While the external temperature can vary dramatically throughout the year, the temperature below ground stays fairly constant.
A geoexchange system uses an earth loop comprised of lengths of pipe filled with a water based solution to extract energy from the ground or a body of water. In winter, the water solution in the pipes absorbs the heat from the surrounding earth and carries it to the heat pump. In summer, the process is reversed and the water solution carries the heat from the building back into the earth.
There are a number of options for the ground loop:
A horizontal closed loop is the most common ground loop and is used when there is an adequate land area available.
The pipes are laid in trenches in the ground at an average depth of 1.5m.
However, the length and width of the trenches is dependent on the size of the building that requires heating or cooling.
The number and depth of the bore holes is dependent on the size of the system. Two separate pipe lengths are placed in each borehole in a U shape and the borehole is then backfilled with a grouting material to seal it off.
A pond loop makes use of a pond, dam or body of water on a property which can be used as a collector. Coils of pipe are attached to a frame and sunk to the bottom of the water body. The amount of pipe is dependent on the size of the system.
There is minimal excavation required and in the majority of cases this is the most economical option.