Description

Underground thermal energy storage with boreholes (BTES) and ground source heat pumps have become popular technologies in several countries worldwide. Larger systems and especially when it comes to heating and cooling require a thorough planning which is often accompanied by simulation of the thermal processes in the underground part of the system. Typically geology is not uniform and can vary significantly from site to site even if they are close together. Consequently thermal properties like thermal conductivity and heat capacity are not constant values which can be taken from tables but should be determined at the site in order to do a reliable design.

The overall objectives of Annex 21 wew to compile Thermal Response Test (TRT) experiences worldwide to identify problems, carry out further development, disseminate gained knowledge, and promote the technology. Based on this overview, a TRT state–of–the–art, new developments and further work were studied.