While net zero carbon in operation is standard for many new developments, London’s 2 Finsbury Avenue goes further. British Land, GIC and Modon, with Danish practice 3XN GXN, aim to reduce both operational emissions and the embodied carbon of construction and manufacturing to net zero. Circularity is central, with materials reused and components designed for future disassembly. Super Spacer T-Spacer SG from Edgetech Europe/Quanex was specified for long-term gas-tightness of the large-scale structural glazing units.
Two towers of 156 and 101 metres provide around 100,000 square metres of office space. The envelope is a structural glazing unitised façade with a three-dimensional sawtooth geometry. Typical façade units combine vision glazing, a shadow box spandrel zone and an opaque aluminium-clad section. The orientation of the sawtooth geometry was informed by simulations of solar gains, making it part of the building’s energy strategy. The project team includes 3XN, Adamson Associates, Sir Robert McAlpine, Focchi Group, FMDC and Ramboll.
The insulating glass units, manufactured by AGC Interpane in Plattling, measure around 1,060 by 2,950 millimetres. In the Amenity Cuts, where the folded sawtooth façade transitions into a planar structural glazing system, they reach up to 2,500 by 7,500 millimetres.
“On projects such as 2 Finsbury Avenue, we need absolute confidence that the edge seal will maintain its performance for decades,” explained Daniel Bruckelt, Head of Insulating Glass Production.
In structural glazing façades, the external silicone seal provides UV protection but is permeable to gas. Long-term gas retention therefore depends on the internal polyisobutylene primary seal. T-Spacer SG features enlarged side contact surfaces, allowing a thicker and more uniform PIB application and thus more robust gas retention throughout the service life of the glazing.
“Wind loads, temperature fluctuations, pressure changes and the thermal expansion of materials all create constant movement within the edge seal. The elasticity of the spacer is a decisive advantage,” said Christoph Rubel, European Technical Manager at Edgetech Europe.
Mike Moran, Vice President of Sales Europe & UK at Edgetech/Quanex, said “The first non-metallic warm edge spacer made from silicone structural foam was a genuine product revolution in 1989. The fact that it is now used as a matter of course in a landmark project such as 2 Finsbury Avenue is something we can be proud of.”