Saturday, October 6, 2012

VENTILATION OF BUILDING

        VENTILATION AND AIR-CONDITIONING
                               The term ventilation is used to mean the free passage of clean air in a structure.  In other words, the removal of all vitiated air from a building  and its replacement with fresh air is known as ventilation. It is important from the engineering view point for the following reasons:
1.       If the room is not properly ventilated, there will be  excessive quantity of carbon dioxide in the air. The more the a mount of carbon dioxide, the more difficult is the breathing. It is observed that breathing is  difficult when the amount of carbon dioxide by volume is about per  cent and a man loses consciousness when it reaches about 10 per cent or so. For comfortable  working, the carbon dioxide  content  should be limited to about. By volume.
2.        The ventilation is required to control dust and other impurities in the air. This is the main cause of insisting proper ventilation in the industrial buildings.
3.        The ventilation  is also  required to suppress odours, smoke, concentration of bacteria, etc.
4.        The proper and sufficient ventilation results in absence of condensation.  The difference of temperature between the outside air and the inside air tends to the deposition of moisture on the room surfaces. This is known as the condensation and it can be effectively controlled by the provision of suitable ventilation of  this is known as he condensation and it can be effectively controlled by the provision of suitable ventilation of the room.
5.        For removal of body heat liberated or generated by the occupants. The ventilation is necessary.
6.       In order to prevent the formation of conditions leading to suffocation in conference rooms. Committee halls, cinema halls, big rooms, etc.   the proper ventilation of such premises must be made.
In this chapter, the topics of ventilation and air-conditioning will be described in brief. 
                       FACTORS AFFECTING VENTILATION
  1.  Air change
  2. Humidity
  3. Quality of air
  4. Temperature
  5. Use of building
                                           MINIMUM RATES OF FRESH AIR

 No.
             Nature of building
Rate of fresh air in m3 per head per hour
1
Factories, Work shops
                                   15
2
Schools
                                   23
3
Assembly halls, canteens, shops, office with light activity
                                   28
4
Restaurants, dining halls
                                    25
5
Theatres, hospitals
                                    35
6
Residential building
                                   50
7
Gymnasiums
                                    80
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