What Is a Smoke Ventilation System?

A smoke ventilation system is a designed system of vents, fans and controls that manages smoke movement within a building in the event of a fire. Its primary purpose is to protect escape routes — keeping corridors, lobbies and stairwells free of smoke long enough for occupants to evacuate safely — and to assist firefighting by clearing smoke from the building to improve visibility and reduce the heat hazard for firefighters.

Types of Smoke Ventilation System

• Natural ventilation: Uses purpose-designed openings — windows, vents, shafts — to allow smoke to escape through natural buoyancy. Cost-effective and reliable, but dependent on weather conditions and building geometry
• Mechanical ventilation: Uses fans to extract smoke from the building, providing more control over smoke movement and able to overcome unfavourable wind conditions
• Pressurisation systems: Maintain a higher air pressure in protected stairwells and lobbies relative to the surrounding areas, preventing smoke from entering the escape route. Used in taller buildings where natural or mechanical extract cannot adequately protect the stairwell
• Smoke shaft systems: Vertical shafts connecting corridors or lobbies to a smoke vent at roof level, used in residential buildings to provide natural ventilation of common corridors

When Are Smoke Ventilation Systems Required?

• Common corridors in residential buildings — Approved Document B requires smoke ventilation of common corridors in blocks of flats, typically through a smoke shaft system
• Protected lobbies in taller buildings — lobbies providing access to protected stairwells in buildings over 20 metres require mechanical or pressurisation smoke control
• Basement car parks — ADB requires smoke ventilation of underground car parks
• Atria — large atria require smoke control systems to maintain tenable conditions in the atrium and adjacent escape routes
• Buildings using performance-based fire engineering — where compensating measures are required to justify extended travel distances or alternative escape strategies

What the Fire Strategy Covers

The fire strategy specifies the smoke ventilation strategy for the building — the type of system, the smoke control zones, the performance requirements (air changes per hour, design smoke temperatures, flow rates), and the interface with the fire detection and alarm system. Smoke ventilation systems must be designed by a specialist M&E engineer, but the performance requirements and strategy are set by the fire engineer in the fire strategy.

Testing and Maintenance

Smoke ventilation systems are active fire safety systems — they must be tested and maintained to ensure they function when needed. The fire strategy specifies the testing and maintenance requirements, and the building owner is responsible for ensuring these are carried out. Failure of smoke ventilation systems due to inadequate maintenance is a recognised fire safety risk.