Nebulous envelope out of glass: New SPG headquarters in Geneva
Client: Thierry Barbier-Muller, SPG - Asset Development
Architects: Giovanni Vaccarini Architetti
Location: Route de Chêne, Genf (CH)
The eight storeys of the office building cannot be made out from the outside. Rather, the structure seems shrouded in a thick haze that blurs all distinctions between outside and inside, thus preventing a clear view of the building. Yet the nebulous appearance does not belie the transparency of the material, and reflects the colours of the surroundings.
Transparent sheathe made of printed glass panels
What appears to be a thick and dense outer layer actually consists of a brise-soleil made up of glass fins anchored at irregular intervals to the fully-glazed outer walls. A steel structure made up of horizontal steel bands and frames lends rhythm to the entire facade. The glass fins range from between a complete storey in height to smaller dimensions. Produced in various sizes, the glass panels involved differ between 20, 40 and 60 cm in depth and are spaced apart at varying intervals. As they are also screen-printed, the sum total of all these effects is a blurring of the building's contour behind a shimmering, transparent envelope.
High energy efficiency
The architect Giovanni Vaccarini emphasizes that the main intention behind this solution was to improve the quality of the work spaces, particularly in terms of shielding them from sunlight. However, as the SPG headquarters is located at the edge of the old quarter of Geneva, the building also had to express a certain degree of visual permeability. The glazed façade incorporating four layers of glass meets all these requirements and at the same time plays an instrumental role in ensuring a high degree of energy efficiency. Triple-insulated glazing forms the innermost layer of the new envelope, followed by a ventilated space that contains finely-perforated blinds, and finally by the fourth glass layer. Although 100 tons of glass have been added to the building altogether, the load transfer elements have been made as inconspicuous as possible. Merely the above-mentioned steel structure lends the façade a certain degree of visual weight and definition.
The way in which the appearance of the building changes is a final special feature, with the sun affecting the way it looks with the passing of the day. At night, the brise-soleil is lit by white LEDs – an effect that recalls a giant luminaire while making the building shimmer in dialogue with the surrounding urban landscape.