Yes. Heat pumps work in cold weather, and today’s cold climate heat pumps keep heating homes in Maine, Minnesota and Alaska. There is usable heat in outdoor air even at −15°F. What changes as it gets colder is how much heat the unit can move and how efficiently it does it.
How cold is too cold for a heat pump?
| Heat pump type | Keeps full heating output to about | Still produces heat down to |
|---|---|---|
| Older single-stage (pre-2015) | 35–40°F | about 0–10°F |
| Modern standard inverter | 17–25°F | about −5°F |
| Cold-climate inverter | 5°F | −13°F to −22°F |
Efficiency at low temperatures
Efficiency is measured as COP, the heat delivered per unit of electricity. Typical cold-climate models reach:
- COP 3.5–4.5 at 47°F
- COP 2.5–3 at 17°F
- COP 1.8–2.2 at 5°F
- COP 1.3–1.7 at −13°F
Even at 5°F, a COP of 2 means the heat pump delivers twice as much heat per kWh as electric baseboard or an electric furnace.
What makes cold climate heat pumps different?
In the US the usual benchmark is the ENERGY STAR cold-climate criteria (built on earlier NEEP specifications). A qualifying unit must deliver at least 70% of its rated heating capacity at 5°F and have a COP of at least 1.75 at 5°F. Variable-speed (inverter) compressors, enhanced vapor injection and larger outdoor coils make that possible.
Sizing a heat pump for a cold climate
In northern states the heating load is often twice the cooling load. Size the heat pump so it covers most or all of the heating load at your local design temperature, using the capacity the manufacturer lists at 5°F, not the nominal tonnage. A “3-ton” unit might deliver 36,000 BTU at 47°F but only 25,000 at 5°F. Our heat pump size calculator shows your approximate heating load.
Backup heat options
- Electric heat strips in the air handler: cheapest to install, expensive to run, but only needed for a few hours a year with a well-sized cold-climate unit.
- Dual fuel: keep your gas or propane furnace and let it take over below a chosen temperature.
- No backup: some homeowners with a correctly sized cold-climate heat pump and a wood stove or a few baseboard heaters skip central backup entirely.
Tips for cold-weather performance
- Mount the outdoor unit on a stand or wall bracket 12–24 inches above the typical snow depth.
- Keep the area under it clear so defrost water can drain instead of refreezing.
- Avoid big thermostat setbacks at night. Recovering from 62°F to 70°F on a cold morning pulls in expensive backup heat. Small setbacks of 2–3°F are fine.
- Seal air leaks and add attic insulation. Every BTU you don’t lose is one the heat pump doesn’t need to find in the cold air.
Is it cheaper to run than oil or propane in the cold?
Usually, yes. Even at an average seasonal COP of 2.3, a heat pump in a cold climate typically beats heating oil and propane at recent prices. Check your own numbers with the heating cost calculator.
Related: heat pump installation cost, heat pump vs furnace.