Numerical Evaluation of Ventilation Efficiency of Window Type Ventilation Systems

Ventilation in buildings is the simplest and most convenient way to purify indoor air. However, when the ventilation is not enough due to natural ventilation, it should be cleaned by mechanical ventilation or air purifier. This process requires building energy. Therefore, it is possible to save the energy of the building by merely increasing the natural ventilation efficiency. This study conducted airflow analysis simulations to investigate the effects of changes in the shape of ventilation openings and louvers on the ventilation efficiency of a window ventilation system. The streamlined window opening exhibited a greater increase in airflow (41.3%) than did the conventional window (24.3%) for the ventilation model with four openings. It was also observed that flow separation and wakes were generated by the adverse pressure gradient arising from the increased airflow speed when a louver was employed. Based on these results, it can be concluded that using a louver as a wind augmentation device is an obstacle to improving the airflow in a window ventilation system.