Seasonal Energy Efficiency Ratio 2 (SEER2) is the updated federal standard for measuring air conditioner and heat pump cooling efficiency, replacing the original SEER rating in 2023. It measures how much cooling a system produces per unit of electricity consumed over a typical cooling season.
SEER2 uses a revised testing methodology (M1 blower coil) that better reflects real-world installation conditions, including higher external static pressure. As a result, SEER2 ratings are roughly 4-5% lower than equivalent SEER ratings for the same equipment.
For residential systems, the minimum SEER2 rating required by federal law is 13.4 in northern states and 14.3 in southern states (as of 2023). High-efficiency systems range from 18 to 26+ SEER2. A higher SEER2 means lower electricity bills and a smaller carbon footprint.