The forest will be the first stage of a £130m process to transform the dome from a failed leisure attraction into a high-tech business park. Under a £125m deal signed last week, Legacy – a consortium including entrepreneur Robert Bourne, letting agent Insignia Richard Ellis and architect Lifschutz Davidson – became preferred bidder to take the maligned structure off the government's hands.
Details of the proposal are still sketchy, with designs still at the concept stage and a veil of secrecy hanging over the bid while Legacy continues negotiations with the government.
However, Building has learned that the dome will almost certainly remain closed throughout 2001 as all the contents except six 1850 m2 internal service buildings are demolished. "We're only preferred bidders and we have to tie up a deal in the new year," said Lifschutz Davidson director Alex Lifschutz. "Within a year of that, the first structures will be able to move in."
Legacy plans to build "Knowledge City" inside the dome – a campus of state-of-the-art facilities for media and technology businesses. The company believes that it can provide about 280 000 m2 of commercial space inside the dome and on surrounding land, providing employment for up to 14 000 people.
But filling the dome will take time, and the forest will ensure that early occupants do not feel marooned. "The forest can be removed bit by bit until critical mass is reached," says Lifschutz.
He compares the proposal to a Tuscan village surrounded by olive groves – but under canvas. The initial, limited collection of buildings will grow organically over time, with new floors added as businesses expand. "The scale is very much that of an Italian hill town," he says. "Although the buildings may be 8-10 storeys high, they won't dwarf you. It really will adapt and evolve as people's working habits change."
The buildings will be arranged informally around a series of concentric streets and public squares bisected by radial tree-lined boulevards. Ground-level units will be given over to retailers, cafes, bars and services such as meeting rooms, IT facilities and print shops, recreating the dense urban grain of areas already popular with media firms, such as Soho or Clerkenwell.
While the dome does not share Tuscany's balmy climate, the temperature inside is an average 3°C higher than outside. With no rain or wind to worry about, the internal structures will be more akin to furniture than traditional buildings, meaning the architect can rethink the construction process from scratch.
"You can build the sort of clip-together buildings inside that architects always warble on about," says Lifschutz. "You can put them up and take them down over a weekend. We could have an all-glass solution as you don't have the glare or solar gain problems you would have outside."
It’s not a business centre with potted palms. It’s a crystal city under canvas
The structures will be made up of lightweight, prefabricated modules capable of being stacked vertically, much like site cabins. Build costs are expected to be 25% lower than open-air offices. Lifschutz expects the contract to fabricate the structures to go to a supplier outside the industry. "There's nobody who makes anything quite like this. We'll be designing a bespoke system and going to the market."
A new raised floor, up to a storey high, will contain services such as heating plant for the modules and the wireless data system that will allow tenants to access the internet from anywhere in the building.
Alterations to the dome itself will be minimal, although Legacy is looking at ways of allowing in more natural light for the benefit of both people and trees. This will almost certainly mean replacing up to 20% of the Teflon-coated fabric roof with transparent panels. Inflated ETFE pillows, like those being used to clad the Eden Project in Cornwall, are the most likely option. "We need sunlight otherwise people will get depressed," Lifschutz says.
The skylights will also help people get their bearings in the circular structure. "One of the problems of the existing building is that you don't know where you are," he says. "We are considering making the skylights different in each part of the building, or using abstract shapes to help people orient themselves."
Richard Rogers Partnership's Mike Davies, who designed the dome, has welcomed the proposed alterations. "It just shows how flexible the dome is. As it happens, about two years ago I sketched some alternative designs with substantial glazed areas in the roof and indoor forests," he says.
Glyn Trippick, project director at dome engineer Buro Happold, says the proposals present few technical challenges. "ETFE panels wouldn't be a problem at all. You'd have to figure out a way of handling the joint between the panels, but that's standard fabric technology." Trippick estimates that replacing one-fifth of the roof with ETFE would cost up to £2m in materials alone.
He adds that the dome's existing foundations – consisting of 10 000 piles on a 3 m grid – could easily support the weight of Lifschutz's high-rise modules without additional strengthening. But the modules would have to be designed to a high specification to meet Building Regulations since the dome itself is exempt, being classed as an enclosure rather than a building.
Knowledge City's success depends on wooing high-tech entrepreneurs away from the vibrant streets of Soho or Clerkenwell. Insignia Richard Ellis director Chris Vydra rejects media suggestions that the project is unviable. "We've got a blank canvas inside the dome in which we can genuinely offer flexible space that you cannot offer anywhere else," he says. "We can also provide it quicker and cheaper."
Sources close to the project suggest that rents will be 10-20% lower than in other fringe areas of London. For their money, businesses will get something a bit better than the standard spec office. "It's not a business centre with a series of floor plates and potted palms," says Lifschutz.