“…In the reviewed literature, application of the DTS technique to GSHP research first appears in the context of distributed thermal response testing (DTRT) [ 20 , 21 , 22 , 23 ]. DTRTs based on DTS is still a current topic of research and even seems to have regained interest in recent years [ 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 ].…”