A turbine ventilator is a device having a combined function of wind turbine and extract fan. Turbine ventilators are attractive replacements for electrical ventilation fans in terms of using wind energy. They are commonly used in attic, loft and rooftop spaces to facilitate ventilation in buildings at both domestic and industrial level. This study presents measurement of flow rates of four commercial turbine ventilators on a specifically designed experimental system. The ventilation flow rates and rotational speeds are taken at different wind speeds and compared with a simple open column and two standard vent hats. Use of a DC motor to power the ventilators in the absence of wind is described and power consumption against flow rate is given. (c) 2008 Elsevier Ltd. All rights reserved.