The two floors added to this 1950s building on Pâquis Street necessarily transformed its image: the difference between old and new is clearly expressed. The added volume consists of a wooden frame supported by tree trunks. On the new façade, the windows develop like a Chinese folding screen, contrasting with the flatness of the building below. The top-floor loft, organized around an earth made wall that acts as a thermal and hygrothermal regulator, is designed for exemplary environmental performance.