Heat pump calculator: What does it use, and what can you save?
The economics of a heat pump depend on the heat demand of the house, the efficiency of the system and the price of electricity. Here you can compare your current heating with a heat pump scenario and see which assumptions drive the result.
Worked example
- Heat demand: Based on current consumption
- Current consumption: 1,800 units/year
- Energy per unit: 11 kWh
- Current efficiency: 90 %
- Seasonal coefficient (SCOP) for space heating: 3.5
- Share for domestic hot water: 20 %
- Seasonal coefficient for hot water: 2.8
- Share from the immersion heater: 5 %
- Auxiliary electricity: 200 kWh/year
- Electricity price: 0.23 GBP
- Price per unit: 1.10 GBP
- Current service: 170.00 GBP
- New service: 110.00 GBP
- Investment: 14,000.00 GBP
The heat pump uses
6,169.7 kWh of electricity per year
Delivered heat 17,820 kWh · new cost 1,529 GBP · current 2,150 GBP per year
Savings: 621 GBP per year · payback about 22.5454 years
A financial estimate based on your assumptions, not a sizing of the system.
Start with your heat consumption
Use the consumption from your bills if you have it. Oil, gas and wood pellets must be converted to the heat the house actually receives. That also requires an assumption about the efficiency of the existing system.
The seasonal efficiency of the heat pump describes the ratio between the heat delivered and the electricity used over a period. A stated maximum efficiency is not necessarily the efficiency in your house. Flow temperature and hot water can affect the result.
How to look into the savings
Use several scenarios
Try a lower efficiency, a higher electricity price and extra operation with an immersion heater. Include service and the costs that actually disappear with the old heat source. Installation and any changes to radiators are part of the investment.
Example of electricity use
A heat demand of 20,000 kWh and a seasonal factor of 4 give 5,000 kWh of electricity for the calculated heat production. Auxiliary electricity and any other consumption come on top if they are not already included in the seasonal factor.
The result is an economic estimate with your assumptions. It is not a sizing of the system. A specific quote must also take into account the heat loss of the house, the installation and the need for hot water. Compare heating types if other solutions are also relevant.