Ventilation

Ventilation is the process of exchanging or replacing air in any space to provide high indoor air quality. This involves temperature control, oxygen replenishment, and removal of moisture, odors, smoke, heat, dust, airborne bacteria, carbon dioxide, and other gases. Ventilation includes both the exchange of air with the outside as well as circulation of air within the building. It is one of the most important factors for maintaining acceptable indoor air quality in buildings.

Methods of ventilation

Ventilation is divided into two types: mechanical or forced and natural ventilation. In forced ventilation, an air handler is used to control the quality of air, usually in closed spaces. In natural ventilation, air moves through opened windows and doors. Air movement associated with infiltration and natural ventilation is caused by air temperature differences between indoors and outdoors and by wind.

Mechanical ventilation

Mechanical or forced ventilation is provided by an air handler and used to control indoor air quality. Excess humidity, odors, and contaminants can often be controlled via dilution or replacement with outside air. However, in humid climates much energy is required to remove excess moisture from ventilation air.

Natural ventilation

Natural ventilation is the ventilation of a building with outside air without the use of a fan or other mechanical system. It can be achieved with openable windows or trickle vents when the spaces to ventilate are small and the architecture permits. In more complex systems warm air in the building can be allowed to rise and flow out upper openings to the outside (Stack effect) thus causing cool outside air to be drawn into the building naturally through openings in the lower areas.

Ventilation and health

Ventilation is important for maintaining good indoor air quality. Poor ventilation can lead to an accumulation of pollutants that can be harmful to health. These pollutants include carbon dioxide, radon, volatile organic compounds, and many others.

See also

• Air changes per hour
• Building services engineering
• HVAC
• Indoor air quality
• Sick building syndrome