Glossary — Fire Engineering
Smoke Control System
Smoke control systems manage the movement of fire smoke to keep escape routes clear, facilitate firefighter access, and limit smoke damage. They include natural smoke vents (AOVs), mechanical extraction fans, stairwell pressurisation, and smoke curtain reservoir systems. Governed by BS EN 12101.
Why smoke control matters
The majority of fire fatalities are caused by smoke inhalation, not direct flame contact. Smoke — particularly the toxic gases produced by modern synthetic materials — can incapacitate within minutes. Smoke control systems buy time: keeping escape routes clear long enough for occupants to evacuate and firefighters to enter. See our flashover and backdraft entries for the fire behaviour context.
Smoke control system types
| System type | Mechanism | Standard | Typical application |
|---|---|---|---|
| Natural smoke vent (AOV) | Actuated roof or wall vent opens on alarm; smoke rises by buoyancy | BS EN 12101-2 | Single-storey industrial, stairwells, car parks |
| Mechanical smoke extract | Powered fans extract smoke at high level; replacement air enters at low level | BS EN 12101-3 | Shopping malls, atriums, underground car parks |
| Stairwell pressurisation | Fans pressurise stairwell above adjacent areas to prevent smoke ingress | BS EN 12101-6 | Escape stairs in tall buildings, protected lobbies |
| Corridor pressurisation | Maintains positive pressure differential to keep escape corridor smoke-free | BS EN 12101-6 | Hospital escape corridors, high-risk occupancies |
| Smoke reservoir / curtain system | Smoke curtains create reservoirs; extract removes smoke from each reservoir | BS EN 12101-1 / BS EN 16034 | Shopping centre malls, airport terminals, atriums |
Integration with compartmentation and detection
Smoke control systems do not work in isolation. They depend on:
- Fire compartmentation — to limit the area from which smoke is produced and from which extract must occur
- Automatic fire detection — to activate the system quickly and accurately; false activations of mechanical smoke extract can be disruptive and costly
- Fire curtains — to form smoke reservoirs that the extract system can clear efficiently
- Means of escape — the smoke control strategy must be designed around actual escape routes and times
See our entries on fire compartmentation, automatic fire detection, fire curtains, and means of escape.
Smoke control in residential buildings
Following the Grenfell fire, smoke control requirements for residential blocks have been reviewed and updated. The 2019 edition of Approved Document B includes updated requirements for AOVs in stairwells (at the head of each stair) and for smoke control lobbies in buildings over 11 metres. For fire safety in multi-occupied residential buildings, see our fire safety for flats guide and our high-rise fire safety 2026 article.
The BS EN 12101 series
BS EN 12101 is a multi-part European standard covering all aspects of smoke and heat control: Part 1 (smoke curtains), Part 2 (natural smoke vents), Part 3 (powered smoke/heat exhaust ventilators), Part 6 (pressure differential systems), and Part 10 (control panels). All components must be CE marked and tested to the relevant part. Systems must be designed by a competent specialist and commissioned with formal performance verification.
Frequently asked questions
FAQ