The BBC has developed a new broadcasting complex consisting of two new, linked buildings and a refurbished Broadcasting House. The project has been constructed in two phases...
To provide an operating environment suitable for broadcasting and recording, the new buildings are acoustically isolated from ground-borne vibrations by steel springs.
The focus of the complex is an atria-lit newsroom at the base of the main building. A Giken tubular piling system was used for the foundations to maximize the size of the new building's footprint, despite the proximity of existing structures.
The nine floors above the new double-height space are supported by a post-tensioned concrete transfer structure springing from four massive columns. The resulting column-free space also facilitates the construction of television studios (including one double-height studio) in the three levels below the newsroom.
The new BBC complex has several faces -— and our façades engineers worked on most of them.
The seven-storey curved façade that overlooks Portland Place creates a unifying front for three redeveloped buildings behind. It's actually a double façade: two screens of glass panelling are suspended from stainless steel hangers propped off the main facade structure.
The panels of the outer layer are acid-etched with gridlines that render the glass transluscent. The inner layer is a glazing sandwich: two panels of laminated glass with fritting between. This complex veil of glazing hangs from roof to first floor level, ending above the glass and stainless steel canopy that protects the main entrance.
As the front elevation winds into Langham Place, the glazed façade gives way to precast and handset stone panels punctuated by oriel windows. These are cantilevered structural glass cubes, 2.3m deep, with front panes that oversail their support on all sides.
fire & safety
Our fire engineering consultants were able to effect considerable savings for the client by developing a bespoke fire strategy for the BBC's redevelopment in central London.
Because the project involves the creation of a basement that is more than 10m deep, generic fire regulations specify that all six access staircases must be pressurised to maintain a smoke-free environment for fire fighters.
We calculated the actual spread of smoke across a range of scenarios and advised on the design of other features so that pressurisation was rendered redundant. Measures include a higher degree of compartmentation at basement levels, an upgraded smoke extraction system and a double lobby for all fire-fighting access stairs — achieving an environment that meets safety standards at considerably reduced capital and maintenance costs.
Another significant feature of our fire engineering solution is a staged evacuation strategy for the development. This will ensure that disruption from false alarms is minimized, particularly to news broadcasting services.
The BBC's new broadcasting complex consists of two linked buildings and a refurbished Broadcasting House. The focus of the development is a double-height newsroom with three television studios — one also double-height — below it.
Given local height restrictions and issues of Right to Light, a three-storey basement was needed to achieve the necessary vertical space. Just one problem: the 14m deep excavation breaches the standard 6m exclusion zone for Victoria Line tunnels running directly beneath the site.
Our geotechnical team provided the necessary expertise to make construction possible. Information from their site investigations and finite element analyses fed into our design of a foundation structure — a concrete raft, 1.2m thick — that alleviates long term heave. Throughout construction, they've monitored both tunnels and All Souls Church, which stands just 2.5m from the excavation, ensuring that any movement is safely within predicted limits.