Climate-change denial appears to be on the verge of becoming official U.S. policy. But all hope for reducing our carbon footprint is not lost. Case in point is the pending Timber Innovation Act, one of the rare eco-friendly pieces of legislation that enjoys bipartisan support. The bill (H.R. 1380, S. 538) seeks to establish a market for so-called mass timber buildings more than 85 feet tall that are built from panelized wood construction products such as cross-laminated timber (CLT) and glued-laminated timber (glulam).
“Building with wood benefits both rural economies and the environment,” U.S. Senator Debbie Stabenow (D-Michigan) said when she announced the legislation in early March. “This bill will help expand markets for wood products coming out of forests in Michigan and all across the country. At the same time, using wood for construction reduces pollution and incentivizes private landowners to keep their land forested, rather than selling it to developers.”
Architects who study the new wood construction materials say mass timber has economic, ecological, seismic, and aesthetic advantages over steel and concrete. “Photosynthesis, the process of growing a tree, absorbs C02,” explained New Haven architect Alan Organschi, adding, “Until it burns or decomposes, that carbon will stay in the wood like a bank investment.”
The concrete and steel industries are adamantly opposed to the Timber Innovation Act. More than 160 stakeholders from the construction, labor, and building materials sectors jointly signed a letter to the U.S. Senate opposing a version of the bill introduced last year. The letter questioned the fire and structural safety of mass timber and stated the bill would create an “imbalance in the marketplace by allowing the federal government to choose winners and losers.”
However, the bill’s supporters say the new wood technology promises to significantly reduce carbon loads in the building industry, which is currently responsible for close to half of the U.S.’s greenhouse gas emissions. A typical mid-rise concrete and steel building, because it relies on pollution-generating resource-extraction industries, is responsible for emitting 3,210 tons of CO2 in its construction and lifetime, according to Timber City, an initiative undertaken by Organschi’s firm, Gray Organschi Architecture, that is supported by the Hines Research Fund for Advanced Sustainability at Yale University. In contrast, because trees are a renewable resource that sequesters CO2, a typical mass timber mid-rise building built from wood harvested from sustainably managed forest is responsible for capturing 4,720 tons of CO2.
Innovations in mass timber technology also resolve fireproofing and seismic issues that, until recently, were a major disincentive to using wood in large urban buildings, according to Yugon Kim, founding partner of the architecture firm IKD, who curated the exhibit Timber City at the National Building Museum in Washington last fall. “U.S. cities in the 1800s used to be made of wood, but then because of urban fires that started to change,” he said. “Now, because of products like CLT, we will be able to use wood in the centers of our cities the way we did in the past.”
Tall wood building construction is most advanced in Europe, especially in Austria, which boasts the world’s largest mass timber industry. An example of a commercially viable mass timber development that garnered worldwide attention is the nine-story Murray Grove designed by Waugh Thistleton Architects, which was built in London in 2009. It consists of wood load-bearing walls, wood elevator cores, and wood floor slabs. In addition to paying off for the environment, Murray Grove took only 49 weeks to build, whereas an equivalent-size concrete structure would typically have taken 72 weeks to build.
The mass timber industry is still in its infancy in the U.S. There are only several wood companies that make mass timber products, and local building codes generally disallow tall wood structures. The Timber Innovation Act seeks to change that situation by funding competitive research on mass timber technology at institutions of higher learning and by making funds available for a tall wood building competition and a wood innovation program for retrofitting sawmills in areas where there is high unemployment.
The pending legislation expands upon a federal program that established an earlier U.S. Tall Wood Building Prize Competition, which in 2015 awarded $3 million to support the construction of two such structures. One was Framework, a 12-story mixed-use building in Portland, Oregon, designed by LEVER Architecture, which is due to break ground this summer. The other was 475 West 18th Street, designed by SHoP Architects, an upscale residential building project near the High Line that was shelved in early March, reportedly in response to a market downturn for high-end properties.
Getting government sponsored research funding was critical to defraying added expenses associated with the extensive testing and research necessary to secure local building department approvals for building wood structures more than six stories, according to Thomas Robinson, founding principal of LEVER Architecture. “Whenever you are doing something for the first time it is more complicated,” he said, noting that a critical aspect of his project was demonstrating that exposed CLT and glulam can achieve a two-hour fire-resistant rating.
Given the increasing environmental concerns over the widespread use of steel and concrete, mass timber promises to be a more palatable alternative. “What the Timber Innovation Act does is make this an even playing field,” Organschi said. “We have these vast forest reserves which are not being utilized.… By using mass configurations of timber, we will get more carbon sequestration.”