Although the internal workings of Government Communications
are generally kept under wraps, the spectacular new Headquarters
building in Cheltenham is certainly garnering a lot of
attention. Topped with almost 12,000 square metres of
tapered Kalzip aluminium standing seam, the huge doughnut-shaped
GCHQ main facility was a winner in the recent Aluminium
Imagination Awards and is actually three buildings in
one - accentuated by Kalzip 'petals' over the connecting
lobbies - surrounding a central courtyard the size of
the Royal Albert Hall.
The use of clad stucco-embossed Kalzip continues in a
group of six ancillary buildings, referred to as the 'String
of Pearls', which house the gatehouse, a visitors centre,
staff lodge and support services.
Under Britain's largest PFI project, the main contractor
Carillion is also part of the consortium Integrated Accommodation
Services which won the bid and is responsible for the
maintenance of the building for the next 30 years.
Proving that a relatively simple design can solve complex
problems, the round shape of the main building provides
a defensive exterior wall, as well as an internal atrium
'street' and the central courtyard garden that is accessible
from all three connected buildings. The new
complex, designed by architects Gensler in London, replaces
50 separate buildings spread over two sites with one efficient
campus that will accommodate over 4,000 employees. Since
the focus is on environmentally friendly design, the building
makes good use of natural lighting with its extensive
glazing; the three-storey 'street' also has a glazed ceiling
and allows ventilation to reach every floor of the offices.
The consolidation of the facilities into one complex will
reduce energy use as much as 40% over the previous, individual
Kalzip approved contractor Prater Limited installed the
roof on the main building, while another approved contractor
in the Teamkal network, Kelsey Roofing Industries Ltd,
was responsible for the 'String of Pearls'. 'It was an
interesting and unusual project,' said Kelsey's Mark Wallace,
'which had to follow a succession of completion dates
for each building, allowing Carillion to achieve specific
milestones within the overall development.'
Both Kelsey and Prater were involved fairly early on,
with Prater suggesting the use of Kalzip to the design
team since the sheets could be curved and tapered to fit
the continuous curve of the building shape. The petal
roofs over the linking lobbies are made from continuous
tapered sheets some 70 metres long. To meet thermal performance
requirements, the specification also includes decks, vapour
barriers and insulation from the Kalzip product portfolio.