There is smoke ventilation regulation in some countries requiring AOV systems or SHEV systems, Smoke and Heat Ventilation System.  The details of the regulations are different across countries. The systems are exhausting heat or smoke from Rooflights/ Roof louvers/ high windows. Some studies show that over 90% of fire-related death are caused by smoke inhalation. With the help of SHEV systems, it will provide people more time to escape from a fire.