Mechanical smoke ventilation systems use powered elements such as fans to force the movement of smoke to allow it to escape through dampers, grills and vents.
Mechanical systems generally utilise a smoke shaft and are often more efficient, sometimes requiring a very small smoke shaft.
A mechanical system is useful where space is at a premium and/or natural airflow is insufficient to achieve the required performance.
Natural smoke ventilation uses the inherent buoyancy of hot smoke and the airflow dynamics of smoke and air to remove smoke. The use of Automatic Opening Vents (AOVs) at a high level
within a building allows smoke to escape from the building when a fire is detected at the vents are automatically opened.
This approach allows the existing building façade, including windows, to be used as an integral element of the smoke ventilation strategy and is particularly useful in building with large atria.
Smoke and Heat Exhaust Ventilation Systems (SHEVS)
Whether these are natural or powered, they remove smoke from the building. Inlet ventilators, dampers and ductwork are also often integrated into the scheme.
Smoke Containment Systems
These prevent the movement of smoke and heat from one area to another. They take the form either of physical barriers such as smoke curtains or fire curtains, or as pressure differential systems, also known as pressurisation systems.
Car Park Ventilation Systems
Induction (or jet) fans clear smoke from enclosed or underground car parks. These are often combined with fume ventilation to prevent the build-up of vehicle exhaust gases in normal day to day use of the car park. Louvres, dampers, and powered smoke extraction fans are also often integrated into the scheme.
The chairman of the Smoke Control Association says: "Smoke is the greatest threat in a fire. A fire can fill an area of 10,000m2 with smoke within minutes. 5 breaths are all it could take to lose consciousness. Effective smoke control saves lives".