BBC Effinergie: wooden frame house in Lozère

Le show forum wood of Marvejols presents a BBC wooden house in Lozère

The first BBC-labeled wooden house in Lozère qualified as “the most waterproof house in France” (BBC: Bâtiment Basse Consommation)

In February 2010, the company ORLHAC sarl built the first wooden house with the BBC label in Lozère (Maison LAGLOIRE in Montrodat) according to the plans of the architect Nathalie Crépin. The results of the infiltrometry test (Q4 = 0,07) allowing the building to be labeled, present a performance much higher than that required for the BBC label (Q4 = 0,60) and even those of the PASSIVE label (Q4 = 0,20, XNUMX).

Tests passed with flying colors, this wooden house has been qualified as “the most waterproof house in France…” by SIRTEME, the certification body. The Grenelle 2 law, published in the official journal on July 13, 2010, aims to improve the energy efficiency of buildings and harmonize planning tools.

In view of this publication, this construction built in February was even avant-garde given the new regulations and test results.

Questions to Jean-Pierre Orlhac, builder and Nathalie Crépin, architect

CCI: Can you clarify what a BBC house is?

JPO: It's a low-energy house. The appellation BBC-Effinergie is an energy performance label constructions. It designates new buildings whose very low energy requirements (for heating, domestic hot water, ventilation, etc.) considerably reduce consumption and therefore the operating cost of the house, but also its gas emissions. Greenhouse effect.

NC: A BBC house also has every interest in respecting the criteria of a bioclimatic building to make the most of environmental contributions before resorting to technology (solar photovoltaic, solar thermal, heating system, etc.). Bioclimatism makes it possible to use, from the design of a house, the advantages of the microclimate of the installation site (sunshine, prevailing winds, ground inertia, etc.) without neglecting the human aspect of the project, that is to say - say functionality and comfort. A bioclimatic house must strive towards energy autonomy thanks to a symbiosis with its natural environment.

CCI: What are the difficulties in implementing this type of work? and what does an infiltrometry test consist of?

JPO: To achieve a high-performance and economical house from an energy point of view, healthy and comfortable for its occupants and at an acceptable cost, it is necessary to adopt a global approach from the design of the house.

In particular, attention will be paid to the compactness of the house, its orientation, the level of insulation of the walls and joinery, the airtightness, the choice of the ventilation and heating system.

Obtaining the BBC-Effinergie Label requires a very high level of insulation, but it also incorporates an imperative parameter: control of the airtightness of the walls. This involves eradicating parasitic cold air inlets, which can represent 25% of heat loss in traditional buildings (cold air inlets through outlets, on the perimeter of openings, through the roof, etc.).
The purpose of the infiltrometry test is to measure these leaks and parasitic air penetrations. To do this, we install a "blower door" and pressure sensors connected to a computer for controlling the measurements. The building is pressurized and depressed to simulate the effect of the wind on the exterior walls and thus measure the rate of air renewal through leaks. This test was carried out during the work (self-checking phase) and at the end of the work to check that the house meets the requirements of the BBC-Effinergie label.

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The results of the infiltrometry test are excellent (9 times better than the requirements of the BBC label, 3 times better than the MAISON PASSIVE label) and confirm the performance of the "Low Energy ORLHAC" timber frame wall developed by our office. 'internal studies, manufactured and implemented by the team of ORLHAC carpenters.

CCI: What are the difficulties in designing this type of project?

NC: The labeling of a BBC building is obtained following tests and studies mainly thermal and energy. The difficulty in the design of this type of building is that the thermal requirements must not take precedence over all the parameters relating to the design of the project: functionality, integration into the site, living comfort, and costs ... Mr. and Mrs. Lagloire is in this respect a success, because no aesthetic and functional concession (eg accessibility) has been made at the expense of its thermal performance.

CCI: Is wood a particularly suitable material for designing BBC homes?

JPO: That's absolutely correct. Timber construction, well designed and well controlled, is in an excellent position to meet the requirements of thermal performance and control of construction costs. Wood is also a natural, renewable and clean resource, which has a beneficial effect on the global warming potential: it allows a large amount of carbon to be stored; between 20 and 30 tonnes for a detached house.

NC: The advantages of designing a BBC wood frame house are multiple. This offers more freedom for the integration of windows or bioclimatic greenhouses. The wood also facilitates the junctions between the vertical walls, the horizontal walls and the openings. The building gains in consistency and therefore the thermal bridges and air are reduced. Thanks to a prefabrication in the wood frame workshop, the duration of the assembly on site is fast and the risks of approximation diminished.

CCI: A popular idea is to say that wooden buildings have a shorter lifespan than so-called “traditional” buildings (concrete, bricks, stone, etc.). What do you think ?

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JPO: There are no particular difficulties with the sustainability of wooden constructions. There are many examples in France and abroad. Here even, one of the oldest houses in Saint Chély d'Apcher, the house of Mlle BONNET, is a half-timbered house with a wooden load-bearing structure ... Of course, as with all building materials, wood requires good design and implementation know-how.

NC: This idea is understandable, here in Lozère, because historically the building material was stone. In regions (eg Alsace) or countries (eg Sweden) in which buildings were built of wood, this preconceived idea does not exist. There are buildings with several centuries built in half-timbering (ancestor of the wooden frame), or adobe houses.

CCI: Do you think that it is possible and profitable to design larger BBC buildings (semi-collective buildings, nurseries, schools, etc.)?

JPO: Of course. The search for thermal performance, control of operating and heating costs, well-being of occupants and respect for the environment is also present in collective buildings. The large BBC buildings appear here and there: social housing, schools, nurseries, administrative buildings. In 2009, we took part in the construction of a 350 m2 “Passive” administrative building: although it is located in an unfavorable climatic zone, this building does not need a traditional heating system or air conditioning.

NC: The larger the building, the easier it is to design it in BBC because the more compact the building can be made, the more it reduces the surface of the outer walls and therefore the sources of waste. Today, for example, I work on the design of a wooden dwelling in Ispagnac, which is common to several families. The combination of buildings allows a reduction of energy expenditure.

CCI: What is the future of the wooden house and the BBC in Lozère?

JPO: Environmental issues, energy management and changes in regulations will lead us to prefer low-energy buildings. To achieve this, wood will remain a reliable, comfortable, economical and environmentally friendly solution.

NC: Following this experience, I direct all my sites towards a tightness test because it brings a guarantee in the quality of the implementation. More companies will experience the BBC more this implementation attention to detail will become obvious.

Moreover, Lozère being the department with the lowest average temperature, the energy expenditure related to heating is important, so the return on investment is very fast. This should logically be very incentive for the development of the BBC in Lozère.

Questions to Mr and Mrs Lagloire, project leaders

CCI: Why and how did you come up with the idea of ​​building this type of house?

SL: At the start, we did not know the concept of BBC, we wanted a bioclimatic house integrated into our construction environment (semi-urban environment, Caussenarde atmosphere). We therefore called on Nathalie CREPIN who was aware of bioclimatism. She designed the house on these principles with the addition of accessibility constraints for a person in a wheelchair. On this basis, we filed the building permit on February 6, 2010 and obtained two months later. At this point, we still had no notion of the BBC.

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Subsequently, during a discussion with Mathieu COUDERC, responsible for renewable energies in the Department, we discovered the BBC and its financial advantages (energy savings and tax advantages).

Very quickly, we looked for information and local craftsmen to adapt our project to BBC requirements. We met the ORLHAC company, which was working on high energy performance wooden houses. The seriousness and motivation of this company decided us to embark on the BBC adventure. So we gathered all the companies we were considering working with and we told them about our BBC project and as no craftsman had any experience in this area, we asked them if they were willing to play the game and all of them said. accepted. We would also like to thank them again because they have been wonderful in the quality of their work.

CCI: Why wood? Is it easy to carry a wood house project in Lozère?

SL: My parents own a timber frame house that came directly from Germany and for thirty years since it has been built, it is still so comfortable and reasonably consuming in energy. Looking at the design of this house, we saw that the Germans were way ahead in timber construction.

CCI: How long did it take from the idea of ​​the project to the installation in your house?

SL: The idea of ​​the BBC stricto sensus project emerged on April 13, 2009 when we met Mathieu Couderc (the permit was already obtained) and we moved in on August 26.

CCI: Is there an additional cost in this project compared to a so-called “classic” house? Is it compensated and how?

SL: Basically, we had a house with an original design (ogive greenhouse), specific equipment (Canadian well, double flow ventilation, solar thermal, solar photovoltaic, sun screens), we used materials that are still little used. by craftsmen (wood wool, fermacell, larch tiles) which increases the cost compared to a so-called classic construction, but it was a personal choice.

The cost of the house is estimated at 1 600 € TTC / m2.

With experience, we have learned that you can still do BBC for a lower cost. In our opinion, the BBC is above all a reflection (often just common sense) on the orientation of the house, the insulation, the choice of materials and electrical equipment (ventilation in particular) and above all, above all, excellent quality. of implementation on parasitic air tightness and on this last point, the ORLHAC company has brilliantly shown that it is very competent.

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