October 28, 2021

I, Science

The science magazine of Imperial College

Wooden skyscrapers and high-rise city farms? Not as crazy an idea as you think - we look at architects predictions for the cities of the future

London buildingsFrom the Gherkin to the Cheese Grater, London’s skyline is being transformed by a spate of controversial high-rise towers. The latest proposal from Shard architect Renzo Piano is for a 65 storey ‘Skinny Shard’ at Paddington, bringing the skyscrapers further west and closer to Imperial’s South Kensington neighbourhood.

High-rises – looking to the future or recycling the past?

So are these giants the future, or just investment vehicles rehashing old models of development? As cutting edge engineering helps architects create ever more extreme shapes, London’s high-rise buildings look increasingly futuristic. But beneath their glitzy skins, most rely on old-fashioned steel and concrete, pretty much the same technology as the first skyscrapers in 1880s Chicago.

More radical is the technology behind multi-storey wooden buildings. It sounds unlikely, but the use of cross-laminated timber (CLT) is booming and looks set to challenge traditional materials. CLT comes in panels built up from multiple layers of softwood bonded by adhesives. Cross-lamination is the key – with the grain of each panel being perpendicular to the next, resulting in structural strength to rival steel.

Building tall with timber

Stadthaus in Shoreditch led the way for CLT in London. This nine floor apartment block was completed in 2009, with structural elements- including the stairs and lift shafts- made of wood. The next big step for CLT could be set to take place in Paris, where the Eiffel Tower pushed the boundaries of construction 126 years ago. Designed by the Canadian firm Michael Green Architecture Inc., Baobab is a 35 storey CLT building including flats, a bus station and urban agriculture proposed for the Reinventer Paris competition.
depiction of a high rise parkArchitects are looking to stretch the possibilities, but timber high-rises are more than a gimmick. CLT is a renewable, low-carbon, precision-engineered material that can cut the carbon footprint of a building by up to 70%. Contrast this with the fossil fuel hungry production of steel and those blingy towers in the City start to look a bit dated.

It is counterintuitive, but wood even performs better than steel in the event of fire. Fire burns at up to 1000°C and steel will warp at a mere 600°C, hence it needs to be surrounded by protective layers within a building. A recent report by the engineering consulting group, Arup, shows that when sheets of engineered wood start to burn on the outside, the resulting charcoal forms an insulating layer which stops the fire from penetrating and prevents further damage. The structural qualities are not affected – much like charred trees standing tall in the wake of a forest fire.

What will future cities look like?

Architects from the University of Westminster, alongside Dr Rhys Morgan, Director of Engineering and Education at the Royal Academy of Engineering, and urbanist Linda Aitken, recently set out their predictions for cities over the next 100 years. Top of the list were:parliamentary buildings with underground park

-Super-deep basements to save space in high-value, high-density locations

-Floating sea cities running on solar and wave power

-High-rise urban farms

-3D-printed homes

-Buildings with their own micro-climates to make harsh environments habitable.

What is the reality?depiction of cows on rooftops in London

It might be fun to gaze into the future and imagine where technology can take us over the next century, but a hard look at where we are in 2016 will bring us back to earth with a crash. Last year, the UK government abandoned two flagship green building policies. In July, the government scrapped a commitment to make all new homes carbon neutral by 2016. The Green Deal– designed to make existing homes energy efficient- was abandoned the same month. New Scientist drew attention to the resulting policy vacuum in october last year. If there is another plan, what is it? The truth is, at the moment we do not know. In the meantime, using more timber in our buildings like a good place to start.

Images: London’s Gherkin, photoLondonUK; impression of wooden buildings courtesy of Michael Green Architecture Inc.; artists impression of basement at Westminster and high rise city farms courtesy of independent.co.uk

Celia Robbins is studying for an MSc in Science Communication