Coefficient of performance (COP)
The single number that describes heat pump efficiency.
You'll learn
- Explain coefficient of performance (cop) at engineering level
- Read the numbers that define the behaviour
- Apply the idea to a real vehicle
Overview
COP compresses the entire efficiency story of a heat pump into one ratio, and it is not constant — it depends heavily on the temperature difference the system is working against.
In depth
Formula
COP = Heat delivered ÷ Electrical energy in
A COP of 3 means three units of heat arrive for every one unit of electricity consumed — the other two units are moved from the environment, not created.
Example: A heat pump delivering 4.5 kW of heat while consuming 1.5 kW electrically has a COP of 3.
| Ambient temperature | Typical COP |
|---|---|
| 10 °C | ~4.0 |
| 0 °C | ~3.0 |
| -10 °C | ~2.0 |
| -20 °C | ~1.3 (near resistive parity) |
Quiz
COP check
- 1
A heat pump delivers 6 kW of heat while consuming 2 kW electrically. What is its COP?
Key takeaways
Remember this
- COP is heat delivered divided by electricity consumed.
- COP falls as ambient temperature drops, converging toward 1 at extreme cold.
- COP of 3+ is typical in mild cold; near-freezing conditions are where heat pumps matter most.
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