Verification of the performance of a vertical ground heat exchanger applied to a test house in Melbourne, Australia

Abstract

The ground heat exchanger is traditionally used as a heat source or sink for the heat pump that raises the temperature of water to about 50 °C to heat houses. However, in winter, the heating thermostat (temperature at which heating begins) in the Australian Nationwide House Energy Rating Scheme (NatHERS) is only 20 °C during daytime and 15 °C at night. In South-East Melbourne, the temperature at the bottom of a 50-m-deep borehole has been recorded with an Emerson™ recorder at 17 °C. Melbourne has an annual average temperature of 15 °C, so the ground temperature increases by 2 °C per 50-m depth. A linear projection gives 23 °C at 200-m of depth, and as the average undisturbed temperature of t..