The greatest immediate danger to the occupants of a large building in the event of a fire comes from the smoke rather than the heat of the fire. Even a small fire can rapidly fill a large building with smoke to an extent where people escaping the building cannot see to find the escape routes and can be overcome by smoke Inhalation.
The recognised method of addressing these problems is to provide a smoke ventilation system with automatically operated roof ventilators. Smoke and Heat Exhaust Ventilation Systems (SHEVS) are therefore an essential component of any building’s fire protection design concept. In a fire situation, smoke and heat exhaust ventilation systems create and maintain a smoke free layer above the floor by removing smoke. They also serve simultaneously to exhaust hot gases released by a fire in the developing stages. Their value in assisting in the evacuation of people from buildings and other constructions works, reducing fire damage and financial loss by preventing smoke damage, facilitating access for firefighting by improving visibility, reducing roof temperatures and retarding the lateral spread of fire is firmly established- so much so, it has become a legal requirement for all SHEV systems to be classified under CE EN12101-2.