CoP is the measure of performance that illustrates how much electrical energy is required for each unit of thermal energy. A CoP of 3.0 means that 1,000 watts of power is consumed by the compressor, pump and blower, to deliver 3,000 watts of heat energy to the building. This is the equivalent of stating that the unit has an efficiency of 300%, or 3 units of heat produced to every one of electricity used.  The 2 kilowatts of 'net' or extra energy is the solar energy that is stored in the ground by nature and transferred into the building by GeoExchange. In Canada, the federal Energy Efficiency Act states that closed-loop units must have a CoP of at least 2.8 and open-loop units must have a CoP of at least 3.2, or 280% and 320% respectively.

A heating system as a whole must meet 100% of a building's heat loss, but a geoexchange system uses an electric resistance heating element to supplement the solar energy transferred from the ground. A residential unit that is sized to 70% of building load will provide 90% of the heat, with the supplemental electric heater providing the other 10%.

The outdoor temperature above which a geoexchange system can provide the entire heating requirement of the building; usually -10 o C. When the outdoor air temperature is above this balance point, the geoexchange system cycles on and off to satisfy the interior demand for heat. When the outdoor air temperature is below this balance point, the geoexchange system runs continuously and invokes the supplementary heater (also called auxiliary or backup or second stage heater) to meet the demand.

The use of soil or water to accept heat that is rejected from the building (to provide cooling).

The use of soil or water to provide heat for the system.

A heat pump is designed to provide full heat to a building until the outdoor air temperature drops below the design balance point, at which time the auxiliary or supplemental or backup or second stage electric heating element is activated. Emergency heat is provided by the same electric element in the unlikely case of failure of any component that shuts down the heat pump operation.

A calculation of the total amount of heat required by a building, considering insulation levels of walls, ceilings and windows, number of occupants, geographic location, soil type and many other factors. The process also calculates the heat gain of the building to determine the summer cooling load.

A measure of the heat required to raise the temperature of one pound of water by one degree Fahrenheit. This is an imperial measurement; approximately 12,000 BTU of capacity equals a one-ton heat pump; an average two-bedroom home requires 4 tonnes or 48,000 BTUs.

After the heat pump has converted the solar energy to warm air, the unit distributes the air throughout the building by means of ductwork.