Analysis of ground-source heat pumps in north-of-England homes

The performance of ground-source heat pumps (GSHPs) for domestic use is an increasing area of study in the UK. This paper examines the thermal performance of three bespoke shallow horizontal GSHPs installed in newly built residential houses in northern England as compared with a control house fitted with a standard gas boiler. A 350 m high-density polyethylene pipe with an external diameter of 40 mm was used for each house as a heat pump loop. The study investigated the performance of a single-loop horizontal ground heat exchanger against a double loop. It also investigated rainfall effects on heat extraction by comparing a system with an infiltration trench connected to roof drainage against a system without an infiltration trench above the ground loops. Parameters were monitored for a full year from October 2013 to September 2014. Using the double-loop exchanger has shown an enhanced performance of up to 20% compared with a single loop. The infiltration trench is found to improve performance of the heat pumps; the double loop with an infiltration trench had a coefficient of performance 5% higher than a double loop without a trench.