Fifteen kilometers west of Montpellier, you have to go deep into the scrubland, on a dirt road, to reach the Mas Dieu ecopark. At first, you can only see, in the middle of the thick and verdant vegetation, rows of photovoltaic roofs supported by wooden poles, the first investment authorized by the mixed syndicate of local authorities which has managed the site since 2005. any landfill project, or even subdivision, after a long fight against the Montpellier conurbation.
At the end of the row, under two roofs covered with solar panels, earthen and wooden constructions are visible. It is a construction site of 2,000 m2 started more than two years ago, entirely ecological, baptized Macondo, name of the mythical village of A hundred years of lonelinessa novel by Gabriel García Márquez.
If it is ecological, it is not only to adapt to the constraints of the ecopark, whose charter imposes the use of natural materials, but to serve as support for an ambitious project. This consists of ” create a third place dedicated to the technical professions of the ecological transition, mainly housing “, starting from an experimental site, describes Anna Pautard, coordinator of the cooperative society of collective interest (scic) which brings together the occupants and the partners of Macondo. This third place would be open to entrepreneurs and associations, to become a “real work and training space with shared tools, everyone paying rent and living from their own activity”she continues.
The Montpellier scop Ecosec, specializing in dry toilets, initiator of the project, has joined forces with the Ecole de l’Etre, an association that trains unemployed young people in ecological transition professions, or the scop Les Zuts, manufacturer of tiny houses (little houses on wheels) autonomous, and, as partners, Enercoop Languedoc-Roussillon, green electricity cooperative, and Collaborative Joinery, shared workshop and training place open to professionals and individuals, based in Montpellier.
Once a thirty-two-year building lease, at a symbolic rent, was signed with the municipality of Montarnaud, owner of the land, the first step therefore consisted in building, for their own use, offices and a technical building, on a experimental mode, based on the circular economy, with clay found on site and the reuse of materials.
“We dug a trench on the site to drain the water, and with the earth, sifted and mixed with straw, we made bricks, as well as a plaster of earth and sand, to build the walls”, relates Benjamin Clouet, manager of Ecosec and president of the scic Macondo. The straw comes from a nearby stable.
At a time when traditional construction sites are experiencing delays, delivery problems and inflation in the price of raw materials, the solutions advocated by Macondo have advantages. The beams and windows come from construction sites in Montpellier, further afield in Nîmes, as part of a partnership with Demcy (Eiffage).
The wood for the frames, floors and facades comes from pallets decommissioned because they were not the right size, given by an integration company, Hérault Collecte, and then unnailed using a machine. Recovered from a Montpellier garage, large tires filled with raw earth serve as foundations for the walls that must be self-supporting.
Earth-straw, known for its insulation and thermal inertia capacities, is not the only natural resource used. A rainwater recycling network supplies the site. And the Ecosec dry toilets, the only ones allowed in the third place, fully autonomous, collect urine, rich in nitrogen and phosphorus, a recognized alternative to chemical fertilizers. Gold for the permaculture vegetable garden created on the site and for the ambitious natural air conditioning project: plant walls fed by gray water (dirty water evacuated from sinks, washbasins and showers, and then filtered) and fertilized by urine, once sterilized.
“We are conducting research to compare different processes and precisely measure the benefits in terms of cooling”explains Sophie Allebone, employee of Ecosec and president of the Calypso association which conducts the tests in situ.
According to Benjamin Clouet, who initiated these innovations in revegetation with two other companies, Ecofilae and Surya, within a common structure, Cycloasis, “with a green wall, the indoor temperature can be 11° lower than that outside”. To be compared with electric air conditioning, which consumes a lot of energy.
“The objective is to look for rustic, rudimentary technological solutions, adapted to the territory”, summarizes Simon Cossus, manager of the Enercoop Languedoc-Roussillon cooperative, associate partner of the scic. It is not surprising that the occupants of the third place are inspired by earthship (literally, vessel of the earth), a model of sustainable habitat, in circular economy, designed in the 1970s, and Low-tech Labs, these platforms collaborative forms that identify, design and share low technologies in all areas.
In their wake, the scop Les Zuts manufactures tiny houses self-sufficient in water and electricity, equipped with solar panels, a rainwater storage tank, or even a low-tech solar water heater and air heater made from reused materials. A few meters away, a carpenter, Emmanuel Cometto, an expert in wooden composters, has settled. And soon, a mobile bakery with a solar oven should see the light of day, whose project leader is accompanied by the third place.
From the start, the desire to transmit was there. “The construction site and the entire third place are also training materials”explains Kaïs Hannachi, who holds the reins of the School of Being created in Macondo a year and a half ago, with subsidies from the Occitanie region, the State and Foundations (Eiffage, Banque Populaire du Sud ).
On the model of its Toulouse big sister, it allows a free introduction to “green or greening professions”to unemployed young people, “school dropouts, or wondering about their orientation, or refugees”, during remobilization or pre-qualifying training sessions, describes the head of the association. On the menu, building mud-straw walls, creating a vegetable garden, sewing, recycling window frames…
On the model of its big sister in Toulouse, the Ecole de l’Etre created in Macondo allows unemployed young people a free introduction to “green or greening professions”
Nothing would have been possible without a building lease, on communal land, which “allows you to be in the shared use of the place, in self-construction, and to mobilize an integration project”, notes Benjamin Clouet. According to him, this device has also made it possible to overcome the ten-year guarantee (insurance for construction) which only covers new materials, not reuse. Unless an intermediary is responsible for guaranteeing what he sells for reuse.
Loans from the Banque Populaire du Sud and the Nef (220,000 euros) made it possible to finance the purchase of machine tools and the construction of the buildings, the rents paid by the occupants ensuring the repayment of the loans. Ademe and the Occitanie region have paid a grant of 90,000 euros for action research on re-employment as part of a call for projects. Ultimate recognition, the ANCT-France Tiers-lieu has decided to support Macondo as part of its “Proximity Manufacture” program.
The major issue: construction waste, which weighs 42.2 million tonnes in France, even more than household and similar waste (38 million tonnes), not to mention the energy consumed by the construction sector (44 % of the total in France) and its greenhouse gas emissions (123 million tonnes of CO2), according to Ademe.
However, reuse is known to be costly, “because you have to clean, repair or adapt what is recovered on a construction site”, says Tom Lamonerie, engineer from Enertech, a design office specializing in high-performance buildings. Question of assembly and organization, nuance the president of the scic Macondo, which ensures “to have carried out the construction at a price of 200 euros/m2instead of 700 euros/m2 on a regular construction site”.
The president of the scic Macondo ensures “to have carried out the construction at the price of 200 euros / m2instead of 700 euros/m2 on a regular construction site”
Everything could change with the RE2020 regulations which promote the circular economy, and even more so because of the current shortage of materials whose prices are soaring. “The more expensive they are, the more it will be worth reusing them”, predicts Tom Lamonerie. Beyond economic issues, “we must encourage reuse because it is very beneficial from an ecological point of view”says Marion Sié, product life cycle analyst, taking into account “transport, which is also an essential criterion: the lighter and more inexpensive a material, the more it must be recovered nearby. »
Bio-based and geo-based materials, in particular, should be preferred “provided that we adapt to the specificities of each territory, for example, take wooden elements from regions where there is a surplus so as not to compete with energy production, or favor unused waste, or agricultural co-products such as straw or hemp [la paille est un co-produit des céréales, par exemple, les graines étant le produit principal, destiné à l’alimentation humaine, NDLR], the priority being to leave to agriculture what it needs to develop. » For Benjamin Clouet, the next step is that “public procurement players impose these reuse and circular economy techniques”.