The sustainable benefits of using mass timber for building construction often rely on assumptions, rather than science. What do the facts say?

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A recent article in The New York Times examined cross-laminated timber (CLT) and mass timber as green building materials. The Times referred to CLT and mass timber as renewable resources. But, is this true?

Based on science or assumptions?

“When citing wood as a renewable resource, the decimation to forests caused by clear-cutting practices, the loss of carbon dioxide from mature trees, and the years it takes to replace those trees are often overlooked,” says American Iron and Steel Institute (AISI) Interim President and CEO, Kevin Dempsey.

“Claims made about the ‘environmental benefits’ of using mass timber for mid- and high-rise building construction often rely on existing assumptions to reinforce them versus scientific studies,” he adds.

Read the full AISI statement: “Steel Industry Response to Inaccurate Claims Regarding Wood in Construction.

The article, “The Urgency of Embodied Carbon and What You Can Do About It, from Building Green highlights the attention called to claims about the carbon impacts of wood. Life-cycle assessments of buildings show that the sustainability benefits of using wood are greatly overestimated, according to some scientists cited by Green Building.

Build With Strength, a coalition within the National Ready Mixed Concrete Association, says over 17 acres of wood is needed to build an 18-story, 180,000 square foot CLT building. Harvesting that much wood releases 11,533 metric tons of carbon dioxide into the atmosphere. In fact, clear-cutting trees emit 12% of the world’s gas — more than the emissions of all of the cars and trucks in the world, Build With Strength says.

Steel framing is recyclable, durable, dimensionally stable, and requires less overall material than wood.

Steel is Truly Sustainable

For these reasons, building owners and designers are turning to cold-formed steel (CFS) framing. CFS is recyclable, durable, dimensionally stable, requires less overall construction material than wood and is recognized by all green building standards.

  • All steel is recycled: More than 65 million tons of steel are recycled every year, according to AISI. CFS framing contains a minimum of 25 percent recycled steel and is continually and completely recyclable.
  • Steel innovations are using less material on projects: New CFS products like EQ steel studs help designers build even more sustainable structures. Their advanced steel formulations create durable structures with less material, providing a more efficient use of steel.
  • Steel’s sustainability can generate revenue: Instead of going to a landfill, CFS can be sold as scrap to be recycled into more steel products, such as cars and studs for other buildings. That allows contractors and framing subcontractors to generate extra revenue on their projects — or even pass along the savings to the building owner.

SFIA Education Resources

SFIA Offers Free Sustainability Education

The Steel Framing Industry Association (SFIA) has developed a video-based education program that introduces participants to the sustainability of CFS framing. The benefits of CFS include material recyclability, energy savings and greenhouse gas reductions.

The course, “SFIA 103-20 — Sustainability of Cold-Formed Steel (LEED Version 4),” is for SFIA members and non-member building professionals.

“We’re very excited about this latest education piece, because sustainability is so important to building owners and their design teams,” says Larry Williams, SFIA executive director. “In this program, participants will learn how cold-formed steel can help your next LEED project, and that makes it worth checking out.”

Learn more about the sustainable benefits of CFS: