A contribution towards the determination of g-functions using the finite line source

► Paper examines the thermal response of bore fields using the concept of g-functions. ► New method based on the analytical finite line source method. ► Temporal superposition of heat extractions rates is applied in the Laplace domain. ► g-function of a large bore field is overestimated by the new method. ► Effect of buried depth is shown to be important for short boreholes.