Architecture has (re)discovered wood as a building material for urban spaces. In recent months, the two tallest wooden buildings in the world were built in Vienna, Austria, and Brumunddal in Norway. Plans are even underway for a skyscraper in Tokyo. There is much to be said for this building material, emphasizes Professor Johannes Konnerth from the University of Natural Resources and Life Sciences (BOKU) in Vienna. Using timber allows you to build faster and more efficiently – and also more environmentally friendly.
At the moment, the most common building material is cement – and as such, concrete. Its production process consumes large quantities of fossil fuels and releases vast amounts of CO2. Wood, on the other hand, is derived from CO2 from the atmosphere, sunlight, and rain. Conversion from trunk to plank and finally to the finished material requires less energy that’s generated from fossil fuels. Wood would thus be a more efficient building material and could cut CO2 emissions considerably, Konnerth explains. However, research still needs to be carried out before the breakthrough becomes a reality. He teaches at BOKU’s Institute of Wood Technology and Renewable Materials. Right now, he’s in the process of introducing two new research specializations there. His focus is on new production technologies and the intelligent properties of wood. Researcher Johannes Konnerth in an interview with Innovation Origins:
Load-bearing materials currently primarily used in Europe are glued laminated timber (GLT) and cross-laminated timber (CLT). Both materials are very safe, extremely versatile, and easy to calculate. Wood as a building material is already economically competitive, especially for large structures such as stadiums, halls, and swimming pools. The advantage over concrete and steel is its lighter weight combined with exceptional strength and rigidity. A dead load of a girder is also something that needs to be supported.
In classic multistory residential construction, the cost of the structural framework is currently around 10% higher than in classic concrete construction. This downside can be partially offset by substantially faster construction times. In addition, using wood also entails lower transport costs due to its relative lightness. Nevertheless, its financial disadvantage is often decisive.
There is still room for improvement in the production of the engineered woods mentioned above which could potentially have a massive impact on their overall cost price. The main problem is the low yield from each log. Tapered and bent trunks must be sawed down to produce square blocks according to the circle to square principle. The off-cuts account for about 50% and are sent to other value chains such as paper, furniture boards, or pellets. The planks are then dried and planed, which also leads to more wastage.
In the end, only about 25% to 45 % of a log is left over in terms of high-quality building material. Alternative manufacturing processes offer tremendous potential yet also pose a challenge. On the one hand, these should have GLT and CLT properties. While on the other, they should be able to significantly reduce wastage. This would enable the production of resource-efficient materials from wood which have an advantageous cost structure.