The City of London’s first ‘six star’ office development combines luxury with strong environmental credentials. Our integrated approach to designing structure and services helped Heron Tower achieve a BREEAM rating of excellent for its overall environmental performance.
Many tall buildings have a simple concrete core, which acts as a backbone, supporting and stabilising the structure. For Heron Tower, the architect wanted an open floor plate with sweeping views to the north. This made a central core out of the question.
With the site hemmed in by roads on all sides, there was also limited space for construction. The answer was a tube structure. This provided the structural stability needed by a 46-storey building while maximising the open floor space (and therefore the lettable area).
To achieve an office space that is flooded with daylight and has unimpeded views of the City of London, we took the unusual step of cutting out a vertical ‘chunk’ down one side of the tube. The strength of a tube structure is in the continuous outside edge, so we devised a framing system to ‘stitch’ the open vertical edges together in key places.
The south side of the building houses double-decker lifts, cabling and fire exits. It also provides Heron Tower with a solar shield. Studded with 48,000 photovoltaic arrays, this supplies enough power for the needs of its basement. The top of the building houses diesel-powered generators to provide 100% standby power in case of power cuts.
The tube had other advantages. It speeded up construction because the basement and the structure above could proceed in tandem. The top-down approach also meant that the load-bearing capacity of the foundations increased as construction advanced. By configuring the foundations to match the demands placed on them as construction moved on, we made construction far less costly.
The office space is designed to be rented out in three-floor chunks, each with a glass atrium overlooking the city. The interior can be configured individually for each tenant.