January - March 2014
Carbon Collectors in the Sky
If cities are serious about tackling climate change, then the solution may be found in building the city of tomorrow to look more like the city of yesterday. As glass and steel towers continue to rise, wood skyscrapers are likely to start sprouting alongside them. Multi-story and high-rise wood buildings are already planned or rising in Europe and Canada. They're architecturally distinct, they're green, and they're safe too. And now the U.S. Department of Agriculture is trying to get America in on the action.
Agriculture Secretary Tom Vilsack recently took the first step to make that happen. He announced that the USDA is entering into a partnership with WoodWorks-an organization that provides support to the wood building industry-to educate architects and engineers on the potential of using wood as material. The department will also invest $1 million into a prize competition for developers and designers to demonstrate the structural viability, and architectural opportunity, of high-rise wood construction.
"Building stronger markets for innovative new wood products supports sustainable forestry, helps buffer greenhouse gas emissions, and puts rural America at the forefront of an emerging industry," said Secretary Vilsack at the announcement.
The secretary understands that designing and building multi-story wood structures won't be easy for architects and engineers-at least not yet. He tells AN that the money included in these initiatives will help offset some of the costs associated with initial design challenges, necessary code-variances, and engineering studies.
"What we're doing is essentially creating a resource that reduces the risk of trying something different," said Secretary Vilsack.
Building-and especially building tall-won't just add much needed architectural variety to our increasingly glass and steel cities; it will dramatically cut down on carbon emissions. Because, for all the green roofs and solar panels that sleek new towers may offer, the process of producing all that steel and concrete releases a significant amount of carbon. By some estimates, the production process accounts for 8% of total global carbon emissions.
"The great thing about wood is that it absorbs carbon and sequesters carbon permanently," says Vilsack. And responsibly harvesting forests, explains the secretary, can actually reduce greenhouse gas emissions by reducing the risk of wildfire.
This isn't necessarily about chopping down healthy trees," says Vilsack. "It can just as easily be about dealing with diseased wood that exists in the western part of the United States."
He points to the 45 million acres of forest, which have been infected by the mountain pine beetle and become highly-susceptible to catching fire. "Better that we use that diseased wood for a new product like cross-laminated timber that can be used in construction projects that can permanently sequester the carbon and reduce the risk of intensive forest fire," says Vilsack.
Cross-laminated technology essentially means crisscrossing and layering lumber to create sturdier and more fire-retardant wood panels. This technique is already being used for wood towers in Canada and Sweden. And last year, SOM conducted the Timber Tower Research Project, which proposed new ways to make wood high-rises a reality.
Fire concerns are an issue, but they shouldn't be. As AN reported last year, "heavy timber and cross-laminated timber actually have a built-in fire protection: dense wood will burn slowly, charring instead of catching fire all at once. Part of bringing a wood building up to code is providing enough wood so that even after fire produces a 'char layer,' there is still enough left to support the structure."
Still, Vilsack says he understands the "hesitation" behind tall, wood structures, but he believes that some investment and education could change that.
While the USDA's new initiatives won't usher in a wave of wood towers, they lay the groundwork for a new type of architecture; and they help designers and developers take the next steps.
"There's momentum building," says Vilsack, "but it's going to take some time."