The Spanish architectural practice L35 Arquitectos designed a spacious leisure centre for the French village of Neydens just 9 km south-west of Geneva. The centre comprises a water park with indoor, outdoor and wellness facilities plus a sports centre, the heart of which is the climbing zone that extends over two storeys. The architects integrated the complex respectfully into the charming landscape of this region by reducing the volume of the structures, designing green roofs and choosing transparent envelopes. In order that visitors to the indoor pool can fully enjoy the surrounding landscape, the pool area is enclosed in transparent ETFE cushions supported by a timber space frame. The rise of the arched lattice girders decreases towards the middle of the building so that the outline of the building seen from the side is like a wave. On top of the max. 16 m high arch structure there are steel posts that support the aluminium framework for the cushions. Some 63 three-layer ETFE cushions up to 26 m long – a total area of 4500 m² – are mounted in this way.
These cushions have to follow not only the curve of the arch trusses, but also the twist due to the different radii of adjacent arches. Cushions also form the façade at the eastern gable. In order to guarantee a tangential line for the rigid perimeter connections of the cushions at the nodes, the line of the springing and the crest to the swimming pool building follow a curve. The long building housing the sports facilities also makes use of lightweight ETFE cushions so that a maximum amount of daylight reaches the climbing zone. In the centre of the green roof there is a rooflight in the shape of a trapezium on plan. Arched steel trusses with seven cushions span the 500 m² of this area. The structural steelwork rises higher in the middle, which results in a roof curving in two directions. The delicate construction gives the climbers underneath the impression that they are climbing under an open sky.
Details of successful ATEx (technical experimental assessment):
www.cstb.fr/actualites/english-webzine/anglais/june-2009/sports-and-leisure-under-air-cushions.html
