Over the last fifty years, the interaction factor method has been widely used to address the vertical displacement and the increased deformation of conventional pile groups subjected to mechanical loads when group effects and interactions occur among the piles. Design charts and analytical models have been proposed to serve the considered analysis method. In recent years, the interaction factor method has been extended to address energy pile groups subjected to thermal loads. Design charts have been proposed. However, prior to this study, no analytical models capable of analysing the vertical displacement and the increased deformation of energy piles subjected to thermal loads in a more comprehensive and flexible way than through design charts have been available. To address this challenge, this study presents two analytical performance models for analysing the vertical displacement of energy pile groups subjected to thermal loads, based on the analysis of a single isolated energy pile. Comparisons with three-dimensional finite element analyses outline that the models can accurately capture the displacement of energy piles without the expense of a full rigorous analysis. This evidence makes the present performance models useful tools for the analysis and design of energy piles under serviceability conditions.