A heat pump is an air conditioner that also heats: how much electricity it uses, and what drives it

How electricity use is measured

The U.S. Energy Information Administration (EIA), the federal energy statistics agency, explains the units. Electricity is measured in units of power called watts. One kilowatt (kW) is equal to 1,000 watts.

Watts measure power at a specific moment. Watthours measure how much electricity is used over a period of time. One watthour is the energy of one watt used for one hour.

Utilities generally measure electricity in kilowatthours (kWh). One kWh is one kilowatt of power for one hour. The EIA's example: a 40-watt light bulb left on for five hours uses 200 watthours, or 0.2 kWh.

The EIA says the British thermal unit (Btu) measures the heat content of fuels or energy sources. It says one Btu is the amount of heat needed to raise the temperature of one pound of water by 1 degree Fahrenheit.

System size is often given in tons. A Penn State energy course says a ton of air conditioning is 12,000 Btu per hour. So a 3-ton system is rated at 36,000 Btu per hour.

Why a heat pump can deliver more heat than the electricity it uses

ENERGY STAR says heat pumps move heat rather than converting it from fuel, as combustion heating systems do. The University of Maryland Extension explains that it moves heat from one place to another. In winter it pulls heat from outdoor air and moves it indoors. In summer it reverses and works like an air conditioner, removing heat from your home.

Because of that, ENERGY STAR says a heat pump can deliver up to three times more heat energy than the electrical energy it consumes. The University of Maryland Extension gives a range of two to four times.

One rating states this directly. The coefficient of performance (COP) is the ratio of heat delivered to electricity consumed. The University of Maryland Extension's example: a COP of 3.0 means about three units of heat for every unit of electricity used.

Backup heat works differently. Carrier, a heat pump manufacturer, says auxiliary heat is a backup heating source built into a heat pump system. It typically uses electric resistance heating strips. It compares them to the coils in a toaster. They sit inside the air handler. The Florida Solar Energy Center, a research institute of the University of Central Florida, calls electric resistance heating much less efficient than a heat pump.

What drives how much electricity it uses

Run hours and weather come first. The EIA notes that the shares of household electricity uses can change from year to year based on the weather. The federal example in the next section shows how many hours a heat pump in its hot-humid and southeast region, which includes Florida, is assumed to run.

The efficiency ratings come next. SEER2, the Seasonal Energy Efficiency Ratio 2, is the cooling rating. ENERGY STAR defines it as the total heat removed from the conditioned space during the annual cooling season, in Btu, divided by the total electricity the heat pump consumes during the same season, in watthours, with the value determined under the federal Appendix M1 test procedure. It says the value determined under Appendix M is SEER. It defines HSPF2, the Heating Seasonal Performance Factor 2, as the total space heating required in region IV during the heating season, in Btu, divided by the electricity the heat pump system uses in that season, in watthours, with the value determined under Appendix M1. It says the value determined under Appendix M is HSPF. The University of Maryland Extension says higher SEER2 ratings typically indicate lower cooling costs. The Department of Energy's Federal Energy Management Program (FEMP), which guides federal agencies on efficient purchases, says the rules changed on Jan. 1, 2023. It says the department changed the way HVAC systems are tested and updated the national standards for HSPF and SEER, and that with this change the new ratings are named HSPF2 and SEER2. Our guide on SEER ratings covers them in more depth.

Backup heat is the third driver. Carrier says auxiliary heat automatically activates when outdoor temperatures drop below freezing, though it says the activation temperature varies by system. It also turns on when the heat pump cannot efficiently reach the thermostat setting alone. It can also come on after a large thermostat increase, or during defrost, when the outdoor unit melts off frost. See our guides to auxiliary heat and defrost mode.

The house itself is the fourth. The Florida Solar Energy Center says cooling energy use is driven by heat gain. The sun's heat enters through the windows, roof, walls and infiltration, meaning hot outside air leaking in.

Ducts matter too. The Florida Solar Energy Center says ducts absorb heat from the attic around them. It adds that duct leakage pulls hot attic air into the system through small holes. Our guide to duct sealing and duct repair explains the difference.

Size and condition round out the list. The Department of Energy's Building Science Education site says rules of thumb too often lead to excessively oversized systems. It says that leads to increased cost, wasted energy and too-frequent on-and-off cycling. The Florida Solar Energy Center says the efficiency of the equipment heavily influences cooling energy use. It recommends service to make sure the refrigerant charge is adequate. ENERGY STAR says heat pumps work best with clean filters.

A federal worked example for a region that includes Florida

FEMP publishes a worked example. It covers hot-humid and southeast states, a region whose list includes Florida.

FEMP bases its example on the test method referenced in federal rules for a 36,000 Btu per hour heat pump, which is a 3-ton system. It assumes 3,259 hours of cooling and 854 hours of heating per year. These hours apply to FEMP's whole hot-humid and southeast region, not Florida alone, but they show cooling running far longer than heating.

For heating and cooling combined, FEMP estimates 12,304 kWh a year for its less efficient model, rated 14.3 SEER2 and 7.5 HSPF2. Its model at the ENERGY STAR level, rated 15.2 SEER2 and 7.8 HSPF2, comes to 11,660 kWh. The best available model it lists, rated 24 SEER2 and 11 HSPF2, comes to 7,683 kWh.

What Florida changes

The Florida Solar Energy Center says that in Florida, most heating and cooling energy goes to cooling. That matches the federal example above, where cooling hours far outnumber heating hours.

Winter still matters during cold snaps. Florida Power & Light (FPL), a Florida electric utility, said in a January 2026 release that cold snaps can significantly impact energy bills, as heating uses two to three times more energy than cooling.

The Florida Solar Energy Center also separates the state by region. It says to select a heat pump in Central and North Florida. In South Florida, it says the heating season is so limited that a straight air conditioner with electric resistance heating, though much less efficient than a heat pump, does not create a significant difference in annual heating and cooling energy use.

That page does not draw the line where one region ends and the next begins. For more on the equipment itself, see our guide to heat pumps in Florida.

How to estimate your heat pump's share from your bills

The Florida Solar Energy Center describes a simple bill check. Gather 12 months of electric bills. Find the month with the lowest use and treat it as an estimate of your base energy use.

It says that base month is mostly water heating, major appliances, lighting, fans and plug loads. It adds that the base load isn't heavily influenced by the weather or seasonal changes.

Next, subtract the base use from each of the other months. The Florida Solar Energy Center treats what is left as an estimate of each month's heating and cooling use. Add up the summer months to estimate cooling, then repeat for the winter months to estimate heating.

This is an estimate, not a meter on the heat pump. The EIA notes that many utilities now use electronic smart meters that send usage data in real time.

ENERGY STAR says that, unlike a furnace or boiler, heat pumps do not save energy by turning the setting down when you are away or asleep. It says to pick a comfortable temperature and leave it there. It also advises avoiding Auto mode and setting the heat pump to heat or cool instead. FPL advises against raising the thermostat more than two degrees at a time, to avoid accidentally turning on auxiliary heat. Our guide to thermostat settings has more.