Eco-urbanism: passive houses take action

Eco-urbanism of the XXIe century exists and it is exciting. The brand new eco-hamlet Les Allouviers in Romette, a town associated with the town of Gap, is a synthesis of all the techniques that can be used to build harmony with nature. This exemplary project, carried by six families since 2012, includes six beautiful houses, where now live eighteen people, on a plot of 4,500 m² on a slope.

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Benjamin, a 34-year-old carpenter, receives in his large rounded living room, opening onto a local wooden deck, suspended from the breathtaking view of Gap: "I hallucinate on the comfort of this house. I made the initial investment, and since then I have been spending nothing or almost nothing: the house is working on its own. " He insists on the coherence of the whole hamlet: "We went to the end of the project, on insulation, consumption, materials, local sources, the balance between density and intimacy …"

These houses are at the same time bioclimatic, energy passive, built with ecological materials produced locally, and are part of a dynamic of collective construction and shared habitat. For the Build Green site, this eco-hamlet represents "One of the most relevant achievements" observed so far: "Difficult to find defects, bioclimatic design, choice of materials, mutualisation, we approach perfection." The project is a laureate – category new housing – grand prize for sustainable construction and development, awarded by the department and the Council of Architecture, Urban Planning and Environment (CAUE) Hautes-Alpes.

"A lifetime of knowledge"

It is Romuald Marlin, 64 years old, high-alpine architect militant and long-time committed in the bioclimatic habitat, who designed these six houses, of which he shares with his companion, Marie. In the morning of late December, after a night of freezing, some flakes flutter behind the large windows but it is good in their home with harmonious and warm lines, walls covered with earth-clay or ash, floors covered with floors and or seagrass: 18.5 degrees everywhere, even near windows. And yet, smiles Marie, "We have not heated for forty-eight hours. We only use our wood stove if we have three days without sun.

The shared habitat Les Allouviers in Romette (Hautes-Alpes) designed using eco-materials and renewable energies, 21-12-18. ORDER N ° 2018-1773Photo Pablo Chignard. Hans Lucas

Romuald Marlin details the conjunction of techniques that allow this result vaguely miraculous, without ostentation: it is the fruit of "A lifetime of knowledge", he concedes it at most … Everything seems obvious and logical, every detail fits into the whole. Let's go back point by point.

The houses in the hamlet of Les Allouviers are bioclimatic: the six families chose a south-facing plot, a few kilometers from downtown Gap, for easy access by bicycle and public transport. The buildings are oriented to be protected from the prevailing winds of the north and to make the most of the contributions of the sun: the living rooms open to the south, the rooms, dressing rooms and cellars are in the north, without big openings but lit by wells. light. The design of the houses has minimized earthworks and the impact on the topography of the land. The majority of them are even built on piles, in order to avoid the heavy concrete foundations, material very expensive in energy for its manufacture (the "gray" energy).

Greenhouse heating

The houses are also "passive": their energy performance is maximum thanks to their perfect insulation (walls of 40 centimeters thick, entrance doors with airlock, triple glazing including a low emissivity outer face) and their ventilation systems double-flow, compact and efficient (the air sucked into the house transmits, before being discharged outside, 98% of its energy to the air entering through small vents). The rooms are heated by external solar gains, greenhouse effect through the windows and energy-sensing walls, which charge the sun's heat during the day, and restore it inside the house. night. The kitchen, the human warmth and the small stove provide the rest. The hot water is essentially solar, the rainwater is recovered and reused at the sink, the bulbs are LEDs, the toilets are dry …

Pierre and Sylvie, in the terraced house, are the oldest occupants of the hamlet: in one year of life here, they burned less than half a stere of wood in total, and their water consumption dropped to 3 m3 per month. They are equipped with photovoltaic panels and produce twice as much electricity as they consume. They themselves are amazed by these reduced consumptions: "This house drives us to be virtuous!"

The six buildings were built with biobased materials, with very low energy gray so, and recyclable. Wooden structure, hemp wool insulation, wood fiber insulation, rice husk insulation, untreated raw wood exterior siding, natural clay and ocher cladding, terracotta tiles, etc. : the proportion of ecomaterials reaches 80% of the total! In addition, almost all of them have been produced or recovered in the surrounding area, less than 50 kilometers away, and all of the companies contacted are local. The site's carbon footprint is exceptionally low …

The hamlet is finally a collective project, concerted, negotiated and chiselled in common, which allowed substantial savings in cost and space. The six families, made up of a civil real estate partnership (SCIA), bought the land together – 70,000 euros per household – were able to force ERDF to bury the medium-voltage line crossing their plot and to file a building permit. unique. Shared purchases have made it possible to eliminate the additional costs of certain biobased materials and energy devices. In the end, each of the houses, which range from 97 to 134 m², will have cost from 1 800 to 2 100 euros per square meter, depending on the degree of personal investment of each one in the works … and the inhabitants of the hamlet have many worked by themselves, learned a lot, supporting each other in turn for the insulation and finishing phases.

House for friends

The SCIA will be dissolved, with each home recovering its home and a minimal parcel around the walls. The remainder of the land remains shared with its terraced gardens, its collective parking, its roads carefully thought to allow the exchange and meetings without ever imposing them, and its collective premises in the process of finishing: laundry, dryer and small light house on stilts with eighteen sleeping for friends.

For Romuald Marlin, "To propose a new form of urban planning is also to develop another living together, pool the efforts and costs of construction, participate in joint work, share and exchange services and equipment"… If he is happy to see his bioclimatic conceptions – finally – welcomed, he has little illusions: "It remains marginal. 90% of the new build is "concrete-polystyrene", including on the side of local authorities. The only thing that matters is the cost of initial construction … while the future cost of bioclimatic is very virtuous! " With a gesture, he points to the city below: "For each house, it is 2,000 euros of fuel oil or gas per year … However, the logic of our hamlet is transposable to renovation in urban areas. The field of possibilities is exciting, but it remains ignored. "

François Carrel Special Envoy to Gap (Hautes-Alpes) Photos Pablo Chignard. Hans Lucas

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