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.