[AIVC, Air infiltration and ventilation glossary, 1992]:the movement of outdoor air into a space through intentionally provided openings, such as windows and doors, or through non powered ventilators or by infiltration.
[ASHRAE Standard 62.1]:ventilation provided by thermal, wind, or diffusion effects through doors, windows, or other intentional openings in the building.
[ASHRAE Standard 62.2]:ventilation occurring as a result of only natural forces, such as wind pressure or differences in air density, through intentional openings such as open windows and doors.
[EN 16798-1:2019, 3.19]:ventilation provided by thermal, wind, or diffusion effects through doors, windows, or other intentional devices in the building designed for ventilation.Note 1 to entry: Natural ventilation systems may be either manually or automatically controlled.
[EN 12792:2003, 264]:ventilation through leakage paths (infiltration) and openings (ventilation) in the building which relies on pressure differences without the aid of powered air movement components:− airing;− shaft ventilation;− cross ventilation.
[ISO 16814:2008,3.24]:ventilation through leakage paths (infiltration) and intentional openings (ventilation) in the building envelope or room enclosure, which relies on pressure differences without the aid of powered air-moving components.