We use cookies from a third-party service (Google Analytics, AddThis) to collect data and improve your browsing activity. For more information, see our legal notices.
Logo pavillon de l'Arsenal
FAIRE 2020


Clément Willemin, WALD

Prototyping a porous and seeping wall prefiltering and regulating certain forms of residential wastewater

Prototyping a porous and seeping wall prefiltering and regulating certain forms of residential wastewater

JULY 2021

A construction site located in Les Mureaux was proposed by our partner Aigo, and a metal support structure was completed. A first attempt to incorporate organic matter into the porous concrete mixture was inconclusive (in the absence of sand, the cement didn’t set), and different compositions of porous concrete were implemented, using different binders.

WALL is a porous concrete wall that filters part of the gray water from our homes. Kept moist, the wall becomes covered with moss, thereby providing habitat for microfauna, while also acting as a natural urban air conditioning unit. It therefore offers a possible response to two key issues of our time: biodiversity and climate.
The porous concrete modules as well as the metal supporting structure were transported to the test site in early July.
We concurrently intensified our research on mosses with Sébastien Leblond, a research and conservation fellow on Bryopythes at the National Museum of Natural History in Paris, who agreed to assist in preparing the seeding mixtures. This phase will likely take place at the start of the academic year.
The next steps are the prototype assembly and the installation of the sprinkler system which will serve to simulate a regular ingress of water.
At the same time, we are continuing to explore other lighter or recycled materials that could be a better alternative to porous concrete.


“WALL is a filtering wall, a vertical irrigation, a living, porous and seeping surface that prefilters and regulates household wastewater (specifically greywater from the shower, sinks, washing machine and so on) while also providing a natural form of urban air conditioning.

WALL offers a combined answer to the two main issues of our time: biodiversity and climate.
WALL is a porous concrete slab with perforations that put to use the surface tension of the water to diffuse it over the entire filtering device. Porous concrete contains up to 30% of empty space. For microvegetation to develop there, all that is required is a constant supply of water, plus a dash of organic matter.

In your new home, get used to the idea that domestic wastewater is returned directly to the exterior walls. To fully benefit from the cooling effect of the irrigated facade, and to allow a microfauna to develop there under your windows, just avoid emptying used motor oil in your bathtub, use less washing powder and dishwashing liquid, and switch to organic shampoos.” - WALD

Clément Willemin, WALD
Clément Willemin  is a landscape architect, urban planner and designer. After having founded and directed BASE for twenty years, he founded his current studio, Wald Willemin Architecture Landscape Design, in 2020. He already has had a project selected for FAIRE in 2017:  a floating environmentally-friendly swimming pool that is now patented. His WALL project is derived from his architectural diploma, obtained in 2019.

AIGO promotion

Bérengère Giaux architecte

TP Drain / Vegedrain