Experimental investigations on a small size solar chimney show that the rate of ventilation increases with increase of the ratio between height of absorber and gap between glass and absorber. This finding is in agreement with results of the steady-state mathematical model developed for analysis of such systems. Nine different combination of absorber height and air gap have been investigated on the experimental set-up. Highest rate of ventilation induced with the help of solar energy was found to be 5.6 air change per hour in a room of 27 m(3), at solar radiation 700 W/m(2) on vertical surface with the stack height-air gap ratio of 2.83 for a I in high chimney. (c) 2005 Elsevier Ltd. All rights reserved.