Originally published on February 23, 2015 by BNP Media through the Walls & Ceilings Blog.
Recently, I was working on an energy model for a high-performance housing prototype. Mostly, I apply energy modeling to non-residential structures. I did not have a coefficient of performance (COP) at my fingertips for the air-source heat pump (ASHP) used in my baseline model.
In this context, the COP is the ratio of the amount of thermal energy (heat) delivered by a heat pump to the amount of energy expended.
COP = heat delivered / energy expended
The COP is kind of like gauging the efficiency of a piece of equipment. However, heat pumps can be over 100 percent. In other words, it is possible for 1 unit of energy input to result in over 1 unit of heat being “pumped” from one environment to another.
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| Air Source Heat Pump Capacity vs. Heating Requirement.Adapted from Air Source Heat Pump Efficiency Gains from Low Ambient Temperature Operation Using Supplemental Electric Heating (Franklin Energy, 2011). |