Environmental issues have become a major concern in public awareness. This was shown by a 2023 study by the European Investment Bank, which ranked global warming as the second biggest concern for Belgians. But between concern and deep understanding, there is another step we still have to take. Understanding environmental issues and determining our individual and collective scope of action are some of the major challenges facing our society today.
We are in the construction sector, which generates one third of European CO₂ emissions, so we are able to play a key role in guiding this industry towards greater sustainability.
The materials used in a building’s structure represent approximately one third of its carbon impact over its life cycle. If we are to reduce this proportion, we must rethink our habits, which are still widely influenced by industrialisation.
Redesigning materials to reduce impact
Concrete, masonry blocks and steel are still very rooted in the culture of Belgian builders. At Wow, our day-to-day work involves demonstrating that it is possible to build differently and select better construction techniques depending on their intended use.
Concrete, which is stable in damp environments but very energy-intensive to produce, should only be used underground or for foundations. Steel is also produced by a high-polluting industry and should be reserved for situations where its very high resistance is essential.
Biosourced alternatives may be preferable everywhere else. In particular, modern wood-based materials such as glued laminated timber, CLT (cross-laminated timber) or GLVL (glued laminated veneer lumber) provide exceptional mechanical performance which, if mastered, can perfectly meet the needs of modern buildings. Solutions based on raw earth, for example, are also suitable for many situations.
The choice of structural materials can no longer be guided by habit alone; it must result from an overall consideration of the environmental impact, price, durability, and architectural and functional coherence.
The practical example: the school La Brise
We were able to apply this structural design approach to the construction of the new École La Brise in Boitsfort, for which we are the design engineers.
The foundations and semi-buried ground floor are made of concrete, masonry and prefabricated slabs. The apron distributes the loads on the ground and the flat slab covering the ground floor forms the foundation of the timber structure. Resting only on a series of columns, this slab creates very open, versatile spaces that can evolve over the life of the building.
The geometry of the complex housing the classrooms on the first and second floors was designed together with the architects (R2D2 Architecture) to create an economical timber structure. Here, the wood blends perfectly with the architecture, combining aesthetics, efficiency and minimal carbon impact. The 573 m³ of wood will even store 470 tonnes of CO2 captured from the air during the trees’ growth.
The floors and roofs are made of ribbed CLT, a combination of CLT panels and glued laminated ribs, enabling large spans to be covered with a minimum amount of material. They are supported by a mixed structure which alternates between timber posts and beams and CLT walls, depending on architectural requirements and the constraints of resistance to horizontal wind loads.
All the wood was PEFC-certified, guaranteeing its sustainable and responsible origin.
The result is a meaningful project and we are convinced that it will soon give great satisfaction to successive generations of pupils. It is also an exemplary demonstration that it is not only possible but also effective to integrate environmental considerations into the design process.
An article by Martin Guillaume, project engineer at Ney & Partners Wow
