[EN 16798-1:2019, 3.4]:intentional opening of windows, doors, vents, etc. for increasing the ventilation in a room.Since airing is the air change by manually operating windows or other openings, it has to be observed that it cannot be considered to be the effect of a ventilation system.[EN 12792:2003, 41]:[EN 16798-7:2017, 3.7]natural ventilation by window opening.