How much electricity does a heat pump use? By month and by year

A heat pump in a family house uses about 5,799 kWh of electricity a year. At $0.18 per kWh, that is $1,044 a year, $87 a month on average. It is far from even, though: in the coldest month it uses 1,383 kWh for $249, and in summer, when it only heats water, around 53 kWh.

• Heat for the house
• Electricity for the heat pump

December

• Heat for the house3,654
• Electricity for the heat pump1,250

The calculator's starting house, an air-to-water heat pump on radiators at 55 °C (131 °F), the weather of a representative year (Kansas City).

Month	Heat (kWh)	Electricity (kWh)	COP	Electricity cost
January	3,792	1,377	2.8	$248
February	3,513	1,383	2.5	$249
March	1,334	384	3.5	$69
April	1,402	395	3.5	$71
May	281	71	4.0	$13
June	242	59	4.1	$11
July	248	57	4.3	$10
August	248	53	4.7	$10
September	270	65	4.1	$12
October	630	149	4.2	$27
November	1,926	555	3.5	$100
December	3,654	1,250	2.9	$225
Whole year	17,540	5,799	3.0	$1,044

Why winter takes the most

In winter the house needs the most heat, and the heat pump works at its worst. It draws heat from cold outdoor air and has to lift it to a higher water temperature. In the coldest month (February) it makes only 2.5 kWh of heat from a kWh of electricity, against 4.7 kWh in its best month. The three heaviest months take 69% of the whole year's electricity. Below −10 °C (14 °F), a backup electric heater takes a growing share of the work, and it makes only a kWh of heat from a kWh of electricity. In the example it uses 212 kWh, 3.6% of the year.

Over the whole year the heat pump makes 3.0 kWh of heat from each kWh of electricity. That is the seasonal COP, and it gives a quick estimate without the calculator: divide the yearly heat need by the seasonal COP.

How much for a bigger or smaller house

Heat for the rooms (kWh/year)	Electricity (kWh/year)	Cost a year	Average a month	Highest month (kWh)
6,000	2,903	$522	$44	623
10,000	4,247	$764	$64	975
15,000	5,927	$1,067	$89	1,417
20,000	7,607	$1,369	$114	1,859

The rows are examples, from a smaller, well-insulated house to a large or poorly insulated one. Electricity use grows almost in step with the heat need; hot water is the same in every row.

Underfloor heating or radiators

Heating	Seasonal COP	Electricity (kWh/year)	Cost a year
Underfloor heating, water at 35 °C (95 °F)	3.8	4,635	$834
Low-temperature radiators, 45 °C (113 °F)	3.4	5,141	$925
Radiators, 55 °C (131 °F)	3.0	5,799	$1,044

The cooler the water the heating needs, the less the heat pump has to work. With underfloor heating the seasonal COP is 3.8 instead of 3.0, and the house uses 1,164 kWh less, $210 a year.

How to use less

• Keep the water as cool as possible. Weather compensation sets the water temperature by the outdoor temperature. Every extra degree costs electricity.
• Hot water. Heating water hotter than you need lowers the COP all year, in summer too.
• Insulation and tight windows. A smaller heat need cuts the electricity almost in the same proportion.
• A heat pump of the right size. One that is too small leaves more work to the backup heater in a cold snap; one that is too big switches on and off often.
• The rate. Compare electricity plans for heat pumps including fixed charges, not only the price per kWh.

Enter your own house, gas use and heat pump quote in the heat pump calculator. Whether a heat pump pays off against gas is compared in Heat pump or gas furnace.