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Heat pump savings calculator

What a heat pump costs to run against your current boiler, from your own fuel bill: the heat you actually need, the electricity a given SCOP would draw, the yearly difference and the payback. Plus the one number that decides it — the electricity price above which the heat pump stops being cheaper.

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Enter Current fuel used per year (kWh), Current heating system, Current fuel price per kWh, Electricity price per kWh, Heat pump SCOP, Installation cost after grants and the Heat pump savings calculator works out Heat actually needed (kWh/year), Electricity the heat pump draws (kWh/year), Current heating bill per year, Heat pump bill per year, Saved per year, Payback (years), Electricity price where the saving disappears straight away. For instance, with Current fuel used per year (kWh) = 20,000, Current heating system = Condensing gas boiler (92%), Current fuel price per kWh = 0.11 $/kWh, Electricity price per kWh = 0.25 $/kWh, Heat pump SCOP = 2.5 — air-to-water, radiators, cold climate and Installation cost after grants = $12,000.00 it returns Heat actually needed (kWh/year) = 18,400, Electricity the heat pump draws (kWh/year) = 7,360 and Current heating bill per year = $2,200.00.

How to use it

  1. Enter your values: Current fuel used per year (kWh), Current heating system, Current fuel price per kWh, Electricity price per kWh, Heat pump SCOP, Installation cost after grants.
  2. Read the result instantly: Heat actually needed (kWh/year), Electricity the heat pump draws (kWh/year), Current heating bill per year, Heat pump bill per year, Saved per year, Payback (years), Electricity price where the saving disappears.

Frequently asked questions

How does the Heat pump savings calculator work?

It takes Current fuel used per year (kWh), Current heating system, Current fuel price per kWh, Electricity price per kWh, Heat pump SCOP and Installation cost after grants and derives Heat actually needed (kWh/year), Electricity the heat pump draws (kWh/year), Current heating bill per year, Heat pump bill per year, Saved per year, Payback (years) and Electricity price where the saving disappears from them. The calculation is live as you type, so the result updates on every change.

Which values does the calculator ask for?

6 values: Current fuel used per year (kWh), Current heating system, Current fuel price per kWh ($/kWh), Electricity price per kWh ($/kWh), Heat pump SCOP and Installation cost after grants ($). Nothing else is required — no account, no file upload.

What does a typical calculation look like?

With Current fuel used per year (kWh) = 20,000, Current heating system = Condensing gas boiler (92%), Current fuel price per kWh = 0.11 $/kWh, Electricity price per kWh = 0.25 $/kWh, Heat pump SCOP = 2.5 — air-to-water, radiators, cold climate and Installation cost after grants = $12,000.00, the calculator returns Heat actually needed (kWh/year) = 18,400, Electricity the heat pump draws (kWh/year) = 7,360 and Current heating bill per year = $2,200.00. Those figures come from running this exact tool, so you can reproduce them by entering the same values.

How much does the result change with different inputs?

It moves a lot. Using Current fuel used per year (kWh) = 40,000, Current heating system = Older gas boiler (80%), Current fuel price per kWh = 0.22 $/kWh, Electricity price per kWh = 0.5 $/kWh, Heat pump SCOP = 3.0 — air-to-water, mixed emitters and Installation cost after grants = $24,000.00 instead, Heat actually needed (kWh/year) goes from 18,400 to 32,000 — which is why it is worth testing a few scenarios rather than trusting a single figure.

Which “Current heating system” option should I choose?

You can pick between « Condensing gas boiler (92%) », « Older gas boiler (80%) », « Oil boiler (85%) », « LPG boiler (90%) », « Electric resistance heating (100%) » and « Wood or pellet boiler (75%) ». Each one changes what the calculator works out, so switch and compare — the default is « Condensing gas boiler (92%) ».

Which units should I enter the values in?

Enter Current fuel price per kWh $/kWh and Electricity price per kWh $/kWh. Metric and US units are both supported — switch system and the figures convert for you.

What does it give for smaller values?

Scaled down to Current fuel used per year (kWh) = 0, Current heating system = Condensing gas boiler (92%), Current fuel price per kWh = 0 $/kWh, Electricity price per kWh = 0 $/kWh, Heat pump SCOP = 2.5 — air-to-water, radiators, cold climate and Installation cost after grants = $0.00, Heat actually needed (kWh/year) comes out at 0. The relationship is worth checking at both ends before you rely on a single result.

When would I actually use this?

Putting a number on a bill: what an appliance costs to run, whether a solar array covers the load, and how much heating a room actually needs.

What is the most common mistake?

Confusing power with energy. A kilowatt is a rate and a kilowatt-hour is a quantity; a 2 kW heater on for half an hour uses 1 kWh, and only the second figure appears on a bill.

How accurate is it, and what are the limits?

An estimate from a seasonal average. A real SCOP falls in a cold snap, exactly when demand peaks, and an unrenovated house on high-temperature radiators will not reach the figure on the datasheet. Take a survey before committing to the payback shown here.

Further reading

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