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Origin and history

The Trans-en-Provence air well is an original architectural structure built in 1931 by Belgian engineer Achille Knapen. Designed to capture the humidity of the air by condensation, this monument takes the form of a massive concrete tower, evoking a giant dovecote. Its principle is based on a passive system: the air passes through the upper part, where a physical filter extracts the water vapour, which then condenses in a tank at the base. Despite its ambition, the project failed due to an insufficient day-night thermal differential in the region, contrary to successful trials in Africa.

Designed as a potential solution for arid areas, this air well uses specific materials: a mixture of porphyry shot and cement mortar, covered with a coating with slate slates. A 2.50-metre thick masonry envelope surrounds the structure, while a 1-metre-diameter central vacuum serves as a collection well. Although its local effectiveness was nil, this experiment inspired further research on dew capacitors and atmospheric water recovery systems.

Ranked in the additional inventory of historical monuments on December 9, 1983, the air well also obtained the label "Twentieth Century Heritage" in the Var. Today, it reflects a bold, though inconclusive, technical innovation on the ground and illustrates the historical challenges of water resource management. Its unique architecture, halfway between utility and experience, makes it a remarkable industrial heritage of the Provence-Alpes-Côte d'Azur region.

The project is part of a similar series of tests, such as that of Montpellier, which is also unsuccessful. However, the technology has found applications in Africa, proving its potential in more suitable climates. Achilles Knapen, the originator of this concept, has marked the history of water innovations, although his work at Trans-en-Provence remains above all a symbol of the technological limitations of the era in the face of local environmental constraints.

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