HSPF

Heating Seasonal Performance Factor—a measure of heat pump heating efficiency over a typical heating season. Higher HSPF indicates better efficiency. Since January 1, 2023, the federal (DOE) minimum is rated in HSPF2: 7.5 HSPF2 for split-system heat pumps nationwide (roughly equivalent to the old 8.8 HSPF). HSPF and HSPF2 ratings are not directly comparable.