22 Bishopsgate

Ingenious engineering by WSP has put the tallest City of London tower on the road to net zero

Located on the site of an abandoned project in the heart of London's financial district, 22 Bishopsgate came with constraints above and below ground that inspired our team to think creatively and seize the opportunity to cut embodied carbon dramatically. As a result, the project has achieved the 2020 target for embodied carbon reduction recommended by the London Energy Transformation Initiative (LETI) in its roadmap to net zero – placing it more than 40% below LETI’s business-as-usual benchmark.

lower than LETI’s 2020 target
2% 2%
lower than LETI’s business-as-usual benchmark
41% 41%
total embodied carbon
591 kgCO2e/m² 591 kgCO2e/m²

The landmark tower, for which WSP provided a full range of consultancy services, is envisaged as a ‘vertical village’ providing facilities including retail, restaurants, fitness centres, an auditorium and spaces for a variety of leisure and learning activities. The basement will accommodate bicycle parking that meets latest TfL standards, and the free public viewing gallery at the top of the building will be the highest in London.

From the beginning, our client had high targets for sustainability, comfort and occupant wellbeing – 22 Bishopsgate is the largest project by floor area in the UK to be registered for WELL certification, and it has also been designed to achieve a BREEAM Excellent rating. However, it was a twist of fate that enabled us to take the innovative approach that has reduced the building’s embodied carbon emissions.

When construction of The Pinnacle was halted in 2009, it left behind a three-storey basement with nine floors of concrete core and piles embedded more than 50m into the ground. Rather than excavating this ‘stump’ and beginning again, our team successfully re-used 100% of the existing foundations and 50% of the basement in a design that also made use of older existing buildings on the site to create 30% more lettable area than The Pinnacle would have had. This approach reduced the embodied carbon and construction emissions of the foundations by 70%.

22 Bishopsgate shows that we need creative thinking and innovative approaches to the way we design and build, to make net zero a reality. And we are already on the path to achieving it.
Diego Padilla Philipps Associate Director, WSP

The project pushed the limits of structural engineering – with mega-transfer girders, inclined columns with high-strength steel cable ties, triple-storey A-frames, partial demolition of the existing basement, and partial top-down construction with 20 storeys of the core built before the foundations were completed. This required the installation of small diameter piles built from within the existing lower basement level, requiring a careful geometrical assessment to place them between the forest of existing elements and piles.

This attention to detail had a direct and significant impact on reducing carbon and streamlining construction. Our design for the core reduced the reinforcement required in the lift front walls by 25%. All the floors were built with concrete that is 30% lighter than the standard mix – producing savings across the board, from foundation size to crane time. We were also able to optimise the size of the beam-to-column connections, reducing them by 40%.

of existing basement reused
50% 50%
of existing foundations reused
100% 100%
more lettable area
30% 30%

These are significant reductions when you consider that the contribution of construction to the overall lifecycle impacts of a building can sometimes even outweigh operational impacts such as energy consumption. Yet this is a project that minimises these operational impacts too.

Our building services engineers were challenged to deliver an extremely efficient building with high targets for sustainability, comfort and occupant wellbeing. The building will require a large volume of services and systems designed with built-in flexibility to accommodate facilities and office layouts for future tenants. The 3.0m ceiling height, and the energy-efficient closed cavity facades with full-height windows, allow for 20% more natural light than the average office building.

With our client keen to make their building smart as well as sustainable, our smart places team looked at how different systems could be integrated together – everything from technical electrical systems, security and fire systems to lifts and the building management system – in a way that could create new value for the building owner and future tenants. This included opportunities for reducing energy consumption and enhancing how equipment was used by introducing intelligent software which were presented to the client team.

Examining how systems could be tied together and identifying software vendors whose products would enable this, we investigated the system architecture required to automate systems for facilities management and operations teams. This would allow them to see at a glance how energy is being used and where the building is under-utilised, enabling them to reduce energy use. We also explored how metrics such as energy consumption could be displayed to tenants and the public through a series of dashboards, empowering them to adopt more sustainable behaviours.

If you supply people with information, they become part of the process. You can’t expect people to become aware of their energy usage or help reduce it unless you give them this information
James McAllister Smart Places Analyst, WSP

When fully occupied, 22 Bishopsgate will stand out – not only as the second-tallest building in Western Europe, but as an example of how innovative engineering can achieve the dramatic carbon reductions that will be required as the world races to net zero.