Oregon State University College of Forestry. MSA.
The Skyscraper Museum in New York City has an unusual exhibit currently underway: “Tall Timber: The Future of Cities in Wood.” This program is unusual in that it focuses on a forgotten material few would have predicted would become a trend in the age of Neo-Futurism. As far as large-scale architecture went, technical and theoretical advances starting in the twentieth century essentially banished wood to the kindling section. From Bauhaus to the International Style, from Brutalism to Postmodernism, wood seemed like a historical afterthought, like dugouts or adobe construction. But the battle to arrest climate change has seen timber stage a remarkable comeback over the last ten years in America.
Since Studio St. Germain last looked at mass timber in 2022, wood construction has skyrocketed in the United States. Walmart is currently building a mass timber corporate campus in Arkansas, and Google (Alphabet) recently completed construction on a mass timber office in Sunnyvale, California. Universities and colleges, many of them with sustainability pledges, have begun using mass timber for new campus structures, including Clemson, Bowdoin, the University of Arkansas, and Michigan State.
Already known as one of the best airports in America, Portland International Airport has also recently upgraded its look, with a new mass timber terminal designed by ZGF. This project, scheduled for completion in 2025, highlights the powerful aesthetic appeal of timber. Even New York City, the steel and glass capital of America, has seen timber developments, including municipal grants to encourage the use of wood.
But mass timber (also known as CLT—cross-laminated timber) has predictably sparked a backlash. According to some studies cited in a recent Bloomberg article, mass timber is less carbon-neutral friendly than advertised. As with any new material or technology, timber proponents go overboard with praise; similarly, timber opponents exaggerate flaws to the point where concrete and steel seem like benign products, even though concrete production alone is responsible for roughly nine percent of all human-generated CO2 emissions worldwide. Steelmaking is also a carbon-intense process, and it is made all the more problematic because the U.S. is the biggest importer of steel in the world, a distinction that translates into untold climate damage from cargo ships releasing greenhouse gasses from port to port across the globe.
Adohi Hall. University of Arkansas. Leers Weinzapfel Associates
Despite the real drawbacks of mass timber—use of natural (albeit renewable) resources, the chemical process of assembling CLT, and the still ever-present need to specify emissions-intensive materials, including concrete for foundations—it is still, from a sustainability point of view, intrinsically superior to steel and concrete construction. Because of its lightness and its prefab qualities, mass timber reduces assembly, making construction footprints smaller and less pollutant. In addition, by speeding up the assembly time, mass timber projects cut excessive emissions produced on-site, which is typically responsible for much of the carbon released from any given project over its lifespan. (Nor does mass timber rely on the sometimes-dubious calculations of embodied-carbon algorithms or the extracurricular—and often questionable— justifications of carbon off-setting strategies.)
A few overlooked attributes of timber vis-à-vis climate change include the fact that timber is a carbon sink, sequestering CO2 under optimum conditions. As Ana Antunes recently wrote in ArchDaily: “The sustainable essence of wood as a renewable raw material is undeniable. During tree growth, carbon dioxide is absorbed, and when used in construction, wood stores this carbon, contributing to the reduction of greenhouse gas emissions.”
Finally, because CLT is lightweight, it can be used for renovating existing structures, encouraging adaptive reuse instead of the often wasteful demolish-rebuild model still dominant today.
One concern that has materialized in the wake of the mass timber trend is the fear of deforestation. Other than logging, the main causes of deforestation in the United States are agricultural expansion, urbanization, and, most important, climate change, as wildfires become more destructive with each passing season. As noted here more than two years ago, increasing logging, to a reasonable extent, might help mitigate wildfires:
At the same time, more mass timber projects might mitigate some of the rampaging fires recently seen on the West Coast. The Timber Wars of the 1990s were so successful that harvesting has declined more than seventy percent in California from federal restrictions imposed decades ago. This may have had serious collateral damage in the form of accelerating wildfires in overcrowded forests. "When John Muir arrived and discovered Yosemite, we had about 40 trees to an acre. Today we have hundreds of trees to an acre," Rich Gordon, president of the California Forestry Association, told Reuters. "We will be better off if we can get closer to the way our forests once were."
Bowdoin College. Mills Hall & Gibbons Center for Arctic Studies. HGA
Another fact that pushes back against deforestation panic is that because mass timber projects are rarely more than mid-size, the amount of wood needed for each structure is limited. Indeed, it is doubtful that there will be mass timber supertalls or needle towers in the near future.
While mass timber buildings are becoming more popular, the process is still evolving. Just as the steel and concrete industries are, after decades of ecological destruction, finally working on decarbonization and manufacturing with clean energy, so too will mass timber make future adjustments based on environmental impact. In the meantime, the harshest critics of mass timber fail to see the forest for the trees.