In Lozère, renovating old buildings with bio-geosourced materials is becoming a challenge

Bio-geosourced materials, such as straw, provide better insulation and, thus, heat less. MAXPPP – FLOUR Valérie

The Departmental Union of Energy and Equipment (SDEE) of Lozère organized, this Tuesday, May 28, 2024, a morning dedicated to bio-geosourced materials.

"In Lozère, 60% of rental housing has an Energy Performance Diagnosis (DPE)F or G, the worst possible grades. Soon, it will no longer be possible to rent them", worries Caroline Entraygues, architect and director of the Council of Architecture, Urban Planning andamp; rsquo;environment (CAUE) of Lozère. Energy renovation is a major subject in the department. It is increasing with galloping inflation and the cost of energy. Enough to raise concerns. We must therefore look for solutions very quickly. Especially since 45% of housing in Lozère is classified as “old building”, because it was built before 1948.

According to Caroline Entraygues, old buildings interact with the environment. "They need to breathe and for that, a renovation must be carried out using old methods and natural materials. Otherwise, there is a great risk of humidity, which risks rotting and damaging the structure, as well as the health of the occupants." In other words In other words, using industrial or transformed materials to renovate the home is not suitable and risks unbalancing the whole. And does not ensure continuity over time.

Faced with this major challenge, the Departmental Union of Energy and Equipment (SDEE) of Lozère organized a morning, Tuesday May 28, 2024, devoted to materials bio-geosourced. These come from nature and come from local soils. Three speakers took turns to present those used in the building to around fifty people. "The idea of ​​this event is to show that there are alternative solutions with sectors that are trying to structure themselves, reports Alain Astruc, president of the SDEE and president of the Association of Mayors of France (AMF) in Lozère. We have already organized a training day on insulation with straw."

More expensive but more durable

Whether it is straw, hemp or raw earth, rehabilitation or energy renovation work generally takes longer than with the new more industrial techniques. The cost is also higher at the time of the work, but not if we plan into the future. "These natural insulators can perform their function much longer if the work carried out is of quality. There will be less maintenance in the end", continues Caroline Entraygues. Generally, this type of work contributes to sustaining the local and circular economy.

Comfort and feeling were also highlighted. The properties of bio-geosourced materials make it possible to insulate better and thus heat less. "By insulating with the lime-hemp mixture, we can make significant savings on heating and air conditioning", says Rémy Chorda, ex- president of the National Hemp School of Mende.

In abundance

Another advantage of these materials, and not the least, is their abundance. "Five million tonnes of straw are available per year in France without competing with other uses", explains Coralie Garcia, administrator of the French Straw Construction Network. It is the same for the exploitable earth, which is found in abundance, one meter under the layer of humus. "Almost all land is suitable for one or more of the construction techniques", underlines Aymone Nicolas, craftswoman and member of the confederation in raw earth. And for hemp, France is the leading European producer with 21,700 hectares of cultivation in 2022.

Finally, and at a time when practices must change to deal with global warming, the use of natural materials to renovate old buildings is becoming almost essential. Laurent Llinas, general director of SDEE, states: "The challenge is the ecological transition with taking into account the’ rsquo;environment."

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