Ecosystem

Ecosystem

To a large extent, the built universe has often been opposed to the vegetal. As for the green spaces, their composition, symbolic meaning and social functions have largely evolved all along the process of densification of our modern cities. Whether in naturalist paintings or in romantic gardens, most of our urban conceptions of the green areas display a clear distinction between two different worlds: buildings on one side, greenery on the other.
Today, more than half of the global population lives in cities -this number could reach two-third by 2050. The densification of the urban areas and their peripheral extensions bring deep changes in landscapes and lifestyles. The green spaces are thought of as major urban elements, maintaining a strong presence of nature in a manmade environment. They make it possible for dense cities to maintain a certain quality of life.

Seen as a vast living environment, the contemporary city could thus provide a fusion of both its usually separate components, buildings on one side, greenery on the other. The interaction of these overlapping, superimposed two elements can generate new urban intensities, in which the built environment could be designed, from the start, as a shelter for the people and a receptacle for the living environment. Apart from the environmental concern, we are interested in this connections as a system, for they allow to create conditions for easier social exchanges around nature and biodiversity. From our standpoint, it is a new project-making tool as well, which introduces an evolution in the conception of core architectural elements, such as roof or façade, generating a new form of expressivity through their additional functions.

The construction of a school, more than any other kind of facilities, provides an opportunity to rethink the synergy between notions of poetry, education and nature, using plastic and spatial apparatuses so as to favour the interaction between the natural environment and a children programme. Located in a dense urban development zone (Zone d’Aménagement Concerté) in Boulogne-Billancourt, on the former Renault plots, the school of Sciences and Biodiversity (école des Sciences et de la Biodiversité) translates these very specific issues. In the first place, priority was given to the connections between filled and empty spaces, and between different topographical levels. The crossed playgrounds offer interacting outdoor areas, providing various points of view. The rhythm and the quality of these views, the communication between inner and outer spaces create a fertile environment for young users: the school is all at once a house, a city, and a landscape. From the upper playground, a supple and comfortable path leads to the green roof, designed to receive a 12-metre high natural reserve. Access is restricted in order preserve the ecological balance required for an evolution of the local biodiversity.

Prefabricated concrete blocks form a thick and uneven rind on the whole building, increasing the probability of spontaneous natural development. Asperities favour the spreading of vegetation; hollows and folds are more specifically meant for animals. Through its support function, the building offers a changing and living shell, which also enables nature to settle in unexpected places… Time here becomes a significant architectural component, going beyond construction timing and contractual framework. In this project, biodiversity is dealt with as a complete programme, as important as the school. As an ecosystem, the facility becomes the environment in which these two worlds merge. Our desire to elaborate a homogeneous entity led us to work on a both vegetal and human continuity, thus creating an experimental organism which also evolves into an educational tool.

Initiated on the occasion of the ‘Reinvent Paris’ consultation (Réinventer Paris), the design of the 183, rue Ordener plot is a manifesto project testing the limits of the proximity between men and nature, in an urban environment. While Paris has got a very rich ecological heritage we tend to observe its uneven geographical repartition. The 18th arrondissement is one the six less vegetated ones, which turn out to be the more densely populated districts of the city. Moreover, this arrondissement contains a great number of small green areas, adding up to only 3% of its whole surface. The district map is thus characterised by a ‘marbling effect’: the scattered vegetation appears to be broken up and compressed by the buildings.

On this narrow plot, the project includes the construction of about twenty housing units and a nursery. A 28 metre-high gable wall borders the site. Its ‘non-constructibility’ constitutes a strong design constraint. Nonetheless, this surface turns out to be a real opportunity, implying a reflection on what could become of these forlorn urban places. Here, the wall becomes an ecosystem, accompanying local residents along their way to the heart of the block. Stairs lead to footbridges and green terraces clinging to the gable wall, like ‘greenery shelves’. The garden thus created is a suspended landscape, accessible at various levels above the ground. The gable wall is clad with a structure receiving biodiversity through a series of green terraces and a three-dimensional network multiplying open surfaces for vegetation and wildlife.

Based on the principle of ecological continuities at a territorial level, the project is envisioned as an experiment which could be declined as a paradigm on many other sites. Just as a fractal, its setting up implies a reflection on various scales: the inhabitant, the block, the city… This competition gave us the opportunity to start our prospective approach by offering the city council a new regulatory tool in order to measure the biodiversity density on the plot. Inspired from the formerly used Land Use Coefficient (Coefficient d’Occupation des Sols), we would establish a ratio between the green surfaces and the whole plot surface, by a simple calculation. The ratio would be equal to 1 for a totally vegetated plot (on the ground surface), and would reduce as the built surface would increase. However, on a densely constructed plot, the ratio could increase, the calculation taking into account all types of green surfaces (walls, roofs, terraces…). This tool would allow to include the forlorn spaces in a global, innovative reflection on the process to a greener city. Combined with the local urban regulations (Plan Local d’Urbanisme), the ratio of biodiversity occupation (Coefficient d’Occupation de la Biodiversité) would adapt according to each district in need of green areas. A natural rebalancing could then develop, modifying the cityscape, as well as the way we look upon this new type of density.

Still as part of the ‘Reinvent Paris’ consultation (Réinventer Paris) but at a different scale, the Ternes project covers the Paris ring road (le périphérique) and receives a joint programme. Designed as a dynamic city block, it invites to unprecedented ways of cohabitation. It is simultaneously a newly created ground (over the ring road), a botanical experience (urban agriculture) and a socio-educational project bringing together different groups or communities through their activities. The operation connects both sides of the périphérique, Paris and Neuilly, covering the ring road with a ‘landscape-bridge’. This self-supporting work includes housing and office buildings having lightweight and modifiable structures. This allows a natural reallocation of activities in the city, in agreement with the evolution of needs, programmes and uses. The green roofs are linked by three footbridges and receive vegetable gardens and a tea field, which will give birth to the first Parisian vintage tea (grand cru), transformed and sold on the spot. The horticultural school situated on the ground floor offers training to all the local residents, and especially to those who live in the block, more than likely to arrange and maintain the green terraces by themselves.