The LWF Blog

Fire Safety Engineering for Design – Risk Assessment & Fire Engineering – Part 60

December 20, 2021 12:02 pm

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 59, LWF began to discuss qualitative risk assessment. In part 60, we continue looking at qualitative risk assessment and how it is used to analyse and support design decisions.

There are a few pieces of guidance available which give help on how to assess risk and apply risk assessment to influence a design in a qualitative way:

BS 7974 – Application of fire safety engineering principles to the design of buildings – Code of Practice

BS 9999 – Fire safety in the design, management and use of buildings – Code of Practice

Both standards talk about ‘risk profiling’, a tool to help inform the design of certain aspects such as means of escape and structural fire resistance. ‘Occupancy characteristics’ are also mentioned and this relates to the likely state of the occupants in terms of wakefulness and awareness of their environment.

The difference between a room with ten staff members working in it and a similar room but with ten in-patients in a care facility could be significant when it comes to their reactions and awareness in a fire situation, especially if there is the possibility that the occupants could be asleep.

Familiarity with the environment is also important. Staff members will have taken part in fire drills and received fire training, therefore they will know the different ways out of a building to a place of safety in a fire situation. Other types of occupancy will need more information and potentially, assistance.

Risk profiling can help with ascertaining the probable fire growth within the building. The combination of probable fire growth and occupancy characteristics can provide a risk ranking which may be used to pinpoint the best design criteria for aspects such as means of escape distance, structural fire resistance, etc.

BS 9999 talks also about fire growth rate and it should be noted that this is different from fire load or potential ultimate fire size. A building may have a high fire growth rate with a low fire load, and vice versa.

In part 61 of LWF’s series on fire engineering, we will continue looking at qualitative risk assessment. 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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