Heat-pump COP and electricity cost in simple words

COP is a ratio

A COP of 3 means three units of heat are delivered for each unit of electrical energy at the stated condition. It does not mean 300% of energy is created; the heat pump moves environmental heat into the building.

Use the same heat demand

Compare technologies only after defining the useful heat the building needs. Historical fuel use may require careful conversion, while a proper heat-loss assessment is better for equipment design.

One COP is not a season

Performance changes with outdoor temperature, source temperature, flow temperature, defrosting and controls. Use a seasonal performance figure when it is credible for the location and system; otherwise label multiple scenarios.

Keep the boundary honest

The energy comparison does not size equipment, confirm emitter suitability or calculate installation cost. Those decisions need property-specific professional assessment.

If another fuel is being replaced, convert that system's delivered heat carefully instead of comparing a fuel bill directly with heat-pump electricity. Fuel unit, appliance efficiency, standing charges and climate period all need their own evidence.