The LWF Blog

Fire Safety Engineering for Design – Means of Escape Design – Part 92

August 1, 2022 11:01 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 91, LWF discussed smoke-filling in rooms with low-level ventilation openings. In part 92, we begin to look at means of escape in terms of designing with life safety in mind.

Most countries around the world have introduced guidance and legislation which requires a standard of fire safety to be implemented when buildings are designed and constructed. The legislation lays out what is required and the guidance describes how effective means of escape provision should be made. Limits are commonly set on maximum travel distance, exit widths and fire-resistance standards.

The solutions given are referred to as prescriptive guidance when considered alongside alternative solutions, which are increasingly permitted provided they can demonstrate results equal to or exceeding those set out in the requirements. Alternative solutions are those implemented after a fire-engineered assessment and design, which may be carried out by a suitably qualified professional.

The objectives of a means of escape design are typified by the Building Regulations for England and Wales, which state:

The building shall be designed and constructed so that there are appropriate provisions for the early warning of fire and appropriate means of escape in case of fire from the building to a place of safety outside the building capable of being safely and effectively used at all material times.

Approved Document B is the guidance supporting the Building Regulations and its primary objective is to ensure an adequate standard of life safety can be achieved in the event of a fire in a building.

NFPA 101 Life Safety Code, in the USA, states the following in relation to fire safety:

A goal of this Code is to provide an environment for the occupants that is reasonably safe from fire and similar emergencies by the following means:

(1) Protection of occupants not intimate with the initial fire development

(2) Improvement of the survivability of occupants intimate with the initial fire development.

Occupant protection: A structure shall be designed and constructed and maintained to protect occupants not intimate with the initial fire development for the time needed to evacuate, relocate or defend in place.

Structural integrity: Structural integrity shall be maintained for the time needed to evacuate, relocate, or defend in place occupants who are not intimate with the initial fire development.

Systems effectiveness: Systems utilised to achieve the goals set out by the Code shall be effective in mitigating the hazard or condition for which they are being used, shall be reliable, shall be maintained to the level at which they were designed to operate and shall remain operational.

The objectives given in these and similar codes should be attainable without outside assistance from the Fire Service, for example. Such codes also assume a single point of fire, rather than the potential for multiple seats of fire in the case of a planned attack of arson.

In part 93 of LWF’s series on fire engineering, we will begin to look at evacuation strategies. 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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