The LWF Blog

Fire Safety Engineering for Design – Design Scenarios – Part 46

September 13, 2021 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 45, LWF examined design objectives, including life safety and environment impact. In part 46, we begin to discuss design scenarios, beginning with occupancy.

The design scenario for escape provision should be based on the likely occupancy of a building at maximum capacity. The number of people that can be contained within a room, part of a building, or entire building. It must also consider the likely distribution of people – whereabouts in the building they are likely to be. In the case of a cinema, for example, there would be many people in the area where the film is shown and potentially, another group of people gathering in the foyer and refreshment areas. There is likely to be a small percentage of people in the toilets, too. In the staff areas, there may not be many people at all.

The design scenario for escape must also consider the response characteristics of building occupants. Issues such as mobility, wakefulness and familiarity with surroundings should all be addressed. In a hotel, for example, the distribution of occupants will be spread out, but a good proportion of the occupants must be assumed to be asleep.

In order for the design to cater for future use, it should make the assumption that a proportion of the occupancy may have mobility issues and/or sensory or cognitive disabilities.

A fire scenario is designed to examine the impact of a fire situation on a building and look at the repercussions and fire safety measures necessary to ensure occupant safety. Even in a small and simple building, the number of potential fire scenarios is great. However, it is not necessary to assess all possible fire scenarios, but simply to identify one or more (as necessary) worst case scenarios for a detailed assessment.

It is wise to agree the design scenarios necessary with the approvals bodies before starting the modelling process which can be time-consuming and costly.

The resulting design scenarios should take account of the following elements:

  • The initial location of the fire
  • The materials used as fuel
  • The rate of fire growth and/or severity
  • The potential for smoke generation

In part 47 of LWF’s series on fire engineering, we will discuss how multiple safeguards should be in place to avoid a single catastrophic failure in fire safety design. 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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