Use this calculator to estimate the difference in running costs when replacing a gas boiler with a heat pump in your home.
How To Use The Heat Pump Running Costs Calculator
The calculator needs the following information:
- The type of heat pump being installed in your home.
- Annual gas usage for your home, from your annual energy statement.
- If you don’t know the gas usage for your home then find out the typical energy consumption of homes like yours at Average Energy Consumption Calculator.
- Number of people living in the home (to estimate the split between gas usage for hot water heating and space heating).
The calculator makes assumptions on gas boiler efficiency and on the Seasonal Performance Factor (SPF) of a typical heat pump, for both space heating and hot water heating (these are different). There is also the option to enter SPF values for a specific heat pump. The calculator assumes that each person in the home uses 1,667 kWh of gas per year for hot water heating. There is the option to enter a specific value for the total hot water usage if you know it.
The calculator assumes default prices for gas usage, daily standing charge and electricity usage. These costs can be adjusted to your own tariff figures using the sliders below the calculator. Note there are smart thermostats available for the control of heat pumps with 30 min tariff electricity supplies to schedule the heat pump to use lower priced electricity and avoid higher tariff times.
Enter Heating Details
Estimated Heat Pump Running Costs v Gas Boiler
* Seasonal Performance Factor (SPF)
Adjust the sliders to use your own energy costs
Take these from your gas and electricity bills (inc VAT figures).
* prices based on EON standard prices inc. 5% VAT effective 1 April 2021
Renewable Heat Incentive (RHI): Heat pumps are included in the domestic Renewable Heat Incentive (RHI) provided claims are made by 31 March 2022. This scheme pays either 10.85p per kWh of electricity used (Air Source Heat Pump) or 21.16p per kWh (Ground Source Heat Pump) for a 7 year period.
Clean Heat Grant: From April 2022, a payment of £4,000 will be made to qualifying homeowners to assist with installation costs for those who install either an Air Source or a Ground Source Heat Pump for space and water heating. This scheme is currently out for consultation. It is possible that the payment may be increased to up to £7,000.
Basis of calculations
The calculator takes actual annual gas usage for the home and, by making assumptions on typical gas boiler and heat pump efficiency, if calculates likely heat pump electricity demand. The SPF data for a typical heat pump installation comes from the UCL (2017) reference below.
Note: System efficiency can be measured at different points. In this case the measure used is SPFH2. The calculator assumes that the efficiency of the rest of the heating system is the same for both the gas boiler being replaced and the heat pump.
It assumes that by switching to a heat pump then the gas supply standing charge is saved. It also assumes there is no increase in electricity standing charge.
- Committee on Climate Change (2019). The costs and benefits of tighter standards for new buildings. Available at: https://www.theccc.org.uk
- Energy Saving Trust (2012). Detailed analysis from the first phase of the Energy Saving Trust’s heat pump field trial. Available at : https://assets.publishing.service.gov.uk/
- MHCLG (2019). October 2019 consultation on future homes standard. Available at: https://assets.publishing.service.gov.uk/
- Ofgem (2013) . The Heat is on: heat pump field trials phase 2. Available at: https://www.energysavingtrust.org.uk/sites/default/files/reports/TheHeatisOnweb%281%29.pdf
- UCL (2017). Investigating variations in performance of heat pumps installed under via the renewable heat premium payment (RHPP) scheme. Available at: https://assets.publishing.service.gov.uk/
Last updated: 22 August 2021