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.

Read more…

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).