Siemen’s urban sustainability centre, London

Contracted to design and install foundations for the new Siemens Urban Sustainability Centre in London’s Green Enterprise District, we delivered a value engineered solution, fitted with specialist geothermal technology that harnesses the energy in the ground to provide efficient heating and cooling for the finished building. 

The structural design featured 160 CFA piles with diameters ranging from 600mm to 1200mm and up to 25m depth – some of the deepest in the UK formed using the CFA technique. Each pile was complete with twin, sealed heating loops to extract subsurface energy from the surrounding ground to heat the building. 

In collaboration with Geothermal International – who led the design, supervision and testing of the geothermal system – we successfully integrated the geothermal function into the geotechnical design. This added complexity to the foundation solution as too much heat in the ground could reduce the structural stability of the pile, while temperatures below 4°C could impact the effectiveness of the geothermal system. 

The geothermal pipes were installed after concrete was pumped into the pile shaft and the auger was removed. Each 50mm diameter pipe was secured into a high-density plastic head and tied to a 40mm H40 steel bar running the full length of the loop, designed to assist with insertion into the pile. 

Due to the challenging ground conditions, the lack of tension loads and specified lateral loading, we developed a CFA pile design that transfers load through a combination of skin friction and end bearing capacity. 

All piles were successfully installed at the targeted daily rate, ensuring the next phase of development could be started on time.