Why SCOP matters
Heat-pump efficiency changes through the year. Seasonal Coefficient of Performance (SCOP) or Seasonal Performance Factor (SPF) is intended to represent performance across a longer period, making it more useful for annual running-cost estimates than a single COP measured under one test condition.
How the calculator works
- Annual useful heat demand is divided by SCOP to estimate electricity consumed by the heat pump.
- Electricity use is multiplied by the unit rate you enter.
- The result is repeated at lower and higher SCOP values so you can see how sensitive the cost is to performance.
Do you want to compare with gas?
Use the Heat Pump vs Gas Break-Even Calculator to compare the same useful heat and calculate the break-even SCOP.
Methodology & sources
Tariff defaults use Ofgem reference rates; heat-pump performance guidance is linked from Energy Saving Trust. Replace defaults with the figures for your home and system design.