SEER2 and HSPF2
also: SEER · SEER2 · HSPF2 · EER2
US seasonal efficiency ratings for air conditioners (SEER2, cooling) and heat pumps (HSPF2, heating), measured under the DOE test procedure in force since 2023.
SEER2 (seasonal energy efficiency ratio) estimates cooling efficiency over a typical season; HSPF2 (heating seasonal performance factor) does the same for heat pump heating; EER2 measures cooling efficiency at a single hot condition. Since 1 January 2023, US minimum efficiency standards and ratings use an updated DOE test procedure (the "2" metrics) with higher external static pressure to better reflect real ductwork, so SEER2 figures are lower than the old SEER figures for the same equipment. Minimums vary by region and equipment type.
These are rating-condition numbers. Installed performance depends on sizing, ductwork, refrigerant charge, airflow and controls.
Founder takeaway
Compare equipment using the current ratings (SEER2, HSPF2), and remember that installation and controls decide real-world efficiency.
sources
engineer review pending