What Is COP and Why Does It Matter for Heat Pumps?

Quick Answer

COP, or coefficient of performance, measures how efficiently a heat pump moves heat. It is the ratio of heat delivered to the energy used, so a COP of 3 means three units of heat for every unit of electricity.

What Is COP?

Quick Answer:

COP is a simple efficiency ratio: the heat a system delivers divided by the energy it consumes. Because a heat pump moves existing heat rather than creating it, its COP is usually well above one, unlike electric resistance heat.

A COP of three means the heat pump delivers three times more heat energy than the electricity it draws. The higher the COP, the more heat you get for each unit of energy you pay for.

Why Does COP Matter for Heat Pumps?

Quick Answer:

It explains why heat pumps can heat so efficiently. They transfer heat from the outdoor air instead of burning fuel or using resistance, so a single unit of electricity can deliver several units of heat to your home.

That efficiency is the main reason heat pumps lower heating costs in mild and moderate cold. COP is the number that captures how much more you get out than you put in.

Does COP Change in Cold Weather?

Quick Answer:

Yes. COP drops as the outdoor temperature falls, because there is less heat in the air to move. A heat pump that posts a high COP in mild weather will be less efficient on the coldest days.

Cold-climate heat pumps are designed to hold a useful COP at lower temperatures. In deep cold, a backup heat source or a dual-fuel setup covers what the heat pump cannot do efficiently.

At a Glance

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Frequently Asked Questions

What is a good COP for a heat pump?

Many heat pumps run a COP between about two and four in moderate conditions, with higher being better. The exact number depends on the equipment and the outdoor temperature, since COP falls as it gets colder.

Does COP drop in cold weather?

Yes. As the outdoor air gets colder, there is less heat to move, so the COP falls. Cold-climate heat pumps are built to hold a useful COP at low temperatures better than standard models.

How is COP different from HSPF or SEER?

COP is an efficiency ratio at a given moment, while HSPF and SEER estimate efficiency averaged over a whole season. COP is a snapshot; the seasonal ratings reflect performance across changing weather.

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