Closer to Nature
American biologist Edward Wilson is known for popularizing the term “biophilia” to explain the inherent pleasure people derive from being in nature. By extension, “biophilic design” incorporates natural materials, natural light, vegetation, nature views and other experiences of the natural world into the modern built environment. A relatively new building material, cross-laminated timber (CLT), is quickly becoming the darling of the biophilic design movement.
CLT is made from layers of dried lumber boards stacked in alternating direction at 90-degree angles, which are then glued and pressed to form solid panels. The resulting panels have exceptional strength, stability and fire resistance. According to a recent USDA study, a seven-inch floor made of CLT is fire-resistant for two hours. CLT structures have proven more resilient to earthquakes than many other types of building materials, fostering great interest among builders in Japan where biophilic design has been part of the culture for centuries. CLT featured prominently in the rebuild of Christchurch, New Zealand, which was severely damaged by earthquakes in 2010 and 2011.
Global Cross-Laminated Timber “Plyscrapers” Reach New Heights
The CLT wood panel system was developed in Europe in the 1990s as an alternative to stone and masonry concrete — and to boost employment in the forests products industry. Europe still leads supply and demand in the CLT market, but use of CLT is rapidly gaining popularity in the United States, Canada and across the world.
CLT is the basis of the “tall wood” movement, as the material’s high strength, dimensional stability and rigidity allow it to be used in mid- and high-rise construction of apartment and office buildings and even power line towers. Growing investment in large-scale wood construction is evident with the completion of several prominent structures over the last several years.
They include luxury apartment buildings in Melbourne, Australia and Bergen, Norway as well as the Brock Commons on the campus of the University of British Columbia. Last year, construction began on a 24-story hotel and office tower composed of 76 percent wood in Vienna, Austria. In 2018, Sumitomo Forestry announced its plan to build the world’s tallest wooden skyscraper – at 70 stories tall, the building will be made 90 percent of wood, capable of sequestering 100,000 tons of CO2. Japan also used CLT extensively in its 2020 Olympic National Stadium to achieve a natural aesthetic.
Building Global Customers
The global CLT market was valued at $773 million in 2019 and was expected to grow to $1.6 billion by 2025. Production of CLT worldwide is estimated based on surveys and reported by the publication Timber-Online at 1.44 million cubic meters in 2019, although data is not available for all production sites. An estimated 65 percent is produced in Italy, Czech Republic, Germany, Austria and Switzerland. With additional production coming online, global annual output is expected to grow to between 2 and 2.5 million cubic meters this year.
How much of this production is traded internationally? It’s not entirely clear. There is no international agreement yet on how to classify CLT on the Harmonized Tariff Schedule. The product currently falls within a broader category with glulam (another laminated timber product), obscuring our understanding of specific trade flows. (With support from USDA’s McIntire-Stennis program, The Center for International Trade in Forest Products at the University of Washington is building a database to better understand international trade in wood products while governments sort this out.)
Japan’s Ministry of Finance recorded 918,000 cubic meters of laminated lumber (glulam and CLT) were imported in 2018, mainly from Europe. U.S. imports of CLT in 2018 were much smaller – less than 20,000 cubic meters, also primarily from Europe. Whether this number will grow remains to be seen – it could be that greater use of CLT drives more trade in architectural design, timber engineering and construction services.
Supporting the Structure of Rural Economies
CLT was pioneered and promoted in Europe in part to bolster rural employment in the timber industry. Though it is also traded, being close to construction is a big advantage in the timber industry. European companies, which dominate their own market and supply American developers, are starting to build mills in the United States to meet growing demand. Austrian firm KLH partnered with International Beams in Dothan, Alabama, to open the first CLT plant east of the Rocky Mountains utilizing the Southern Yellow Pine native to the region.
To support more CLT production in rural economies, the United States is in the process of updating U.S. building codes to expand the use of CLT, as the International Building Code has already done. The 2018 Farm Bill contains provisions from the Timber Innovation Act intended to advance domestic research and development of further applications for structural wood in the building sector.
The United States isn’t alone in its efforts to build CLT capacity. Japan’s Forest Agency instituted a road map in 2014 for greater utilization of CLT as a follow up to Japan’s Promotion for the Use of Wood in Public Buildings Act. The agency provides subsidies to drive the establishment of CLT facilities with a target of increasing the country’s CLT production capacity to supply both the domestic and international markets. Through the effort, the government also seeks to support employment of women in rural areas, including through encouraging female lumberjacks.
A Breath of Fresh Air
In responding to industry feedback surveys, customers say wood construction, exposed structural wood and biophilic design have a positive impact on their shopping experience because such structures are ecological, healthful and warm. Some studies even suggest wood is a multi-sensory experience for occupants, evoking a sense of calm that can lower blood pressure.
As for environmental benefits, CLT emits less carbon dioxide during the manufacturing phase and finished buildings made with CLT even help sequester existing carbon for a longer period. Murray Grove in London was the first tall urban housing project to be constructed entirely from CLT. Due to its wooden construction, it was calculated to be carbon negative from the start and will take twenty-one years before the building will even reach carbon neutrality, far less than if the building had used concrete. Even tearing down a CLT building at the end of its life is more environmentally friendly than taking down one made of traditional materials.
Photo credit: Lever Architecture, cross-laminated timber community center added to the The Nature Conservancy in Oregon.
Trade in Sustainability
A thriving wood industry must embrace sustainability by replanting and harvesting efficiently. The CLT process allows smaller diameter softwood trees to be utilized, more so than in most commercial timber. It also makes use of millions of acres of pine that have been killed by the pine beetle epidemic. Pine beetles have penetrated forests in all nineteen western states, some eastern states and Canada, effectively decimating some 88 million acres of timber. Processing the downed trees mitigates some of the carbon emitted by the decaying wood, which remains strong enough to be useful in CLT processing for up to two years.
Cross-laminated timber provides many possible benefits, including reduced costs, rural employment, strength, fire-resistance, beauty and a sense of being closer to nature. We can also credit trade in CLT with stimulating a global movement that could help all of us live and work more harmoniously on this planet.
The author began her U.S. Government career in the U.S. Department of Commerce, International Trade Administration’s Forest Products division and is still convinced this industry has the best site visits and field trips.
Feature image: The Kajstaden Tall Timber Building by CF Møller Architects in the Swedish city of Västerås.