News on 06 December 2000
Architects
come in for a lot of (frequently justified) criticism from facilities
managers, so it is good once in a while to be able to report on a project
which lifts the spirits.
The Great Court, which opens to the public tomorrow, is a spectacular
covered square at the heart of the British Musem. The design, by Foster
and Partners, turns a hidden space previously filled with book storage
into a grand new public piazza.
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| Aerial view of the Great Court roof at night. | View of elliptical staircase and the East Portico. |
At the centre
of the new square is the historic round Reading Room, restored to its
original 19th century splendour and open to the general public for the
first time.
Sir Norman's team may have come up with the inspired plan to cover the
6,700 sq m (92m x 73m) square with a stunning glass and steel roof but
it was engineers Buro Happold who had to make it work.
The architects wanted a roof with a light and clear appearance. The engineers
initially turned to natural shapes for inspiration – taking the surface
of an inflated soap film as their starting point. The variable torodial
geometry of the roof provides an easy transition from the circular form
of the Reading Room to the quadrangle of the surrounding Museum buildings.
The roof has just one line of symmetry, 6000 individual steel members
and 1826 structural nodes. Grade D steel with low carbon content, more
often used for marine or petro-chemical applications, was used because
it is more ductile and will prevent brittle failure of the connections
as the roof moves with diurnal temperature changes.
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| Interior of the restored Reading Room. |
The steel
structure weighs around 420 tonnes or 75kg/sq m. The double glazing adds
another 60kg/sq m. The Reading Room itself carries none of this weight,
it is actually an independent element within the square. The roof is supported
on sliding bearings atop a ring of 20 columns surrounding the Reading
Room and hidden within the new stone cladding.
Building services
Buro Happold Building Services engineers also designed a range of mechanical
and passive systems for the Great Court and its buildings which receive
a massive 45 cubic metres of air every second. Systems range from tight
control full air conditioning for the exhibition gallery areas to the
tempered environment of the Great Court itself.
The roof is fritted to optimise solar control with heat loss and appropriate
daylight penetration. Peak summertime heat build up is limited by an integrated
perimeter displacement ventilation system, natural ventilation and some
mechanical extract. Chillers used to facilitate air conditioning are also
used during off peak hours to pre-cool the concourse slab.
The Museum's staff began familiarising themselves with the operation of
the new services almost a year ago thanks to the early appointment of
Dome in 1997 as commissioning manager and technical author. Dome was also
appointed to provide operational support to the Museum to ensure a seamless
handover.
If you can, visit the Great Court and when you enter just forget the technical
details for a moment and enjoy the creation of a wonderful new space.
www.thebritishmuseum.ac.uk
www.fosterandpartners.com
www.burohappold.com
