Heat pump ratings explained
Four numbers decide how much a heat pump costs to run. Here is what each one measures, and where certified models actually land.
SEER2: seasonal cooling efficiency
Cooling output over a typical season divided by the electricity used, in BTU per watt-hour. A 20 SEER2 unit uses about 28% less electricity for the same cooling as a 14.3 SEER2 unit.
| Federal minimum (split heat pump) | 14.3 |
|---|---|
| Bottom quarter of certified models | 17.5 or less |
| Median certified model | 20.0 |
| Top 10% | 25.0 or more |
EER2: cooling efficiency on a hot day
Measured at a single 95°F outdoor condition. It matters most in hot, dry climates where the system runs flat out through the afternoon, and for utilities worried about peak demand.
HSPF2: seasonal heating efficiency
Heating output over a season divided by electricity used. The test assumes a moderate climate, so it says little about performance during a cold snap.
| Federal minimum (split heat pump) | 7.5 |
|---|---|
| Bottom quarter of certified models | 8.8 or less |
| Median certified model | 9.7 |
| Top 10% | 11.5 or more |
Capacity and COP at 5°F
A heat pump loses capacity as it gets colder outside. Capacity at 5°F tells you how much heat is left; COP at 5°F tells you how efficiently it is made (a COP of 2 is twice as efficient as a baseboard heater). ENERGY STAR's cold-climate label requires a COP of at least 1.75 and at least 70% of rated capacity at 5°F.
Why one unit has many ratings
Ratings belong to a matched system - an outdoor unit plus a specific indoor unit, and sometimes a furnace. The same condenser can be certified with dozens of indoor units, each with its own SEER2 and HSPF2. Every certified combination has an AHRI reference number; ask your installer for it.
Questions
- What is a good SEER2 rating?
- Across all ENERGY STAR heat pumps in our database, the median is 20.0 SEER2 and the top 10% reach 25.0 or more. The federal minimum for split-system heat pumps is 14.3 SEER2.
- What is a good HSPF2 rating?
- The median certified heat pump is rated 9.7 HSPF2 and the top 10% reach 11.5 or more. The federal minimum for split systems is 7.5 HSPF2.
- What is the difference between SEER and SEER2?
- SEER2 replaced SEER in January 2023. The M1 test procedure behind it uses higher external static pressure, closer to real ductwork, so the same unit scores lower: roughly SEER2 ≈ SEER × 0.95 for ducted systems.