20 Jun 2019

Mile-high skyscrapers 'could be made out of wood'

Mile-high skyscrapers 'could be made out of wood'

Taller, greener, hairier? I'm not talking about your next internet date but perhaps the next office you work in.

The buildings of the future could be more than a mile high, made out of plywood or covered in algae. Building taller, given rising population density in cities, has been the case for New York, London, the Middle East and so many other cities. When there's not enough room on the ground, the only way is up.

By 2050, a study predicted, there is a 9% chance the world's tallest building will be a mile high. In fact, plans for one such structure have already been drawn up. Since plans were first drawn, the Jeddah Tower in Saudi Arabia (currently under construction) was scaled back to a more modest 1,000 metres. At this height, it would still grab the title of the world's tallest building from the incumbent, the 830-metre Burj Khalifa in Dubai which is considered 'megatall' (above 600 metres). We could build higher still.

The tallest structure for which there are blueprints is the X-Seed 4000. Designed in 1995 but as yet unbuilt, the steel structure would top Mount Fuji at 2.5 miles high and would cost more than $1 trillion ('790bn) to construct. Mile high ply? Concrete and steel have been the favoured building materials for tall buildings but, with climate change intensifying, the pressure is on the find more sustainable alternatives. 'Concrete is an environmental disaster,' futurologist Ed Gillespie tells Metro.co.uk.

It is an incredibly energy intensive resource. We need to move beyond that and look at alternative mechanisms of construction.' Some architects are choosing to build instead with wood. Some of the more recent engineered wood products include cross-laminated timber (CLT), where wood is glued together in pieces or layers, similar to the plywood you get at the DIY store. It's very strong, light, easy to work with and transport, and lasts as long as concrete or steel without being much more expensive.

Responsibly-produced timber can also be used to create carbon negative buildings which actually absorb more carbon from the atmosphere than they create. On the downside, timber needs to be protected from water to avoid rot and wooden buildings must be designed with fire risk in mind. Ron Bakker is founding partner of PLP Architecture, which designs and builds timber skyscrapers. He recently conducted some research with Cambridge University to see if wood structures can be built to 300 metres, and says 'the answer is we can'. Currently, the world's tallest timber building is Mj'st'rnet, an 85 metre, 18-storey tower in Norway made from sustainable CLT.

PLP is working on concepts for the timber Oakwood Tower at Barbican which, at nearly 300 metres high, would be the second tallest building in London after The Shard. But there is already a taller plyscraper snapping at its heels: in Japan, Sumitomo Forestry is planning to build a 70-storey, 350-metre timber structure in 2041. The W350 Project would be the tallest building in Japan and the tallest wooden structure in the world, costing $5.5bn ('4.4bn) to build.'

But just because we can build taller and taller buildings, should we? 'They can't be too near to each other,' Bakker tells Metro.co.uk. This is a problem given that the base of a very tall building must be huge if it is to be stable ' the X-Seed 4000, for example, would require a base 3.7 miles across, a tall order (sorry) in the city for which it was designed: Tokyo. For this reason, it was going to have its base in the sea. This often makes for an impractical process.

Supertall buildings (300 metres plus) need to be stable enough to withstand high winds without too much swaying and the ground underneath it needs to be favourable enough that the building won't tilt when the foundation settles under its immense weight. They are also harder to make profitable, because they need to have large cores to allows space for thing like lifts, reducing the building's usable area.

Creating the infrastructure to move people around huge buildings (and not so quickly that they get nauseous) is a big challenge: The Burj Khalifa has eight escalators and 57 lifts, while the X-Seed 4000 was designed with its own maglev train system (think monorail). Bakker suggests the tallest buildings are just created to show off and a degree of restraint is needed.'

'We need to reach a balance,' he says. 'Buildings a mile high are more symbols of prowess than they are reasonable structures. 'Anything over 300 or 400 metres is really difficult and expensive to make because structurally they are very strange things. 'It doesn't make much sense to go that high unless you want to make a statement.'

So is there a maximum height? The X-Seed 4000 is the tallest building ever actually planned but, in theory, the sky is the limit. William Baker, a structural engineer who worked on the Burj Khalifa, says it's feasible to do 'at least a mile and probably quite a bit more'. What else can we build with? Aside from wood, some more futuristic materials may have applications in construction eventually.

Miracle material graphene, written about elsewhere in the Future Of Everything series, is both flexible and strong enough to win the first people to demonstrate it the Nobel Prize. Now it is being used in concrete production to make it more resilient, waterproof and environmentally friendly.

Source: METRO'


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