The main purpose behind the use of energy piles is to enable the exploitation of geothermal energy for meeting the heating/cooling demands of buildings in an efficient and environment-friendly manner. However, the long-term performance of energy piles in different climatic conditions, along with their actual environmental impacts, has not been fully assessed. In this paper, the results of a finite element model taking into consideration the heating and cooling demands of a reference building, and the intermittent operation of a ground source heat pump, are revealed to examine the long-term performance of energy piles. Furthermore, a life cycle assessment model is implemented to compare the environmental performance of energy piles and a group of conventional piles. The environmental enhancement provided by the adoption of a ground source heat pump system is quantified with respect to a conventional heating and cooling system. The obtained results show that (i) the energy pile system can meet the majority of the heating/cooling demands, except during the peak demands, (ii) the geothermal operation results in temperature fluctuations within the energy piles and the soil, (iii) the use of energy piles results in a significant reduction in environmental impacts in the majority of the examined cases.