VENTILATION
Definition :-
Exchange of air between indoor and out door atmosphere is called as Ventilation.
Ventilation is classified as-
Natural ventilation and
Mechanical ventilation
Natural ventilation is the simplest system of ventilating small houses, schools and offices. In this method, certain forces work which are present in nature. These are:
The wind
Diffusion and
Temperature
• Wind:-The wind is have a natural force. When it blows through a room, it is called Perflation. Some times due to obstruction it exerts a suction action at its tail end - this is called Aspiration. Doors and windows facing each other provide "cross-ventilation". It is best system of natural ventilation
• Diffusion is the movement of molecules from high concentration to low concentration. It is a very slow process of ventilation and ineffective if it is the only of ventilation
• Temperature:- There is always a temperature difference between indoors and outdoors , indoors being cooler than outdoors.
Movement of air occurs when temperature is difference from hotter regions moving towards the cooler regions.
Mechanical or artificial ventilation may be of the following types :
(1) Exhaust ventilation.
(2) Plenum ventilation.
(3) Balanced ventilation.
(4) Air conditioning.
(1) Exhaust ventilation: Air is exhausted by special fans known as exhaust fans, these fans are driven by electricity . As air is exhausted, a vacuum is created which results in fresh air to enter the room through windows, doors and other inlets.
This system is generally provided in large halls and auditorium for removal of vitiated air
(2) Plenum ventilation: Plenum ventilation is opposite to exhaust system. In this system, fresh air is blown into the room by electric fans so as to create a positive pressure, and displace the vitiated air
(3) Balanced ventilation: This system of ventilation is a combination of the exhaust ventilation and plenum ventilation systems. The blowing fan must balance the exhaust fan and air is circulated in continuous balanced process.
(4) Air conditioning :- Air conditioning is defined as "the simultaneous control of all”( i.e.- temperature, humidity, air movement, distribution)
Air conditioning is popular in large institutions, hospitals, industries and dwellings.
Standards of Ventilation:-
1).Cubic Space:- per person, a supply of 3,000 cubic feet air is needed.
2). Floor Space:- 5-100 Sqft floor space per person is considered.
3) Air Change:- For an one hour 2-3 times air changes recommended in living rooms.
2. Definition :-
Exchange of air between indoor and out door atmosphere is called as Ventilation.
Ventilation is classified as-
Natural ventilation and
Mechanical ventilation
Natural ventilation is the simplest system of ventilating small houses, schools and
offices. In this method, certain forces work which are present in nature. These are:
The wind
Diffusion and
Temperature
3. Wind:-
The wind is have a natural force. When it blows through a room, it is called
Perflation. Some times due to obstruction it exerts a suction action at its tail end
- this is called Aspiration. Doors and windows facing each other provide "cross-
ventilation". It is best system of natural ventilation
Diffusion :-
It is the movement of molecules from high concentration to low concentration. It
is a very slow process of ventilation and ineffective if it is the only of ventilation
Temperature:-
There is always a temperature difference between indoors and outdoors , indoors
being cooler than outdoors.
Movement of air occurs when temperature is difference from hotter regions
moving towards the cooler regions.
4. Mechanical or artificial ventilation may be of the following types :
(1) Exhaust ventilation.
(2) Plenum ventilation.
(3) Balanced ventilation.
(4) Air conditioning
Exhaust ventilation:-
Air is exhausted by special fans known as exhaust fans, these fans are
driven by electricity . As air is exhausted, a vacuum is created which
results in fresh air to enter the room through windows, doors and other
inlets.
This system is generally provided in large halls and auditorium for
removal of vitiated air.
Plenum ventilation:-
Plenum ventilation is opposite to exhaust system. In this system, fresh
air is blown into the room by electric fans so as to create a positive
pressure, and displace the vitiated air
5. Balanced ventilation:-
This system of ventilation is a combination of the exhaust
ventilation and plenum ventilation systems. The blowing fan
must balance the exhaust fan and air is circulated in continuous
balanced process.
Air conditioning :-
Air conditioning is defined as "the simultaneous control of all”
( i.e.- temperature, humidity, air movement, distribution)
Air conditioning is popular in large institutions, hospitals,
industries and dwellings
6. Standards of Ventilation:-
1).Cubic Space:- 3,000 cubic feet supply of air is needed per person, .
2). Floor Space:- 5-100 Sqft floor space per person is considered.
3) Air Change:- For an one hour 2-3 times air changes recommended in
living rooms.
