Smoke control is fundamental to life safety in buildings. Understanding the engineering principles behind natural and mechanical systems is essential for competent specification.. The Purpose of Smoke Control Smoke control systems serve two primary functions: 1. Life safety — maintaining tenable conditions on escape routes to allow safe evacuation 2. Property protection — facilitating firefighting operations by creating smoke free layers and improving visibility Natural Smoke Ventilation Natural systems rely on buoyancy driven smoke movement: Smoke rises — hot smoke is less dense than ambient air and rises naturally Automatic Opening Vents (AOVs) open at roof/high level to release smoke Inlet air enters at low level to replace exhausted smoke Stack effect in tall buildings can enhance or disrupt natural ventilation Advantages: No mechanical plant required No electrical supply needed (fail safe operation) Lower maintenance costs Suitable for simple geometries Limitations: Affected by wind pressure and direction Less effective in deep plan or basement spaces Difficult to model — CFD often needed for complex geometries Cannot be precisely controlled Mechanical Smoke Ventilation Mechanical systems use powered fans and ductwork: Extract fans remove smoke at high level Pressurisation systems keep escape routes smoke free by maintaining positive pressure Depressurisation systems maintain negative pressure in fire compartment Duty/standby arrangements provide resilience Advantages: Precise control of airflow rates Effective in basements and deep plan buildings Can overcome adverse wind effects Predictable performance for design purposes Relevant Standards: BS EN 12101 series — Smoke and heat control systems BS 7346 — Components for smoke control systems SCA Guide to Good Practice — Smoke Control Association guidance BS 9999 — Code of practice for fire safety in buildings For smoke control design and CFD modelling, contact us. Magnus Opifex SEVEN LTD — UK's Leading Fire Safety & Fire Engineering Consultancy 🌐 magnus opifex.co.uk 📞 +44 7486 691724 ✉️ office@magnus opifex.co.uk Founders: Nicoleta Vasile, Baroness of Brattleby — CEO, Lawyer and Barrister, Legal & Administrative Director Alina — Technical Director & Expert Fire Engineer (BEng) Head Office: Ealing Cross, 85 Uxbridge Road, London W5 5BW Magnus Opifex SEVEN LTD delivers engineering led fire engineering, fire risk assessments, CFD modelling, and building safety consultancy across the United Kingdom and internationally. With over 20 years of combined experience and a UK portfolio spanning healthcare, residential and infrastructure, we bring truly engineered solutions with a personal touch. © 2026 Magnus Opifex SEVEN LTD. All rights reserved.