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 t
he natural ground. The dynamic thermal performance of the system durin
g 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 hav
e been used as inputs to the model. Furthermore, an extensive sensitiv
ity investigation was carried out in order to evaluate the effect of t
he main design parameters on the system's heating capacity. The key va
riables influencing the performance of earth-to-air heat exchangers we
re considered to be pipe length, pipe radius, air velocity inside the
tube and pipe depth below the surface of the earth. Cumulative frequen
cy distributions of the air temperature at the pipe's exit have been d
eveloped as a function of all the input parameters.