Fabrice Toussaint,MSEng., Voraggo Limited — Sofia, Bulgaria f.toussaint@voraggo.com Abstract Standard thermal response test (TRT) interpretation reads ground thermal conductivity (ks) from the slope of a straight line fitted to mean fluid temperature versus the logarithm of elapsed time, and the borehole thermal resistance (Rb) from that same fit's intercept. The method is simple, but the choice of where the straight-line segment begins is left to the analyst's judgment, and