Ventilation fans are used to circulate the air in the buildings or houses. This type of ventilation is known as mechanical ventilation in which fans or blowers are used to create movement of the air. The other way to ventilate a house is using the natural ventilation where the air is moved by natural forces.
A good design of a house will incorporate the natural ventilation as much as possible to reduce the electricity bill as well as the conservation of the environment. However, it is inevitable that suitable fans will have to be installed to ensure that the air quality in the house is fresh and safe for the people to stay.