Ecoquartier de la Gare - Cachan


Sustainable development neighbourhood,
Cachan, France

Competition 2022
MOA : Cachan city council, SGP
Architects : CoBe lead architects, SAME architectes, BECHU & associés, Atelier WOA
Team : Sylva conseil, sbp, eva, impact acoustic, Pouget consultants
Partners : palabreo, cmarue, le grand réservoir, collecticity, climate city, resallience, forestor
Floor area : 30.960m²
Cost : N/A
Labels : NF HQE Excellent, BREEAM bâtiment durable excellent, Biodiversity, E3C2, Bâtiment biosourcé engagement 3, BBCA

Renders and video : Engram

With the emergence of a new pole station, a new page opens for Cachan. Crescendo seizes this historic opportunity to give substance to an intense destination, mixing uses and mixing flows from all walks of life. He does this by betting, above all, for the Cachanais. Because the imperative of intensity is combined with the imperative of proximity: the eco-neighborhood is lived and inhabited on a daily basis, at all ages of life.

Crescendo also makes Cachan a city at the forefront of the ecological transition: wood construction, taking into account global warming, dereliction of the soil, new modes of movement, work, consumption. A requirement that results from a bet: that of the collective intelligence deployed by all the expertise mobilized, and by the Cachanais themselves, whose expectations irrigate the entire project.



The Guichon plot is facing the west exit of the station. Located at the crossroads of pedestrian and railway flows, it ensures the delicate transition between the existing fabric of the Quartier des Lumières and the new eco-district. We propose a division of the block into two entities whose positioning is carefully studied to contribute to the improvement of the public space along the rue de la Coopérative:
. the Project House located in the South and whose purpose is to make it an identity building for the Cachanais.
. the collective dwelling “Guichon” located opposite the Station. 

This division of the Guichon lot into two buildings, accompanied by the desire to return about half of the surface of the plot to the city, generates a new public square. We offer a long court to the inhabitants and want to develop associative programming. The work on the massing, the roofs and the series of epannelages formed by the Project House, the collective dwelling Guichon and the Cooperative lot allows the link between the new urban project and the old pavilion fabric.

The Project House plays a very important role for the Cachanaise community. This space is conceived and built totally for the city and its inhabitants as an extension of the public space. It is open on 4 sides, and extends over 3 levels: 1 basement including a large event room, a ground floor and a floor. Built with materials from the deconstruction of the site we highlight the uniqueness of this place using a particular language element: the bow. The latter echoes the history of Cachan by taking the archetypal form of the brick aqueduct. With its rounded forms, which host large bay windows, the building invites you to appropriate it. It wants to be welcoming, open and transparent.

The “Guichon” collective dwelling, located between the project house and the Coopérative block, has a sober and qualitative writing. Its massing is designed to distance the dwellings of the neighbors (station, pavilion). Guidance work is carried out on the following fronts:
. passageways follow the frame along its length. They not only provide sun protection on the east and west facades but also serve the housing from the outside.
The exterior west stairwell is treated with perforated metal to ensure a visual filter with surrounding buildings. This element, perfectly integrated into the architecture of the building, serves the dwellings while constituting a decorative element of the rear façade. The 8 housing units proposed are worked in a «tunnel». Accessible by common passageways, they open onto private balconies to the east. They are all crossing from the smallest typology, T1, to the largest, T5.
Our reflection on the materiality of the project focused on the search for the best compromises in order to achieve a decarbonized structure and an important use of biosourced materials. Convinced that this type of construction will be part of the traditional domain in the next decade, this project is an opportunity to raise the subject of dry and low-carbon construction by proposing a skeleton dominated wood and in harmony with the other lots of the project.
The mouldy structural work of the balconies restores the verticality of the lot while dialoguing with the lot Cooperative. The fine brick facade unifies the materials of the Project House and Guichon housing, built on both sides of the new urban square.


The South island stretches between the avenue Léon Eyrolles and the railway tracks for more than a hundred meters. It links the entrance to the eco-district to the south and the Place Verte to the north, which is located between the central and southern islets. It benefits from an East West orientation with two very different urban situations: to the east, the Avenue Léon Eyrolles, animated by an active base, the market facing it; In the west, the railway tracks and the embankment create a constraint which the project takes advantage of to offer both kinetic façades and pleasant housing.

The project’s bias is about unity and diversity. A common base whose sober and patterned writing lends itself to accommodate the active programs of the DRC and R+1 on the avenue while it becomes the support of a garden on two levels side tracks. On this base are three emergences whose objective is twofold: sequencing this great linear and multiplying the potential of views perpendicular to the railway tracks.

The emergences are conceived as objects placed on this base but reveal a common discourse. To the west and following the proximity of the buildings to the tracks, the facades of the buildings unfold, to the point of simplification to the extreme and reconnect the base to the entrance of the district. In the other direction from the RER, it is Crescendo: the facades fold on themselves to protect themselves from the noise, this system extends on the central island where the double skins of the winter gardens undulate on a rhythm that calms down until the island station and the northern entrance of the district. The fragmented facades help to break the sound waves and in the same way energize the facade overlooking the tracks. This facade composition also makes it possible to orient the views of the dwellings not directly towards the paths, but rather to look for views of the distant. Each building will develop this principle of façade crenellation in a different way.

The brick is Cachan’s identity. Whether it is the city centre, remarkable facilities such as the Town Hall, or the theatre where it is reinterpreted, it is a marker for the Cachanais. We wanted to find it at the base level. It gives the ecoquartier the image of a coherent set of buildings, vibrant in a subtle play of frame and tones between bases and emergences rather than independent objects.

The South Islet brings a new singularity once again putting plant life on stage. On a single base, a set of 2 faults is drawn between 3 plots. These faults shelter pieces of nature represented in a richness of forms, vocabularies and heights, trees, groves, shrubs, on a carpet of grasses and ferns… These spaces of contemplation will symbolize spaces sanctuarized and in this sense largely dedicated to the reception of the fauna on the basis of a flora reflected and adapted to their reception. This base represents a vegetal matrix from which the vegetation colonizes the façades of plots A/B and C. These façades will also come in dialogue with the vegetal forms encountered on the railway rights-of-way inspired by the spontaneous and wild character inhabited by this ecological continuum. In this sense, the façades play on a plurality of foliage and low grasses, mainly emphasizing various green tones alternating large flowering masses of white colors.

A sustainable architecture is, by essence, an adaptable and reversible architecture. Able to mutate over time according to the needs of density, functions, typologies, it follows the economic, demographic and social fluctuations of the city, and thus avoids the traps of the accelerated obsolescence of the built. The choice of pole/slab support systems is closely linked to this desire for adaptability. It avoids the use of structural overlaps, and offers free trays. All of our residential and tertiary buildings are therefore naturally based on this principle of increased reversibility. This system makes it possible to create neutral floors at the R+1 level. Today’s office or tertiary program, these provisions could allow the very easy transformation of a housing program into offices, offices into housing, into activities and so on. Finally, we want to propose a frugal and intelligent project in its ability to anticipate future needs and not close the door to any of its evolutions.