Question

Define Ventilation of air.

Answer 1

This is a pretty basic and simple question. You can look for the answer by approaching what we call the flow of air, most generally fresh and cleaner air, which replaces the stale or dirty and polluted air.

Complete step by step answer:
Simply put, Ventilation of air can be defined as the phenomenon by which impure, stale and warm air inside a room is continuously replaced by a flow of fresh and clean air from outside is called ventilation.

There are some other types of ventilation of air as well, like:
Purpose provided ventilation: Ventilation is the process by which ‘clean’ and ‘fresh’ air (normally outdoor air) is intentionally provided to a space or room and stale and warm air is removed. This may be accomplished by either natural or mechanical means.

Air infiltration and exfiltration: In addition to Purpose provided ventilation, air inevitably enters a building by the process of ‘air infiltration’. This is the uncontrolled flow of air into a space through adventitious or unintentional gaps and cracks in the building envelope. This is what we mostly refer to when we are talking about Ventilation of air. The corresponding loss of air from an enclosed space is called ‘exfiltration’. The rate of air infiltration is dependent on various factors like, the porosity of the building shell and the magnitude of the natural driving forces of wind and temperature. Vents and other openings incorporated into a building as part of ventilation design can also become routes for unintentional air flow when the pressures acting across such openings are dominated by weather conditions rather than intentionally (e.g. mechanically) induced driving forces. Air infiltration not only adds to the quantity of air entering the building but may also distort the intended air flow pattern to the detriment of overall indoor air quality and comfort.

Note: A main thing to take away from this solution is that ventilation of air is generally used when we are talking about ventilation of air in a room or a building, and not in open space. For open spaces, we use air-flow to describe the same process or phenomenon.