Mechanical ventilation is simply a duct coming into the building with a fan blowing fresh air in and a duct going out of the building with a fan blowing stale air out. Since the fans are powered and controlled, the ventilation is considered “mechanical” as opposed to a ventilation system with no power and no control such as ‘natural ventilation’.
Buildings are intentionally made more airtight, and consequently less well ventilated. Since all buildings require a source of fresh air, the need for Heat Recovery Ventilation has become obvious. While opening a window does provide ventilation, the building’s heat and humidity will then be lost in the winter and gained in the summer, both of which are undesirable for the indoor climate and for energy efficiency, since the building’s heating, ventilating/ventilation, and air conditioning (HVAC) systems must compensate. Heat Recovery Ventilation introduces fresh air to a building and improves climate control, whilst promoting efficient energy use.
Having considered the application of the ventilation required, it is important to select the correct type of fan to ensure that the requirement is met.
It is not sufficient to fit just any fan. It is important that the fan performs efficiently by extracting the minimum flow rate at the grille outlet as required by the latest Building Regulations. This is known as installed performance.
The number of bends and the length of duct attached to the fan will create resistance to flow that must be overcome to ensure adequate extraction.
You should first consider which type of fan will be best suited to provide quiet, efficient ventilation