The biggest new idea in sustainable building is also one of the oldest construction materials around: timber. But this isn’t ordinary wood. Cross-laminated timber, as it’s known, is arguably the first major structural innovation since the invention of reinforced concrete more than 150 years ago.

Cross-laminated timber itself has been in use for decades, particularly in Austria and Germany. Interest in the material is surging along with concern about the greenhouse-gas emissions associated with concrete and steel. The production of construction materials such as steel, cement and glass accounts for 10% of global energy-related CO2 emissions, according to a United Nations report.

Green-building benefits

By contrast, cross-laminated timber and other engineered wood products can benefit the climate in three ways: trees capture and store carbon as they grow; long-lived wood products lock in carbon; and these products can be used instead of high-impact materials like concrete in many cases.

Crucially, these products – often referred to under the catch-all term “mass timber” – are strong enough to replace concrete and steel in many of the taller buildings going up in cities around the world. And they have inherent fire-resistant properties that allow their use on a commercial scale, according to Lisa Podesto, Senior Business Development Manager at Lendlease, a global real-estate and investment company that has built more than 20 cross-laminated timber structures.

Competing with concrete

“The beauty of this new product type – mass timber – is that it’s competing in a market space with materials that timber couldn’t compete with in prior building generations,” Podesto said during a panel discussion at the World Economic Forum’s Sustainable Development Impact Summit 2021. “It’s opening opportunities to offset carbon in a different landscape.”

The carbon-reducing impact of green building with mass timber goes beyond the sustainable forests that produce these products and the carbon they lock away. While concrete is essential in foundations, timber buildings are lighter so those foundations can be smaller. Mass-timber products are modular and can be produced in a factory, which means faster construction, fewer trucks delivering materials and less disruption to communities around building sites.

Mass timber set for take-off

“Mass timber is likely to take off at scale over the next decade,” Caitlin Clarke, Senior Conservation Fellow, Supply Chains at The Nature Conservancy, said during the panel discussion.

Yet, while the use of mass-timber products can contribute to climate solutions in some places, there’s no one-size-fits-all approach that can be applied around the world, according to Clarke. We need to know more about how increased use of mass timber would affect forests, the carbon they store and the ways we manage them. The Nature Conservancy is part of a broad research effort to model the impact of mass-timber demand, and is helping develop guidelines for development of the industry.

“We’re doing scientific research that is informing how this is going to happen, and working on safeguards to help inform how it should happen,” Clarke said.

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