As a fluid is circulated through the buried pipe, it attracts heat from the surrounding ground; the further the fluid flows, the more heat it can extract. When the warm fluid returns to the compressor, heat is taken from the fluid and transferred to the heat pump, where it warms air prior to circulation throughout the building. In summer, the compressor transfers building heat into the loop fluid, which then dissipates heat into the ground as it circulates, and returns to the building in a cooled state.

The solar heat that is transferred out of the ground can be used either to warm air (for use in a forced air distribution system) or to heat water (for drinking or service applications, or in radiant heating or swimming pools).

The loop is buried below the frost line, and insulation is used to protect any section that may rise above the frost line (e.g.: as the pipe enters the building) to avoid freezing in winter.

Twenty percent of the average energy demand in a residential home is for water heating, and most units include a component to heat water for potable or sanitary use. Heat pumps can also be used to dehumidify indoor swimming pool areas, by controlling condensation with a minimum of ventilation and using the recovered heat in the main heating process.

When the loop cannot obtain sufficient heat from the ground, most systems include a back-up electric element to provide supplemental heat. If the demand for heat is higher than the combined supply from the outside loop and the electric backup, most systems will shut down.  Note: the backup electric system continues to provide heat until the problem is fixed.

Most space heating and water heating in Canada are provided by combustion of natural gas, oil or propane, or by electric resistance, while most cooling is provided by electric air conditioning. A geoexchange system does not use combustion to make heat; it simply transfers solar heat from the ground at very high efficiency. This lack of combustion makes a geoexchange system a best choice from an environmental and safety standpoint.

The ground loop is buried in the soil and enters the building through an underground penetration. There are no visual components outdoors.

In Canada, a geoexchange unit is used more for heating than for cooling, and a reversing valve can be switched between seasons to reverse the flow of the loop fluid and the operation of the heat pump. The system design may be over-sized for the second application, but that means the unit cycles less frequently.

The generator must be of sufficient capacity and have a constant voltage, to meet the electrical demands of the heat pump operation, including circulating pump for the loop and distribution pump for the hot air.

An air-source system is a similar concept to a geoexchange system, but it extracts heat from outside air instead of from the ground. Winter air does not contain much latent heat, and the efficiency of an air-source unit drops significantly when outside temperatures drop below 0 o Celsius. The compressor in an air-source unit is located in the outdoor compartment, where it is noisy and exposed to weather elements. By comparison, a geoexchange system is more efficient due to higher ground temperatures in winter, and the absence of any outdoor equipment makes a geoexchange system quieter, more aesthetically pleasing and longer lasting.

Absolutely.  Research conducted for NRCan indicates that these applications are very cost-effective and offer high reductions of greenhouse gas emissions. Often, these applications offer a more balanced load profile than a residential home and, therefore, are less expensive for the heating or cooling supplied. More than half the geoexchange systems installed in Canada are used in these applications.

Yes. Each heat pump unit can perform only one function at a time, but a larger building (with more than one unit) can provide heating to one spot and cooling to another. This is a common application in schools and other institutional facilities, which have a diverse load. The practice also increases the efficiency of the overall system because the heat removed from room A can be transferred to room B, reducing the need for the ground loop to provide both heating and cooling (and thereby reducing the total installed cost).

Some units integrate a HRV unit that can provide fresh air and enhance building comfort, and offer enhanced defrosting without creating negative pressure inside the building.

In principle, yes. A refrigerator is designed to cool food by extracting heat from the package and transferring the warm air into the kitchen. A geoexchange system can be reversed to provide cooling or heating, depending on the season. There are numerous compressors on the market, all of which use the same general principles, although the specific models used in a geoexchange system are different from the kitchen appliance.

Design and installation are covered under national CSA standards C447 (commercial) and C445 (residential). As of March 2002, both applications are covered under the CSA C448 standard. CGC is not aware of any mandatory provincial regulations pertaining to geoexchange systems, although some municipalities or regulatory agencies may have guidelines or rules, which have an impact on the design or installation of geoexchange systems.