Ratio of Biodiversity Occupation




* Coefficient d’Occupation des sols (Land Use Coefficient)
** Coefficient d’Occupation de la Biodiversité (Ratio of Biodiversity Occupation )


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.