Like a metaphor, the open window evokes positive images; namely the connection with the outside world. Because most windows are human-sized, there is usually an intimate connection called “one on one”. It is therefore easy to imagine why we like the concept of open windows. The open window, however, fails miserably as a reliable ventilation device for air renewal. Building professionals need to understand why windows can not provide ventilation at all times. They are economically efficient with energy leakage to open the window to sanitize indoor air.
The bad news is that often fresh air is loaded with moisture and the lively life near our homes imposes undesirable external pollution. Dust, Pollen and air pollution which could be easily filtered a ventilation systems such as mechanical ventilation by insufflation and which is not achievable by simple opening of the window.