Frequently Asked Questions

In rooms with a need for impact ventilation, an exhaust fan is placed to create a negative pressure. This is then compensated by drawing in fresh air through dedicated openings (ventilation shafts), but often also through leaky areas of the building that are not designed for this purpose, for example through window frames (micro-ventilation), around window sills, goosenecks and other penetrations.

Under-pressure ventilation is a direct cause of mould, through the cooling and condensation of moisture in leaky areas of the building that are not designed for ventilation.