Abstract
A ground source heat pump system was installed for a small office building in Central Tokyo. It is made up of a water-source heat pump unit, 8 boreholes of 75 m deep for heat exchanger, and polyethylene pipes. Coefficient of Performance (COP) of the heat pump system was 4.3 in average for the first year. Forty nine percent of electricity was reduced by the ground source heat pump system, compared to the conventional air source heat pump system which previously worked there. Geology of the building site is unconsolidated Quaternary sediments of gravel, sand and silt, and their thermal conductivity was estimated to be 1.8 W/(m·K). Thermal energy of 51 GJ was produced from the ground source and that of 53 GJ was discharged there during the first year. Such good balance of subsurface heat exchange suggests sustainability of the heat pump system working for the Sasada Building.
