The shallow geothermal system is a Renewable Energy Source (RES) that utilizes the constant temperature of the subsoil. Ιnside the Earth the temperature remains constant starting at 1.5 m depth and for the first 100 m. This temperature is kept constant throughout the year and is not affected by external conditions (e.g. heat or frost). In Greece this temperature is 17-20OC.
Geothermal system can therefore offer us heating and cooling using the technology of Heat Pumps. Where the Heat Pump is the machine that draws heat from a source in the case of Geothermal, this source is the ground and then by consuming electricity, it offers us Heating, Cooling and Hot Water Generation.
How does Geothermal applied in a building?
The application of a Geothermal system consists of two different parts as shown in the image below (the distribution network is not included, e.g. Underfloor, FANCOIL, AC, etc.)
In the 1st part we see the engine room which includes the ground source Heat Pump and the centrifugal pump , while in the 2nd part the Soil is presented where the Geoexchanger is included.
As can be seen in the image above, the Geoexchanger includes 6 boreholes 100 m deep in which 1-U type geoexchangers (polyethylene pipes) have been placed. water (if required also antifreeze).
The image below shows the complete placement of a 1-U type geoexchanger in the borehole.
(1) 1-U type Geoexchanger (polyethylene pipe)
(2) Grout
(3) Soil
A closed Loop geothermal system circulates water in a closed ground loop. It takes the constant temperature of the Earth as a heat source for the Heat Pump, resulting in constant performance in both Heating and Cooling. A comparative advantage of this system is that it is not affected by the outside air temperature as is the case with Air Source Heat Pumps.
Andreas Koutelidakis
MSc Mineral Resources Engineer TUC
Accredited Installer (International Ground Source Heat Pump Association)
