The behavior of an energy pile in a group is different from that of an isolated energy pile due to thermal and mechanical interactions. This study aims to extend the load transfer method to consider the mechanical and thermal interactions of energy piles in groups. The load displacement curve of an energy pile in a group is modified from that of the isolated pile through a displacement factor to account for group effects. This paper presents the results of a full-scale field test of four operating energy piles over 12 months, against which the proposed method is validated. Temperature changes of ΔT = 5°C, 10°C, 15°C, and 20°C were applied in the analyses. A comparison between the experimental and numerical results reveals the capability of the approach to provide information about the vertical displacement, vertical stress, and mobilized shaft resistance profile for an energy pile in a group subjected to both mechanical and heating thermal loads.