The heating potential of a single earth-to-air heat exchanger as well as of a multiple parallel earth tubes system has been investigated in this paper using real climatic data. The heating system consists of a single tube or multiple parallel tubes, buried in the ground, through which ambient air is propelled and heated by the bulk temperature of the natural ground. The dynamic thermal performance of the system during the winter period and its operational limits have been calculated in Ireland using an accurate numerical model. For this reason multi-year ambient air and soil climatic measurements for the city of Dublin have been used as inputs to the model. Furthermore, an extensive sensitivity investigation was carried out in order to evaluate the effect of the main design parameters on the system＇s heating capacity. The key variables influencing the performance of earth-to-air heat exchangers were considered to be pipe length, pipe radius, air velocity inside the tube and pipe depth below the surface of the earth. Cumulative frequency distributions of the air temperature at the pipe＇s exit have been developed as a function of all the input parameters.