Bercy is a shopping centre and therefore, above all, has to be visible. It cannot fade into the urban background, but it needs to attract the attention on potential customers: a gleaming airship with the ramps of the motorway furled around it. The roof is made of 27.000 panels of perforated stainless steel, in 34 different sizes; under the roof we find the idea of the double skin to create an airspace that slows down the exchange of heat with the outside.