The global building industry has a skyscraper-sized carbon problem.
If cement were a country, it would be the third largest emitter of carbon dioxide (CO2), trailing only China and the United States. Every tonne of cement produced releases about a tonne of CO2. By some accounts, cement accounts for 8% of global CO2 emissions. Nearly half of this cement is used in construction, much of it in buildings.
Steel – the world’s second most-commonly used construction material – is every bit as detrimental to the planet. Every tonne of steel produced emits about 1.85 tonnes of CO2. Globally, steel also accounts for about 8% of CO2 emissions, according to come experts. Half of steel globally is used in construction, of which 60% is used in buildings.
Cement and steel: these are the key ingredients of the majority of buildings erected today. And they are big contributors to the warming of our planet.
Yet there is another material that can be used to construct buildings, one that actually captures carbon: wood.
Trees are very effective carbon traps. As they grow, they capture CO2. A cubic meter of wood binds 1.3 tonnes of CO2 from the atmosphere. When trees are harvested, that CO2 remains intact in the wood.
And trees are a renewable resource that can be sustainably grown and harvested over and over again.
Wood has long been used to build small structures. But in recent years, thanks to the advent of a technology called cross-laminated timber (CLT) panels, multi-storey wooden buildings are becoming a reality.
Cities in Europe, the UK and Canada have seen CLT buildings shoot for the skies in recent years. The world’s tallest wooden building, an 85.4-meter, 18-storey mixed use structure, went up in Brumunddal, Norway in 2019. Changes to the building code in the US that came into force in January allow timber structures up to 18 stories and 82 feet.
If we can accelerate and broaden this trend and ensure that CLT is always made from wood harvested from sustainably managed forests, the building industry can have a positive impact on climate change.
As Canadian architect Michael Green has pointed out, a 20-storey building made from concrete accounts for 1,215 tonnes of CO2 emissions. By contrast, the same building made from wood would sequester 3,1250 tonnes of CO2, for a net difference of 4,360 tons of CO2. That’s the equivalent of 900 cars removed from the road for a year.
Canadian researchers Adam Robertson, Frank Lam and Raymond Cole have analyzed the environmental impact of a five-story office building constructed from a traditional cast-in-place, reinforced concrete frame and compared it with the same building if it were built using a laminated timber hybrid design, utilizing CLT and glulam.
They found that, “cradle to gate”, the wood structure outperformed the concrete-framed alternative by more than 70% in terms of greenhouse gas emissions when factoring in the carbon storage property of wood (and by 17% even when carbon storage was not taken into account).
My company, Segezha Group, is nearing completion of Russia’s first plant producing CLT panels. Our first CLT panel came off the line last year, and eventually we will be able to manufacture panels as long as 16 meters, as wide as 3.5 meters and as thick at 0.4 meters.
It is exciting to be part of an innovative new industry that can have a positive impact on the planet. I am confident that constructing multi-storey buildings of the future with wood can become part of the solution to climate change.