Foster + Partners secures planning approval for 1 St James’s Square retrofit

Latest News Tue, Dec 9, 2025 6:13 AM

Westminster City Council has granted planning permission for the redevelopment of 1 St James's Square, which is located in London’s prestigious St James's district.

Foster + Partners is retaining over 50 percent of the office building’s structure, while completely redesigning and optimising its façade, and providing two new levels with green outdoor spaces that bring a myriad of benefits.

The aim is to exceed GLA targets for embodied and operational energy and meet the highest sustainability targets, including BREEAM Outstanding, NABERS 5.5* and WELL Platinum.

Luke Fox, Head of Studio, Foster + Partners, said: “Working as an integrated team, which includes our in-house sustainability experts, we are preventing the building from becoming a stranded asset. The decision to retain as much of the existing structure as possible saves embodied carbon, while the introduction of a new breathable façade gives the building a brand-new lease of life.”

Made from Portland stone, the new façade is in keeping with the square’s traditional Georgian buildings, with new chamfered windows that allow air movement within the office spaces. A mixed mode ventilation system enables natural ventilation for 40 percent of the year and, together with a smart control philosophy, will target an approximate 70 percent reduction in energy savings associated with cooling.

The building offers 11,000 square metres of premium office space across ten flexible floors, complemented by terraces with expansive views over the city. A green roof and landscaped terraces enhance biodiversity, while sloping canopies with integrated photovoltaic panels deliver on-site energy generation and solar control. The all-electric scheme uses a mixed-mode ventilation system, air-source heat pumps, and a high-performance façade to keep operational energy to a minimum.

Radwa Ahmed (El-Fayoumy), Partner, Foster + Partners, added: “After close collaboration with all the relevant parties, we are delighted to receive planning permission from Westminster City Council and now look forward to delivering the next phase of the project.”

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