What is COP?
COP (Coefficient of Performance) is the simplest way to describe how a heat pump can be more than 100% efficient. It's the ratio of heat energy delivered to electrical energy consumed. A COP of 3 means the system moves three units of heat into your home for every unit of electricity it uses.
Why it can beat 100%
A furnace burns fuel to create heat, so it can never deliver more energy than the fuel contained. A heat pump works differently. It moves heat that already exists in the outdoor air into your home rather than creating heat from scratch, which is why it can deliver far more energy than it consumes. Stephen Lake explains the idea:
"The heat pump's 300%... it's not creating that heat. It's taking existing heat energy that exists in the air outside the home, and it's using the refrigerant in the heat pump to basically take that heat, increase the temperature, and move it inside the home." (listen, 12:01)
To see what a system running at 300% efficiency would cost in your home, check your price and rebates. For the fuller explanation of how it pulls that off, see how a heat pump works.
Common questions
Does COP stay the same in winter? No. COP drops as it gets colder outside, which is exactly why a true cold-climate heat pump is engineered to hold a high COP at low temperatures.
How does COP relate to SEER2 and HSPF2? SEER2 and HSPF2 are seasonal ratings built on the same idea, measuring how much heating or cooling you get per unit of electricity.