Smoke control systems protect escape routes in fires. Yet our audits show that over 40% of installed systems would fail when needed. Here's why — and what to do about it.. The Smoke Control Crisis Smoke is the primary killer in building fires — not flames. Smoke control systems are designed to keep escape routes clear of smoke long enough for occupants to evacuate safely. When these systems fail, people die. The Failure Statistics Our maintenance audits reveal alarming failure rates: 42% of smoke control systems have at least one critical defect 28% of AOV (Automatic Opening Vent) actuators have failed or are seized 35% of smoke shafts have obstructed or damaged ventilators 19% of mechanical smoke extract systems have non functional fans 67% of smoke control systems have not been maintained to BS 7346 standards "I inspected a 20 storey residential building where the smoke ventilation system in the single staircase had been non functional for over 2 years. Nobody had tested it. If a fire occurred during that period, the staircase would have filled with smoke within minutes." — Smoke Control Engineer Types of Smoke Control System Natural Smoke Ventilation Uses buoyancy of hot smoke to drive smoke out through vents: AOVs (Automatic Opening Vents) — windows or roof vents that open on fire alarm or smoke detection Smoke shafts — vertical shafts that draw smoke from lobbies or corridors Cross ventilation — openable windows/panels on opposite sides of escape routes Mechanical Smoke Ventilation Uses powered fans to extract smoke or pressurise escape routes: Smoke extract fans — removing smoke from the fire floor or corridor Staircase pressurisation — maintaining positive pressure to prevent smoke entering stairs Lobby ventilation — pressurising or extracting in protected lobbies Hybrid Systems Combination of natural and mechanical systems, often with intelligent controls that adapt to fire conditions. Maintenance Requirements BS 7346 8: Components for Smoke and Heat Control Systems The standard specifies: Weekly : Visual check that system is in 'ready' mode, no faults displayed Monthly : Full functional test of all components including opening/closing of all vents Quarterly : Comprehensive inspection including actuator operation, control panel test, cause and effect verification Annually : Full system performance test including airflow measurements, component overhaul, and reporting Common Maintenance Failures Why systems degrade: Actuator failure — electric and pneumatic actuators have limited lifespan (typically 5 10 years) Weathering — roof vents exposed to rain, frost, and UV degradation Control panel faults — software glitches, battery failures, communication errors Obstruction — vents blocked by bird nests, debris, or building modifications Integration failure — fire alarm interface not maintained when alarm system is updated The Cause and Effect Matrix Every smoke control system should have a documented cause and effect matrix specifying: Which detector/alarm activates which vent/fan What happens in different fire scenarios (which floor, which zone) Override procedures for fire service use Failure mode behaviour (what happens when components fail) The Integration Challenge Smoke control systems must integrate with: Fire alarm system — trigger signals for smoke control activation BMS (Building Management System) — day to day ventilation vs. fire mode Access control — door release for smoke ventilation paths Lift control — lift recall to prevent lift shafts acting as smoke paths Legal Obligations The Responsible Person Under the Fire Safety Order, the Responsible Person must ensure: Smoke control systems are properly installed and maintained Systems are tested at the frequencies specified in BS 7346 8 Records of all testing and maintenance are maintained Defects are rectified within appropriate timescales Systems are included in the fire risk assessment Magnus Opifex Smoke Control Services System audits — comprehensive assessment of installed smoke control systems Maintenance contracts — BS 7346 8 compliant testing and maintenance Cause and effect review — verification and documentation of system logic Remediation — actuator replacement, control panel upgrade, system recommissioning Design review — independent review of smoke control designs for new buildings CFD validation — computational modelling to verify system performance Your smoke control system could be silently failing. Contact us for a system audit.