Is mass timber a climate panacea? This question has become one for the ages, or at least, for this particular age. And despite numerous advances in manufacturing and sustainable forestry, the answer to this query remains the same: to be determined.

The mass-timber construction industry has grown adept at marketing its sustainability bona fides, touting everything from associated biophilic properties and advancements in seismic resistance to estimated carbon savings—including avoided emissions and carbon storage—per each square meter of floor space. Such efforts have paid dividends. As of June of 2023, there were 1860 recorded mass-timber projects built or in progress in the U.S. alone, according to the non-profit WoodWorks. This represents exponential growth over at least the last decade.

Tall timber is also trending. Thanks to new construction codes in the 2021 International Building Code (and refinements in the 2024 IBC), viable pathways to constructing towers of a dozen or more stories, typically composed of cross-laminated timber (CLT) panels and glulam beams, are no longer hard to come by. Insurers are getting on board as well, clearly convinced that such buildings will perform as advertised.

Australia, Canada, and the U.S. are all ascending forces in this market category, but its epicenter remains in Europe. Of the 20 tallest mass-timber buildings across the globe, 13 of them are in Western and Central Europe and Scandinavia, where projects largely benefit from responsible forest management and regional manufacturing. (Lumber production in Central Europe recently experienced a slight decline due to a bark beetle infestation in the Czech Republic and Germany, which peaked in 2019, and Russia’s invasion of Ukraine, which has put a halt to forest product imports from Russia and Belarus.) Of course, these are all standalone projects, each one a singular edifice that is being leveraged, to varying degrees of success, as one more victory in the crusade against global warming. But as wiser minds have previously asserted, “we can’t build our way out of the climate crisis.” Or can we?

A city made of wood

In the Swedish city of Sickla, just south of Stockholm, the urban developer Atrium Ljungberg announced its plans last summer to build an entire neighborhood made from wood. Appropriately dubbed Stockholm Wood City, the development’s scope will include 32 buildings spread throughout 25 blocks, and comprise approximately 250,000 square meters (~2.7 million square feet) of gross floor area devoted to residential, offices, schools, and retail. The estimated tally includes 2000 new homes and 7000 new office spaces. The project is expected to break ground in 2025, with the first buildings ready for occupancy by 2027.

Atrium Ljungberg’s business developer in Sickla, Håkan Hyllengren, confides that throughout the projected course of building out the entire neighborhood, which he estimates at 10 years, calculating the precise cumulative carbon savings isn’t feasible. From there Hyllengren pivots, comparing the development’s use of timber versus concrete and steel options. “On average, the calculations tell us we can reduce our carbon footprint in the production phase by about 40 percent,” he says, which will prove critical to getting his company to its stated goal of carbon neutrality by 2030.

As for its ledger, Hyllengren doesn’t claim cost parity between timber and steel or concrete products of equal measure, but he does see a not-too-distant future where things break even. “We estimated the cost of using timber instead of steel or concrete will be the same. Alright, [timber is] a little bit more pricey, but the total yield on the project will be the same because we will build it faster, so we can rent faster, and shorter production times will also reduce the cost even if the material is a bit more expensive. On the whole, if you look on the total production cost, it’s equal.”

Like every other mass timber project in Europe, the materials supply chain is a regional matter. In the case of Stockholm Wood City, Atrium Ljungberg’s leadership confirms that “most of the lumber” used for the CLT that will comprise this neighborhood will be sourced and manufactured within Sweden, with possible remainder amounts coming from Finland next door. Sweden has the largest forest area among all EU countries, with about 28 million hectares, but also one of the lowest employment rates per area of forest. “I think we’re exporting about 70 percent of what we produce each year. If we can use more of it in Sweden, that’s good. And we have a sufficient amount of wood in Sweden to build houses,” Hyllengren says.

Mass timber meets the five-minute city

For Stockholm Wood City to live up to its hype, it will have to promise far more than a 40% reduction in embodied emissions relative to steel and concrete. And it will have to bill itself as more than an “ambitious sustainability project” that benefits “people’s health and well-being.” In the mass timber game, that’s old hat. For this project to matter, its impacts will need to span generations.

Atrium Ljungberg has made the redevelopment of Sickla—formerly an industrial area of mid-rise factories and modest brick homes—a cornerstone of its business model. The mostly undeveloped parcel of land that Stockholm Wood City will eventually occupy has been on the company’s books since 1997. But the infrastructure that will feed into this new development is already largely in place. High- and medium-density development, which includes existing offices, homes, schools, healthcare, cultural facilities, hotels, and access to nature, has already yielded what the developer calls a “5-minute city” (a clever bit of one-upmanship on the popular 15-Minute City concept), where everything one could need is conceivably just a five-minute walk away.

While Stockholm Wood City doesn’t yet have a master plan or even the necessary zoning approvals to move forward (zoning planning is currently ongoing at select sites, according to Hyllengren), the larger design and development team doesn’t appear concerned. Danish architecture firm Henning Larsen and Swedish firm White Arkitekter are collaborating on the broader design scope that will include buildings with green roofs, PV arrays, and large high-performance windows. Additionally, the proposed neighborhood will further “minimize its climate impact” with the use of “internally produced, stored, and shared energy” and “underground borehole energy storage for heating and cooling.” (Translation: a district energy system and geothermal heat pumps.)

But any 15-Minute City (or 5) can never truly be so without robust public transit. Currently, a tram line and railroad already connect to the area, and an expansion of the Stockholm Metro is planned for Sickla by 2030. “So, there will be three different public transport options for this area,” Hyllengren says. He adds, “We are working hard to reduce the uses of cars to the area. Our focus is on services and safety, having a good mixture of offices and residential and culture, all the things that make a livable city.”

In light of this proposed urban development, for which there really is no precedent, skeptics will – and should – take its stakeholders to task. After all, building anything big and new and calling it the solution to our woes (or at least part of the solution) is about as brazen a gesture there is. But build anew we must, to varying degrees, and if we must, then let us do so on a scale that both minimizes the long-term impacts of manufacturing and construction as well as services as many people as possible in a manner that is clean, efficient, and equitable.

Indeed, we can’t build our way out of the climate crisis. But something as grand as Stockholm Wood City can, in theory, provide a new kind of foundation for sustainable development and urbanization on which future innovators may design said solutions. It’s not a panacea, but it’s also far from nothing.

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Justin R. Wolf is a Maine-based writer who covers green building trends and energy policy.