The original building was approaching 20 years old when its occupiers lease was due for renewal. The owners (British Land) decided that it would be more cost effective to redevelop the existing building rather than demolish and re-build. Arup were brought on board with the focus being on taking this principal concept and maximising the sustainability credentials of the redevelopment – with a particular focus on making many marginal gains to generate an overall major improvement.
William Hare erected an additional three storeys and four corner cores on top of the original concrete frame to create additional floor space. The original building featured London's largest enclosed atrium at 36m across – but this was reduced to 18m across by adding further new floor space. Combining the above with other changes such as re-gaining office floor space from plant areas due to newer smaller MEP systems meant that the re-developed building has an increase in net floor area of 57% compared to the original structure.
While the original building leant itself to being enlarged, there was still significant work to strengthen the existing concrete structure with enlarged members, carbon-fibre wrapped columns and similar exercises. Another innovative feature of the project was the client’s decision to dismantle, refurbish, and re-install the original limestone façade system.