Natural ventilation by windcatcher (Badgir): A review on the impacts of geometry, microclimate and macroclimate

Abstract

The significant energy use and increasing requirement for good indoor environment quality in the built environment have led to a renewed interest in natural ventilation strategies such as windcatchers. Windcatcher is a roof-mounted device that supplies fresh airflow into a room and expels polluted air under the action of wind pressure and buoyancy forces. The aim of this review is to investigate factors which affect the natural ventilation performance of windcatcher including internal factors (related to geometry/design of windcatcher), external building features (microclimate) and surrounding environment (macroclimate) plus the impact of integration with other passive systems. From reviewing the literature, it was found that windcatcher with a square cross-section and curved roof demonstrates better ventilation in the room compared to other configurations. Moreover, the overall findings indicated that the integration of windcatcher with other natural ventilation systems such as solar chimney and wing wall has a considerable effect on the ventilation efficiency. In urban environments, buildings are often located quite close to each other, and the effect of surrounding structures on airflow profile cannot be ignored but only a limited number of works considered the impact of urban environment and objects (upstream or downstream) on the ventilation efficiency of windcatcher. Finally, the impact of vegetation, techno-economic cost and energy saving in a building are some significant gaps of current studies.