Evaluation of a two-sided windcatcher integrated with wing wall (as a new design) and comparison with a conventional windcatcher

Abstract

In buildings, 60% of the energy consumption is associated to Heating, Ventilation and Air-conditioning (HVAC) systems. One solution to reduce this share is the application of natural ventilation systems. Windcatcher and wing wall are two well-known techniques for natural ventilation which have been used in different regions. Nevertheless, in areas with low wind speed such as the tropical climate of Malaysia there is hesitation for application of natural ventilation systems. The integration of windcatcher with wing wall can potentially enhance the ventilation performance. However, this configuration was not looked into by previous investigations thus, this study aims to address this research gap by first evaluating the effect of wing wall with various angles on the ventilation performance and second compare the performance of this new design with a conventional windcatcher. This research used two main investigative steps: experimental scaled wind tunnel testing and Computational Fluid Dynamics (CFD) simulation. Four reduced-scale models of two-sided windcatcher were tested in a low speed wind tunnel. Three models were integrated with wing wall in 30°, 45° and 60° incident angles and another windcatcher was a conventional two-sided windcatcher, which is typical in regions with predominant wind direction. The CFD validation against experiment showed good agreement. The best operation was observed in the windcatcher with 30° wing wall angle which could supply 910L/s fresh air into the room in 2.5m/s wind speed. Hence, the new design had 50% more ventilation performance comparing with conventional two-sided windcatcher in the same external wind speed. Finally, it was concluded that the new design satisfied requirements of ASHRAE 62.1.