The LWF Blog
Fire Engineering Design and Risk Assessment – Sprinklers & Fire Engineering – Part 9August 24, 2017 10:14 am
In LWF’s Fire Engineering Design and Risk Assessment blog series for architects and others in the building design business, we have been discussing the effectiveness of sprinkler use as part of the fire protection plan of a building.
In part 8, we finished by talking about fire size and how this can be predicted using prescriptive design codes through hazard areas, water discharge rates and anticipated area of operation. We pick it up today by looking at how it can also be achieved through fire engineering design.
Fire Engineers would approach the issue by determining the rate of heat release of the fuel load and construction materials of the building, although it is likely that a fire engineered solution would be most appropriate in more unusual building projects, rather than in a straightforward building which could be used in the future for different uses. The reason for this is that the recommendations of the fire engineers will be particular and bespoke and so would be less suitable for a change of use in the future, potentially leading to an inability to control fire growth if it occurs.
One area of potential sprinkler use which is not effectively covered by current design codes is that of using sprinklered water to assist with protection against fire spread between buildings and to enhance the fire-resistant properties of glass. Sprinkler heads which have been placed to cool glass will prolong the amount of time that the glass can withstand the heat from fire, and so avoid the glass breaking.
However, it should be noted that fire-rated glazing is the only glass which can be considered for compartmentation purposes and as part of a fire safe design. With standard glass, the sprinklered water would have to reach and cool the glass before it reached a certain temperature to avoid the glass breaking. In addition, any ‘dry spots’ on the glass would certainly heat up and cause the whole pane to break, so thorough dousing would be required.
The use of sprinkler-type systems to cool and wet external walls of buildings is not commonplace in the UK, but is seen more often in Australasia and Hong Kong, where the aim is to avoid the spread of fire between buildings in close proximity to each other. Often known as ‘Drencher’ systems, it is possible to get such a system in the US, where it is covered by NFPA guidance.
In part 10 of this series, we will look more closely at sprinkler systems designed to extend the structural integrity of windows. 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.