Shed roof air extractors and collectors: the influence of geometry and inlet and outlet openings on the performance of natural ventilation

Abstract Natural ventilation is an efficient strategy for the passive cooling of buildings, occurring through wind action, through stack effect, or a combination of both. Among ventilation strategies, shed roofs stand out. These structures contain roof openings that work as either air collectors or extractors, depending on their location relative to prevailing wind directions. The aim of this paper is to evaluate the influence of the shed geometries and the dimensions of the inlet and outlet openings on the performance of natural ventilation. The system was evaluated for different external wind incidence angles: 0° and 45° (air extraction) and 135° and 180° (air capture). The methodology adopted the CFX software for Computational Fluid Dynamic simulation. Quantitative analyses (air change rates per hour and pressure coefficients in the openings) and qualitative analyses (internal airflow path) were performed. The results indicate that shed roofs with aerodynamic geometries and increased outlet openings increase internal airflow. In case of sheds for air capture, increasing inlet openings did not cause significant improvement in air capture.