Ventilation is the process of changing or replacing air in any space to control temperature or remove any combination of moisture, odors, smoke, heat, dust, airborne bacteria, or carbon dioxide, and to replenish oxygen. Ventilation includes both the exchange of air with the outside as well as circulation of air within the building. It is one of the most important factors for maintaining acceptable indoor air quality in buildings.  Methods for ventilating a building may be divided into controlled (fan forced)  and uncontrolled (open windows).

There are only three types of ventilation, In, Out and Around. Each type has is advantages and is used differently (see below);

Air flows into the home faster than it can leak out causing
positive pressure within the building.

  • Fresh air ventilation
  • Condensation control
  • Heat recovery – winter
  • Cooling – summer
  • Sub floor ventilation

Air flows out the home faster than it can leak in causing
negative pressure within the building.

  • Hot air extraction from the roof space
  • Kitchen, bathroom, toilet extraction
  • Sub floor ventilation

Air flows around the home, no pressure difference.

  • Heat transfer
  • Cool transfer