Permeable paving provides saturated ground for GSHP installation
All the heating needed for the new 6000 m2 Kimberley commercial building on a former brickworks site at Stewartby in Bedfordshire is provided by five 130 kW heat pumps drawing energy from permanently saturated ground beneath the 6500 m2 car park. The installation is based on Hanson Formpave’s Aquaflow ThermaPave system, a combination of the Aquaflow permeable paving system and ground-source heat pumps from Geothermal International.
A 200 mm-deep reservoir of permanently saturated stone has been formed using an impermeable welded membrane, ensuring that the 8.4 km of slinky pipes are constantly immersed in water. The pipes are at a depth of 700 mm to ensure they do not freeze, in contrast with a typical car-park excavation depth of 300 mm. Overflow from the reservoir is directed to a lake on the site.
The ground floor has underfloor heating. Offices on the upper floor have specialist geothermal radiators with a much larger surface area than standard radiators. These radiators have double panels and double the amount of fins.
The building has an ‘Excellent’ BREEAM rating and a B-rated Energy Performance certificate. It will have CO2 emissions 26% lower than required by Building Regulations. Fuel costs will be 42% lower, giving a payback of five to six years.
Architects were Form4, and building-services designer was Scott Wilson.
