Hold a heat pump steady instead of setting it back at night

Pick one comfortable temperature, set the heat pump to Heat, and leave it there day and night. ENERGY STAR's heat pump page says a heat pump can deliver up to three times more heat energy than the electricity it consumes, and that, unlike a furnace or boiler, it does not save energy when you turn it down while you are away or asleep. The one condition comes from DOE's 2022 Energy Saver guide: a setback is fine only with a smart or programmable thermostat designed for heat pumps, and not at all if it brings on backup electric-resistance heat. Holding one setting is free, and renters and owners can both do it.

A heat pump saves nothing when you turn it down

The night setback is a furnace rule. DOE's Energy Saver guide (2022) says you can save as much as 10% a year on heating and cooling by turning the thermostat down 7 to 10°F for 8 hours a day in fall and winter, the rule behind setting back a furnace thermostat. The same passage adds, in parentheses, that heat pump owners should not do this without a smart or programmable thermostat designed for use with heat pumps.

ENERGY STAR goes further. Its saving tips tell heat pump owners to stick with a steady temperature: pick a comfortable one and leave it there, because turning a heat pump down when you are away or asleep does not save energy. Where the two sources differ, a steady setting is the one both accept. It costs nothing.

Backup heat is what turns a setback into a cost

DOE's 2022 guide names the risk in its heat pump tips: do not set back the thermostat manually if it causes backup electric-resistance heating to come on, because that type of heating is more expensive. For this example, assume the backup strips deliver 1 kWh of heat for each kWh they draw (a COP of 1); that is the example's assumption, not a figure from a linked page. A heat pump moves heat in from outdoors. It gets more heat from each kWh.

Example, with published figures and one assumption. On a 5°F morning, a heat pump certified as cold-climate is rated to deliver at least 1.75 kWh of heat for each kWh it draws at that temperature, a coefficient of performance (COP) of 1.75, under ENERGY STAR's key product criteria; the ENERGY STAR heat pump page dates those requirements to January 1, 2023. North Carolina's average residential price was 15.16 cents per kWh in July 2026, the latest month in EIA's Electric Power Monthly, Table 5.6.A (preliminary). Take 10 kWh of heat to bring the house back up, a round figure for illustration. Backup strips draw 10 kWh: 10 × 15.16 cents = $1.52. The heat pump draws at most 10 ÷ 1.75 = 5.71 kWh: 5.71 × 15.16 cents = $0.87. The strips use at least 1.75 times the kWh for the same heat, and the arithmetic is the one used to price any appliance.

Use Heat or Cool instead of Auto, and keep the filter clean

ENERGY STAR's saving tips add three free settings. Set the mode to Heat in winter and Cool in summer rather than Auto, so the system does not switch modes on an unseasonably warm or cold day. Leave the fan on its auto setting, or at the lowest speed that still spreads the air far enough. Clean the filters when they look dirty or when the filter light comes on; DOE's 2022 guide says to clean or change them once a month or as needed.

In summer, set the mode to Cool and, as ENERGY STAR advises, pick a comfortable temperature and leave it there; a ceiling fan saves only when you raise the thermostat while it runs.

Set it back only with a thermostat made for heat pumps

A cooler bedroom at night is still possible. DOE's Energy Saver guide allows the setback with a smart or programmable thermostat designed for heat pumps, and its heat pump tips say to install one with functions suitable for a heat pump, yourself or through a professional. That is a small buy for an owner; a renter asks the landlord before swapping it. ENERGY STAR's smart thermostat page adds one buying check: make sure the model is compatible with your heating and cooling system.

Two checks come first. The thermostat's manual says whether it is designed for heat pumps; if it does not, hold one setting. Then find out whether the setback brings on backup heat: the manual shows how the thermostat signals backup heat running, and if your utility shows daily kWh, compare mornings after a setback with mornings at a steady setting in similar weather. Even with the right thermostat, ENERGY STAR says a heat pump does not save energy by turning it down, so steady stays the default.

When backup heat is normal, and when to call an HVAC contractor

Some backup heat is by design. ENERGY STAR tests cold-climate heat pumps down to 5°F and says they keep working below that, but that pairing one with a backup energy source heats the home most efficiently when temperatures are even lower. Where winter temperatures regularly dip below freezing, its advice to owners replacing a system is to ask the contractor for an ENERGY STAR unit suited to the home.

Backup heat that runs at a steady setting on mild days is another matter. Call a licensed HVAC contractor: the refrigerant, the outdoor unit and the wiring of the backup heat strips are their work. Ask why backup heat comes on at a steady setting, and whether the thermostat is configured for a heat pump.