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A ground source heat pump is a heating and cooling system that transfers heat between a building and the shallow ground through a closed loop of circulating heat-exchange fluid buried in vertical boreholes or horizontal trenches ^[1]. The ground acts as a thermal reservoir whose temperature remains nearly constant throughout the year at depths of several meters, so that heat is extracted from the ground in winter and rejected into the ground in summer by means of a vapor-compression refrigeration cycle operating in reverse ^[2]. The ground heat exchanger consists of high-density polyethylene pipes embedded in the borehole and grouted with thermally conductive material, and the required borehole length is determined by the building's annual heating and cooling loads, the ground thermal conductivity, and the undisturbed ground temperature measured through an in-situ thermal response test. The heat pump unit raises the temperature of the extracted low-grade heat to a usable level for space heating and domestic hot water, and reverses its cycle to provide space cooling.