Roof Windows

Low energy buildings, being highly insulated, are subject to important overheating risks. Thermal simulation as well as experimental studies have shown the large potential of ventilative cooling. One barrier against this approach is the difficulty of evaluating air flows. Appropriate calculation methods and characterization of openings are needed, so that these systems can be dealt with in design, regulation and certification tools.

This study is focused on the efficient use of cross-ventilation in a densely populated area by using roofwindows in particular. Wind tunnel experiments were conducted to understand not only the relationbetween the building coverage ratio and the coefficient of wind pressure (Cp) but also the relationbetween the roof slope of a residence and Cp value. To simulate an urban area, dummy models wereplaced around a target model, and the building densities were set to 0, 10, 20, and 40%. The roofslopes of residences were set to 0 (flat roof), 15, and 26.7.