Grosvenor's proposals include significantly refurbishing this 1980s office building to create a high-quality, flexible and sustainable workspace. There will be an extension on the top floor

Holbein Gardens is a retained and extended 1980s commercial building, refurbished to create a modern workplace with increased floor area. Sustainability and circularity are at the heart of the development, reusing much of the existing building fabric paired with low carbon engineered timber extensions. The project is a pioneer for the direct reuse of structural steel in London, a first of many currently being developed and implemented across the Grosvenor portfolio.

Grosvenor are committed to circularity and prioritising retention over demolition, re-use, recycling, trialling innovations such as material passports, and procurement and waste management. Holbein Gardens is the first project that champions this level of circularity.

93% of the existing structure was retained, and a new vertical extension added to provide additional workspace and terrace area. The new structure is formed from a partially reused steel frame with cross-laminated timber (CLT) floor slabs. The steel being used is 9 tonnes of reused steel from other Grosvenor projects and 16 tonnes reclaimed steelwork from other sites, with the remaining sourced from traditional (new) steel. This reused steel, alongside the use of CLT gives an overall embodied carbon for the structure of 65 kgCO2e/m2.

The steels reused on Holbein Gardens were taken from low load applications, roofs or temporary works and so only steel primer needed to be removed. If steels are encased in concrete encasement or covered in intumescent/vermiculite fire protection, have shear studs etc. this would require further consideration as more de-fabrication and processing would be required for the steels to be reused, increasing energy consumption and embodied carbon. The steel frame was completed in Summer 2022 and practical completion is expected in April 2023.

Furthering our study into the reuse of structural steel, working with Grosvenor and with funding from Innovate UK, we are undertaking research into the re-use of pre-1970 steel and how concrete encasement removal may affect how steelwork can be reused. Results of this will be used to inform further work and is expected to be concluded in Summer 2023.

“Holbein Gardens is set to have just over 35% of the new steel from reused sources and demonstrates how the challenges of using reclaimed steelwork can be overcome. With increased interest in reusing steel and incentives to get building owners to extract steel, this will help reuse of steel become a more economic, efficient and mainstream way to reduce carbon in the construction industry.”
Rob Mills, Senior Associate, Heyne Tillett Steel