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Floating on the land

January 1st, 2014 / By: / Projects

ETFE is the solution for a lively French resort.

Located in Neydens, France, Vitam Parc is a 50,000-square-meter tourism destination that is part spa, part sports center and part shopping mall. Its new-age offerings include meditation rooms, climbing walls, a water park with indoor and outdoor swimming pools, a health spa, hotel, restaurants and a shopping area with a supermarket. There’s a variety of aquatic exercise programs, organized children’s games and even a “laser labyrinth” where kids can play at being a cat burglar, snaking their way between the beams.

For a project of this scale, transparent materials are essential to minimize its visual impact on the landscape and to bring light inside its cavernous, aquatic spaces. Founded in Barcelona, Spain, in 1967, L35 Arquitectos architects are specialists in destination shopping and leisure projects of this type; and they have built up a portfolio in Spain, France, Italy, Portugal, Morocco, Bulgaria and Turkey.

Based in Gersthofen, Germany, SEELE was responsible for design and construction of the roof. Having completed ETFE projects around the world for zoo pavilions, research centers, train stations, and, most prominently, Beijing’s National (Bird’s Nest) Stadium, SEELE is now increasingly working in France where ETFE is becoming popular.

Light, and lightweight

Architects Luisa Badía and Néstor Soldate from L35 explain that ETFE was the ideal choice to tie the immense building into the landscape. “Inside, the water slide area recreates an organic atmosphere with its geometry of sloping planes and its vegetation,” they say, “as if the hill located at the northern end of the site actually continued and extended right into the building.”

Green roofs blend the center into the rural landscape and help to absorb rainwater, reused as landscape irrigation. Waterpark visitors experience a strong sense of the changing light, passing clouds and vistas. At night, the aquatic center glows against the sky, its ETFE canopy resting above the wood space frame.

So far, L35 has used ETFE in two projects—at Vitam Parc and for the roof of the Islazul shopping center in Madrid, Spain—both pioneering ETFE applications in those regions. Luminosity and lightness of weight were key reasons for choosing it. Vitam Parc
features two ETFE roof coverings: the roof of the aquatic center and the skylight set in the green roof of the main building above the two-story climbing wall. The aquatic center’s ETFE roof is supported by an intricate wooden form in a wave-like shape. The wood structure supports 53 ETFE cushions with a total surface area of 4,300 square meters. The cushions range in size up to 22 meters high and 3.5 meters wide and are inflated at a pressure of 300 Pa with two DG 100 T air pumps.

Arched steel trusses span Vitam Parc’s dramatic rock climbing area and support seven cushions at the roof. The structural steelwork rises higher in the middle, allowing the roof to curve in two directions. The delicate construction gives climbers underneath the impression that they are ascending into an open sky.

The project’s ETFE cushions in the aquatic center and climbing wall are inflated with air at low pressure to provide an insulating layer against heat and cold and to withstand the effects of wind load. “ETFE responds well to the structural demands made of it,” Badía and Soldate say. This durability is “a factor worth bearing in mind in an alpine climate with cold and harsh winters, abundant snowfall and strong winds. Another advantage [of ETFE] for our project is its resistance to great variations in temperatures and chemical damage, such as from chlorine in the swimming pools.”

Explaining ETFE

Badía and Soldate explain that because of its light weight, ETFE has lower embedded energy costs in shipment and installation. The Vitam Parc project meets French HQE (High Environmental Quality) objectives by reducing the visual impact on the landscape through the organic “freedom of form” afforded by ETFE.

They add that ETFE allows for energy saving by “being an extremely sturdy polymer material that has good durability (high life expectancy of at least 25 years), high transparency (95 percent light permeability), and allows temperature control and good insulation thanks to its three-membrane configuration.”

Like the wooden structure, ETFE is also recyclable, an important consideration in green design.

L35 offers the following technical information on the fabrication of the ETFE bubbles and their attachment to the underlying structure, both key details for long-term durability:

“Each cushion or ‘bubble’ is made up of three layers of thermally welded ETFE membrane. The thickness of the two exterior layers is 250 μm (micrometers); the third interior layer is 100 μm. This configuration allows it to support exterior forces safely on its fixed structure. The pneumatic system forms a secondary system, while the wooden load-bearing structure or frame is the primary system.

“To ensure the air-tightness and water-tightness of the seals, the edge of each roof element or ETFE membrane cushion is edged with aluminum bolted to a piece of steel. This piece forms part of the primary structure.”

Economical and adaptable

For large sports facilities or greenhouses, ETFE is an effective material both for its 95 percent light permeability and its cost, which can be three times lower than traditional glass roofs. Remarkably, according to L35, ETFE weighs only 2 percent of what a traditional glass roof and structure might weigh. Because of its light weight and ease of handling, ETFE “has an impact on transportation and installation and therefore on the construction time,” the architects add. Its anti-adhesive qualities also make it less attractive to dirt and easier to clean.

Most important for destination tourism, ETFE air cushions offer adaptability to many playful and organic shapes—a great advantage for projects like this one that make a large footprint on an historic piece of countryside. Although only 10 km from the Swiss urban center of Geneva, Vitam’Parc offers a rural escape for families seeking a water park vacation or couples on a spa retreat. Its architecture is airy, expansive and festive—an effect achieved by a sophisticated blend of wood and metal structural design and a floating carpet of ETFE.

Vitam Parc is a hybrid project type that is largely unknown in the United States. If such projects come to North America, whether to warm tourist meccas like Orlando or winter cities like Minneapolis, ETFE cushions will likely play a part in the solution.

Frank Edgerton Martin, a regular contributor to
Fabric Architecture, writes frequently about landscapes and design for international design journals.

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