Thermo-active foundations utilise heat energy stored in the ground to provide a reliable and effective means of
space heating and cooling. Previous studies have shown that the effects of temperature changes on their response are
highly dependent on their interaction with the surrounding ground. Consequently, it is necessary to consider this
interaction and include both the thermal and mechanical behaviour of the ground in design. This paper addresses this
issue by performing state-of-the-art finite-element analyses using the Imperial College Finite Element Program, which is
capable of simulating the fully coupled thermo-hydro-mechanical behaviour of porous materials. First, the Lambeth
College pile test is analysed to demonstrate the capability of the adopted modelling approach to capture the observed
response under thermo-mechanical loading. Subsequently, a detailed study is carried out, demonstrating the impact of
capturing the fully coupled thermo-hydro-mechanical response of the ground, the use of appropriate boundary conditions
and the uncertainty surrounding thermal ground properties. It is demonstrated that the modelling approach has a large
impact on the computed results, and therefore potentially on the design of thermo-active piles. Conversely, the effects of
thermal conductivity and permeability of the soil are shown not to influence the pile behaviour significantly.