Water recycling and ground Source heat pump system within permeable paving – System Consideration and On-site Construction Considerations

The recycling and reuse of rainwater, using permeable paving as the reservoir for storage, shows great potential in the reduction of mains water use for low grade uses. Water for toilet flushing, landscaping and car washing can be stored in the pavement structure and pumped out for reuse. Hanson-Formpave have constructed a field site at BRE Watford, UK that incorporates not only the Aquaflow system to replace traditional drainage infrastructure but rainwater recycling and a ground source heat pump (GSHP) system. Linked to the Hanson EcoHouse, the paving system will provide over 50 % of the mains water for non-potable uses and when full could provide a family of 4 with 30 days water without any extra rainfall. The GSHP is linked to underfloor heating and cooling technology this and can provide 6kW for these purposes. Up to 80 % of the costs incurred for annual heating and cooling can be removed by the use of this technology and the typical period payback on the up-front investment is 3-6 years.