150 Holborn

150 Holborn unites London-based members of the Sidara Collaborative—Dar, Perkins&Will, Portland Design, Currie & Brown, Introba, Maffeis Engineering, and Penspen—under one roof. This state-of-the-art workplace accommodates over 1,000 staff who are committed to advancing ecological health and well-being through design and engineering. The building fosters collaboration and the exchange of ideas between the firms, while ensuring each firm retains its unique identity. Our design of 150 Holborn is modern, yet responsive to its historical context. It’s both environmentally responsible and inspirational, encouraging curiosity, and providing a sense of community. It’s a place that instils a sense of pride and belonging—bringing together creative minds to help solve some of the world’s most complex design challenges. Located in the thriving Midtown area of London, the building maintains views of St. Paul’s Cathedral and respects its context through visual continuity. 150 Holborn replaces a 1980s office block. Though the existing building was removed, we conducted a pre-demolition audit to determine which materials could be reused on site, and which could be taken off site and recycled. Our demolition report showed that 97% of potential waste was reused or recycled. The main lobby combines reception with a public café, serving as a window to the companies’ brands and ethos. Interactivity and knowledge-sharing are promoted throughout. The central atrium is linked by four glass lifts and a shared grand staircase. We designed this staircase to promote chance meetings and discussion between the member firms. Additionally, individuals and teams are empowered to choose where and how they work, with a variety of spaces and social settings throughout the building. 150 Holborn is a “living lab”. A digital twin of the building measures staff well-being, operational efficiency, and asset performance, allowing us to continuously optimise environmental performance and occupant comfort. This is the first-time intelligent building technology has been collected in such a way, and for these purposes, in the UK. 150 Holborn is energy-efficient and adaptable to climate change. The high-performing building envelope optimises daylight and views while façade fins provide solidity and reduce solar exposure. While conceived as a headquarters, the building may be adapted for use as a different type of commercial space in future. A range of low-carbon and circular interior design strategies include all task chairs and 70% of furniture are refurbished and reused; partitions and new furniture are designed for disassembly and manufactured locally; modular meeting pods can be reconfigured, dismantled, and fully recycled; and all textiles are low-VOC and fully recyclable. Photovoltaic cells on the roof generate renewable energy, while a blue roof system retains rainwater, mitigating the risk of over flooding. Grey water from basins and showers is treated and redistributed for irrigation. A pavilion and roof terrace planted with native planting help reduce the urban heat island effect, promote biodiversity, and give staff respite with excellent views. The building also provides 231 bicycle parking spaces and is located within walking distance to several major transport interchanges. Healthy food and beverages are available to all employees.