The renovation wave is upon us and that gives a new opportunity to choose sustainable. Not only through the renovation itself, but also through the materials we choose. With these, you can go quite original. Think eggshells, hemp or seaweed. How does that work, you ask?

Bio-based materials are what the word says: they are bio. They are partly or completely natural materials that absorb CO2. They also have a renewable origin: crops or plants can keep growing, they don't run out like fossil sources. So it is the source of the material that determines whether a material is bio-based.

Many of these materials also absorb CO2 from the environment, which is a big plus. That CO2 does get released back at some point (so it is not negative CO2 emissions, as is sometimes claimed), but is stored in the meantime. This gives room to work towards a better climate: if you combine the use of bio-based materials with a drastic approach to reduce CO2 emissions, this has a significant positive effect.

Another plus: bio-based materials simply already exist. Just think of wood and flax, which we have been using to build with for centuries. Moreover, agriculture produces a lot of crops that generate residual flows. We can use these for all kinds of purposes. With the current production of flax, 10 000 houses a year can already be insulated. So the bio-based materials are out there, that is a fact. Those who go for sustainability not only look at availability, but also at proximity: produce the materials close to where you use them, so that you do not create extra emissions through transport. 

So, how are they applied

If they are so good, why are they still not often used? There are several reasons for this. Often, contractors and property developers are not that familiar with these materials yet. The current way of building is highly standardised, meaning that everything is geared to the familiar materials such as cement and brick. Not only does this determine the choice in materials, but also prices, how contractors work, training, you name it. As a result, contractors often do not know how to factor in prices and risks.

For now, another stumbling block is certification. Any material put on the market has to be certified for structural safety, fire, health and environment. A lot of testing therefore precedes certification, which is a long and expensive process. Therefore, it is not always obvious to show certification for all materials, and this is often required for public buildings. A lot of bio-based materials have long proved their worth and are an important material in the building process. We can perfectly build a house made entirely of these materials without sacrificing quality. Just think of a foundation base, which must have a high load-bearing and insulating capacity, and must also be moisture-resistant: a complex combination for which a good bio-based solution is being sought today. The challenge for the construction sector therefore lies in finding and using the right materials in the right place. Bio-based materials are the future, so we benefit from testing them and using them wherever possible.