Enhancements of an Integrated Simulation Tool for Ground- Source Heat Pump System Design and Energy Analysis

Ground-source heat pump (GSHP) utilizes the immense renewable storage capacity of the ground as a heat source or sink to provide space heating, cooling, and domestic hot water. GSHP systems are generally comprised of water source heat pumps and ground heat exchangers (GHX). Vertical closed-loop GHX is used predominantly in commercial and institutional applications. Closed loop GHX consists of a borehole or a group of boreholes into which is inserted a loop of pipe with a ‘U’ bend at the bottom. The borehole is then either back-filled or, more commonly, grouted over its full depth. Grouting is normally required to prevent contamination of the ground water and give better thermal contact between the pipe and the ground. Since the ground temperature is generally much closer to room conditions than the ambient dry or wet bulb temperatures over the whole year, GSHP systems are potentially more efficient than conventional HVAC systems. As a result, worldwide applications of GSHP have been growing at an annual rate of 10% over the past ten years (Rybach 2005).