Definition
Heating Seasonal Performance Factor — the efficiency rating for a heat pump's heating mode. Higher HSPF means lower winter energy bills.
Why this matters for your home
HSPF rates how efficiently a heat pump heats over an entire season, accounting for the colder, less-efficient hours as well as the mild ones. The higher the HSPF, the more heat the unit delivers per kilowatt-hour across the winter.
It's the heating-mode counterpart to SEER2's cooling rating, and it's the number to focus on if winter performance drives your decision — which, in Minnesota, it usually does. We compare HSPF alongside a unit's rated low-temperature output so you know how it behaves on the coldest days, not just on average.