Smoke control systems may not be as high profile as other fire safety equipment but their proper design, installation and maintenance is essential, as Ian Doncaster explains.

When it comes to fire and life safety systems it’s a safe bet that most people in building services, facilities management and property services will have an understanding of why they have fire alarms, sprinkler systems and fire extinguishers. However when it comes to smoke ventilation systems, the purpose and importance of what may be very a complex system is often unknown. Since smoke ventilation systems are often hidden away in the fabric of a building, responsible staff in all sizes of organisation are frequently unaware of their function, operation or even existence.

The Antonine shopping centre in Aberdeen includes over 100 Shadow ventilation windows in the glazed ceiling

Smoke control – what is it?
A common question is: What is the purpose of a smoke ventilation system and what does it do? In simple terms it allows smoke and heat to be vented from a building, primarily to protect means of escape; it is well documented that most injuries and deaths in fire incidents are as a result of smoke not fire. If smoke is not effectively vented, contained or controlled it will rapidly fill a building space, resulting in reduced visibility, causing confusion and panic. This compromises escape and leaves occupants vulnerable to the effects of exposure to hot and poisonous gasses.

Another major reason for providing smoke ventilation is to provide improved conditions for firefighter access. Firefighting operations can be facilitated by improving visibility and reducing heat build up, the risk of flashover, explosion, roof collapse and fire spread. The other main function is asset protection.

Understanding the system
Smoke ventilation systems vary greatly in complexity. Some comprise of just a few natural vents, while others are very complex and include powered ventilation, shafts, dampers, pressure control systems and fixed or retractable smoke curtains. There may also be a dual function to provide day-to-day ventilation as well as smoke ventilation. The correct integration of these systems with other fire safety systems such as fire alarms and sprinklers is vital. Worryingly, it is often the case that organisations have the components of fire systems tested and certified but never test the integrity of the overall package or even know what it should do – in the case of shopping centres, testing should be carried out weekly.

Smoke control at the Purley Way Urban Village includes passive ventilation and pressurised systems for escape routes

Technology and principles of design
Smoke control designs should be based on expert understanding of the fundamentals of airflow and fire behaviour, which are then considered in the context of the geometry of a building. Engineers need to understand how smoke flows through complex buildings such as shopping centres and atria with mezzanine levels, and apply appropriate measures to make the building safe and compliant with building regulations.

In terms of technology, systems can, for example, use attractive glazed ventilators in shopping centre atrium roofs to allow smoke to escape in an emergency, with deployable smoke curtains lowering to create smoke compartments – these prevent smoke spreading and compromising escape routes. Where floor space is at a premium or there is an unusual building layout, a mechanical extract system may be used.

In enclosed car parks small, powerful fans can be used to push smoke toward extraction points, allowing firefighters to access the blaze unhindered. In apartment buildings, damper arrangements can be designed to shut to prevent fire spread, or open to allow smoke to leave the structure, away from escape routes such as stairwells. All of these elements can be centrally controlled via systems which measure changes in environmental conditions and monitor safety signals.

Regular service and maintenance of systems is essential

Service is crucial
As well as having the right systems installed, building owners and relevant responsible persons also have a legal obligation to ensure the system receives regular testing and service, as required by the Regulatory Reform (Fire Safety) Order 2005. Cutting corners by using non-specialist maintenance staff risks lives, breaks regulations and can lead to early equipment failure and additional cost in the medium term.

Ian Doncaster BTech(Hons) MPhil MBA CEng MIMechE is fire engineering manager at Airvent. To register your interest for a new brochure on smoke control design and service Email Airvent .