Heat Pump Savings Calculator

How to use the heat pump savings calculator

Enter three numbers and you get back what a heat pump saves you each month on heating: the monthly energy a plain resistance electric heater would use to deliver your heat, the heat pump COP, and your electricity rate. The tool turns those into the monthly dollar saving, the kilowatt-hours the heat pump actually draws to make the same heat, and the annual saving.

It answers one question only — for the same warmth, how much less does a heat pump cost to run than electric-resistance baseboards or strips — and it answers it in money you can put on a calendar. On the defaults that is $116.67 a month and $1,400 a year, and every figure moves in direct proportion to the rate you enter.

Start with the resistance baseline in kWh. This is the energy a 100 percent efficient electric heater — baseboards, a fan heater, or the resistance strips in an older system — would burn in a month to keep you warm. If you already heat that way, read it straight off your bill; if you are shopping, the default of 1,000 kWh is a fair winter month for a mid-size home.

Whatever you enter, it represents the heat you need rather than the way you make it, so the same figure is the honest starting point for both heaters. That is the whole basis of the comparison: identical warmth delivered, two very different amounts of electricity bought to deliver it.

What does COP actually mean for the saving?

Next set the COP, the coefficient of performance, which is the efficiency multiplier at the centre of the calculation. A COP of 3.0, the default, means the unit is roughly 300 percent efficient: for every one unit of electricity it consumes it moves about three units of heat into your home.

It manages that because it does not burn electricity to make heat the way a resistance coil does — it runs a refrigeration cycle in reverse to pump heat that already exists in the outdoor air indoors, so most of the warmth is free ambient heat relocated rather than energy converted.

If your rating is an HSPF2 figure rather than a COP, divide by 3.412 to convert: the 7.5 HSPF2 federal minimum for split-system heat pumps works out to a seasonal COP of about 2.2.

The formula, worked line by line

The saving is the gap between two ways of making the same heat. Cost the resistance heater at full price, because every kilowatt-hour it draws becomes exactly one kilowatt-hour of heat and it can do no better.

Then cost the heat pump, which needs only a fraction of that energy because its COP lets one unit of electricity move several units of heat. Subtract the second from the first and you have the monthly saving; multiply by twelve for the year.

The saving curve that falls out of that arithmetic is not linear, and knowing its shape saves money. Because the heat pump draws heating kWh divided by COP, the electricity drawn falls off hyperbolically: going from COP 1 to COP 2 halves the energy, but going from COP 4 to COP 5 removes only another five percent of the original.

That is why a system that holds a mediocre COP through the cold months beats one with a spectacular mild-weather rating that collapses in January, and why the lower rungs of the table matter more than the upper ones.

resistance cost = heating kWh × rate
heat-pump kWh = heating kWh ÷ COP
monthly saving = resistance cost − (heat-pump kWh × rate)
COP from a rating plate = HSPF2 ÷ 3.412

COP is why a heat pump beats a resistance heater so decisively. A resistance coil converts electricity to heat at a fixed one-to-one, while a heat pump moves roughly its COP in heat for each unit of electricity, so a COP of 3 does the same job for about a third of the energy.

Nothing is created from nothing: the machine relocates ambient heat rather than generating it, which is why efficiency above 100 percent is possible for a heat pump and impossible for a resistor. If your equipment quotes HSPF2 rather than COP, divide by 3.412 — HSPF2 is measured in BTU per watt-hour and there are 3,412 BTU in a kilowatt-hour — so 7.5 HSPF2, the federal split-system minimum, is a seasonal COP of about 2.2.

Three limits on the result

COP is not constant: it falls as outdoor temperatures drop, and many units switch to resistance strips at COP 1 in deep cold, which is the top row of the table and a saving of exactly zero, so a seasonal average sits below any nameplate figure.

Ratings themselves changed on 1 January 2023, when HSPF2 and SEER2 replaced HSPF and SEER for US equipment under the appendix M1 test procedure with its more realistic external static pressure, so older HSPF numbers are not directly comparable to HSPF2 ones.

And the output is running cost only: it excludes the purchase price, the installation, any rebate, and any payback calculation, and it is not financial advice. To weigh a heat pump against burning gas instead, use the gas-vs-electric-heating-calculator.

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