To renovate France, biosourced does not necessarily mean decarbonized!

That's almost a quarter of the emissions in the whole country. The challenge is therefore colossal: rapidly deploying solutions on a large scale with a low impact or even a positive impact for our planet. To do so, the public authorities have established THE miracle solution as a dogma, the use of biosourced materials.

However, is the diagnosis correct? I do not believe that. Above all, you have to ask yourself the right questions. If we refer to the building decarbonization levers proposed by the think tank The Shift Project, the recommendations are first of all to show sobriety in new constructions, to massiveize the global and efficient energy renovation or even to mobilize the building as a well of carbon. Insulation has a major role to play in renovation and for solidification, External Thermal Insulation (ITE) is the best placed to meet the needs. Its advantages are well established: clean and fast work that does not disturb the interior of housing, compatible with pre-industrialization, breaking of thermal bridges in floors, embellishment of facades, etc.

Indeed, this type of insulation is at the heart of many issues. The specifications are complete: to insulate thermally, acoustically and to embellish the facades. But also protect the building from fire risks, behave well in the event of earthquakes and avoid water infiltration or condensation problems which would reduce the performance of the insulation in place. As there is so much to do in such a short time, the sites must be quick and clean, all while meeting an acceptable budget! When we understand this, we realize that the solution to be provided is not simple, it is complex. And the ITE is best placed to respond.

Then, we quickly realize that the all-biosourced solution does not work for ITE. Why will you tell me? There are a multitude of biosourced insulators! From hemp to straw, passing through sheep's wool or even duck feathers, there is no shortage of choice. However, these solutions are now suitable for Interior Thermal Insulation (ITI), for a local market, as close as possible to the resource and indeed, in this context, it works! But the issue we are talking about is to insulate millions of homes at an unprecedented rate. All with an obligation of results (durability of materials) to achieve energy savings and thus prepare for real decarbonization. And this is where things get complicated for the biobased. As we speak, there is only one type of biosourced insulation that meets part of the demanding specifications that will really make it possible to decarbonize: wood fibre. It is the only one that presents both ACERMI certificate, Environmental and Health Declaration Sheet (FDES) and validity with regard to fire safety.

We summarize. We need to renovate buildings rather than build new ones. It is necessary to use the ITE (adapted to the massification) rather than the ITI (to be used when the ITE is not possible). It is necessary to have the guarantees that the ITE solution chosen lasts over the long term and compensates for its initial carbon impact in a few years maximum thanks to the savings it generates.

Before proposing a particular solution on a system that meets these requirements, it must begin by subjecting it to the exercise of massification. However, wood cladding and/or wood fiber alone cannot meet the challenge. It is easy to understand that a facing in wooden strips produced in the forests of the Morvan is not able to equip all the wooden facades of France! Same observation for wood fiber insulation. Indeed, imported and transported over long distances, wood then sees its carbon impact skyrocket. In other words, carrying out niche projects is good for the image of those who commission and execute them, but they are light years away from the challenge of carbon neutrality. Biosourced alone is not a solution for decarbonizing on a large scale: Using hybrid systems is a necessity!

To avoid falling into the “all-biosourced” trap, it is essential to look first and foremost at the impact of these materials on the planet. In this matter, the one and only justice of the peace can be summed up in four letters: FDES. Everything else is just subjectivity, emotion and religion. The Environmental and Health Declaration Sheets (FDES) are independently certified and list the CO2 emissions of all the components of a product, from the manufacture of its raw materials to its end of life, including its production, transport and implementation. Compare the FDES of ITE solutions, you may have surprises! Some systems presented as "biosourced and ecological" have a stronger carbon footprint than Myral systems, composed of polyurethane insulation, with a high content of recycled materials, resistant, easy to install, without a framework and more recognized durability 50 years old. It is therefore time to base your analysis on objective data to make the right diagnosis!

Through the game of blind subsidies, public authorities are forgetting the essential: it is the reduction of the carbon impact that counts, and not subscribing to a solution that is attractive at first sight but much more complex in reality. The use of biosourced materials can be one of the solutions to lower our emissions, but certainly not the only one. In addition, the frantic race for 100% biobased is accentuated by financial aid, no one takes the time to look at what really matters. And this short-term vision does not take us on the path to success against global warming. It's a snake biting its own tail.

Clients, architects, installers or manufacturers, we all have a role to play in raising public awareness of the need to mix solutions, arrive at intelligent compromises and innovate. Myral is committed to transparency. Soon, everyone will be able to compare our solution systems and their impact on the environment. To be enlightened before deciding. And to really, sustainably, massively and together reduce the building's carbon emissions.

Stop misconceptions! Let's ask ourselves the right questions, let's open our eyes, let's be honest and objective: to renovate France, biosourced does not necessarily mean low-carbon!

Tribune by Julien Bagnard, development manager Myral (LinkedIn).