HSPF and HSPF2
Heating seasonal performance factor, the heat delivered over a season divided by the electricity used, with HSPF2 the current United States test procedure. It is the heating counterpart to SEER and is not comparable with European SCOP figures.
Also called HSPF, HSPF2
What is HSPF2?
HSPF is seasonal heating output divided by the electricity used, expressed in BTU per watt-hour. HSPF2 is the current United States procedure and reads lower than HSPF for the same equipment.
HSPF and HSPF2: how it works
The procedure totals the heat delivered across a representative heating season, including the electricity used by auxiliary heat and by defrost cycles, and divides by the total electricity consumed. Because output is counted in BTU and input in watt-hours, the result is not a plain ratio, which is why an HSPF of around 8 and a COP of around 8 describe entirely different performance.
Where you meet the term
- On a North American heat pump label, alongside the SEER2 cooling rating.
- In a minimum standard, where a heat pump has to meet an HSPF2 floor to be installed.
- In an incentive programme, where the threshold is set in HSPF2 rather than in COP.
How to check it
- Confirm the figure is HSPF2. The older HSPF number is higher for the same equipment. Comparing across the two makes older equipment look better than it is. Owner check
- Divide by 3.412 for a rough COP comparison. HSPF is BTU per watt-hour, so dividing by 3.412 puts it on a dimensionless footing. It remains a different test from SCOP. Owner check
Figures you will see
| Condition | Figure | What it tells you |
|---|---|---|
| Units | BTU per watt-hour | Divide by 3.412 to express it as a dimensionless seasonal efficiency |
| Current test procedure | HSPF2 | Replaced HSPF for United States ratings from 2023 |
| European counterpart | SCOP | Dimensionless, and measured against a different climate profile |
HSPF and HSPF2: what it is not
- HSPF is not a dimensionless efficiency. Its units are BTU per watt-hour, so it cannot be read as though it were a COP.
- HSPF and SCOP are not the same measurement in different markets. The seasons, the climate profiles, and the treatment of auxiliary heat all differ.
HSPF and HSPF2 questions
How does HSPF2 differ from HSPF?
It is the updated United States test, with revised conditions including the higher external static pressure used across the 2023 procedures. For the same equipment the HSPF2 figure is lower.
Can I convert HSPF to COP?
Dividing by 3.412 converts the units, which gives a seasonal figure on a dimensionless scale. It still is not a COP, because COP is measured at a single operating condition rather than across a season.
Why is HSPF not used in Europe?
Europe rates seasonal heating performance with SCOP under the ecodesign framework, using its own climate profiles and test conditions. Each market publishes the figure its own regulation requires.
Where this definition comes from
Written from standards body publication, government guidance material held in the HVAC Bench evidence record. Where a document limits a definition to certain models, that limit is repeated here rather than generalised across a brand.
- AHRI Directory of Certified Product PerformanceCertified SEER2, EER2, and HSPF2 ratings for matched North American equipment combinations.
- Heat Pump SystemsConsumer-facing explanation of air source, ductless, and geothermal heat pump operation and efficiency metrics.