The LWF Blog

Fire Engineering Design and Risk Assessment – Fire and Smoke Ventilation – Part 7

March 3, 2017 10:58 am

In this Fire Engineering Design and Risk Assessment blog series for Architects and others involved in the design and construction industry, we have most recently been looking at fire and smoke ventilation and its use within structures as a part of the fire protection provision. In Part 6 of this series, we talked about ventilation in car parks and the difference between ducted systems and impulse fan systems.


We continue today with a summary of some of the benefits of impulse fan systems.


While the distribution ductwork required for a ducted system can be extensive, it is possible to reduce or even omit this completely when using an impulse jet fan system. Because of this, the system will have considerably less power consumption when an impulse fan jet system is used.


Such a system can also be used on a more regular basis when it is connected to CO censors, which trigger the system when the air reaches a certain level of pollution and push out the pollution, leaving more breathable air in its place.

An impulse fan system would usually cost less in construction to install than a ducted system, and there would be less upheaval.


In the case of a car park where stackers are a part of the design, a correspondingly more complex ventilation system will be required so that smoke is not pushed towards exit doors.


Of course, smoke and fire ventilation systems have other applications within buildings and one of the most important is that of protecting the escape routes and firefighting shafts, so that the building occupants can escape safely in case of fire and the Fire Service can attend and reach the site of the fire without undue danger to themselves.


Most buildings are constructed with passive fire protection measures in place to assist with containing smoke in the area of fire origin. This simply means that the structure surrounding a given space is constructed of fire resisting materials including appropriately fire resistant doors, which are self-closing to avoid the spread of smoke from one compartment area to the next.


BS 476-31.1:1983 – Fire tests on building materials and structures. Methods for measuring smoke penetration through doorsets and shutter assemblies. Method of measurement under ambient temperature condition gives details of the calculations to ensure sufficient smoke resistance.


In the next blog in this series, we will continue to discuss the design of systems to protect escape routes and firefighting shafts. 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 for over 25 years to produce innovative and exciting building projects. If you would like further information on how LWF and fire strategies could assist you, please contact Peter Gyere on 020 8668 8663.


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