Mass timber construction is on the rise, with advocates saying it could revolutionize the building industry and be part of a climate change solution. But some are questioning whether the logging and manufacturing required to produce the new material outweigh any benefits.
The eight-story Carbon 12 building in Portland, Oregon is the tallest commercial structure in the United States to be built from something called mass timber.
If the many fervent boosters of this new construction material are right, however, it is only one of the first mass timber buildings among many, the beginning of a construction revolution. “The design community in Portland is enthralled with the material,” said Emily Dawson, an architect at Kaiser + Path, the locally-based firm that designed Carbon 12.
The move to mass timber is even farther along in Europe. That’s because mass timber – large structural panels, posts, and beams glued under pressure or nailed together in layers, with the wood’s grain stacked perpendicular for extra strength – is not only prized as an innovative building material, superior to concrete and steel in many ways, it is also hoped it will come into its own as a significant part of a climate change solution.
Among architects, manufacturers, and environmentalists, many want nothing less than to turn the coming decades of global commercial construction from a giant source of carbon emissions into a giant carbon sink by replacing concrete and steel construction with mass timber. That, they say, would avoid the CO2 generated in the production of those building materials and sequester massive amounts of carbon by tying up the wood in buildings for decades or even longer, perhaps in perpetuity.
“Say the typical steel and concrete building has an emissions profile of 2,000 metric tons of CO2,” said Andrew Ruff, of Connecticut-based Gray Organschi Architecture, a leading proponent of the laminated wood revolution. “With mass timber you can easily invert so you are sequestering 2,000 tons of CO2. Instead of adding to climate change you are mitigating climate change. That’s the goal.”
And it is taking off. Mass timber has a two-decade track record in Europe. The 18-story Mjösa Tower just opened last month in Norway. An 18-story mass timber building was recently built in Vancouver as well, and an 80-story high-rise is proposed for Chicago. There are new commercial mass timber buildings in London, Atlanta, and Minneapolis. Some 21 timber buildings over 50 meters (164 feet) tall will be completed in Europe by the end of the year, according to one report.
But there are big questions being asked about just how sustainable the new building material is –especially about how forests that produce mass timber are managed, and how much CO2 would be emitted in the logging, manufacture, and transport of the wood products used in the construction. So far, critics say, there aren’t good answers to these questions…
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