A wooden school centre for 1,000 pupils has been completed in the town of Limeil-Brévannes near Paris. The school centre, which covers an area of 9,500 m², contains three pre-school/day-care centres and two schools. France’s largest wooden school centre was designed by French architect Véronique Klimine and Finnish architect Olavi Koponen who is currently working in Grenoble. It was the first project that they had done together.
According to Koponen, building the school centre of wood was a requirement of the town’s leaders. Public wood construction is growing in France, as a result of the debate on the mitigation of climate change, the energy efficiency of construction and emissions from construction. According to the builder of the school centre, the competitiveness of wood construction is based on the shorter time required to install wooden elements on site compared to traditional construction. The landmark of the school building is a high triangular tower, which has on it a mermaid and octopus by Finnish artist Lauri Ahlgren.
A wooden school requested by the town
As the customer for the school centre, the town set an objective of at least a zero-energy building with an option for ‘plus-energy’ building, which would generate for itself more than its own energy requirement. And that is what happened. The building became a plus-energy house. The Pasteur Limeil-Brévannes School Centre has been built using the ’conception-construction’ method, in which competitors offer the plans and construction at a fixed price. The firm of architects bears complete responsibility for its offer.
According to Olavi Koponen, right from the start the leaders of the town had a key role and influence in building the school from wood.
”The Mayor wanted wood construction and the preference for the use of wood was expressed when the competition was announced. In France, the energy efficiency and ecology of construction are strongly highlighted in public building projects. The basic structures of the other firms participating in the competition were concrete, but we set out using wood in the structural elements of the building,” says Koponen.
”The work was done on a really tight schedule, which required fast decision-making throughout. If the firm was late, things were decided on-site,” says Koponen. Our demanding and key role as architects was to coordinate the regulation requirements for the engineers and other participants, and to combine them in the building in a feasible way. From the start of design to the completion of the building took 18 months.
Construction completed in a year
The school building has 2-3 storeys and all the hollow-core slab elements were brought to the site ready for installation. The German company Holzbau Amann GmbH supplied the wooden parts and systems for the building, and was also the main contractor in the project. The construction company also owns Lignotrend’s production of wooden components.
”The most demanding things in this project was the short period of time for construction,” says Tobias Döbele, Project Manager of Holzbau Amann. ”During the year, we implemented all the technical structural solutions and sound insulation based on the architectural plan, and we got different contractors to work together, first on a technical level prior to construction and then during construction on-site.
According to Döbele, the manufacture of the timber elements in a short period of time was challenging, but the problem was solved by doing two or three shifts in a day. Organising the transportation of the wooden parts from the Germany factory to the building site was also challenging.
”We wanted to get the elements to the site at just the right time, so that they could be installed directly from the truck. Whilst one truck was being loaded the other was on the road, so we avoided wasted time for both the transportation equipment and the installation engineers,” says Döbele describing the logistical challenges of the construction.
Focus of work on prefabrication
The school centre covers 9,500 m², measures 100 x 150 m and is the largest wooden building containing several schools in France. In the implemented solution, concrete has only been used in places where the building is partially against the ground and in the lift shafts. Otherwise it is made completely of wood, and the intermediate floors and upper bottoms are Lignotrend timber elements. The elements have a massive wood basic structure and a hollow-core slab made of timber, into which the building technology, electrical and internet connections have been fitted. The span of the longest timber elements in the school centre is nine metres. In the intermediate floors, concrete and sand have been used in order to ensure good sound insulation. The facade is larch treated with a graffiti-proof coating.
”The competitiveness and advantages of this kind of construction are particularly based on shorter installation time on-site for the timber elements compared to traditional bricks and mortar construction. The focus of the work in timber element construction shifts to the factory and industrial prefabrication,” says Tobias Döbele.
”This requires the technical details and other issues to be solved with the architects and subcontractors before starting the elements and the actual construction.”
A big change going on in construction
France is currently having a debate on the mitigation of climate change and the energy efficiency of and emissions from construction. Koponen believes that a major structural change in construction can be expected, once the EU regulations on energy efficiency come into full effect.
”Now that the functions of the Minister of the Environmental and Minister of Housing are looked after by the same minister in the French government, we can expect that environmental values will be increasingly emphasised in construction,” believes Koponen.
The major construction companies in France are traditionally concrete builders, which buy in wood construction expertise and carpentry products from outside. Up to now, wood construction has been prevalent in small houses and schools. A great deal of wood has also been used in sports halls and day-care centres, especially in the French Alps where wood construction has long traditions. Now wood construction is also coming to apartment blocks.
”The debate on energy efficiency and carbon footprints will increase wood construction in future, which is a major strategic policy,” predicts Koponen. “”The environmental impact of construction, energy efficiency norms and the rising price of concrete will lead to a situation where wood construction will be used to purchase space for concrete construction elsewhere. This means that each construction company will have to provide a certain amount of low-emission and energy-efficient construction, if they want to continue on the old road of concrete construction.”
Koponen says that, in wood construction, structures must be protected well from the weather during the construction phase. ”In concrete construction, much serious damage has been caused when the concrete structures have got wet. In wood construction, the building site must organise things better, but in the end everyone benefits from the speed and lightness of the construction.”
Wood construction expanding to apartment block construction
”For us, wood construction is obvious, because we are carpenters and come from a forest region. Wood construction is no ideology, it’s just normal for us,” says Tobias Döbele.
”Wood construction is clearly growing and in future the growth will especially be targeted at wooden apartment blocks and architecturally varied public construction as we are doing at the Pompidou Centre in Metz.”
The company has built not only the Pompidou Centre, but also a Paris exhibition centre for the Hermès fashion house, which used demanding curved glued timber structures.
”The Hermès project was more interior design that actual wood construction. The use of wood in the shelves, tables and staircases of the exhibition facilities and shops is part of the menu of the luxury brand, and in this project it was used more than usual.”
Wood construction expertise a calling card for the architects’ firm
A partner in the Grenoble-based r2k-architects firm, architect Véronique Klimine, says that in France attitudes have become more favourable towards wood construction. The firm has designed a wooden school and sports hall in Grenoble, where there is a desire to build more using wood. Klimine is sorry that there is no wood component industry or wood construction system supplier in the Grenoble area. Wooden products used in construction and wood construction systems are imported from Germany. The firm buys in the services of a wood engineer for structural component design.
”I want to develop a wood construction image for this firm, and communicate our expertise in wood construction,” says Klimine. “Wood construction expertise can be used as a calling card for an architects’ firm. Since there are not many architects’ firms in France operating in the wood construction market, the new school centre serves as a good reference for us in the field of conceptual architecture. We feel we are now one of the credible operators in wood construction,” says Klimine.
”The end-result was good for the self-esteem of the firm. When the bar was set high right from the start and we didn’t flop, this was a big thing for us. Our credibility as a wood constructor was strengthened,” says Koponen.
Opportunities in the growth of wood construction are evident in France, for example in social housing production where local councils provide land and public funding is available for projects. The same building may contain social housing, rental housing and owner-occupier housing. In such cases, the customer, for example a local council, may set the level of how much wood the buildings must contain.
Puuinfo article service/Markku Laukkanen
Additional information:
Olavi Koponen, architect, +358 405000668, olavi.koponen@r2k-architecte.com
Véronique Klimine, architect, +33 476 12 25 30, veronique.klimine@r2k-architecte.com
Tobias Döbele, M.Sc. (Tech.), +49 7755 920118, t.doebele@holzbau-amann.de