Horizontal fire ventilation
This is where the outlets are on the same level as the fire, so that the flow of fire gases takes place horizontally. This would be the case, for example, in apartment fires or in certain types of industrial buildings where it is difficult, or in fact impossible, to create openings in the roof and where there are no skylights or vents.
Vertical fire ventilation
This is where the outlets are above the fire, often as high as possible in the building so that the flow of fire gases takes place vertically. The outlet is normally implemented by making an opening in the roof structure, or by using existing vents (windows/apertures or vents/shutters).
Mechanical fire ventilation
This can mainly be implemented as positive pressure ventilation or negative pressure ventilation. The mechanical ventilation must be combined with creating openings, so as to achieve horizontal or vertical ventilation.