Thermal energy performance of a Bore-hole Heat Exchange System (BHES) was studied through field experiments and computations. From the comparison of experimental data on fluid temperature profiles in the bore-hole with numerical results, it was seen that a proposed numerical model is reliable and effective for numerical experiments to comprehend the annual and seasonal energy changes associated with the injection and extraction of the BHES. The present computation could offer significant information with respect to the effects of the bore-hole length, fluid flow rate and circulation direction of the fluid in the bore-hole on the heat transfer capacity between the bore-hole and the surrounding ground. It also indicated that the injection to the ground of the surplus heat in summer leads to the increase in the extraction of the ground heat in winter of 3% ten years later.