The LWF Blog

Fire Engineering Design and Risk Assessment – Firefighting – Part 65

October 28, 2019 3:17 pm

In LWF’s Fire Engineering blog series for Architects and others involved in building design, we have been looking at the provisions which should be made for firefighting activities. In part 64, we continued with a general overview of firefighting in relation to building design and provision for firefighters. In part 65, we continue from that point.

Ventilation of firefighting staircases and lobbies can assist with keeping the conditions clear and breathable while the Fire Service travel to the floor of fire origin and set up their equipment. It can also assist in the early stages of a fire when building occupants are evacuating.

When considering whether ventilation is required in a building for fire safety purposes – and if so, what method of ventilation should be employed – an assessment of the potential smoke production for all floors should be carried out. Other elements should be taken into account in the assessment, such as the extent of compartmentation between the potential seats of fire and the lobby and the effects on smoke production and smoke flow resulting from any automatic fire suppression system.

Whether or not ventilation is required to ventilate large-compartment single-storey buildings for firefighting access is dependent upon the objectives of firefighting, the type of goods kept on site, rate of smoke production, the size of the smoke reservoir created by the volume of the building and the timeline for the Fire Service.

Where ventilation is required in spaces within large buildings, underground car parks, basements and firefighting shafts, it is important to undertake three processes:

– The functional ventilation requirements for the spaces and/or shafts must be determined.
– The height of clear layers and smoke temperatures as a function of time must be established.
– The circumstances fulfilling the requirements should be calculated.

In ultra high-rise buildings which have refuge zone floors and vertical sectors, firefighting access might be based on the following points:

– The provision of high-speed lifts to transport firefighters and equipment from the access level to the refuge zone below the fire floor.
– Additional lifts to transport firefighters and equipment from the refuge zone to all floors in the vertical sector.
– Power supplies backed-up and protected so that a single event cannot cause power failure.
– Landing valves to be provided and the provision and design of firefighting shafts and general access to be applied in each vertical sector.

While a large single-storey building is not subject to any special requirements relating to internal access, the owner/developer should be made aware that if a fire is not extinguished in its early stages, it is likely to result in the total loss of building and contents. For this reason, automatic fire suppression systems are recommended.

In the next blog in the series, LWF will begin looking at Fire Safety Management. 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 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.

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