Thermal investigation of geothermally activated building systems using Thermal-Response-Test method

This work presents an evaluation method for thermal response tests (TRT) on geothermally activated building systems (gTABS). In contrast to borehole heat exchangers (BHEs), the infinite plane source model is appropriate for a gTABS. However, the time criteria defining the applicability of the analytical model are more restrictive than those for BHEs. A minimum time criterion serves as the starting point for the evaluation and a maximum time criterion sets an upper limit. With consistent values for the heat penetration coefficient in all three TRTs performed, the method shows good consistency in compliance with these criteria. Together with the investigation of the undisturbed ground temperatures, the TRT method presented here yields valuable data that allows to assess the performance of a gTABS as a heat source for heat pump applications.