VIP 11: Use of Earth to Air Heat Exchangers for Cooling

The present Ventilation Information Paper aims to present the basic knowledge on the use of earth to air heat exchangers. The increased need for air conditioning has made alternative passive and hybrid cooling techniques very attractive.
The technique is based on the use of the ground as a heat sink during the summer and winter period. In fact, the soil at a certain depth is at a much lower temperature than the ambient one, during summer and much higher during winter. Thus, the excess heat from a building may be dissipated to the ground through horizontally positioned buried pipes, reducing thus the indoor temperature in summer. In winter the pipes are used for preheating of the ventilation air, reducing thus the heating load of buildings.
The principles of operation as well as the way to apply earth to air heat exchangers are described. Performance data from various examples are presented as well. Finally, information on various methodologies to calculate the performance of the systems is given. Detailed information on earth to air heat exchangers can be found in Santamouris and Assimakopoulos (1996).