Since the dawn of civilization, humans have used wood as a primary building material. Strong, bountiful, easy to shape—its suitability for construction is well-established.
Other materials, such as steel and concrete, have long supplanted wood as staples of the building and architecture sectors, but both steel and concrete leave enormous carbon footprints. Concrete is used so abundantly worldwide that it was estimated to be responsible for about 8% of the world’s total CO2 emissions by The Royal Institute of International Affairs in 2018. Steel use, which involves mining, processing, and smelting, is estimated to account for more than 7% of CO2 emissions, according to Carbon Chain, a company that tracks carbon emissions in the global supply chain.
In comparison, timber has multiple benefits when it comes to sustainability and eco-friendly construction. Wood captures and stores carbon, is renewable, and produces minimal waste. It is also biodegradable, and efforts to source it are fairly easy. In addition to its green credentials, wood is also versatile, strong, and flexible. It also provides good insulation and is easy to maintain.
‘Mass Timber’ Movement
Not surprisingly, wood is once again becoming a desired building source for architects. A “mass timber” movement is growing, especially in Europe, according to a 2022 Axios article titled, “The race to build wooden skyscrapers.”
“Today, the tallest mass timber building is the 25-story Ascent skyscraper in Milwaukee, completed in 2022,” Kurt Kleiner wrote in Knowable Magazine in October. As of 2022, Kleiner added, “there were 84 mass timber buildings eight stories or higher either built or under construction worldwide, with another 55 proposed.” A report from the Council on Tall Buildings and Urban Habitat said 70% of projects were in Europe, with another 20% in North America.
Modern wood construction uses new methods—such as cross-laminated timber (CLT), in which multiple layers of wood are glued together—to help stabilize tall buildings without using concrete.
One example is the stunning Sara Kulturhus Center in Sweden. Designed by White Arkitekter and standing at around 75 meters (246 feet), the timber development features a 20-story tower made of prefabricated timber modules that the company said will be “carbon negative” over its lifetime. The timber used within the building sequesters twice as much carbon as the embodied carbon emitted during the building's construction.
Built from a combination of CLT and glued laminated timber (glulam)—where smaller layers of timber are glued together to make a larger, single component—the project in the city of Skellefteå includes a theater, gallery, library, museum, and hotel. The use of wood is something its designers say is a huge boost to the sustainability agenda.
“The primary benefit of using wood structures is the lower environmental impact,” says Oskar Norelius, partner at White Arkitekter.
The firm is one of Scandinavia’s leading architectural studios, and its vision is that by 2030 all its architecture will be regenerative and climate neutral. Its impressive portfolio includes Stockholm Wood City, slated to be the world’s largest urban development project constructed entirely from wood and spanning 250,000 square meters (2.7 million square feet).
“The greenhouse gas emissions related to the production and construction of a timber structure are significantly lower compared to conventional solutions, meaning less embodied carbon.”
“The greenhouse gas emissions related to the production and construction of a timber structure are significantly lower compared to conventional solutions, meaning less embodied carbon,” said Norelius.
The need for change is driven by environmental challenges facing the world, said Dean Maltz, managing partner at the Shigeru Ban Architects New York office. The company was founded by Shigeru Ban, a Pritzker Architecture Prize-winning Japanese architect, humanitarian, and author of Timber in Architecture (2022).
The company has designed temporary timber housing for earthquake victims, along with some of the world’s most iconic wooden buildings. Projects have included the Swatch and Omega Campus in Biel, Switzerland, and the recently completed Toyota City Museum in Japan—the first museum to receive ZEB (Net Zero Energy Buildings) Ready certification.
Maltz—who counts the Aspen Art Museum as one of his favorite structures that incorporates wood—said: “I think sustainable practice is becoming more prevalent now due to the extreme weather conditions suffered the world over and the recognition that we, as responsible citizens, must do something about it. As buildings account for 40% of the carbon expended globally, through sustainable practices, we as architects can support carbon reduction.”
Good for Earth and Soul
But beyond the environmental benefits of wood construction, there are those associated with mental and physical health. The term “concrete jungle” is a byword for ugly cityscapes that can make people feel worse about their immediate environment. Wooden structures, on the other hand, are known to slightly decrease cortisol (stress) and modestly decrease blood pressure.
“Wood is also an attractive material. The tactility, warmth, and softness add value to buildings inside and out,” Norelius said. “Studies have also shown that timber structures have a positive effect on occupiers—students concentrate better, patients in hospital heal faster, and office workers have lower stress levels and heart rates.”
“Studies have also shown that timber structures have a positive effect on occupiers—students concentrate better, patients in hospital heal faster, and office workers have lower stress levels and heart rates.”
Deforestation Fears
A material that can reduce carbon emissions, produce stunning buildings, and improve health and mood sounds ideal. It also prompts critical questions, such as where will all that wood come from? This can lead to fears that increased demand for wood for construction could contribute to deforestation.
The Earth loses an area the size of Portugal in forests every year, with only around half of that offset by growing more trees, according to OurWorldinData.org.
The key, said Norelius, is to ensure the wood used is part of a circular economy and that timber taken for building projects is replaced.
“Sustainable forestry is key for sustainable construction,” he said. “In terms of carbon, replanting ensures that the forest is not eradicated. In Sweden, the forest is larger in 2024 than it was in the 1920s, and it is growing year by year.”
But he also cautioned that deforestation is not simply about the removal of trees.
“Forests are a habitat for many species, a space for recreation, and in many cases, a space with strong cultural connotations for local communities. The impact of forestry on biodiversity, land use and other potentially conflicting interests must be taken into consideration.”
Maltz agrees, but said it was a “myth” that greater timber use in construction will destroy that resource.
“The reality is that the greater use of wood is beneficial to the planet if the wood is harvested through sustainable practices,” he said. He added that by using sustainably sourced wood with certifications, like FSC (Forest Stewardship Council in America) or PEFC (Program for the Endorsement of Forest Certification in Europe), the industry can ensure the viability of forests and their ability to thrive.
“In our Swatch/Omega Campus, comprising over 500,000 square feet of construction with three buildings, we utilized 160,000 cubic feet of certified wood from Switzerland. Despite the enormity of the project, the timber utilized takes 10 hours to regrow in the Swiss forests,” he said. (The 10-hour figure is based on “the total annual growth of Swiss forests volumetrically,” according to a 2024 Texas Architect article.)
Fire Risks
Building tall structures with wood is not without its difficulties, including one that once made building with wood unpopular—fire.
Think of the Great Fire of London in 1666, where a small blaze in a bakery near Pudding Lane tore through the city due to all its wooden houses. The blaze destroyed 13,000 homes, 87 churches, and St. Paul’s Cathedral. A royal proclamation that followed stated: "No man whatsoever shall presume to erect any house or building, whether great or small, but of brick or stone."
The fire ended the widespread use of wood for building in that city, as anyone found to be flouting the rules would be punished by having their house pulled down.
“The benefit of wood is that wood burns at a predictable rate as compared to concrete and steel. That predictability allows wood to be used as a fire protective layer.”
“The challenge with wood is that it burns,” said Maltz. However, “the benefit of wood is that wood burns at a predictable rate as compared to concrete and steel. That predictability allows wood to be used as a fire protective layer,” he said.
When an exposed wood surface burns, it creates a charred layer that is naturally protective, acting as insulation, retarding heating of the core. Mass timber construction facilitates fire resistance by means of the insulation of inner layers. The solid block construct technique of mass timber inhibits air flow and fire spread. According to an article in Arch Daily, a 7-inch thick (about 18 cm) wall of plaster-coated CLT lasted 3 hours and 6 minutes in a fire test, one hour longer than fire code requirements.
Moisture in tall wood buildings is also a concern due in part to potential deterioration from fungus and termites. Architects design heat and ventilation systems to prevent moisture from accumulating, use treated wood, or surround wood at the ground level with mesh or other physical barriers.
Another challenge in building with wood is acoustics. While wood structures are marvelous for concert halls, anyone who has lived in an old wooden home knows it creaks and groans. This is because a light, rigid material with a smooth, compact surface doesn’t have the ability to suppress noises like voices and footsteps, according to a 2021 article on premanufactured wooden homes.
“That said, all these issues are manageable if tackled with an innovative mindset,” said Norelius. When the process for the Sara Kulturhus Center began, some of these solutions were not yet available, so we adopted innovative and holistic strategies to implement integrated solutions.”
Cultural Shift
While mainstream architects are looking more at the use of wood, certain parts of the globe—such as Scandinavia and Japan—have long used it.
In Japanese culture, the term “mottainai,” roughly translated as “what a waste!” is a concept that encourages people to reduce waste and recycle.
“Shigeru Ban Architects has been engaged in sustainable design since the beginning of our practice, even before sustainability started being embraced at large by the design community. Our position on sustainability inherent to our work comes from a desire to not make waste,” said Maltz.
Norelius added: “What is interesting is that timber construction is evolving differently across countries due to local building culture, regulations and legislation. For instance, Belgium is very advanced in natural materials that complement timber very well, while Germany has developed an array of hybrid structural systems. The key to decarbonizing the construction industry lies in cross-border knowledge-sharing and exchange of experiences.”
What Does the Future Hold?
Maltz said he is excited about how the use of wood is developing.
“As for now, most buildings in mass timber are residential and commercial buildings. I am also excited about the opportunity to develop more types of structures for project types not traditionally using wood, such as concert halls and laboratory buildings,” he said.
In Kleiner’s article, posted in November in JSTOR Daily, he wrote, “Though still relatively uncommon, it is growing in popularity and beginning to pop up in skylines around the world.”
As industries look to the future as well as the past for solutions to the most pressing climate and sustainability issues, it is becoming clear that wood can once again become a staple of construction.
*Mark Smith is a journalist and author from the UK. He has written on subjects ranging from business and technology to world affairs, history, and popular culture for the Guardian, BBC, Telegraph, and magazines in the United States, Europe, and Southeast Asia.
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