## All You Know About Ventilation

It is a supply of outside air into, or the removed of inside air from an enclosed space. Ventilation includes both the exchange of an air to the outside as well as circulation of air within the building. It is one of the most important factors for maintaining adequate indoor air quality in buildings.

It is used to remove unpleasant smells and excessive moisture and introduce outside air, to keep interior building air circulating and to prevent stagnation of the internal air. Therefore good ventilation is necessary for the safety and comfort of building occupants, and in many cases subject to a legal minimum requirement.

##### Must Read: What is Make-Up Air?

Methods for ventilating a building may be divided into local, mechanical and natural.

### Local Exhaust Ventilation:

Basically, it is an engineering control system that reduces exposure to airborne contaminants such as dust, fume, mist, vapour or gas in the workplace.

OR

Ventilation effected by the exhaust of air through an exhaust appliance, such as a hood with or without fan located as closely as possible to the point at which contaminants are released, so as to capture effectively the contaminants and convey them through ducts to a safe point of discharge.

However, the basic elements of Local exhaust ventilation (LEV) are:

• A hood or a collector to capture the contaminant close to the point of generation.
• Ductwork to pass on the contaminant away from the source.
• A filter or an air cleaning device to remove the contaminant from the extracted air stream.
• A fan or an air moving device to provide the necessary air flow.

### Mechanical Ventilation:

It is supply of outside air either by positive ventilation or by infiltration by reduction of pressure inside due to exhaust of air, or by a combination of positive ventilation and exhaust of air.

• Ductwork to discharge cleaned air to the external atmosphere at a suitable point.
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A building ventilation system that uses powered blowers or fans to provide fresh air or outside air to rooms when the natural force of air pressure and gravity are not sufficient to circulate air through a building. Therefore, mechanical ventilation is used to control indoor air quality, odours, excess humidity, and contaminants can often be controlled via dilution or replacement with outside air. However, in humid climates specialized ventilation systems can remove excess moisture from the air.

### Natural Ventilation:

It is a supply of outside air into a building through a window or other openings due to wind outside and convection effects arising from temperature or vapour pressure differences (or both) between inside and outside of the building.

Courtesy - 123rf

In general sense natural ventilation consists of using natural forces to drive airflow through space. The two main natural ventilation strategies are cross ventilation and stack ventilation.

### Dilution Ventilation:

Dilution ventilation supplies and exhausts a large amount of air to and from an area or building. It usually involves large exhaust fans which are placed in the walls or roof of a room. Dilution ventilation maintains the control of low toxicity gases and vapours below acceptable levels through dilution of concentration.

In other words, it is a supply of outside air to reduce the air-borne concentration of contaminants in the building.

Dilution ventilation can be made more effective if the exhaust fan is positioned close to workers and the makeup air is located behind the worker so that contaminated air is removed from the worker’s breathing zone.

Thus, the ventilation is important factor for home to maintain healthy and fresh environment in home. And if the indoor air quality is good ,it will give happiness to the user of it.

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