Glossary · Heating, cooling & ventilation

COP (coefficient of performance)

Also called: COP at 5°F · heating COP

Heat delivered divided by electricity used at a given moment; a COP of 3 means three units of heat for each unit of electricity.

What it means

Electric baseboards and furnaces turn electricity into heat one-for-one, so their COP is about 1. Heat pumps reach COPs of 2 to 5 in mild weather because they move heat instead of making it, but COP falls as the outdoor temperature drops. Seasonal ratings such as HSPF average this over a whole winter.

Why it matters in an audit

COP at cold temperatures, such as −15°C (5°F), shows how cheaply a heat pump will run in your coldest weather and helps find the economic balance point against gas or oil.

Typical numbers

Reference values with their sources. Your auditor’s report gives the figure for your own house.

What	Value	Source
Air-source heat pumps (NRCan)	2.0–5.4 at 46°F (8°C); 1.1–3.7 at 18°F (−8°C)	natural-resources.canada.ca ↗
Ground-source heat pumps (NRCan)	About 3 in the coldest months	natural-resources.canada.ca ↗
ENERGY STAR Cold Climate minimum	1.75 at 5°F (−15°C)	energystar.gov ↗

Sources

Learn more here

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Related terms

Heat pump An electric system that moves heat instead of making it: out of the house in summer and into it in winter, using a refrigerant loop.
HSPF / HSPF2 A heat pump's heating efficiency averaged over a whole heating season; higher is better, and HSPF2 numbers can't be compared directly with older HSPF.
Balance point The outdoor temperature where something changes: below the thermal balance point a heat pump needs help; below the economic one, fuel is cheaper.
Electric resistance heat Heating with electric elements that turn electricity directly into heat, such as baseboards, electric furnaces and heat pump backup strips.
Cold-climate heat pump (ccASHP) An air-source heat pump built to keep heating efficiently in deep cold, usually verified by ENERGY STAR Cold Climate or the NEEP list.
Seasonal COP A heat pump's average heat output per unit of electricity over a whole heating season, including defrost and backup heat, instead of at one temperature.

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