During the summer, solar heat is stored in the soil. This is either directly absorbed as insulation or as heat from rain and the air from the near-surface layer of the soil. Using this energy for heating is a cost effective method. The highest yield can be obtained from soil with high water content. The heat is extracted from the soil by means of buried plastic tubing. An environmentally-friendly, non-freezing emulsion of water- and glycol circulates in the tubing. The soil above the earth collector may not be sealed off under any circumstances, i.e. by buildings, asphalt or concrete.

Installation depth is approx. 20 cm below the local frost line, in Ireland that’s usually no more than one metre deep.

The area needed for a surface collector is usually around 2.5 to 3 times the footprint of the building being heated.

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