The LWF Blog

Fire Engineering Design and Risk Assessment – E.F.R. and Firefighting – Part 12

November 1, 2018 12:59 pm

In LWFs Fire Engineering blog series for architects and others in the building design business, we have been looking at compartmentation. In part 11, the advantages and disadvantages of using equivalent fire resistance were discussed. In part 12, we look at equivalent fire resistance (E.F.R.) from the perspective of BS 9999.


BS 9999:2017 – Fire safety in the design, management and use of buildings. Code of practice looks at equivalent fire resistance for use in conjunction with a concept named ‘occupancy characteristic’ (oc). The combination allows recommendations for compartmentation in different types of building and occupancy. It also takes into account the risk profile. BS 9999 relays this information in a table format which allows the reader to discern a fire-resistance period calculated using equivalent fire resistance and which considers key parameters such as height of the building.


The calculation method used in BS 9999 differs from the methods used in CIB and Eurocode.




Although most readers will associate the term ‘firefighting with the Fire Service, it can also be used to refer to the efforts to subdue a fire taken by building occupiers or any other individual or organisation. Although the official fire service in different parts of the world will be known by different names, we shall refer to them all as ‘fire service’ throughout to avoid confusion.


Just as there are standards which relate to fire safety and fire engineering solutions, there are codes containing prescriptive standards for the fire service too. The methods involved can be grouped into three headings – strategy, tactics and operation.


Strategy relates to the planning of fire service objectives, such as saving the lives of persons affected by fire, mitigating damage to property and to the environment from fire and from the firefighting activities undertaken.


Tactics refers to those methods employed at the site of a fire to achieve the objectives listed in strategy, above.


Operations are how the equipment and techniques can be used to fulfil the tactical plan.


Of course, for the maximum effectiveness of the methods, it is important that the fire service are able to attend the fire as soon as possible, however, due to geographical location, demand for the service and facilities available, attendance times can vary significantly. Because of this, it is important that fire safety measures are in place at the destination to enable an assessment of potential maximum size of a fire for when the fire service arrive. In addition, any resources inside and outside of the building, such as water mains, should be available and functioning.


In part 13 of this series, LWF will continue to look at firefighting from the point of view of the occupier of a building. 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.


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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