Ventilation fans do not necessarily have to be installed on the outside, but it depends on the specific application and the type of ventilation system you are using. Let's explore a few scenarios:
Exhaust Fans: Exhaust fans are typically installed on the inside of a building to remove stale air, odors, and pollutants. They are commonly used in bathrooms, kitchens, and other areas that require air extraction. In this case, the fan is placed inside the room, and the exhaust air is directed to the outside through ductwork that connects the fan to an exterior vent.
Attic Fans: Attic fans are installed in the attic space of a building to help regulate the temperature and reduce heat buildup. These fans are designed to draw air from the living spaces below and exhaust it to the outside. Attic fans are mounted inside the attic and have vents or louvers that open on the exterior to allow air to escape.
Industrial Ventilation Systems: In some industrial settings, ventilation fans may be installed both inside and outside the building. For example, large industrial exhaust systems might use fans inside the facility to extract polluted air from specific areas, and then duct it to an exterior fan that discharges the air away from the building.
Whole-House Ventilation Systems: Whole-house ventilation systems, like heat recovery ventilation (HRV) or energy recovery ventilation (ERV) systems, are designed to provide continuous air exchange throughout the entire building. These systems often have a unit installed inside the building that exchanges indoor and outdoor air while recovering heat or energy. Some whole-house systems may also have additional exhaust fans to expel stale air to the outside.
In summary, the location of ventilation fans depends on the specific purpose and type of ventilation system being used. In many cases, they are installed on the inside and connected to the outside through ducts or vents to facilitate air exchange and improve indoor air quality.