Buildings produce a huge amount of carbon. Using more wood would be greener. The construction industry favours brick, concrete and steel.
However, timber construction would help reduce pollution and slow global warming.
Building Materials and Carbon Emissions
In 2015, world leaders meeting in Paris agreed to move towards zero net greenhouse-gas emissions in the second half of this century. That is a tall order and the building industry makes it even taller. Cement making along produces 6% of the world’s carbon emissions. Steel, half of which goes into buildings, accounts for another 8%. If you factor in all of the energy that goes into lighting, heating and cooling homes and offices, the world’s buildings start to look like a giant environmental problem.
Current Legislation towards Zero Carbon
Governments in the rich world are now trying to promote greener behaviour by obliging developers to build new projects to zero carbon standards. From 2019, the building of all new public sector buildings in the European Union must be to nearly zero energy standards. All other types of buildings will follow in January 2021. Governments in eight further countries are being lobbied to introduce a similar policy.
Recycling and Cradle to Grave
These standards are less green than they seem. Wind turbines and solar panels on top of buildings look good but are much less productive than wind and solar farms. Standards only count the emissions from running a building, not those from the production. Those account for between 30-60% of the total over a structure’s lifetime.
Carbon Reducing Wood
Buildings can become greener. They can use more recycled steel. Also, we can prefabricate them in off-site factories, greatly reducing lorry journeys.
However, no other building material has environmental credentials as exciting and overlooked as wood. The energy required to produce a laminated wooden beam is 1/6 of that required for a steel one of comparable strength. As trees take carbon out of the atmosphere when growing, wooden buildings contribute to negative emissions by storing the stuff. When a mature tree is cut down, a new one can be planted to replace it, capturing more carbon. After buildings are demolished, old beams and panels are easy to recycle into new structures. For retrofitting older buildings to be more energy efficient, wood is a good insulator. A softwood window frame provides nearly 400 times as much insulation as a plain steel one of the same thickness and over 1000 times as much as an aluminium equivalent.
A race is on to build the world’s tallest fully wooden skyscraper. But such edifices are still uncommon. Industry fragmentation, vicious competition for contracts and low-profit margins mean that most building firms have little money to invest in greener construction methods beyond what regulation dictates.
Governments need to do more
Governments can help nudge the industry to use more wood, particularly in the public sector – the construction industry’s biggest client. That would help wood building specialists achieve greater scale and lower costs. Zero carbon building regulations should be altered to take account of the emissions that are embodied in materials. This would favour wood as well as innovative ways of producing other materials.
Construction codes could be tweaked to make building with wood easier. Here the direction of travel is wrong. Britain, for instance, is banning the use of timber on the outside of tall buildings after 72 people died in Grenfell Tower. This is nonsense since the tower was covered in aluminium and plastic, not wood. Modern cross-laminated timber panels perform better in fire tests than steel ones do.
Carpentry alone will not bring the environmental cost of the world’s buildings into line. But using timber construction can do much more than is appreciated. SpaceShapers is also trying to promote this traditional material in both our commercial and residential sector projects.
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