COP: The Coefficient of Performance is calculated by dividing the amount of heat put out by a heating system divided by the amount of energy put in to it. If the output of a heat pump is 56,000 BTUH (56,000 / 3,412 = 16.4 kW), and the compressor, fan and pumps consume 4.82 kW, the COP is:

16.4 / 4.82 = 3.4

In simple terms, you pay for 4.82 kW to operate the heat pump, and you get 16.4 kW to heat your home. That means you get 16.4 – 4.82 = 11.58 kW from the earth. (You don’t have to pay for those kW)

Combined COP: In a system that integrates the refrigeration with the heating, ventilating and air conditioning (HVAC) system, it is often possible that both the COLD and the HEAT put out by the heat pump can be used. For example, when a system is making ice, and at the same time the heat taken from the ice can be used to heat the building, the COP is the COLD produced by the heat pump PLUS the HEAT produced by the heat pump divided by the electrical input.

For example, if the refrigeration supplied by a heat pump is 122,500 BTUH, and the heat supplied is 163,100 BTUH, the total useable output of the heat pump is:

122,500 + 163,100 = 285,600 (83.7 kW)

If the electrical input is 11.9 kW, the COP is:

83.7 / 11.9 = 7.03

Using thermal storage, such as the “thermal storage buffer” in an ice rink, or ice storage tanks helps make the most use of both the heating and refrigeration outputs of an integrated system