For more than a century, countries have raced to build the world’s tallest buildings with concrete and steel. Now, a quiet contest in constructing tall wooden buildings, from Amsterdam to Tokyo, underlines growing environmental concerns over concrete.
With rapid advances in engineered wood and authorities relaxing building codes, wooden structures are sprouting across Europe, Canada, the US and in the Asia-Pacific region.
At 73m, Amsterdam’s Haut building is said to be the world’s tallest wooden residential tower.
Illustration: Constance Chou
Vancouver plans a 40-story building that it says will be the world’s tallest, a title also claimed by Sumitomo Forestry’s 350m skyscraper in Tokyo.
“The interest is definitely being driven by environmental concerns — the amount of damage we’re doing with concrete is unbelievable,” said John Hardy, a sustainability expert in Bali, Indonesia.
“Bamboo and wood are carbon sequestering materials. So the other advantage of building with them is that you will look better to your children and grandchildren,” he said.
Construction of office towers, bridges, airports and highways is booming in developing nations across the world.
The manufacture of steel, concrete and brick accounts for about 16 percent of global fossil-fuel consumption and up to 30 percent when transport and assembly of the materials is considered, according to the Yale School of Forestry and Environmental Studies.
Concrete is also blamed for rampant sand mining, which has damaged the environment and hurt livelihoods in Southeast Asia.
In addition, an abundance of concrete has worsened urban flooding and made cities hotter, environmentalists say.
In contrast, wood requires fewer fossil fuels to transport and assemble, and also effectively stores large amounts of carbon — trapped as the trees grew — for years, helping curb emissions, said Andy Buchanan, professor of timber design at the University of Canterbury in New Zealand.
Each cubic meter of timber used in construction stores a carbon equivalent of over 900kg of carbon dioxide emissions, meaning a reduction of 135kg to 360kg of emissions per square meter of floor area, Buchanan said.
Innovations such as glue-laminated timber, laminated veneer lumber and cross-laminated timber — strips of wood glued together to make beams — are creating more uses for structural timber in residential and commercial projects, he said.
Structural timber is much lighter than concrete, cuts risks in earthquakes and can “create far more attractive interiors,” he said. “As tall, timber buildings become more popular, the perceived disadvantages — fire safety, durability and the supply chain — are being overcome with good design, excellent case study buildings and technology for engineered-wood products.”
Examples are easy to find, from London’s nine-story residential Stadthaus to Melbourne’s 10-story Forte apartment building.
A 54m wooden building in Vancouver that was thought to be the world’s tallest was quickly overtaken by an 85m tower in Norway.
Amsterdam’s 73m Haut will begin handing over its 55 apartments from 2021. Vancouver’s planned 40-story building will include 200 apartments, while the 70-story Tokyo tower is slated to be completed by 2041.
“New technology, combined with accurate computer fabrication, now enables a wooden building to be assembled incredibly fast, like a giant piece of flat-packed furniture,” said Andrew Lawrence, a timber specialist at Arup, which designed Haut.
“Wood is ideally suited for lower-rise buildings, but it is really exciting that engineers and architects worldwide are experimenting with the use of wood for taller structures,” he said.
Such buildings are particularly suited to cities, where buildings are constantly being adapted and refurbished for new uses, said Eleena Jamil, a Malaysian architect who has designed residential and commercial structures with bamboo and wood.
“Cities go through fast-paced changes. The advantage of using bamboo and timber is that they are easy to dismantle, reuse and adapt, compared to concrete,” she said.
However, with excessive logging and deforestation already a problem in many Southeast Asian countries, it is important to balance demand for wood with “tighter regulations and more efficient management of forests,” she cautioned.
Under pressure to act on a material that produces 7 percent of the world’s carbon dioxide emissions, cement manufacturers also have been experimenting with lower-carbon concrete.
Authorities in several US states are exploring the use of carbon-injected concrete that will use less cement, while trapping carbon emissions.
Meanwhile, policy initiatives are hastening the move to wood from steel and concrete.
In Christchurch, New Zealand, where authorities have encouraged a more environmentally friendly approach after a 2011 earthquake that flattened much of the central business district, timber is a favored material.
The city, which creates about 600,000 square meters of new buildings each year, has the opportunity to store the equivalent of 30,000 to 200,000 tonnes of carbon dioxide emissions per year if all new buildings were made of wood, Buchanan said.
Regions including British Columbia and Tasmania have adopted a “wood first” or “wood encouragement” policy that requires building designers to show that they have considered wood as an option.
Japan has a law to promote use of wood in public materials.
Such policies are “probably the most effective to encourage greater use of wood as a construction material, especially if supported through a carbon encouragement grant,” Buchanan said.
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