With efforts to find new ways to lock up carbon, developers, architects and net zero committed companies are asking, "Is wood the new concrete?" New technology in what’s called "mass timber" production offers a carbon-cutting alternative to concrete and steel in the building sector.
In addition to the aesthetic benefits of wood as a building material, advocates say that using timber can substantially reduce the building sector’s greenhouse gas emissions. Its use can also slash waste, pollution, costs and time compared with the materials more commonly used now.
"Mass timber isn’t the right material forever, but it’s the right material for now," says architect Michael Green, a timber building proponent based in Vancouver. "If we had other carbon-neutral ways of building, we wouldn’t need mass timber."
New techniques to trim, dry and glue planks of wood together — including waste wood — to create large "slabs," mass timber is being used for everything from floors, walls and ceilings to entire buildings and skyscrapers — even cities.
Tech giant Microsoft is updating its campus in Silicon Valley, using timber with its carbon and other eco benefits in mind. At 644,000 square feet, the campus will be the largest mass timber project in North America.
Mass timber isn’t the right material forever, but it’s the right material for now.
"The use of mass timber is part of Microsoft’s commitment to becoming carbon negative by 2030, including reducing our Scope 3 emissions by 55 percent," said Darren Lombardi, senior real estate manager at Microsoft SVC. Scope 3 Emissions are those from customers or assets not owned or controlled by a company but that indirectly impact its value chain and emissions. Microsoft uses data from an Embodied Carbon Calculator for Construction (EC3) tool, which analyzes construction materials, for data to drive building decisions including the most effective ways to reduce carbon.
Currently, the world’s tallest mass timber building is in Norway at 18 stories and 280 feet. City planners in Helsinki, Finland, are creating what’s called Wood City, an entire city made using timber as the key building material.
"Mass timber encompasses a suite of building elements that transform relatively low-value timber feedstock into structural elements that have superior weight-to-strength performance than steel or concrete," says Keith Crews, a professor at Australia’s University of Queensland. Supporting energy-efficient buildings throughout their life cycle can be an effective way to reduce long-term carbon emissions and push toward net zero, he said.
See our related story: Calix lands a $17.7 million investment from Carbon Direct to capture carbon in concrete.
Typically, mass timber is made using fast-growing softwood trees such as fir, pine and spruce. A variety of methods are used to make it into a durable and adaptable building material, including dowel-laminated (DLT), glue-laminated (Glulam or GLT) beams, laminated veneer lumber (LVL) and nail-laminated timber (NLT). The type that shows the most promise for large construction projects is cross-laminated timber (CLT).
"It’s a bit like what IKEA has done with furniture," Crews says. "Everything is prefabricated to very high tolerances, arrives in a flat pack and is assembled into the final product."
The great carbon capture
Emissions from the building sector accounted for nearly 38 percent of total greenhouse gas emissions globally and hit an all-time high in 2019, according to a new U.N. Environment Program report. Using timber in place of steel and concrete can significantly reduce construction’s carbon footprint by preventing carbon from entering the atmosphere and sequestering it for the lifetime of the building. Because wood captures and stores carbon via photosynthesis, proponents say mass timber functions as a form of carbon removal.
Emissions from the building sector accounted for nearly 38% of total greenhouse gas emissions globally and hit an all-time high in 2019.
By 2050, the U.N. expects 70 percent of the world’s population to live in cities, which means building more infrastructure. This doesn’t bode well for tackling climate change. Steel and concrete, currently the two most common building materials used worldwide, generate roughly 8 percent of the world’s carbon emissions.
Efforts are already in place that use technology to reduce the carbon footprint of concrete and steel. Concrete can be used as carbon sequestration when recycled carbon dioxide is permanently embedded in the cement during the mixing process. Green hydrogen, produced using renewable energy, looks to be the most promising solution to lower steel’s carbon footprint if it can be produced in large quantities and transported.
Not new, not forever
Opponents of mass timber say cutting down trees for buildings shouldn’t be an option. But Bodie Cabiyo, a Ph.D. candidate at the University of California, Berkeley, disagrees. He says he doesn’t see massive demand becoming a problem soon, but sustainable forest management is essential.
"We really do need to be mindful that we don’t create an uptick in demand for mass timber without sustainable forest practices," he says. "We don’t want to chop down 1,000-year-old trees for mass timber."
"Consumers forget we’re already cutting down trees for paper and lumber production," Cabiyo says. Wood is used for everything from toilet paper and notebooks to decking and furniture. The fact is, he says, trees are planted and grown to be chopped down for myriad daily uses.
Mass timber can play a role in creating a circular economy and provides jobs in forestry, design, construction and installation.
Construction is a $9 trillion industry, and mass timber production is a growing enterprise that is newly part of the climate change solution. It’s estimated that the global CLT market, just one of a variety of mass timber products, will reach $3.5 billion by 2027.
Green says there needs to be a continued push on investment and innovation to find ways to build better, and mass timber is just a stepping stone for what we can ultimately do.
Some global leaders using mass timber include Stora Enso in Finland, Mayr Melnhof Holz Holding AG in Austria and Xlam Ltd. in Australia and New Zealand. Global developer Lendlease has built several multi-story timber buildings in its home base of Australia. Walmart is even getting into the mass timber game and contracting with Structurlam, North America’s leading provider of mass timber, to build its new campus offices.
Mass timber can play a role in creating a circular economy and provides jobs in forestry, design, construction and installation, according to a report from the Forest Economic Advisors. In an ideal world, Bodie said, we’d use less wood for pulp and paper — through increased recycling and other means — so that it can be used for mass timber instead.
"Shifting our wood use from short-lived products to long-lived products like [buildings] would have huge climate benefits," Bodie said.