Architects Hermann & Valentiny et Associés, Jim Clemes, and Witry & Witry have designed a spa-cum-sports centre at Strassen-Bertrange in Luxembourg. “Les Thermes” is a large complex including swimming pools, a fitness and a wellness area, a restaurant and outdoor facilities for sports and games. The site lies between a small industrial estate and a residential area. The building shell was made to turn its back on the industrial landscape and concentrate its windows on the residential side and intervening greenery. The whole elliptical structure is aligned north-south, maximizing use of daylight. The western elevation has two recesses gouged into it, offering certain rooms another view. Cement, laminated wood, glass and aluminium were the materials chosen, while indoor features are the cosy bamboo lining of the wellness area and the maroon padding of the pool and fitness zone. Depending on how one views it, the outside seems wrapped in an enfolding shell or suggests the wings of a theatre, glazed floor to ceiling, overlooking lawns and vegetation - a see-through effect and visual indoor/outdoor balance. Gleaming aluminium frames the clear glass apertures. The whole exterior is clad in rounded shingles and Prefa’s Prefalz ribbon in zinc grey. The rounded shingles lining the entranceways and ventilation tower are both lightweight and resistant - to frost, loads, wind and atmospheric corrosion. Originally designed as roofing, they can equally be employed on a façade, and adapt to the curvature of any bearing structure. Two alternative styles of mounting and a broad colour-range make for harmony and a pleasing look. The seaming lengthwise and crosswise ensures perfect weatherproofing. Double-seamed Prefalz ribbon was used to line the upper parts of the building where the pitch is slight, and also to close in the glazed portions of the thermal area. Prefalz is highly ductile, suitable for broad expanses raked from 5° upwards, and easily moulded to shape. It comes in 13 standard colours, the surface smooth or embossed. It also meets the highest safety standards even in extreme climates. Prefa linings are a guarantee of high performance, durability and ease of maintenance, but were here also chosen for their look: they pick out and highlight the innovatory shape of this whole spa complex.