Transforming Trees Into Skyscrapers | The New Yorker

Brumunddal, a small municipality on the northeastern shore of Lake Mjøsa, in Norway, has for most of its history had little to recommend it to the passing visitor. There are no picturesque streets with cafés and boutiques, as there are in the ski resort of Lillehammer, some thirty miles to the north. Industrial buildings, mostly for the lumber industry, occupy the area closest to the lake, and the waterfront is cut off by a highway. The town, which has a population of eleven thousand, was until recently best known to Norwegians for a series of attacks on immigrant residents three decades ago, which led to street clashes between anti-racism protesters and supporters of the far right. Since 2019, however, Brumunddal has achieved a more welcome identity: as the site of Mjøstårnet, the tallest all-timber building in the world.

Mjøstårnet—the name means “Tower of Mjøsa”—stands at two hundred and eighty feet and consists of eighteen floors, combining office space, residential units, and a seventy-two-room hotel that has become a destination for visitors curious about the future of sustainable architecture and of novel achievements in structural engineering. It’s the third-tallest tower in Norway, a country whose buildings rarely extend above ten stories. Although Mjøstårnet dominates the Brumunddal skyline, it is a tenth the height of the world’s tallest structure, the Burj Khalifa, in Dubai. Its scale is similar to that of New York’s Flatiron Building, which, when completed in 1902, topped out at just over three hundred feet. (Three years later, it was capped with a penthouse.)

Like the Flatiron Building—one of the earliest steel-frame skyscrapers, which defied public skepticism about the sturdiness of a building that tapers to the extreme angle of about twenty-five degrees—Mjøstårnet is an audacious gesture and a proof of concept. It depends for its strength and stability not on steel and concrete but on giant wooden beams of glulam—short for “glued laminated timber”—an engineered product in which pieces of lumber are bound together with water-resistant adhesives. Glulam is manufactured at industrial scale from the spruce and pine forests that cover about a third of Norway’s landmass, including the slopes around Brumunddal, from which the timber for Mjøstårnet was harvested.

I went to see the building in mid-December, arriving by a train from Oslo that passed through farmland and woodland before reaching the edge of Lake Mjøsa, which is Norway’s biggest. The steely waters lapped a shoreline of charcoal-colored rock, on which traces of the previous weekend’s snow remained. The forested bank opposite, when it emerged from clouds of fog, was dark green against the pallid sky. The journey north from the capital takes about an hour and a half, but I didn’t need a watch to tell me when I had arrived at Brumunddal—the incongruous sight of a tower block rising from the water’s edge was a sufficient signpost. Descending from the train, I wheeled my suitcase for fifteen minutes across town—past the parking lot of the local McDonald’s and across the highway, which was nearly empty. As I walked, Mjøstårnet loomed in the mist, resembling from a distance a box of matches. On the roof, there was an angled wooden canopy that might have been fashioned from a handful of matches taken from the box’s drawer.

The tower is flanked by two other all-timber structures: on one side, a low building that houses the municipal swimming pool; on the other, an office building. Some low-rise wooden apartment buildings edge the lake. Mjøstårnet’s sheer façade is clad in panels of orange-brown knotty timber, whose dark vertical lines of wood grain lure the eye upward. By the entrance, an English-language sign attests that a group called the Council on Tall Buildings and Urban Habitat has certified the tower’s record-breaking status. Passing through a revolving door, I smelled the enticing scent of pine—though its source, I realized, to my mild disappointment, was a Christmas tree.

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The material from which the tower had been built was evident, though, in the airy ground-floor lobby and restaurant, where wooden dining tables and chairs were arrayed on bare wooden floorboards, wooden pendant lampshades dangled on long cords, and large bamboo palms in pots were clustered at the base of a curved wooden staircase that rose to a mezzanine. Large columns supporting the building, as well as angled braces cutting across the restaurant’s walls of windows, were formed from massive glulam blocks, the thickest of which were almost five feet by two feet, like pieces from a monstrous Jenga set. Riding a glass-walled elevator to my room, on the eleventh floor, I noticed that the elevator shaft was built from similar chunky blocks.

I had been assigned a corner room with two huge picture windows. One faced southwest, across the lake, where the view was obscured by fog; the other faced southeast, along the waterfront, offering a painterly sweep of gray skies and water, the shoreline clustered with denuded deciduous birches and evergreen spruces. An enormous glulam pillar between the windows held up the corner of the building. Its surface had been treated with a translucent white-tinted wax, but otherwise it was recognizably derived from the forests through which I’d passed on the journey from Oslo. I rapped my knuckles on the glulam: it was smooth, resonant, and much less cold than a metal pillar would have been.

I put my bag down on a blond-wood coffee table by the window, and settled into a low swivel chair, its comfortable backrest fashioned from bent-wood strips. In December, Brumunddal enjoys less than six hours of daylight; had I sat there long enough, I could have watched the sun rise and set with only the barest swivel to adjust my line of sight. The room was quiet and, despite the lowering skies, it was light. With its minimal, tasteful furnishings—a narrow blond-wood desk; a double bed made up with white linens and a crimson blanket—it had the virtuous feel of a spa. I had no desire to go elsewhere, and, given the town’s lack of other attractions, that was just as well. Between the heft of the wooden building and the evanescence of the fog encircling it, the atmosphere was seductively calming—as long as my mind did not linger on the metaphor of the matchbox.

Buildings are among the worst contributors to greenhouse gases. The Global Alliance for Buildings and Construction has reported that twenty-eight per cent of global emissions are generated by building operations—heat, lighting, and so on. An additional eleven per cent comes from the manufacture of materials and from the construction process. A 2019 report by Chatham House, a British think tank, estimated that the four billion tons of cement that are produced annually worldwide account for eight per cent of emissions; carbon is released into the atmosphere by the combustion required for the manufacture of cement, and by the chemical processes involved. (By contrast, the aviation industry contributes just under two per cent of emissions.) Buildings have an environmental cost when they go up and when they come down: concrete waste usually ends up as landfill, especially in countries whose economies are still emerging. Even in places where technologies for recycling the material have been developed, the process is complex, since structural concrete is threaded unpredictably with rebar, which is difficult to remove. Because of the relatively low cost of manufacturing concrete, recycling it—into gravel, say, or fill-in material for landscaping—is hard to justify in purely economic terms.

Engineered wood products such as glulam and cross-laminated timber—a close relative in which flat boards are glued in perpendicular layers—offer an alternative model for the construction industry. Lumber pillars, given their earlier incarnation as trees, retain carbon dioxide captured from the atmosphere. One cubic metre of glulam timber stores about seven hundred kilograms of carbon dioxide. About eighteen thousand trees were required to produce the wood products used in the construction of Mjøstårnet and the adjoining pool. In aggregate, those trees sequester more than two thousand tons of carbon dioxide. (Norwegian law requires harvested acres to be replanted.)

Many municipalities and nations are embracing the environmental advantages of building with timber. In 2020, the housing minister of France stated that new public buildings should incorporate wood or other biological materials such as hempcrete—a composite of hemp, water, and lime. The city government in Amsterdam has decreed that, starting in 2025, a fifth of all new buildings must be constructed mainly with bio-based materials. Other countries have taken a different tack: in the United Kingdom, recent legislation has banned the use of combustible materials, including wood, on the exterior of residential buildings more than sixty feet tall. This ruling was introduced after the Grenfell Tower fire, in 2017, when a twenty-four-story housing block burned like a terrible beacon over West London, killing seventy-two people. The fire was exacerbated by the building’s cladding, which was made not from timber but from aluminum and highly flammable polyethylene. Historically, cities have restricted the use of timber in buildings after deadly conflagrations. In 1667, after the Great Fire of London destroyed in excess of thirteen thousand houses—and more than eighty churches—the city passed legislation mandating construction in brick or stone. In the wake of the Great Chicago Fire of 1871, in which more than seventeen thousand buildings were destroyed and nearly a hundred thousand people left homeless, local officials expanded requirements to use fireproof materials in the downtown area. In Norway, timber structures were outlawed in urban contexts in 1904, after the town of Ålesund was ravaged by fire. (That law has since been rescinded.)

Architects and engineers who specialize in mass-timber buildings say that fears of fire are misplaced. I met with Martin Lunke, a project manager for Hent, the contractor responsible for the wooden complex in Brumunddal, and he told me that some locals initially referred to Mjøstårnet as “the world’s biggest torch.” Lunke explained that the kind of laminated wooden blocks used in Mjøstårnet exceed modern fire standards. Unlike wood planks or beams cut from individual trees, the massive blocks of engineered timber used in large-scale construction projects do not burn through: they char only on the surface, to a depth of one or two centimetres, much the way a large log placed in a fireplace will the next morning be blackened but not incinerated. At least, that’s what has been demonstrated in tests: Lunke, like others in the industry with whom I spoke, could not cite any fires in the real world which involved mass-timber buildings. A recent architectural competition in Oslo provided an oblique endorsement of the material’s safety: the city’s fire department elicited proposals for a new station and elected a firm that had designed a two-story structure built from wood and clad in panels of scorched timber.

Engineering wood to make it stronger and more adaptable is not a recent innovation: plywood, in which thin strips of lumber are glued together, with the grain running in alternating directions, has been used as a building material since the early twentieth century. Glulam and cross-laminated timber, which are more recent innovations, are manufactured according to similar principles. Large planks of sawn timber are dried in a kiln—a process that can take weeks—then glued together and compressed. Computer imaging allows pieces of engineered wood to be cut precisely to size before they’re transported to a building site, producing less waste than conventional construction methods. (Unlike steel, timber elements don’t clang, so less noise is generated by the raising of a timber building.)

Because building with glulam and cross-laminated timber is still in its infancy, it can be more expensive than conventional construction: the Mjøstårnet development cost approximately a hundred and thirteen million dollars, about eleven per cent more than an equivalent development would have cost in concrete and steel. Although some regions of the world have plentiful forests of harvestable, renewable trees—Germany, Austria, Canada—others lack a ready supply of wood to turn into engineered timber. Despite Dubai’s appetite for architectural innovation, it wouldn’t be a sensible location for a timber tower: the ecological cost of shipping the wood would cancel out its green credentials.

Building towers with wood poses certain design challenges: the supporting columns in a timber office tower must be thicker than those in steel-and-concrete towers, causing precious metres of rentable floor space to be lost. The inherent lightness of wood can also prove tricky for architects. The engineers of Mjøstårnet determined that the upper levels needed to be equipped with concrete floors to weigh the tower down. Rune Abrahamsen, the C.E.O. of Moelven Limtre AS, the Norwegian company that provided the timber elements for Mjøstårnet, explained to me that, otherwise, although the tower would have been structurally sound, the wind that blows off the lake would have caused it to sway so much that some occupants would have become nauseated, “as when you’re on a boat.”

Other developers are now making plans to build hybrid timber buildings that are even taller than Mjøstårnet—and their designs break from the geometric simplicity of the Brumunddal tower. The architectural firm Penda has designed a jagged eighteen-story apartment building whose modular structure will have large jutting balconies that can accommodate fully grown trees. Vancouver will soon become home to several innovative timber buildings, including the Earth Tower, a forty-story apartment block that incorporates shared winter gardens for residents and a rooftop greenhouse. A new home for the Vancouver Art Gallery, designed by Herzog & de Meuron, combines structural-timber elements with a woven-copper façade. The New York architectural firm SHoP, which recently completed the skinniest skyscraper in the world—Steinway Tower, in midtown Manhattan—has designed a forty-story wooden tower, in Sydney, for the tech company Atlassian. An internal-timber structure is to be wrapped with a curvy exoskeleton of steel and glass; solar panels will adorn the façade, and indoor terraces will have naturally ventilated gardens.