Principles of Natural Ventilation

PRINCIPLES OF NATURAL VENTILATION

1. Natural Ventilation

In this system of ventilation, doors, windows, ventilators and skylights are used to make the room properly ventilated. This system is useful for small buildings. But, it cannot be adopted for big offices, theatres, auditoriums, etc.

The advantage of this system is it's economic, because, no special equipment is necessary for making the room adequately ventilated.

The important points to be considered for natural ventilating system are as follows

• The location, size and type of windows play a great role eldsties in imparting natural ventilation to the room.

 • The efficiency of roof ventilators depends on location, wind direction and height of building.

• The window ventilation with a combination of radiator,  deflector and exhaust, as shown in fig. 2.1, can give better results.

• The radiators are situated below the sill level of the windows and they extend for the full length of the window.

• The windows, deflectors and radiators should be properly Jneme manipulated for achieving the desired effects.

• The exhaust duct is provided near the ceiling of the noids opposite wall. It is taken out of  the roof to act more or  less like a chimney.

• The windows open from bottom and the deflectors may be of curved vanes (Fig. 2.1)

• Generally, the outside air is cooler than the inside air. emote Hence, the cooler air enters from the bottom. When it becomes hot during, it leaves from the top.

• Fig. 2.3 shows the natural ventilation when inlets are at the bottom and roof ventilator is at the top.

• The term cross ventilation is sometimes used to indicate the position of outlets just opposite to inlets as shown in fig. 2.4.

(b) Mechanical or artificial ventilation

In this system of ventilation, some mechanical arrangement is adopted to provide enough ventilation to the room.

Following are the five methods of the artificial ventilation:

(i) Exhaust system

(ii) Supply system

(iii) Combination of exhaust and supply systems

(iv) Plenum process

(v) Air-conditioning