HSPF2

Definition

HSPF2 measures how efficiently a heat pump moves heat from outside air into your home over a full heating season. Like SEER2 (which rates the cooling side), HSPF2 replaced HSPF on January 1, 2023, and uses the same updated DOE test methodology — higher static duct pressure, modified defrost-cycle accounting, and a temperature bin that better matches real-world conditions.

The federal minimum is HSPF2 7.5 for split-system heat pumps. Mid-tier heat pumps run HSPF2 8.0-8.5; premium variable-speed units rate HSPF2 9.0-10+. For comparison, an HSPF2 9 heat pump produces about 2.6 units of heat per unit of electricity in average winter conditions — that's the COP (coefficient of performance) leverage that makes heat pumps cheaper to run than electric resistance heat.

HSPF2 is one of the two numbers (alongside SEER2) the Austin Energy and IRA HEAR rebate programs reference. Most rebate-tier eligibility requires HSPF2 ≥ 8.1 plus SEER2 ≥ 15.2.

Why it matters in Austin

Central Texas winters sit in heat-pump sweet-spot territory — outdoor temperatures rarely drop below 25°F for more than a few hours, and a modern variable-speed heat pump runs at near-full HSPF2 efficiency above ~35°F. That means most Austin homeowners spend their heating season inside the range where the heat pump is doing its best work.

If you're sizing a new system in Austin, the HSPF2 number alongside SEER2 tells you the operating cost story. The capacity-and-cost story comes from Manual J + tonnage + variable-speed compressor decisions.