Initial buoyancy reduction in exhausting smoke with solar chimney design

A possible problem in using solar chimney as a natural smoke exhaust system will be identified in this paper. Smoke generated in a fire might not be removed effectively if the glazing walls are heated up due to exposure to solar radiation. It is because the buoyancy of the smoke is reduced initially in the solar chimney. This phenomenon of reducing buoyancy will be discussed. A simple equation of motion on smoke movement was set up. Some of the results of full-scale burning experiments carried out earlier for assessing the fire response of a glass façade system were applied to support the argument. Experiments indicated that smoke would take a longer time to move up when the glazing wall temperature is higher. A better smoke exhaust design accounting the reduction in buoyancy at this early stage of a fire should be worked out.