There is an argument for making the cities of the future out of wood. And more and more people support him

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The future of cities—those that aspire to be sustainable, at least—might not be through perovskite pane windows, 3D printing, algae facades, recycled plastic blocks, concrete made from waste, or any other latest technology. The key is perhaps much more “traditional” and has had its whole life right under our noses: wood. Yes, the same one with which we built children’s cabins or still use in garden sheds.

Of course there are studies that already point out its virtues.

It´s the CO2, stupid. turning around that famous phrase From the 1992 election campaign led by Bill Clinton and George HW Bush we could effectively say that the key is carbon dioxide emissions. Nature just published A study which points out the large amount of CO2 that we could save if instead of using concrete and steel we switched to wood.

His calculations are resounding: if 90% of the new urban population were housed in mid-rise buildings built with planks, we would save the emission of about 106,000 million tons of carbon by 2100. What’s more, if we changed materials, leaving steel and concrete behind, we would pave the way towards the goal of controlling global warming this century.

A solution for cities. The researchers focus their attention on cities. The shot is more than understandable. The World Bank calculates that currently about 55% of the world’s population already resides in urban centers, which is equivalent to around 4,200 million people. And, as the agency itself acknowledges, “it is believed that this trend will continue.” “By 2050 the urban population will double and almost seven out of ten people will live in cities,” he concludes.

The increase in population, of course, will not only be noticed in statistics and censuses. Your footprint on the streets will be clear. “More than half of the world’s population currently lives in cities and by 2100 the number will increase significantly. This means that more houses will be built with steel and concrete, most with a significant carbon footprint”, alert to Guardian Abhijeet Mishra, one of the study’s authors. Is there an alternative? For her yes: wooden blocks from 4 to 12 floors.

But… How much wood are we talking about? That is another of the great keys. The researchers calculate that if we followed their recipe we would need to significantly increase the area dedicated to the production of future planks. “Forest plantations would have to expand to 149 million hectares by 2100 and harvests from unprotected natural forests would increase,” points out the study Nature. Its authors are also convinced that such an expansion could be achieved without affecting agricultural production.

When drawing up the calculations, the researchers claim, a crucial maxim has been followed: respect for virgin forests and biodiversity conservation areas. “The explicit safeguarding of these protected areas is key,” says one of the authors.

We have a new ally to build skyscrapers that already competes with steel and concrete: wood

The other big key: biodiversity. One of the great concerns generated by the proposal, even assuming that virgin forests are respected, is how it would affect biodiversity. The environmentalists —says the British newspaper— point out that the around 131 million hectares already devoted to tree plantations tend to have poorer biodiversity than natural forests. Not only that. They would also be more exposed to forest fires and more vulnerable to other serious threats, such as drought or pests.

“Wood can play a larger role in construction, but doubling the world’s tree plantations at the expense of priceless nature is folly when modest reductions in meat and milk production would free up needed land,” says Sini Eräjää. , from Greenpeace. the report itself published in Nature points out that the invasion of natural forests could imply losses in biodiversity or even soil carbon.

But… Is wood a good material? The question is vital. At the end of the day, if the search for new materials for construction is about, the logical thing is that they are suitable for erecting buildings. Wood has clear benefits, such as its ability to store and reduce the CO2 footprint, but it has a major handicap: it is flammable. The sector is aware and is already looking for solutions.

In recent years it has been gaining strength the CLTa type of cross-laminated planks that would have given good results in fire tests. Think Wood points out that a CLT wall with five-layer panels has been able to withstand more than three hours subjected to temperatures of about 980ºC. Its defenders point out other advantages, such as the resistance of the wood or that its weight saves time and costs in manufacturing. The buildings of the known as mass timber They are lighter than concrete ones, which would allow them to respond well to earthquakes.

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And for sample… a skyscraper. Not everything is laboratory studies and distributor catalogs. We already have large buildings built with wood. In Skelleftea, in Sweden, they have built a 75 meter high block built with wood and in the UK, USA, Japan or Germany there are even more ambitious projects. Proof that the mass-timber gains weight in the sector is that, according to the data you handle The Wall Street JournalBetween July 2020 and December of last year, the number of multi-story buildings built in the United States with this material soared by approximately 50% to more than 1,300 structures.

Images | Charlie Gregory (Unsplash) Y Grand Canyon National Park (Flickr)

The future of cities—those that aspire to be sustainable, at least—might not be through perovskite pane windows, 3D printing, algae…

The future of cities—those that aspire to be sustainable, at least—might not be through perovskite pane windows, 3D printing, algae…

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