January 27, 2023
Sonya Angelica Diehn
Senior editor

Wood: renewable construction material of the future?

When you think "sustainability," building with wood isn'tnecessarily the first thing that comes to mind. But a deeper look at thegrowing trend begs the question: Could wood be a key sustainable resource ofour future?

Travel to a developing country, and once you get off the beaten path andout into any forested area, you are likely to see truckloads of felled treesbeing ferried away.

Wood comes from forests — so typically, timber is associated withdeforestation. And deforestation is a key environmental problem: not only doesit destroy ecosystems and habitat; it's also a major factor driving climate change .

So wood isn't an obvious choice for eco-friendly construction. But withman-made materials leaving a huge carbon footprint, wooden architecture isenjoying a resurgence.

It's even being touted as our only significant renewable constructionmaterial.

Secondary forests, sustainably managed.

To assess sustainability, the entire life cycle of a product must beconsidered. And that starts with the source. If primal forests are clear cut toprovide timber — be they in the Amazon, Indonesia or the Pacific Northwest ofthe United States — that does not represent a sustainable source.

But in many densely populated parts of the world, including in CentralEurope, people have used forests for many generations, and changed them in theprocess.

"Our European forests have been used for centuries, and are highlyhumanized in many ways," says Marc Palahí, director of the European ForestInstitute, an international research organization.

In Germany, for example, most forest is secondary, meaning it's been cutdown and has regrown.

Timber extraction meant German forests were already shrinking in the18th century, and foresters responded by considering how to manage themsustainably.

German forester Bernd Sommerhäuser explains the fundament of sustainableforestry: "What's used does not exceed what grows back — constantconservation is the goal."

Sommerhäuser says intervention in German forests isn't just sustainable— it's actually essential to preserve their biodiversity. "If we were toleave the forest over to itself here, it would normally develop into a stand ofpure beech trees."

Building carbon-neutral(ish)

Once upon a time, wood was a primary building material across much ofthe world. But with industrialization, that changed in the West.

German architect Arnim Seidel explains that steel and concrete becamethe dominant building materials for to meet 20th-century demands: wide bridges,tall buildings, heavy loads.

"Wood came to be seen as backwards," Seidel told DW.

Now, its environmental advantages are being recognized.

Materials like steel and concrete require massive amounts of energy to produce, and areusually transported over long distances. This emits CO2 that contributes toclimate change .

By some estimates, producing a ton of concrete, or about a cubic meter,generates 410 kilograms of CO2 equivalent — the same amount of energy couldpower an average house for more than 10 days.

Locally harvested wood from sustainably managed forests not only has amuch smaller carbon footprint in its production.

Using wood in buildings also sequesters carbon dioxide. When plantsperform photosynthesis, this removes CO2 from the atmosphere and stores it inthe wood.

"When we build with wood, we can conserve this stored CO2 for alonger period of time, and not emit it into the atmosphere," Seidel toldDW.

Building with wood, a growing trend

Wood has many benefits when it comes to construction: It's relativelylightweight and flexible, but also strong. It can be molded into variousshapes, and is easy to transport to construction sites. Seidel says thepossibilities of building with wood are virtually limitless.

Wooden skyscrapers are springing up in Canada, the United States and citiesacross Europe. Seidel describes these as "lighthouse projects" forsustainable building with wood.

But more mundane projects make up the bulk of wooden construction — evenif they draw less attention. In Germany, about a quarter of residential homesand apartment buildings are now being built out of wood.

For public relations consultant Susanne Roth, sustainability — includingcarbon sequestration — was a major reason to invest in a multistory cohousingapartment on the outskirts of Bonn.

Although there's not a lot of wood visible, the building — whichconsists of eight apartments — uses 190 cubic meters of wood, amounting to 190tons of CO2 pulled out of the atmosphere. That's equivalent to taking about 40cars off the road.

Building with wood involves highly developed, efficient technology,explains master carpenter Sebastian Adams, who's been hired to build theproject.

"Wood waste, for example unusable sizes and shapes, is pressed intoparticle board, which helps brace the building," Adams told DW.

Wooden buildings are stable, durable and safe, Adams says. Wood is notnearly as flammable as you might imagine — and working with other materialshelps encapsulate fire risks.

And there other advantages: "There's nothing so pleasant as walkingbarefoot over a nice, warm wooden floor. It also smells nice," Roth sayshappily.

Enough wood for a bioeconomy future?

So all is well and good with wood. Or is it?

Critics point out that wood is only as sustainable as its harvestingprocess. And that depends on sustainability certification schemes, which can have holes .

Then, there's only so much secondary forest that can be harvested andreplanted. So what happens when demand exceeds supply?

"We need to ensure that the few old forests we have in Europe —because in Europe, we have very few primal forests — are preserved," Palahísays.

So, no clear-cutting of old-growth forests. One possibility would be toplant more trees, which would also help the climate.

Palahí says we need to "compromise between using the forest forwood and at the same time preserving biodiversity."

Forests don’t just harbor biodiversity. They also protect water sourcesand sustain soils. Beyond that, they could increasingly provide the buildingblocks of the future bioeconomy — an economic system based on renewable,bio-based resources.

"European forests are important sources of renewable biologicalresources, which we will need to replace the existing petroleum-based steel andconcrete if we want to address the problem of climate change," Palahí says.