This paper describes evaluation on energy conservation, environmental protection and economical aspect through long-term operating results of air conditioning with an energy pile system, which was applied to pile foundations of an actual building, for the purpose of the cost reduction of an underground heat exchanger. First, as a result of measuring space cooling systems, energy efficiency ratio of a direct cooling operation and coefficient of performance of a heat pump were 18.6 and 3.9, respectively. Second, it was clarified that the energy pile system could be utilized over a long period of time by monitoring long-term fluctuation and characteristics of the system performance and earth temperature. In addition, we carried out evaluation on annual energy balance of the energy pile system and comparison with conventional air conditioning systems. The reduction rate of the primary energy and CO_2 emissions to a typical air conditioning system reached 31.0% and 33.2%, respectively.
