CFD analysis for residential apartments is performed to demonstrate that smoke ventilation is designed to provide the expected standard of smoke clearance and protection for the stairwell.
Where there is only a small lobby, smoke ventilation is provided to protect the stairwell. It is critical that the stairwell remains clear of smoke so than occupants or firefighters can use it safely. Many buildings are provided with natural ventilation shafts which rely on stack and buoyancy effects to provide ventilation. Alternatively mechanical ventilation can provide better protection and often requires less space than natural ventilation systems. CFD analysis is used to demonstrate the mechanical smoke ventilation system is at least as good as compliant natural ventilation approaches or that the conditions are acceptable as assessed using fire engineering principles.
Where there are longer common corridors that provide access to residential apartments there is a need to clear smoke from the corridors that may enter following escaping occupants. This is to ensure other occupants on the floor can escape through relatively smoke free conditions.
It is inevitable that the smoke floods the common lobby during firefighting. Smoke extract systems need to prevent this smoke entering the stair and provide acceptable temperatures for firefighters in the lobby.