Jean Nouvel

The façade of the Renaissance hotel in L’Hospitalet has a peculiar thermal behaviour. It is based on retarding thermal loss with the concrete wall (thermal inertia), while minimizing the thermal difference between the two sides of this wall with a closed air cavity on its outer side. This closed air cavity has its thermal insulation improved by a reflective membrane coating one of its sides. Thermal gain in summer is controlled by the reflective capacity of the white serigraphy in the glass and, again, the reflective membrane.

It is difficult to understand the need for building this thick, load bearing, cast in-situ concrete wall hidden behind a light cladding composed of different layers: mineral wool, coloured ribbed plates and glass slats. On the inside, the concrete wall is again hidden, on this occasion by furniture. The climbing formwork system that made this wall possible had to be successively cut to adapt to the changes in the diameter and curvature of the tower. The preparation of the reinforcement must have been equally difficult.

Saint Paul's Crossing building is a good example of using various façade solutions for a continuous glass skin.