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HSPF2

HSPF2 is the federal seasonal heating efficiency rating for heat pumps, in Btu of heat per watt-hour of electricity.

Editorial staffEdited by heatpumpwiki

History 1

HSPF2 (Heating Seasonal Performance Factor 2) rates a heat pump's heating efficiency over a whole season. The federal definition: "the total space heating required during the heating season, expressed in Btu, divided by the total electrical energy consumed by the heat pump system during the same season, expressed in watt-hours."Source 1 It is calculated for climate Region IV.Source 1

The federal minimum for split-system heat pumps made on or after January 1, 2023 is 7.5 HSPF2; for single-package heat pumps it is 6.7.Source 2

HSPF2 replaced HSPF in 2023 under a test with higher assumed duct resistance, so the numbers are lower. DOE's example: "an 8.8 HSPF would equate to a 7.5 HSPF2."Source 3 Dividing HSPF2 by 3.412 gives a rough season-average COP (coefficient of performance). See Heat pump ratings explained: SEER2, EER2, HSPF2 and AHRI certificates.

Sources

  1. 1.10 CFR Appendix M1 to Subpart B of Part 430, Uniform Test Method for Measuring the Energy Consumption of Central Air Conditioners and Heat Pumps. Electronic Code of Federal Regulations (U.S. DOE rule). Accessed Oct 25, 2026
  2. 2.10 CFR 430.32, Energy and water conservation standards and their compliance dates. Electronic Code of Federal Regulations (U.S. DOE rule). Accessed Oct 25, 2026
  3. 3.Air-Source Heat Pumps (archived copy of energy.gov/energysaver/air-source-heat-pumps, captured June 20, 2026). U.S. Department of Energy. Accessed Oct 25, 2026

More in Glossary

  • AHRI certificateAn AHRI certificate shows the certified efficiency ratings for one exact combination of outdoor and indoor heat pump equipment.
  • Aux heat (auxiliary heat)Aux heat is a backup heat source that a heat pump thermostat turns on automatically when the heat pump needs help.
  • Btu (British thermal unit)A Btu is the heat needed to raise one pound of water by one degree Fahrenheit, and heat pump capacity is given in Btu per hour.
  • COP (coefficient of performance)COP is the heat a heat pump delivers divided by the electricity it uses, at one set of conditions.
  • DefrostDefrost is the cycle in which a heat pump briefly reverses to melt frost off its outdoor coil.
  • EER2EER2 is a cooling efficiency rating at a single hot test condition, in Btu per hour of cooling per watt.