VDI 4640 Blatt 5:2016-08

The standard describes a measurement method for the determination of thermal properties of the underground and the heat transfer characteristics of the ground heat exchanger. These parameters are necessary for the design of a heat source system. The thermal response test (TRT) is such a measuremt method and allows a site survey in which following parameters can be determind: the effective thermal conductivity of the rock over the entire length of a borehole heat exchanger and the borehole resistance, the thermal resistance from the fluid to the rock for the used borehole heat exchanger.