Study of a Cooling System by Chimney Effect


Environmental Engineering/Architecture

This project was developed within the framework of a renovation project of old storage rooms on two levels. I imagined a passive cooling system that would would allow to benefit from the difference of temperature between the two levels in order to cool the upper level.

Since the basement is close to a water table and has a high thermal inertia, the temperature is maintained at about 15°C all year round. Based on my research on passive solar techniques, I proposed to bring this fresh air to the first floor through the use of a solar chimney. By heating the air at the top in a solar air collector, this system creates a "chimney effect" (or "stack effect") and allows the fresh air that tends to stagnate in the basement by gravity to rise. In addition to working solely with solar radiation, this system is naturally regulated: the more sunshine there is in summer, the greater the cooling effect.

Thermal Chimney Sketch by Clément Gaillard Research on the integration of the chimney and the solar air collectors

Thermal Chimney Site Project by Clément Gaillard Organization of the different climatic flows on the site

Dreyfus' formula (Le Confort dans l'habitat en pays tropical, 1960) for calculating the stack effect shows that the airflow is primarily a function of the temperature difference between the cold point (here, the basement) and the hot point (here, the solar collectors on the southeast roof slope). This flow rate is also a function of the surface of the inlet and outlet openings.

The higher the temperature of the collectors, the more efficient the ventilation and cooling of the air inside the station. In order to maximize the chimney effect, the air collectors are composed of a large surface of blackened sheet metal placed behind a glazing that creates a greenhouse effect.

Dreyfus equation Empirical calculation method of the stack effect flow rate proposed by Dreyfus in Le Confort dans l'habitat en pays tropical

Thermal Chimney Project by Clément Gaillard Scheme of the chimney cooling system that exploits the temperature difference between the basement and the solar air collectors on the roof

Solar Air Collector by Clément Gaillard Detail of a simplified solar air collector