code compliance before ordering equipment.