Experimental study on natural ventilation of a room with a windward window and different windexchangers

•Natural ventilation of a room with a windward window and different windexchangers.•Experiments with scaled models in an open water channel.•Evaluation of the flow rate through the window and windexchanger.•Assessment of the flow velocities inside the room.•The windexchangers can improve the flow rate up to 420%. A windexchanger is a small structure placed on the roof of a building with the aim of increasing the wind driven ventilation. In the literature, this structure is usually named as a windcatcher. Depending on its orientation to the wind direction, the same structure can perform as a windcatcher or a windextractor. Six windexchanger configurations with different wind orientations, placed in a room with a window at windward, are experimentally evaluated. The room without a windexchanger is used as a reference. The experiments were carried out in a water channel using scale models. Flow velocity measurements were performed using stereoscopic particle image velocimetry (SPIV) on the central plane. The velocity vertical profile in the test section corresponding to a small town was generated. The flow rate into the building and the area percentage of the central plane with flow speed greater than a reference value are used as evaluation parameters. It was found that, the performance of a windexchanger strongly depends on the orientation of its openings to the wind. The ventilation performance of the room with a windexchanger ranges from a significant to a negligible improvement. This stresses the importance of the adequate design of this kind of structure.