This air is provided in one of two ways, known as natural or forced ventilation, each of which introduces fresh air into the compartment through an inlet and allows the foul air to escape through an exhaust .
Lo moya unikezelwa ngendlela enye kwezi mbini, eyaziwa ngokuba kukungena nokuphuma komoya indalo okanye unyazelwe, indlela nganye kwesi ingenisa umoya omtsha kwindawo yokuhlala ngendawo ewungenisayo umoya omtsha uze wona omdaka ukhutshwe kumbhobho wokukhupha umoya omdaka.