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The Abrises: Enhance Outdoor Natural Ventilation


2022

Urban furniture (contest)


The abrises are a new generation of outdoor shelters designed to enhance outdoor natural ventilation. Improving the summer thermal comfort of outdoor spaces is already a critical issue in urban areas due to the urban heat island (UHI) phenomenon and will become even more so in the future due to climate change.

The use of natural ventilation is one of the simplest ways to improve thermal comfort, especially if the air humidity is high.

Design drawing by Clément Gaillard First research for the shape of the abrise

Design drawing by Clément Gaillard Principle of operation of an abrise.

The design of an abrise is based on the principle of madyafa. The madyafa is an outdoor shelter designed to promote ventilation and described by the Egyptian architect Hassan Fathy in the book Architecture for the poors. There is very little data available for the design of a madyafa.

It is known that its operation is based on a counter-intuitive principle: the facade with the smallest openings must be oriented facing the wind and in overpressure, while the largest opening is downwind in a depression zone. This difference between the proportions of the openings creates a Venturi effect that generates a regular breeze that favors cooling.


Picture of a madyafa by Hassan Fathy Picture of a madyafa in Architecture for the poors by Hassan Fathy

Cut of a madyafa by Hassan Fathy Cut of a madyafa draw by Hassan Fathy

The goal is to identify the most appropriate areas to install the shelter so that it can produce a steady breeze when temperatures are highest.

The first prototype of the abrise would be built in wood (from reuse) for its thermal qualities and its low environmental impact. The choice of wood is also explained by the desire to improve the image of this material whose use in urban space is sometimes criticized.

Rainwater could be stored on the roof of the abrise so that it could flow by gravity into horizontally positioned clay bushels in the direction of the breeze. Evaporation of water along the humidified bushels would create "adiabatic" cooling: if the humidity is low enough, evaporation of the water can lower the air temperature by a few degrees. Thus, the air would be both accelerated and cooled.

Axonometry of an abrise with Blender Axonometry of the first prototype of an abrise

Prototype of an abrise in the place de la Bastille Prototype of an abrise in the Place de la Bastille in Paris