Analytical solution and economic impact for improved p(t)-linear average method to estimate the ground thermal properties during in situ thermal response test

One potential problem for designing a ground-coupled heat pump systems is the difficulty of identifying ground thermal properties due to complicated ground environment. A p(t)-linear average method was proposed to improve the accuracy of the identification and was shown to be an effecitive method. However, the p-value in this method is only a fitted value. Thus, an improved p(t)-linear average method is proposed in this study, in which the p-value is calculated using theoretical models inside the borehole. The relative errors for the borehole thermal resistance for the optimal improved p(t)-linear average method is 1.90%.