Making the most of Switzerland’s wood

However, little is known about how much wood is available for all of these desired applications and in what form. To shed light on this issue, researchers from Empa and WSL have now conducted a comprehensive analysis of all recorded wood material flows in Switzerland. Their research, recently published in the journal Industrial Ecology, was conducted as part of the ETH Domain joint initiative SCENE (see box).

Rich data for accurate assessment

During the analysis, the researchers used 2020 data from 21 different sources, which was a methodological challenge because the numbers in the various sources did not always match. Wood is a diverse raw material that can take many forms from harvest to use, often varying in volume and moisture content: logs, sawn timber, wood chips, wood pulp for the paper industry, and more. Therefore, coordinating different material flows is a difficult task.

But the effort is worth it. “Similar studies abroad rely heavily on models. They have data on the amount of wood harvested in forests and use these data to calculate subsequent material flows,” said the study’s lead author Nadia of Empa’s Technology and Society Laboratory. · Nadia Malinverno explains. The Empa team, on the other hand, uses “real” data almost from start to finish, from timber harvesting, import and export to processing, recycling and disposal. Malin Furneau stresses that this results in a more accurate image – albeit not a perfect one. “We must thank our colleagues at WSL and the Federal Office for the Environment (FOEN) in Switzerland for providing good data,” adds co-author Claudia Som, researcher at Empa.

Wood should remain in wood condition for as long as possible

Conclusion: Switzerland still has great potential for the sustainable use of wood. For example, wood is recycled at just under 8%, while paper is recycled at around 70%. What’s more: “About 40% of the five to seven million cubic meters of wood harvested in Switzerland each year is used directly for energy – in other words, it is burned,” says Malinverno. Researchers agree that this is far from ideal. Because: “Wood has to fulfill its function as a long-term carbon dioxide₂ Sink, it should remain as a material in the technical field for as long as possible,” Som explains.

The vision of the researchers and the SCENE project is the so-called layered use of wood. In this method, harvested trees are first processed into the largest possible high-quality products, such as beams and slabs for construction. The wood should then be (re)used for this function for as long as possible. Only when reuse is no longer feasible is the wood broken down into the next material stage, such as smaller boards, chips or wood materials. It should only enter the furnace if it can no longer be used as a material.

This is just one possible example of a wooden ladder. As part of SCENE, researchers want to investigate in more detail which uses of wood make the most sense from an ecological and economic perspective. One of their goals is to carefully study selected material flows: In what form does wood exist in a specific flow? Where exactly is it produced? How to treat? How else can it be used? Nadia Malinverno, Claudia Som and their research colleagues will study these questions in the coming years.