Abstract: The concept of borehole heat exchanger (BHE) field exploitation is described, along with problems with the sustainibility of heat resources in rock masses. A BHE field sometimes has problems with the stability of the heat carrier temperaturę during long-term exploitation. The main reason for this is an insufficient heat stream, with which to transfer heat by conduction in rock. Based on experiences at the Geoenergetics Laboratory (Drilling, Oil and Gas Faculty, AGH University of Science and Technology), possibilities for the regeneration of heat in rock masses are described.