Air-to-water or ground-source: which heat pump suits your home?
One pulls heat from the outdoor air, the other from the earth beneath the garden. The difference shows on the coldest day of the year.
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Heat pump running cost calculator
Estimate the electricity use and running cost of a heat pump and compare it with a gas boiler, based on floor area, building standard and flow temperature.
How the calculation works
Heat demand is floor area times the typical space heating demand of the building standard, plus 700 kWh of hot water per person and year. The heat pump's electricity use is space heating divided by the seasonal performance factor, plus hot water at a lower factor (2.8 for air-to-water, 3.3 for ground-source), because hot water needs higher temperatures.
- The SCOP presets are typical field values: air-to-water 4.0 at 35 °C down to 2.6 at 65 °C, ground-source 4.8 down to 3.1. Real results depend on planning and installation.
- The gas boiler is assumed to convert 90 percent of the gas into heat; gas emits about 0.2 kg CO₂ per kWh.
- Solar power used by the heat pump is valued at the feed-in tariff you give up. Standing charges, maintenance and the purchase price are not included.
Background
All calculatorsGuides to go with it
Heat pumps in older homes: flow temperature is the number that decides
Whether a heat pump works in a 1930s villa is rarely a question of the building's age. It is a question of how hot the radiators need to be.
Where a house loses heat: the efficiency checklist before you buy hardware
The cheapest kilowatt hour is the one you no longer need. A clear look at the building first saves money on every device that follows.