Is not it good, Swedish plywood: the miraculous environmental city with a 20-storey wooden skyscraper | Architecture
As you come in to land at Skellefteå airport in northern northern Sweden, you are greeted by a wooden flight control tower that pokes up from an endless forest of pine and spruce. After boarding a biogas bus into town, you glide past apartment buildings and wooden schools, cross a wooden road bridge and pass a parking garage on several floors, before finally reaching the center, now home to one of the tallest new wooden buildings in the world.
“We are not the wooden Taliban,” says Bo Wikström, from Skellefteå’s tourist office, while leading a group of visitors on a “wooden safari” in its buildings. “Other material is allowed.” But why build in something else – when you are surrounded by 480,000 hectares of forest?
If you are wondering what a climate-conscious future looks like, small subarctic Skellefteå (pronounced “she left you”) has some of the answers. In a clearing on its outskirts, Europe’s largest battery factory is currently under construction. The next generation of electric batteries will not only be produced here, but also recycled. Electric helicopters will soon be able to send visitors to the giant Northvolt gigafactory, while long-distance electric aircraft are being tested nearby.
Skellefteå is powered by 100% renewable energy from hydropower and wind, and recycles 120,000 tonnes of electronic waste per year, with surplus heat from the process that is returned to the city-wide heating system. And now, with 20 floors above the low silhouette, Skellefteå has a fitting monument to its carbon dioxide-saving references. Sara Cultural Center and its high Wood Hotel stand as guiding stars for what it is possible to do with wood – and store approximately 9,000 tonnes of carbon from the atmosphere in the process.
“When I saw the competition proposal, I did not think it would be possible to build,” said Mayor Lorents Burman. “Twenty storeys high in wood? In Skellefteå? Thanks to three teams of construction engineers and the region’s prefabrication expertise, the timber tower now stands as a blueprint for a new generation of plush scrapers.
The technology behind it is surprisingly simple. The two main materials glued laminated wood (glulam) and cross laminate (CLT). The former is made of layers of wood that are joined to the grain in the same direction, which gives it a higher bearing capacity than both steel and concrete, in relation to its weight. It is ideal for pillars and beams and forms structural bones in the cultural center, which has two theaters, a museum, an art gallery and a library.
CLT, meanwhile, is like super-sized plywood, with each layer fixed at right angles to the next. This makes it strong in all directions, so it is perfect for walls and floor tiles. The lifting cores at each end of the 20-story tower are made of CLT, with prefabricated hotel room beams stacked between them, with glulam pillars in the corners for strength. Finally, the double-glazed glass facade keeps the rooms insulated in winter and cool in summer when the heated air rises between the glass panes.
The “self-finish” character of the structural mass, which can simply be left exposed, means that the tower was incredibly quick to build, which put an end to the usual wet crafts for plastering and decoration. An entire year was saved by using wood, compared to steel and concrete, with one floor completed every other day. The number of truck deliveries also decreased by about 90%, with virtually zero waste on site. Just like pieces of a giant balsa wood model, the pieces came from factories that were ready to be screwed together, some in panels 27 meters long, while the trees were harvested within a radius of 60 km from the site — and have since been replenished. As the region’s forest-fed restaurant menus, this is meaningful local shopping rather than a green veneer.
The climate is not the only beneficiary. Building in wood seems to have a positive effect on construction workers. While a regular construction site is a noisy, toxic place for fumes and dust, a timber is a picture of calm. “The people who build this would never go back to steel and concrete,” says Jesper Åkerlund from contractor Holmen, who analyzes improvements in the mental health of the workforce after the project. However, there is a downside, at least from the hotel perspective: “The raw wooden walls absorb stains like red wine much faster than a painted wall”, says Sara Johansson, from the hotel group Elite, “so we must be ready to clean much faster!”
With all these exposed wooden walls, ceilings and floors, the place feels like a giant sauna – with the scent that suits. But look closely and you will see that not everything is wood. Large steel plates are bolted through the giant plywood walls on the fifth floor, revealing the presence of a large steel chair — which is used to transfer the weight of the tower to the walls of the cultural center, making it possible to have a column-free space below. Concrete is also used on the top two floors to prevent the tower from swaying too much in the wind.
“We wanted the building to be legible,” he says Oskar Norelius from White Arkitekter, the largest architecture in Scandinavia, with many years of experience in building in wood, “so that people can see how it goes together.” Accordingly, thin steel rods form a cat cradle of bracings in trusses above the main open level of the culture head, stretched between clumsy wooden blocks. The main lounge, which seats 1,200, is a touring force of wood, with large glulam beams that jump over the ceiling and faceted wooden wedges that act as acoustic diffusers around the walls. “There is a softness throughout the place,” says Fransesca Quartey, director of Västerbotten’s regional theater. “It just makes you feel happy.”
It is also fireproof. CLT is very slow to ignite, designed here with an additional 4 cm sacrificial layer on each side that would char in the event of a fire and protect the structure for 120 minutes. The surfaces have also been treated with fire protection agents, and the complex is completely sprinkled, powered by batteries rather than the regular diesel engine.
In accordance with the city’s advanced (and municipally owned) energy network, the building uses artificial intelligence to monitor energy use and predict heating needs as well as communicate with surrounding buildings. Excess energy produced by the building’s solar panels can, for example, be sent to the nearby travel center or saved in batteries in the basement. If the culture house needs more heat, the surplus from a neighboring building that is cooled can be transferred. “Many buildings now have a brain,” says Patrik Sundberg from Skellefteå Kraft, the city’s energy company. “But we have added ears. It will be listening and learning all the time. ”
This wooden wonder may seem like a novelty once, a trophy to showcase the local wood industry, just because of the location. But the architects are keen to emphasize that the same process can be replicated anywhere, many hundreds of miles from a forest. “We are currently studying how far we could transport this building without regretting the carbon dioxide savings,” said White Architects Robert Schmitz. “We think it can probably go twice around the world and still be carbon neutral.”
There are still many obstacles in the way: the lobbying power of concrete manufacturers, an insurance industry that is reluctant to innovate, retrograde building regulations and a building culture that is reluctant to change. But as the only truly sustainable building material – with benefits in speed, health and well-being beyond carbon dioxide savings – the future is wood.