GDC
WHAT IS GROUND SOURCE HEATING?
Ground Source Heating is the process of taking heat from the ground and converting it into energy, which can then be used to heat buildings.
The earth is heated by radiation from the sun and maintains a temperature of around 8-12⁰c throughout winter. This heat store can be tapped into through the installation of a Ground Source Heat Pump System.
The system itself comprises three elements; a ground loop, the heat pump and a heat distribution system.
The ground loop is a pipe which is buried in the ground either through a horizontal trench or a vertical borehole. Boreholes benefit from higher ground temperatures than trenches and obviously a horizontal trench requires a greater amount of land to lay the ground loop. A water/anti-freeze mixture is pumped through the pipe where it absorbs heat from the ground. A heat exchanger then extracts the absorbed heat and transfers it to the heat pump.
The Heat Pump itself is most simply explained as a refrigerator in reverse. A refrigerator sucks the heat out of its interior (and by so doing lowers the temperature of the interior) and then dumps this heat through a radiator on the back (and so raises the temperature of the radiator).
The third basic element of a ground source heat pump, the heat distribution system, can be either low temperature radiators or, preferably, underfloor heating. If the heat pump is asked to produce higher temperatures, for example in a conventional radiator circuit, then its efficiency will reduce.
For every unit of electricity used to power the heat pump system, approximately 3-4 units of heat are captured and distributed. In effect this means a Ground Source Heat Pump is 300-400% efficient in terms of its use of electricity. At this efficiency level there will be less carbon dioxide emissions than for a gas boiler heating system. In many cases it may also be possible to provide the required electricity by means of renewable energy, thus virtually doing away with any use of fossil fuels and reducing carbon emissions to zero.
Once a ground source heat pump is installed, there are no external fans and no visible external equipment. The system is quiet in operation, very safe and requires very little maintenance. Savings in running costs of 25% to 50% are possible depending on the type and price of fuel being displaced.
Exact installation costs depend on the site and the amount of heat output required. A survey is necessary to ensure that the ground at the location is suitable and to decide whether a horizontal trench or vertical borehole is most appropriate.