ABSTRACT This paper presents the background@ development and the validation of new analytical and numerical solutions for the modeling of short-term response of borehole heat exchangers. The new analytical solution studies the borehole's heat transfer and the related boundary conditions in the Laplace domain. A set of equations for the Laplace transforms for the boundary temperatures and heat-fluxes is obtained. These equations are represented by a thermal network. The use of the thermal network enables swift and precise evaluation of any thermal or physical setting of the borehole. Finally@ very concise formulas of the inversion integrals are developed to obtain the time-dependent solutions. The new analytical solution considers the thermal capacities@ the thermal resistances and the thermal properties of all the borehole elements and provides a complete solution to the radial heat transfer problem in vertical boreholes. The numerical solution uses a special coordinate transformation. The new solutions can either be used as autonomous models or easily be incorporated in any building energy simulation software.