A new parametrical model for the prediction of the thermal performance of the earth to air heat exchangers is presented. The system consists of an earth tube, buried in the ground, through which ambient or indoor air is propelled and cooled by the bulk temperature of the natural ground. The proposed model has been developed by analysing temperature data of the circulated air at the pipe＇s outlet using a systematic parametrical process. Four variables influencing the thermal performance of the earth to air heat exchangers were taken into account: pipe length (L), pipe radius (r), velocity of the air inside the tube (V) and depth of the buried pipe below earth surface (D). The developed algorithm is suitable for the calculation of the exit air temperature, and therefore of the cooling potential of the system. The model was validated against experimental data as well as a data set which was obtained by an accurate numerical model describing the thermal performance of the earth tube system.