A new temperature response function for the energy pile under adiabatic surface

For the energy pile under the building, existing methods typically assume a constant temperature boundary at the ground surface, while current studies have demonstrated that the ground surface surrounding the pile head is close to adiabatic conditions. To overcome these shortcomings, this paper presents a new pile temperature response function which is designed to consider the effect of an adiabatic surface on the energy pile. This new function effectively characterizes the influence of key parameters on the temperature response of the energy pile under adiabatic surface conditions, including pile dimensions and thermal properties of both the pile material and surrounding soil. Neglecting the impact of the adiabatic surface would lead to an underestimation of the change in heat exchange fluid temperature, resulting in an overestimation of 5.8% (building heating) and 4.5% (building cooling) in the available heat exchange amount of the energy pile, respectively.