Bachy green approach to piling in Cambridge

Leading geotechnical specialist, Bachy Soletanche has installed piles with geothermal piping at the Hauser Forum Development in Cambridge.

The project team proposed the use of a closed loop geothermal heating and cooling system.

As such, geothermal pipes were required to be incorporated into bored continuous flight auger (CFA) foundation piles of the building.

All the pipes in the piles are later plumbed in, via a series of other pipes, to convey the liquid to the heat exchanger.

Working with main contractor Wilmott Dixon, Bachy Soletanche installed 25m long, 150no.

600mm diameter piles using the CFA technique.

Twin loop (four pipe), 32mm diameter geothermal pipes were then plunged into the piles followed by the reinforcement cages, which were up to 6m long with 6no.

T16 bars designed to accommodate up to 1.5MN.

The site team devised a system to successfully plunge the geothermal pipes down to between 15m and 24m deep, using a central T32 bar.

Incorporating Geothermal pipes into piles allows the constant temperature of the ground (around 12oC) to supply liquid of the same temperature to a heat exchanger unit via the pile concrete.

The heat exchange units are installed to replace conventional boilers and air conditioning units.

Geothermal International designed the closed loop system for the client, providing the required pipe length to finally supply up to 117kW of cooling and 188kW of heating to the completed buildings.

The firm also supplied the pipe, connectors and the heat exchangers.

The Hauser Forum Development is the centre for Entrepreneurship and home to Cambridge Enterprise - the University's science and technology commercialisation office.

It was therefore with no surprise that the client, Turnstone Estates and Cambridge University, wanted to incorporate the latest geothermal technology into the new buildings.

Bachy Soletanche's Business Development Manager, Paul Hodgson commented: "Combining piled foundations with geothermal piping is not only practical, but is also financially and environmentally viable".

"The future aim is to incorporate such systems into more comprehensive geotechnical systems and hopefully make geothermal pipe installation the norm in building designs.

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