Question

What is the difference between direct and common ventilation?
And I want to put a picture of each and create a simple diagram explaining both of these methods.
In addition to making a comparison between them in terms of features, preference, and uses.
And two examples for each of them.

Answer 1

DIRECT VENTILATION SYSTEMS

This is a simple type of ventilation system which is applicable for large storehouse or rooms or even workplace which are isolated from surroundings. In this system the design and placement of the ventilation unit is done based on the single room and its requirements. Here the surrounding air is taken in conditioned and circulated around the room in a desired manner and a part of the air is sucked out to exhaust creating a good ventilation. The air is supplied only to a particular zone or room and it is commonly preferred in case of large single rooms. The design and arrangement is simple with low power requirement and less maintenance.

COMMON VENTILATION SYSTEMS

It is a type of system in which the outside conditioned air is supplied to a series of rooms or zones as per their requirement. It is commonly used in small storage rooms with different sections or appartments. In this system air is taken from outside and conditioned and supplied to different rooms according through their requirements using the common duct. Also a certain amount of air from the rooms are sucked out and expelled using an exhaust duct. This is a complicated system in which the design of duct and power requirements comes into play. The back pressure loss from the duct increases the power consumption and the system may have leakages through the duct and require proper maintenance. Its used only when a series of zones has to be ventilized and used often in high storey buildings.