The LWF Blog

Fire Safety Engineering for Design – Smoke Ventilation – Part 183

May 13, 2024 10:50 am

LWF’s Fire Safety Engineering blog series is written for Architects, building designers and others in the construction industry to highlight and promote discussion on all topics around fire engineering. In part 182, LWF began to look at smoke ventilation and the potential hazards of smoke spread to occupants of enclosed spaces. In part 183, we continue discussing smoke ventilation, beginning with the principles of smoke ventilation systems.

A smoke ventilation system may operate on one of the following principles, or a combination thereof, and can be natural and/or mechanical:

• Smoke management or control systems are based on ensuring adequate ventilation and containment of smoke to provide a smoke-free clear layer above finished floor level. The purpose of the clear layer is to provide suitable conditions for occupants to evacuate or to minimise smoke damage to property and goods.
• Systems designed to dilute the smoke with fresh air or smoke clearance are based on providing sufficient ventilation to dilute the smoke to the point where conditions are tenable. In circumstances where normal internal conditions or outside wind pressures can adversely affect the formation of a stable smoke layer, these systems are particularly appropriate. A similar system can be used to remove heat and smoke from spaces such as basements and some atria to assist the Fire Service in their operations.
• Opposed air flow systems work by a flow of air being used to prevent the flow of smoke into adjoining spaces. They tend to be most useful in small enclosed areas, such as staircases and corridors.
• Pressure differential systems typically work on either pressurisation or depressurisation of a space or an adjoining space.

When designing a smoke control system for a building or area of a building, there are certain key aspects which should be considered as a part of the design.

• Maintaining a smoke-free layer
• Area of reservoir
• Reservoir screens and curtains
• Replacement air
• Number of extract points
• Smoke layer depths
• Suspended ceilings
• Pressure differentials

Each of these areas will be visited in more detail as a part of this blog series, beginning with ‘Maintaining a smoke-free layer’ in the next blog.

In part 184 of LWF’s series on fire engineering we will continue to discuss smoke ventilation. In the meantime, if you have any questions about this blog, or wish to discuss your own project with one of our fire engineers, please contact us.

Lawrence Webster Forrest has been working with their clients since 1986 to produce innovative and exciting building projects. If you would like further information on how LWF and fire strategies could assist you, please contact the LWF office on 0800 410 1130.

While care has been taken to ensure that information contained in LWF’s publications is true and correct at the time of publication, changes in circumstances after the time of publication may impact on the accuracy of this information.