Ground source heating/cooling utilises heat pump technology. A heat pump is a device that moves heat energy from one place to another and from a lower to a higher temperature, or visa versa. Heat pumps are available as both heating only or reverse cycle heating/cooling systems and are classified according to the type of heat source and the heat distribution medium used.

There are many different variations of ground source energy systems available, but the main types involve utilising the natural thermal conditions of the ground, large bodies of underground water, or large bodies of surface water. Ground source heat pump systems (GSHP) can be used for heating or cooling purposes and obtain their thermal energy from the ground, which has a much more stable temperature profile throughout the year. For heating, the system pump-extract the heat from the underground and distributes it through a pipe system. For cooling, the process works in the opposite way, extracting heat from the building and injecting it into the ground.

heat pumps

A GSHP system contains three main components:

1) The ground side to get heat out of or into the ground.

2) The heat pump to convert that heat to a suitable temperature level.

3) The building side transferring the heat or cold into the rooms.

heat pumps

The system is a process which allows the transport of heat from a lower temperature level to a higher one, by using external energy. The thermodynamic principle behind a compression heat pump is the fact that a gas becomes warmer when it is compressed into a smaller volume. In a heat pump, a medium with low boiling point (“refrigerant”) is evaporated by the ground heat, the resulting vapour (gas) is compressed (by using external energy, typically electric power) and thus heated, and then the hot gas can supply its heat to the heating system. Still being in the high pressure part, the vapour now condenses again to a liquid after the heat has been transferred. Finally, the fluid enters back into the low-pressure part through an expansion valve, gets very cold and can be evaporated again to continue the cycle.