Jean Nouvel

The façade of the Renaissance hotel in l’Hospitalet has a peculiar thermal behaviour. It is based on retarding thermal loses with the concrete wall –thermal inertia- while minimizing the thermal leap between the two sides of this wall with a closed air cavity at its outer side. This closed air cavity has its thermal insulation improved by a reflective membrane coating one of its sides. Thermal gains in summer are controlled by the reflective capacity of the white serigraphy in the glass and, again, the reflective membrane.

It is difficult to understand the need of building this thick, load bearing, cast in-situ concrete wall hidden behind a light cladding made of different layers: mineral wool; coloured ribbed plates; glass slats. In the inside, the concrete wall is again hidden, in this occasion by furniture. The climbing formwork system that made possible this wall had to be successively cut so as to be adapted to the changes on the diameter and curvature of the tower. Not less must have been the difficulty when preparing the reinforcement.

Saint Paul's Crossing building attracts our attention as an example of using different façades solutions for a continuous glassed skin.On the one hand, are used unitized prefabricated panels; on the second hand, a stick curtain wall system.If the first covers most of the façade surface combining single layer panels with double skin ventilated ones, according to the façade sun exposure; the second, the curtain wall, resorts to steel profiles to resolve those areas with higher mechanical requirements or geometrical complexity.