The design of energy pile is hampered by the complex interaction between the piles and the slab subjected to thermal loads. Although finite element analysis is used to account explicitly for the interactions, this method is mainly considered as a research tool. A more practical approach for the routine design is the interaction factor method. However, to date no attention has been paid to address the pile-slab-soil interaction problem. This work investigates the energy pile-cap interaction and integrates the available formulation of the method. The method is compared with results from more rigorous finite element analyses to evaluate its performance.