Quick answer
HSPF2 is the heating seasonal performance factor of an air-source heat pump: the total heat it delivers over a model heating season, in BTUs, divided by the electricity it uses, in watt-hours, measured under the federal Appendix M1 test required since 1 January 2023.
It is the heating twin of SEER2. A higher HSPF2 means less electricity for the same warmth. It replaced HSPF, which used an older test.
Quick facts
The key facts about HSPF2, with sources:
- Applies to
- Air-source heat pumps (ducted and ductless), not furnaces or boilers
- Federal minimum, split heat pump
- 7.5 HSPF2 (made from 1 January 2023) 1
- Federal minimum, packaged heat pump
- 6.7 HSPF2 1
- ENERGY STAR
- 7.8 HSPF2 split; 7.2 packaged 3
- ENERGY STAR cold climate
- 8.1 ducted / 8.5 ductless, plus COP 1.75 or more at 5°F 3
- Old rating it replaced
- HSPF; 2015–2022 floor 8.2 split, 8.0 packaged 1
Key takeaways
- HSPF2 is the winter efficiency score for a heat pump. Higher means lower heating bills.
- Divide HSPF2 by 3.412 to get the average seasonal COP. A 7.5 HSPF2 heat pump delivers about 2.2 units of heat per unit of electricity.
- The federal floor for a new split heat pump is 7.5 HSPF2. ENERGY STAR starts at 7.8 1 3.
- HSPF2 is weighted for a moderate climate. In very cold places, check output and COP at 5°F too.
- Old HSPF numbers ran higher because the test was different. Compare HSPF2 only with HSPF2.
What HSPF2 means
A heat pump heats your home by moving heat in from outdoors, not by burning fuel. HSPF2 tells you how much heat it moves for the electricity it uses, across a whole winter. A heat pump rated 8.0 HSPF2 delivers 8,000 BTUs of heat for every kilowatt-hour.
The test runs the heat pump at several outdoor temperatures, from mild to cold, and counts the times it must defrost or switch on backup electric strips. It weights those results into one seasonal number.
The federal rule says the HSPF standards are based on Region IV, a moderate climate zone in the test procedure, using its minimum design heating requirement 1.
HSPF2 has its own heat pump rule set, separate from cooling. Every heat pump carries both a SEER2 for summer and an HSPF2 for winter.
HSPF vs HSPF2: what the 2023 change did
Before 2023, heat pumps were rated in HSPF under the Appendix M test. From 1 January 2023, DOE required Appendix M1 and the new name HSPF2 2. Two things changed.
First, the indoor fan now pushes against 0.50 inches of duct resistance for a conventional ducted system, up from 0.10 to 0.20 2.
Second, M1 revised how the test models a home’s heating need, which changes how hard the heat pump works at each temperature point.
The result is a noticeably lower number for the same hardware. You can see it in the federal floors. From 2015 to 2022, a split heat pump needed 8.2 HSPF. Since 2023 it needs 7.5 HSPF2 1. That looks like a cut, but it reflects the tougher test, not weaker equipment.
As with SEER2, there is no one official conversion factor. Products were retested. If you are holding an old HSPF figure, look up the HSPF2 for the replacement pair instead of converting.
HSPF2 levels you will see on paperwork
| Level | Split system | Packaged unit |
|---|---|---|
| Federal minimum (made from 1 Jan 2023) | 7.5 HSPF2 | 6.7 HSPF2 |
| ENERGY STAR | 7.8 HSPF2 | 7.2 HSPF2 |
| ENERGY STAR cold climate, ducted | 8.1 HSPF2 | 8.1 HSPF2 |
| ENERGY STAR cold climate, ductless | 8.5 HSPF2 | n/a |
| Small-duct, high-velocity (federal) | 6.1 HSPF2 | n/a |
| Space-constrained heat pump (federal) | 6.3 HSPF2 | n/a |
Heating ratings side by side, and the cooling ratings beside them
| Rating | Season | Unit | What it misses |
|---|---|---|---|
| HSPF2 (this page) | Winter, heat pump | BTU per watt-hour, seasonal | Performance in long spells below about 17°F |
| AFUE | Winter, furnace or boiler | Percent of fuel turned into heat | Blower electricity, duct losses |
| COP | Any one test temperature | Heat out ÷ energy in, no units | A season; it is one moment |
| SEER2 | Summer, seasonal | BTU per watt-hour | Heating and peak heat |
| EER2 | Summer, 95°F peak | BTU/h per watt | Mild days and heating |
Example: what HSPF2 means for a winter of heat
Assume a home needs 40 million BTU of heat over a winter (an example input; your figure depends on climate and insulation). Electricity is priced at the US residential average of 18.31 cents per kWh for July 2026 5; winter rates differ by utility. kWh = 40,000,000 ÷ (HSPF2 × 1,000).
| Heat source | Seasonal COP | kWh for the winter | Energy cost at 18.31¢ |
|---|---|---|---|
| Electric resistance (baseboard or strips) | 1.0 | 11,723 | about $2,146 |
| Heat pump, 7.5 HSPF2 (federal floor) | 2.2 | 5,333 | about $976 |
| Heat pump, 8.1 HSPF2 (cold-climate ducted level) | 2.4 | 4,938 | about $904 |
| Heat pump, 9.0 HSPF2 | 2.6 | 4,444 | about $814 |
The big jump is from resistance heat to any heat pump. Steps within heat pumps are smaller. In a cold climate the real seasonal COP will be lower than the label suggests, because the label assumes a moderate winter. Compare with gas on the heat pump vs furnace tool.
Where to find HSPF2
- On the AHRI certificate for the exact outdoor unit and indoor coil or air handler 6.
- On the yellow EnergyGuide label on a new heat pump, next to SEER2.
- On rebate forms. Heat pump rebates usually set an HSPF2 floor; check the heat pump rebate guide.
- On older paperwork as HSPF. Treat that as a different scale.
Sources: [6]
What HSPF2 does well and where it stops
Useful for
- Comparing heat pumps of different brands on winter efficiency, tested the same way.
- Estimating seasonal kWh with one division.
- Checking federal, ENERGY STAR and rebate eligibility.
- Seeing the gap between a heat pump and resistance heat at a glance.
Not useful for
- Judging performance in Minnesota or Maine winters, where hours below 5°F matter.
- Telling you how much heat the unit still produces when it is very cold.
- Comparing to a gas furnace directly, since AFUE uses a different basis.
- Showing the effect of leaky ducts or a poor install.
The cold-weather blind spot
HSPF2 is a seasonal average built for a moderate winter. The NEEP cold-climate specification was created because the HSPF metric has no test points below 17°F 4. Two heat pumps with the same HSPF2 can behave very differently at 0°F.
That is why ENERGY STAR’s cold-climate tier adds two more checks: a COP of at least 1.75 at 5°F, and heating capacity at 5°F of at least 70% of capacity at 47°F 3.
If you live in IECC climate zone 5 or colder, look at those numbers beside HSPF2. See our cold-climate heat pump research.
Cost drivers linked to HSPF2
High HSPF2 usually comes from a variable-speed compressor, a larger outdoor coil and smarter defrost control. These raise the purchase price. Cold-climate models add vapor-injection or enhanced compressors, which cost more again.
HSPF2 does not predict lifespan. Install quality and upkeep matter more; see our maintenance and lifespan research.
HyreHVAC publishes no equipment prices until enough dated quotes support them. Use the heat pump savings calculator to see what drives the total.
How to check HSPF2 before you buy
- Get the outdoor and indoor model numbers from the quote.
- Look up the AHRI reference and confirm HSPF2, SEER2 and heating capacity at 47°F and 17°F 6.
- In a cold climate, ask for the capacity and COP at 5°F from the spec sheet or the NEEP list.
- Make sure the load calculation covers your design winter temperature, so backup heat is sized right.
- Ask how backup heat is set up: electric strips, or a furnace in a dual-fuel setup.
A licensed contractor installs and starts up the system. Refrigerant handling requires EPA Section 608 certification.
Keeping winter efficiency close to the label
- Keep snow and ice clear of the outdoor unit and its base so air and meltwater can move.
- Check the filter monthly in heating season 8.
- Expect a defrost cycle with a little steam in cold, damp weather. It is normal.
- Use moderate setbacks. Big setbacks can call backup strips on recovery and cut your real efficiency.
- Book a fall check of charge, airflow and defrost controls 8.
Sources: [8]
Signs your heat pump is losing efficiency
- The outdoor coil stays covered in ice for hours.
- The thermostat shows "aux" or "emergency heat" often on mild days.
- Winter bills climb with no change in use or weather.
- Cool air from vents in heating mode for long stretches.
- Call a licensed technician. Do not pour hot water on the coil or remove panels.
The rules behind HSPF2
DOE sets HSPF2 minimums by date of manufacture in 10 CFR 430.32(c)(5). There are no regional HSPF2 rules 1.
The test is Appendix M1 to subpart B of 10 CFR part 430, required since 1 January 2023 2. Manufacturers rate to AHRI 210/240 7.
ENERGY STAR is voluntary: 7.8 HSPF2 for split systems and 7.2 for packaged units, with a cold-climate tier on top 3.
HSPF and HSPF2 misconceptions
- Myth A new 7.5 HSPF2 unit is worse than my old 8.2 HSPF one.
- Reality The tests differ. The new unit may perform the same or better.
- Myth High HSPF2 means it heats well at 0°F.
- Reality Not necessarily. Check COP and capacity at 5°F.
- Myth HSPF2 can be compared to AFUE.
- Reality Not directly. Convert both to cost per unit of heat with your fuel prices.
- Myth Heat pumps stop working below freezing.
- Reality Modern heat pumps keep heating well below freezing; cold-climate models list ratings at 5°F.
How climate changes the value of HSPF2
HSPF2 assumes a moderate winter, so it fits states like Georgia, North Carolina and Texas closely.
In colder places such as Ohio or eastern Washington, heating degree days are higher and more hours fall below the test points, so real efficiency will run lower than the label. Use heating degree days to scale the example above.
How much HSPF2 should you pay for?
If heat is your main use, HSPF2 matters more than SEER2. A simple rule: in mild winters, any ENERGY STAR heat pump is a large step up from resistance heat; in cold winters, pick on 5°F capacity and COP first, then HSPF2.
Next step: compare options on our cold-climate heat pump shortlist and run your own fuel prices through the electric vs gas price ratio.
Questions about HSPF2
What is a good HSPF2 rating?
A good HSPF2 rating is 7.8 or higher, the ENERGY STAR level for split heat pumps. The federal floor is 7.5. Cold-climate ENERGY STAR models start at 8.1 for ducted and 8.5 for ductless systems. In cold areas, also check COP and capacity at 5°F, which HSPF2 does not show.
What is the difference between HSPF and HSPF2?
HSPF2 uses the Appendix M1 test that DOE required from 1 January 2023, while HSPF used Appendix M. M1 adds more duct resistance and models heating need differently. The same heat pump scores lower in HSPF2. That is why the federal floor went from 8.2 HSPF to 7.5 HSPF2. Compare like with like.
How do I convert HSPF2 to COP?
Divide HSPF2 by 3.412, the number of BTUs in a watt-hour times 1,000. A 7.5 HSPF2 heat pump has a seasonal average COP of about 2.2. That means it delivers about 2.2 units of heat for each unit of electricity across a moderate winter. The COP at any one temperature can be higher or lower.
Is HSPF2 or SEER2 more important?
It depends on what you use more. In cold and mixed climates, heating costs usually outweigh cooling, so HSPF2 matters more. In hot climates, SEER2 and EER2 matter more. Every heat pump has both, and federal rules set a floor for each, so check both numbers on the AHRI certificate.
Does HSPF2 apply to furnaces?
No. HSPF2 rates air-source heat pumps only. Gas and oil furnaces and boilers use AFUE, which is the share of fuel turned into heat. Geothermal heat pumps use COP and EER from a different test. To compare a heat pump with a furnace, convert each to cost per unit of heat using local prices.
What HSPF2 do I need for a cold climate?
ENERGY STAR’s cold-climate level is 8.1 HSPF2 for ducted systems and 8.5 for ductless. It also requires a COP of 1.75 or more at 5°F and at least 70% of rated heating capacity at 5°F. Those last two numbers tell you more about real cold-weather comfort than HSPF2 alone.
Why does my heat pump use more power than its HSPF2 suggests?
HSPF2 is weighted for a moderate climate and a correct install. Colder weather, frequent defrost, backup strip heat, leaky ducts and low airflow all lower real efficiency. Large thermostat setbacks can also trigger strips. A technician can check charge, airflow and the backup heat settings.
What was the minimum HSPF before 2023?
From 2015 to 2022, split heat pumps needed at least 8.2 HSPF and packaged heat pumps 8.0 HSPF, under 10 CFR 430.32(c)(1). Since 1 January 2023 the floors are 7.5 and 6.7 HSPF2. The new figures are on a different test, so they are not a loosening of the rule.
Where is the HSPF2 on my heat pump?
Look at the yellow EnergyGuide label on the outdoor unit or the AHRI certificate from your installer. The AHRI Directory lets you search by model number. Units made before 2023 show HSPF only, so look up their HSPF2 replacement pairs if you are comparing quotes.
Sources
- eCFR, 10 CFR 430.32 Energy and water conservation standards and their compliance dates (current text), retrieved .
- GovInfo, 10 CFR part 430 (2024 annual edition), subpart B appendices M and M1, retrieved .
- ENERGY STAR, Air-Source Heat Pumps key product criteria (incl. cold climate), retrieved .
- NEEP, Cold Climate Air Source Heat Pump Specification and Product List (Version 4.0), retrieved .
- U.S. EIA, Electric Power Monthly, Table 5.6.A Average price of electricity by state, July 2026 and 2025, retrieved .
- AHRI Directory of Certified Product Performance, retrieved .
- AHRI Standard 210/240, Performance Rating of Unitary Air-conditioning and Air-source Heat Pump Equipment, retrieved .
- ENERGY STAR, Maintenance Checklist for heating and cooling, retrieved .
Expert review
Written by the HyreHVAC Research team. Not yet reviewed by an outside expert. We say so rather than imply a review that has not happened; see our editorial policy.
How the numbers were checked: Federal HSPF and HSPF2 floors read from the current eCFR text of 10 CFR 430.32; test changes from Appendices M and M1; ENERGY STAR and cold-climate criteria from its key product criteria page; NEEP spec version from its product-list page. The heating load is a labelled example input.
Suggest a correction. We fix errors and say what changed.