Why wood will play an even greater role in construction
Wood has obvious advantages as a building material, both in terms of reducing the building’s environmental and carbon footprint, but also in terms of creating robust, durable and healthy homes. However, several factors are hindering an increase in the use of wood, explains one expert.
Our buildings and building style reflect the possibilities and limitations that our country and landscape have historically had. In Norway and Sweden, where the subsoil is rocky, there is an unsurprising love for wood as a building material and today wood in the two countries accounts for 20 per cent of the raw materials used in construction. On the other side of the Kattegat and the North Sea lies Denmark with its clay-rich soil, where in 2023 wood will account for just eight per cent of the raw materials used in construction.
"We can see from other countries that it is possible to build significantly more with wood. But construction in Denmark today is conditioned by a whole range of historical factors. For example, those who calculate a building in terms of static calculations, are largely used to doing so in concrete or similar products. They are not used to calculating with wood in the same way – yet. And this, along with other historical conditions, is a large part of the challenge in the short term," says Martin L. Petersen, vice chairman of the interest organisation Træ i Byggeriet and also CEO of the company Frøslev Træ A/S.
But despite the fact that building traditions are working against it, Martin L. Petersen is confident that in the coming years we will see an increasing proportion of wood in construction.
"It’s only in the last 10–15 years that we’ve really started to become aware of and talk about the ability of wood to help with climate challenges: that the more wood we use in our buildings, the more carbon capture there is. When the tree is in the forest, it absorbs carbon. When we then cut it down and use it in a building, we have a source of carbon storage. And out in the forest, where the tree used to be, a new one has now been planted. A renewable cycle occurs and wood is the only building material that renews itself in this way," he says.
EPDs make the comparison objective
For this very reason, wood as a building material has been increasing in momentum in the construction industry in recent years, as the demand (and requirements) for more sustainability in construction gains ground. Not least the demand for certified construction (the Nordic Swan Ecolabel, DGNB, BREEAM and LEED) is increasing the appetite for building with more wood, and the requirements for documentation in the form of environmental product declarations (EPDs) also favour wood, says Martin L. Petersen:
"EPDs take the entire process into account. As material manufacturers, we think this is great because you can start comparing building materials in a more objective way," he says.
According to Martin L. Petersen, the reason EPDs for building materials with wood often perform better than building materials based on other elements is also because EPDs are a tool for visualising the hierarchy between different materials. Here he emphasises the material pyramid, which, like the well-known food pyramid, indicates the respective climate and environmental impact of different building materials.
"The material pyramid indicates what is good to use more of in construction. We can't just use wood for everything. We can't just use concrete for everything, or steel for everything. Instead it has to be a mix. Most buildings are best when they are hybrids of several types of materials, he says.
He adds that neither EPDs nor LCA analyses are perfect today, because they assume that the wood will be burned off at the end of its service life, where it can typically be recycled. But he stresses that documentation is the way forward.
"Today we have an incredibly energy-efficient production of wood here in Denmark and throughout Europe. But we need to become even better at recycling wood, because then we get significantly better LCA analyses," he says, adding that using recycled wood in new construction will have a carbon footprint of 0 g/CO2.
Heading towards material passports
And when it comes to more reuse and recycling in construction, Martin L. Petersen points to the need to work systematically with material passports in construction:
"A major obstacle to the recycling of building materials today is that no one knows what exactly is in the materials they remove. New products today must have documentation for what is in them. The requirement for a so-called “material passport” is becoming more and more widespread. So our descendants, who will take hold of these materials and reuse them at some point in the future, will know exactly what is in the products and what they have been treated with," he says.
But if more wood is to be used in construction, old building habits must also be broken, and according to Martin L. Petersen, there are several advantages to wood that not all construction professionals are aware of:
“Building with wood often results in a faster and also drier construction process, because you don't have the same problems as with concrete that needs to dry,” he says.
In Norway and Sweden, workers also experience a cleaner and less noisy building site. Martin L. Pedersen adds further that the increased use of wood makes it possible to build higher:
"After all, wood is a lightweight building material. So you can build higher on existing foundations. In London, when they're building new buildings over there, they have many examples of how, as a rule of thumb, they can add an extra storey onto their building when they build with more wood. Because they can't just keep loading the subsoil over there. There they have underground railways and all sorts of other considerations," he says, adding that experience from London also shows that construction processes are shorter because the number of heavy hauls of construction equipment can be reduced compared to concrete construction.