Why might a heat pump save less than expected?

If electricity is expensive, the heat pump is underspecified, or the system runs at high flow temperatures, savings can shrink or even turn negative.

Should I rely on this before buying a system?

Use it as a planning tool only. Always get a professional heat loss survey and installer quote before committing.

Calculator

Heat Pump Savings Calculator

Estimate current heating cost, likely heat pump electricity use, annual savings, grant-adjusted upfront cost, and simple payback.

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How to use this heat pump cost calculator

This calculator is designed for homeowners comparing an existing heating system with a future heat pump using their own assumptions for fuel price, annual heat demand, system efficiency, and grants.

It is most useful as an estimate-only planning tool before speaking to installers. For a buying decision, pair the result with a professional heat loss survey, emitter check, and live tariff review.

How the formula works

Current system input energy equals annual heat demand divided by current system efficiency. Current cost equals that input energy multiplied by your current fuel price.

Heat pump electricity use equals annual heat demand divided by SCOP. Heat pump cost equals that electricity use multiplied by your electricity price. Payback uses net installation cost after grants divided by annual savings.

Example calculation

If a home needs 12,000 kWh of heat and a heat pump achieves SCOP 3.2, estimated electricity use is 3,750 kWh.

At 30p per kWh, that is about GBP1,125 per year. If the current system costs GBP1,500 per year, estimated annual savings are about GBP375 before maintenance and other factors.

Country or regionHome size in square metresCurrent heating typeEstimated annual heating demand in kWhCurrent fuel price per kWh

Heat pump electricity price per kWhBoiler or heater efficiency percentageHeat pump SCOPInstallation costGrant amount

United Kingdom assumptions

Currency: GBP. Electricity: Check current official sources. Gas: Check current official sources. Heating oil: Check current official sources.

Last reviewed: 2026-04-27. Confidence: medium. Prices are not pre-filled because supplier tariffs and price caps change. Enter your current unit rates from a bill.

Current annual heating cost

£0

Estimated heat pump electricity use

4,375 kWh

Estimated heat pump annual cost

£0

Annual savings

£0

Net installation cost after grants

£12,000

Estimated payback period

No simple payback

CO2 reduction estimate

2,067 kg/year

Recommendation summary

This estimate suggests limited or negative savings. Improving insulation, emitters, or tariff choice may be important before moving ahead.

Calculators on this site are estimates only. Always get a professional heat loss survey and verify current grant rules, tariffs, and product suitability before making purchase decisions.

Heat pump savings FAQs

No. These figures are estimates based on the assumptions you enter. Real-world results depend on design, controls, insulation, weather, and how the system is used.

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