"600,000 hours of monitoring proves efficiency
of ground source heat pumps"
The useful space heating requirement averaged 5750 kWh pa ( = c. 100 kWh /
m² ) across all the sites, both those heated by heat pump and those heated by gas, although the range across individual houses was quite wide, varying between 3500 and 8000 kWh.
Average domestic hot water usage varied between 2000 and 2500 kWh per annum per house ( = c. 6.5 kWh / house / day)
Average annual electricity consumption by the heat pump for space heating was just over 1400 kWh , and for domestic hot water provision around 1000 kWh.
The average Seasonal Performance Factors for the heat pumps were therefore calculated as 4.1 when delivering low temperature water to the underfloor heating, and 2.25 when delivering high temperature water to the primary coil of the hot water cylinder.
These results are consistent with the data from the gas condensing boiler heated houses if space heating was delivered at an efficiency of 85% and hot water at an efficiency of 75%.
Carbon dioxide emissions related to heating and hot water averaged just over 1 tonne per annum per house (17.7 kg/
m² ), compared with 2 tonnes for the gas heated houses.
Average annual running costs worked out at just over £200 per annum.
