This standard is specified for deaerators with fans for the ventilation of bathrooms and WCs without outside window in appartments and similar locations, eg. hotelrooms. Other rooms in an appartment, eg. the kitchen or the storage room can also be ventilated by deaerators specified by this standard. The ventilation of kitchens without window is not the subject matter of this standard. The standard does not apply to ventilation systems with which more than twice the planned minimum exhaust air volume flows are conveyed. For the ventilation of kitchens without windows, the requirements of the Building Inspectorate Directive on the ventilation of kitchens, bathrooms and toilet rooms without window(s) in apartments must be observed. This standard requires that a fresh air flow corresponding to the extract air volume flow can flow directly into the extract air rooms via leaks in the building envelope and, if necessary, via fresh air outlets, from outside via the living and recreation rooms or via a supply air pipe.