“Architectural heritage and contemporary pixellation” From urban downfall to urban renewal At the turn of the twentieth century, the Courtillières neighbourhood was in decline and suffered from a degraded image: the isolated community had become subject to overpopulated housing units, a deteriorated housing stock, an increasingly impoverished population, rising unemployment rates, tension and violence in public spaces and schools, and dangerously high rates of illegal activity. In response to this alarming situation, the French state and local government authorities chose to implement public funds through the National Urban Renewal Agency (ANRU previously known as the “Grand Projet de Ville”) in an effort to remediate the existing conditions for the welfare of the community and its residents. To facilitate the process, the cities, Pantin and Bobigny (the two cities within which the Serpentin project site is situated), created a public interest group (GIP) through which a public tender was launched calling for urban renewal proposals from teams regrouping expertise in the fields of urban planning and design, architecture, landscape architecture, engineering and sociology.
Over a period of several months, three teams including that led by Agence RVA carried out diagnostic and programme studies for the site. The teams’ analyses and programme recommendations were presented to the community for feedback before being submitted to a jury composed of community representatives, design and engineering specialists, and local and state level officials for review. In 2002, Agence RVA was awarded the contract for the design and rehabilitation of the ensemble of properties belonging to the public housing developer, HLM de Pantin, including the Serpentin housing development, the Fonds d’Eaubonne and Point-de-Pierre housing developments and a public park.
The façades: “artwork and work” The aesthetic aspects of a building’s façade and its colour scheme are of extreme importance for the architect, Émile Aillaud. No matter our opinion of the colouration of the public housing development, Nuage Towers, in Nanterre, that of the Grande Borne’s abstract frescos (Rimbaud’s portrait) in Grigny or that of the Serpentin’s nuances of pink and blue (softening the limit between the façade and sky), colour is a key element of Aillaud’s architecture and essential to its understanding. Aillaud’s attention to colour is a result of his collaboration with the artist, Fabio Rieti. The Serpentin’s coloured cement plaster façades were damaged over time due to multiple hasty building interventions (including the removal of the balconies) and to the wear and tear of the fragile plaster surface material. Similarly damaged, an initial façade rehabilitation of the Fonds d’Eaubonne and Pont-de-Pierre housing developments was realised in the 1980’s; a layer of brick was added onto the existing cement plaster. (Aillaud approved of the intervention.)
The rehabilitation of the Serpentin’s façades, however, would not be evoked for another thirty years. Insulation was added in the 1980’s, but the damaged cement plaster and its fading colours remained untouched.
Before undertaking the complete façade rehabilitation, the design team identified four possible approaches, keeping in mind the inherent constraints of rehabilitating an inhabited architectural heritage site: restore the façades as they were originally designed by Émile Aillaud; restore the façades “in the style of” Émile Aillaud; renovate the façades entirely, greatly altering the original architecture; innovate : seek out a contemporary project solution based on the original architectural parti - an approach akin to the spirit of Émile Aillaud.
The first approach was discounted due to an incomplete understanding of the architect’s original intentions combined with the high costs, both in terms of construction and maintenance, associated with restoring the façades as they were initially designed. Attempting to restore the building envelope “in the style of” Émile Aillaud risked to further stigmatize the public housing development. A complete renovation, implying the radical transformation of the façade’s materials and colour scheme, was problematic in terms of honouring the building’s architectural heritage. Having negated the first three design approaches, the team is left with the fourth approach: innovate. This solution permits the design of a contemporary, sustainable project, able to adapt to existing technical challenges while simultaneously honouring Aillaud’s original design intentions.
The façades’ architectural and graphic conception Once Agence RVA had selected opaque glass tile for its durability and versatile colour range, the design team defined the project’s guiding principles: - evanescent contemporary, pixellated motif; - intensity of colour that dissipates as it rises; - differentiated colour schemes between intrados and extrados; - independent treatment of the ground floor level (contrasting light and dark rhythm of precast concrete wall panels and the pre-existing cellar doors).
The architects wished to collaborate with a graphic artist to elaborate the building envelope’s colour scheme. After a public tender process, the choice of graphic designer, Pierre di Sciullo, resulted in a unique and distinguished design. The street front is treated uniformly: a continuous, vertical colour gradient signals the Serpentin within its immediate context. The park-facing façade is treated with multiple, sparkling horizontal colour gradients, varying in length such that the building’s entryways are differentiated from one another. The façade’s colour choice is intended to complement the park’s verdure. This contemporary design proposal for the building’s envelope was agreed upon by all parties and participants involved.
The glass tile mosaic is made up of the following elements: - 25,000m² of opaque glass tiles; - 200,000 glass tile sheets; - 32,000,000 pixels (2x2cm opaque glass tile squares); - 11 colours: red, orange, peach, salmon, white, mouse grey, slate, sky blue, lapis-lazuli and deep-sea blue; - 1 vertical colour gradient along the street front; - 38 horizontal gradients along the park-facing façade.
The urban façade: a unified street front A building’s street front should be designed in relation to its context. Given the exceptional length of the Serpentin, the building’s street front is presented with a multitude of different urban typologies. The façade is asked to respond to a major thruway, avenue de la Division Leclerc, planted with mature canopy trees, a large plot of community gardens, Aillaud’s public housing tower blocks and the construction of contemporary multifamily housing units resulting from ongoing urban renewal projects.
In response to the Serpentin’s diverse context, the project team designed a continuous, unifying monolithic façade composed of an undulating vertical grey colour gradient.
Breaking with the previous address system which was composed of a street number followed by a entryway letter and a street name, today, each entry is indicated with a conventional address: a street number, followed by a street name and the city.
Each street number is indicated on a customized address post.
The park-facing façade: “diversity and intimacy”
In contrast to the busy urban street front, the park-facing façade sinuously winds its way around a vast open space, creating intimate pockets of green within the Serpentin’s curves. The building’s concave sections envelop portions of the park creating identifiable, human-scale outdoor spaces. The façade’s horizontal colour gradients are tailored to the building’s undulations. Each curve and open-space “alcove” is associated with a particular gradient.
The housing units: renovation to meet current standards One of the causes of the community’s social woes is the substandard living conditions resulting from substandard housing. The Serpentin housing complex is made up of undersized and poorly equipped housing units dating from the 1950’s and 1960’s. The building measures six storeys high (one ground floor and five upper levels) without an elevator.
The Urban Renewal Programme (PRU) and its associated funding enable the amelioration of the housing units’ spatial organisation (via the regrouping of existing surfaces), the modernization of each unit’s kitchen and sanitary equipment as well as increased thermal and energy performance. The goal is to rehabilitate the Serpentin so that it meets current housing stock standards and codes (except for its lack of elevators which are impossible to integrate given the narrow building width and the decision to respect the building’s architectural heritage).
Housing unit figures: - 635 original housing units > 511 housing units after rehabilitation + a facilities management office; - 21 housing unit typologies; - 100 % of housing units with street and park views (except studio units); - 100 % of housing units with a park view.
Construction programme: - Complete interior renovation: only the exterior walls, floors and windows are conserved; - Equipment and finish upgrades: o Installation of new electric and sanitary equipment; o Installation of a new controlled mechanical ventilation system; o Realisation of new wall and floor finishes.
The entryways : Renewed transparency Common area design principles: As with the rest of the building’s interiors and exteriors, the Serpentin’s common areas were subjected to the ravages of time as well as numerous, shoddy maintenance interventions. The exterior cellar doorways were walled up to put an end to the myriad of illegal activities and associated police chases that took place on the cellars’ ground floor. The entrance halls’ park access doors were also walled up for similar reasons. The original metal awnings were left weighted down in appearance after an initial rehabilitation attempt.
In keeping with the project’s overarching design principles, instead of attempting to recreate the original architecture, the project team envisioned a contemporary solution taking into consideration existing maintenance and security issues (regrouping cellar access by stairwell) while simultaneously respecting Aillaud’s initial intentions (establishing a visual connection with the park and integrating streamlined awnings).
Actions: - Creation of transparent entryways that open the view onto the park from the street; - Reconfiguration of cellar access (interior access as opposed to exterior access); - Installation of a security control system (interphones and access badges); - Rehabilitation of glazed entryway panels; - Preservation of original precast concrete stairs.
The façade system The building underwent an initial rehabilitation in the 1980’s. At this time, insulation was added onto the exterior levels 1 to 5. The new façade from levels 1 to 5 is composed of the following elements: - the existing rigid foam polystyrene insulation (60mm thick) reinforced with plaster (10mm thick); - a wood framing structure; - an air gap; - a reinforced precast concrete curved panel (12mm thick); - a film of reinforced plaster; - sheets of glass tile mosaics affixed with a bi-component adhesive.
Prior to and during construction, the façade system was subjected to numerous security and safety checks. The ground level façade is composed of the following elements: - existing load bearing walls overlaid with 1,200 precast concrete panels treated with anti-graffiti glazing; - prefabricated sheet metal panels (to cover pre-existing cellar doors); - precast polymer concrete awnings.
