‘Grange Hill’ shows way to green energy
Coils under the playground of a school in west London provide the energy source for the underfloor in this new extension.
An ave.rage COP over the course of a year is the design target for the ground-source heat pump serving an underfloor heating system in a London School and generating domestic hot water. Some 250 m of pipework buried below the playground at Wormholt school in west London extracts heat from the ground using a water-glycol mixture. The wet underfloor heating system in a new extension of this school, the exterior of which appeared as the exterior of Grange Hill in the BBV television series, is supplied with water at 40°C. Efficient heat transfer in the built-in storage tank of the Eco Diplomat heat pump for the DHW system is achieved by a tap-water stratificator. The tank can hold 180 l of water at 60°C. The advanced scroll compressor is specially designed for heat-pump applications. Diplomat units have a 3-stage electric heating element that can supply heating in 1.3, 3 and 4.5 kW stages for the few days a year when it may be necessary. To cope with the expansion and contraction of the ground caused by the buried heat exchangers, a special porous asphalt to cover the trenches in the playground.