Ventilation circulates air within the building, as well as exchanges the inside air with the outside air. Ventilation systems control temperature and humidity levels, and remove airborne bacteria, odor, and dust. The two types of ventilation are natural and mechanical.
A forced ventilation method that circulates the air, removes odors, and controls humidity within the building. It is often used in wet areas such as food preparation rooms and bathrooms to control odor. Ceiling and window fans or portable ventilation devices are used to circulate the air within the space. They cannot be used for air replacement unless a clear indoor/outdoor circulation pattern is established.
A method that uses operable windows and direct outside air circulation, when the temperature, wind, precipitation, humidity, and pollution levels are acceptable. The amount of natural ventilation depends on the type, shape, placement, and size of the building and its openings. There are two primary natural ventilation methods: cross-ventilation and stack-ventilation. Cross-ventilation depends on wind-driven breezes, whereas stack-ventilation uses air density differences to create air movement across a building.