The ground source heat pump system at Winnersh uses a so-called “open loop” technology to provide cooling for the offices. In most ground source heat pump systems a special heat transfer fluid flows around a “closed loop” of plastic pipes which are buried in the ground. In an “open loop” system groundwater is used directly to provide heating or cooling. Water is extracted from a well and passed through a heat exchanger before being pumped back into the ground via a second well. The groundwater in the area stays at a more or less constant temperature of around 14°C all year round. During the summer this source of chilled water is used to remove excess heat from the building via the heat exchangers. This method of cooling produces much lower CO2 emissions than conventional air conditioning systems. Cooling is one of the largest energy consumers in many commercial buildings.
We were brought in by Wates Construction to manage the installation of the well equipment and heat exchangers as part of the circa £1.9M cooling and heating installation. A total of four wells have been sunk at the site, two for the abstraction of water and two for the re-injection of the water after it has been used. Each pair of wells is connected to a large plate heat exchanger that forms part of the cooling system of the buildings. The heat exchangers themselves are over 2metres high and water flows through them at up to 20 litres a second. Each heat exchanger can provide up to 500kW of cooling for the offices.