The Research of light and lightness
Sanaa’s architecture is characterized by lightness and sleek precision, economy of means, delicate transparency, energy efficiency and an open fluidity that encourages exchanges. Rarely have architects gone to such lengths in their sense of detail. Every element is calibrated with millimetric precision, such as the miniscule screen-printed dots on the façade of La Samaritaine, which are never identical. The shapes designed by Sanaa are never completely regular: the canopy over the patio is neither perfectly oval nor perfectly flat, and the studied asymmetry of the folds in the façade evoke the natural draping of a veil. Sanaa worked with meticulous precision on the reflections of the Rue de Rivoli façade viewed from every angle to create a dynamic, aquatic texture. A line by French poet Philippe Jaccottet elegantly encapsulates their architecture: “effaced so that I might shine.”
La Samaritaine’s contemporary façade on Rue de Rivoli is a masterpiece that combines the sense of simplicity, passion for detail and poetic inspiration of the Sanaa studio’s architects. The rippling glass façade – the most visible component – is the outer envelope of a triple glass skin that functions as the Rivoli building’s core and shell, as well as providing its thermal regulation and fire resistance capabilities. The outer façade of the building has an irregular undulating form, and comprises 343 curved, screen-printed glass panels measuring 2.7 by 3.5 meters, and weighing between 600 and 1,250 kg. The panels rest on just four support points, giving them the appearance of being balanced in position. The construction of the façade constitutes an amazing feat of complexity and precision in itself, combining laminated float glass from Pilkington of England, chromium treatment in Germany by Interpane, custom-tailored bending by Cricursa in Spain, and installation by the Italian glass façade specialists Frener & Reifer. The chrome screen prints on the curved external panels, and the white screen prints on the straight internal panels, made up of rasterized points measuring approximately 1 millimeter, vary on the different floors and depending on the orientation of the façade panels. By modulating the incoming daylight, this design choice ensures optimum natural lighting, and reduces the solar factor (and therefore its contribution to heating). In addition, Sanaa has conducted detailed studies into attenuation of the Moiré effect, achieved by ensuring that the screen print patterns are out of alignment with each other. Finally, a series of samples, mockups and prototypes was developed to precisely define the unique texture of reflections that gives the building its soft appearance.
Sanaa has re-interpreted Jourdain’s taste for light by supplementing the route leading to the historic glass roof with a patio covered by a glass umbrella in the Rivoli entrance, and a dome rising to the height of the second floor in the Jourdain building patio. The umbrella, designed by Sanaa, magically conceals the support structures to appear as a glass oval suspended above the Rivoli patio. The apparently simple dome, meanwhile, conceals an array of engineering marvels that deliver 13-meter spans with no intermediate support points.