Arc en ciel by Bernard Bühler in Bordeaux, France

The "Arc en ciel" project designed by the agence Bernard Bühler stands at the entrance to the Grand Parc district of Bordeaux, at the corner of rue Portmann, rue Huyard and avenue Émile Counord. With its bright colours, the building wakes up Bordeaux tram users. The programme comprises some forty homes along with offices.

The practice repeats its principle for defining the building's levels (see the article of 16 April). At the base of the structure, some thirty parking spaces are spread over two levels and screened by metal grilles. These protect residents against theft and will later serve as a framework for climbing plants.

The first floor houses offices. Fully glazed, it marks the transition between the various circulation flows and the housing. The top five levels are given over to homes. The concrete structure is concealed behind multicoloured Stadip laminated glass blades, with only the slab-edge facings (planelles) of the horizontal structural elements left visible. The effect is to create a buffer between the homes and the neighbourhood.

The rhythm of the façades is broken by "glazed bow windows" that project from three elevations. Terraces sit behind them, giving residents unobstructed views while keeping them out of their neighbours' sight. On the fourth façade, the coloured boxes line up flush with the elevation.

The generously wide access galleries are meeting places for residents, set apart from the dwellings so as to create a void. The aim was to design dual-aspect flats, which would hardly work if the galleries ran right up against the openings.

Note that the living rooms systematically face the loggias, allowing the flats to receive all the natural light they need. The glass blades are spaced according to need, and the air gap between them makes the building a light, airy structure. The architects wanted to convey a sense of movement that accompanies the tram on its journey.