The Carnot Building was completed in 1997, when the École Nationale des Ponts et Chaussées moved from rue des Saints-Pères, where it had been based since the mid-18th century.It houses two schools, the school that became École des Ponts ParisTech on July 1, 2008 and École nationale supérieure de géographie (higher national school of geography), which is an offshoot of IGN (national geographical information institute).
It was decided that the two schools should combine to form a single whole. Two long, low glass buildings running parallel to the road are connected by an intersecting atrium.The courtyards formed by this arrangement are partially covered by two large curved roofs containing joint or separate premises.
The two schools are separated by the atrium:to the west, geographical sciences, to the east, occupying the largest share of the space, École des Ponts ParisTech. At the intersection of the two, the atrium serves as a meeting place and a showcase to the outside world.It is intersected by two 1500 m² vaults, beneath which are a restaurant, library and maproom.
In the middle of the atrium, a staircase runs down to the reception area leading into the Cauchy and Picard lecture halls and the multipurpose hall. On the upper levels, passageways connect the different buildings. The shape of the prisms is identical and mirror the structural principle governing the whole. Each of the three blocks is built on a mixed steel and concrete frame, to match the braced structure that supports the vaults.
This structure consists of a system of hangers that span the volume of the buildings and are distanced from these by means of diagonal braces that form banks of roof terraces.The hangers are anchored to the ground at the southern and northern facades or, where they run through the atrium, supported by internal cables that pre-stress the structure and form parabolic curves. This weblike structure is continuous: each of the parts depends on the others, none can be removed without destabilising the whole, like a vast motionless swing that balances the weather, light and atmospheric conditions for these two linked institutions. The roof of each prism is covered with aluminium strips that break up the sunlight and highlight the buildings.
Accentuating the linearity of the structure, the facades are formed of curtain walls punctuated horizontally at each floor level by hollow joints running the whole length of the building. Automated windows made of structural sealant glazing (SSG) slide along the outside, above patterned glass spandrels.The ground floor is slightly indented, to create a visual distinction between the buildings and the ground.
The great glass facades of the hall are suspended and shuttered internally by a cable system.
Client:Ministry of Infrastructure and Housing, DDE 77
Architects:Philippe Chaix, Jean-Paul Morel, Rémy Van Nieuwenhove, Benoît Sigros project leader
1% cultural component:Jean-Charles Blais, Pierre Buraglio
Surface area:30,000 m²
Plot size: 44,900 m²
Floor area for École des Ponts ParisTech :19,500 m²
Floor area for ENSG: 6,500 m²
Height:18 m - Length: 133 m - Width: 74 m
Jean-Charles Blais and Pierre Buraglio brought a touch of artistry to the building.On the transparent glass of the facade, Jean-Charles Blais devised an engraved double image representing the profile of a human face, which changes appearance in response to the play and intensity of the light.
In the hall, the floor engraving forms a sort of carpet, like a projected references to the images on the facades.Further down, in miniature, at the entrance to the Cauchy lecture hall, an engraved glass panel reproduces the same faces from the facade.
In the lecture hall, Pierre Buraglio has played on the formal and symbolic image of the rearview mirror, with a series of painted milky glass compositions called Paysages et marines au rétroviseur surrounded by brushed stainless steel, producing an effect of fragmented landscapes.
For the reception hall, above the figures on the ground, the artist created a coloured astral version of the sun and moon, devising a set of 10 enamelled metal discs, each 70 cm in diameter.
(Photo credits:B. Foucaud / École des Ponts ParisTech)