An atrium smoke evacuation system is generally intended for use by Fire Service personnel to clear smoke from a building after a fire has been controlled. It is therefore not usually linked to an automatic detection system.
Rooflight AOVs (R) are installed in the roof above the atrium, with a free area not less than 10% of the effective floor area of the atrium, i.e. the area on the ground floor not covered by the floor slabs above. Alternatively, Computational Fluid Dynamic (CFD) modelling can be used to determine the required free area.
When the Fire Service personnel deem it necessary, the Break Glass Switch (B) is activated and a signal is sent from the Control Panel (A) to open the rooflight AOVs. This allows the atrium to be cleared of smoke, as the natural buoyancy of the hotter air will encourage the smoke to rise to the highest point in the building.
To aid this effect, it is usual to add ground floor vents to the system, which open simultaneously to allow cooler replacement air to enter the building at the lowest level.