Wind and solar energy are currently used to power many building ventilation devices. Such devices rely exclusively on either solar or wind energy, which limits their usefulness. A low-cost hybrid ventilation device that utilizes both wind and solar energy as power sources was designed to overcome some of the shortcomings of these devices. Wind tunnel testing conducted at the aerodynamics laboratory of the University of New South Wales revealed that the hybrid device had improved operational and performance benefits compared with conventional commercial roof top ventilators, particularly at zero to low wind speeds. This represents a significant step forward and will have an immediate impact in promoting the use of clean energy for the purposes of building ventilation. (C) 2007 Elsevier Ltd. All rights reserved.