Mace’s Steel Reuse Sets a New Benchmark for Office Builds

Commercial construction is under growing pressure to cut embodied carbon without compromising design quality or programme certainty. 

Reusing structural materials rather than manufacturing new ones is one of the clearest ways to close that gap, yet doing so at scale on a dense urban site has long been considered difficult. 

Great Portland Estates’ (GPE) 30 Duke Street St James’ project scheme shows that circular construction is achievable well beyond pilot level. 

It provides a working template for lowering carbon footprints while still delivering premium, fully let space in a prime location.

A landmark in circular construction

The 68,000 square foot scheme transformed the former French Railways House and 48-50 Jermyn Street into a fully electric office and retail destination. 

More than 78% of the building's structural steel came from reclaimed material, including steel recovered from elsewhere within GPE's own portfolio, making it the largest commercial steel reuse project for an office building in the UK. 

The approach saved approximately 744 tonnes of embodied carbon.

"30 Duke Street St James's shows what's possible when sustainability ambitions are embedded from the very beginning of a project,” says Ged Simmonds, Managing Director for Commercial at Mace Construct.”Working in close partnership with GPE and our supply chain, we've delivered a building that not only provides exceptional workspace in one of London's most prestigious locations, but also demonstrates how circular construction can be delivered at scale."

New materials backing the approach

Delivering the scheme required innovation beyond steel reuse. 

The project introduced several industry firsts, including the use of Hydro CIRCAL 100R recycled aluminium, marking the first time the material has been used on a UK commercial development, alongside ORAÉ glass manufactured entirely from recycled content. 

The circular strategy extended throughout the building fabric:

• Reclaimed structural steel, including material sourced from within the developer's own portfolio
• Hydro CIRCAL 100R, made from 100% post-consumer scrap formed the aluminium window frames
• ORAÉ low-carbon glass manufactured from 100% recycled content
• Reclaimed Portland stone and marble retained from the original buildings
• Restored raised access flooring and the historic French Railways House mosaic

"This project is a brilliant example of how innovation and collaboration can drive meaningful change in the built environment. We're proud to have contributed to a scheme that not only redefines sustainable construction but also delivers tangible carbon savings through the reuse of structural steel," says Simon Bourne, Project Director at steelwork contractor William Hare Group, which installed 580 tonnes of structural steel on the scheme, of which 439 tonnes were recovered and reused.

Lessons for the wider industry

The project underlines a consistent theme. Outcomes at this scale depend on sustainability being designed in from inception, and on close coordination between client, contractor, design team and supply chain, rather than being retrofitted once a scheme is underway.

The reuse-first approach also demonstrates that circularity need not compromise commercial outcomes. The building was designed to compete for prime occupiers on quality and location terms, not simply on sustainability credentials.

Mace Construct’s business partners:

GPE

The project's developer and client, GPE worked in close partnership with Mace on the 68,000 square foot office and retail scheme. Early collaboration was formalised through a full Playbook review workshop at project launch, building a shared appreciation of priorities that defined the project's collaborative tone throughout delivery. 

Mace Business School 

Mace's internal training arm supported the project's early Playbook review workshop, with dedicated experts designing and delivering interactive, tailored training for the supply chain partners involved. This helped align the integrated project team around shared goals and collaborative working methods from the outset.

Make Architects 

Serving as lead architect on 30 Duke Street, Make Architects designed the eight-storey Grade A office and retail scheme, championing circular economy principles throughout. The team embraced material reuse creatively, incorporating reclaimed Portland stone cladding, granite plinths, and marble-lined interiors originally designed by Charlotte Perriand into the new building's design.