What is the current context around emissions in the building sector, and what reluctance do you perceive to adopt biomaterials?
The context is changing rapidly in Switzerland and the emphasis is increasingly placed on reducing emissions. For example, carbon targets and limits will soon be integrated into standards (MOPEC, SIA, CECB). Players in the sector are increasingly committed to limiting carbon emissions from buildings.
As for the storage of biogenic carbon, the subject remains debated, because during a life cycle analysis, the standards force us to count everything that is stored, but also removed from storage at the end of the building’s life, and we then assume very often that the biomaterials will all be burned, that they will release the stored carbon and that therefore, the result is zero.
So are we just postponing the problem?
Yes and no. We are aiming for 2050 with the net zero objective, and it is contradictory to assume that all buildings will be burned at the same time in 60 years, and that all the stored carbon will be released at once. If a solution needs to be found for the end of life of materials, why not seriously consider reuse or repurposing? Of course, this postpones the problem a little, but scientifically, storage allows the peak of emissions to be shifted, giving time for emission reductions to stabilize temperatures.
We are in the midst of a transition towards a “net zero” target to be achieved in around 25 years. To achieve this, the 2050 Energy Strategy relies, among other things, on CO2 capture technologies, the effectiveness of which remains to be proven. On the other hand, the use of biosourced materials in construction offers a concrete and effective solution.
Did anything surprise you during this Bioloop research work?
What surprised me is that certain biosourced materials can already be integrated into construction projects, although their standardization is still incomplete, leading to administrative and technical constraints. Their flammability and low density also pose challenges in fire safety, acoustic and thermal insulation. Combinations with geo-sourced materials, such as earth, however, make it possible to overcome some of these limitations. In Switzerland, certain actors have developed the necessary know-how and have produced concrete examples, but we are far from large-scale practice.
We also discovered that when it comes to biogenic carbon storage, it is not necessary to maximize the amount of wood in each building.
For example, a wooden frame instead of solid wood reduces the quantity of wood used per building, but allows the resource to be distributed over several constructions. This approach optimizes the use of wood at the scale of the building stock while offering the same overall storage benefit. The key is therefore to think in terms of the overall built stock, rather than focusing on individual structures. At the same time, it is essential to increase the rate of renovation by 2050 to reduce operational emissions, while paying attention to the materials used, in order to guarantee a consistent environmental impact.
The Bioloop project will end at the end of December 2024. What will you do next, as an individual?
I have started a thesis work exploring solutions for net zero buildings. Although the use of bio-based materials is a key element, it is not the only strategy. We must also think about the reuse of resources and overall design, including reducing the surface area built per person and optimizing the energy efficiency of buildings. Bioloop has focused on bio-based materials, but reaching net zero in construction requires much broader solutions.
