This comprehensive redevelopment has become one of the most sought-after City office addresses of its type. Every aspect of what had become a tired and outdated structure has been reviewed, redesigned and refreshed – it now offers highly sustainable, column-free, grade-A office space enjoying 360-degree views of the City.
By adopting new technology and following a comprehensive review of the structural requirements of the building, the size of the existing core was reduced by 30% to deliver a highly efficient, increase in lettable area. At the same time, the former roof level plant area was dramatically reduced through the replacement of outdated and redundant equipment with smaller, more efficient plant. The design was therefore able to carefully integrate an additional floor, further expanding the net area, whilst working within the building envelope.
The scale, grain and texture of the new elevations work together to complement the adjacent St. Paul’s Cathedral, maintaining consistency with the surrounding architecture, whilst achieving an appropriate subservience in the presence of this landmark building.
The existing building was stand alone and isolated from any of its neighbouring buildings, without any visual relationship to its surroundings. The building is located in an extremely prominent location and is highly visible from long views; particularly those along Cheapside itself.
The majority of the buildings opposite and surrounding the site, with the exception of St Pauls Cathedral, had been redeveloped. This included Paternoster Square to the West which further reinforces the ‘out of place’ nature of the existing building.
The existing building has an octagonal floor plan, predominantly clad in roach stone panels with small insert metal windows. This gave a very heavy and solid appearance to the overall form with the small windows creating very dark interiors. This, coupled with low floor to floor heights, led to cavernous and oppressive internal spaces.
The existing building fabric was tired and weathered and very thermally inefficient with building services and air conditioning systems that had reached the end of their design life. Internal services were out of date and all areas needed to be updated and remodelled. As such the environmental performance of the building was very poor by comparison to current standards, particularly in terms of heat loss from the envelope (external walls, roofs, etc).
The design aimed to modify the existing building to create highly efficient, sustainable office accommodation over retail space, whilst presenting an appropriate envelope that could complement the updated surrounding area and be attractive to tenants and passers-by alike. The initial reaction to the existing building was to open up internal views, allowing for improved connections from inside and out, and secondly to greatly improve the building’s ability to act as a place-marker for the area. Although the weighty facade had reached the end of its design life, the form of the building was of interest and we looked to design a new envelope that not only retained the existing octagonal floor plates but reinforced the shape of the building.
The design approach divided the building into three elements:
This is the largest portion of the building elevation, comprising 6 floors, and as such, it is this that forms the greatest impression. This forms the solid mass of the building and when wrapped in glass, created an apparent ‘soft centre’ to which solid elements were introduced to reinforce the building corners and separate floors. The solidity manifested itself as a frame around each floor to which solid ‘panels’ are added to each of the 8 individual elevations.
The Ground floor is separated from the central portion of the building by a cantilever projecting the primary office floors over the base. To reinforce this cantilever a metal ‘apron’ is formed to the underside of the stone which then slopes back from the outer face to the edge of the Ground Floor. This uplift from the Ground Floor cladding ‘floats’ the central floors and emphasises the solidness of the central portion.
The 7th floor was originally expressed as a solid roof element. The redesign gave this floor a similar language to the rest of the building but creating a capping for the development and a recess was created to separate this roof element from the central area.
Internally the floor plates were simplified and expanded as previously outlined. A reconfigured core allowed for lobbies and toilets to be connected to each floor plate, giving flexibility in letting options.
Through the use of a improved technology, the lifts were able to be extended to the new top floor within the existing concrete shaft walls, having previously stopped a floor below, without increasing the height of the existing building.