SD-95-13-1 -- A Comparison of Measured and Predicted Performance of a Ground-Source Heat Pump System in a Large Building

A building energy analysis program and a separate spreadsheet implementation of a ground heat exchanger model have been used together to simulate the performance of a closed-loop ground-source heat pump (GSHP) system installed in a large secondary school. Predicted electrical energy use and demand and entering water temperatures to the heat pump system are compared to measured data from the same building. Predictions in both areas compare favourably to the measured data. As it was thought that the ground heat exchanger was oversized, additional runs were undertaken to assess the sensitivity of the entering water temperature to reductions in installed heat exchanger length from the original design. Under favourable conditions, with soils of fairly high permeability and sufficient groundwater movement through the borefield, considerable reductions in the installed heat exchanger length would be possible without significantly increasing the maximum entering water temperature in this cooling load dominated building.

KEYWORDS: year 1995, comparing, measuring, calculating, performance, soil, heat pumps, accuracy, electricity consumption, water temperature, comparing, weather, soil heat exchangers, size, computer programs, oversizing, heat exchangers