The LWF Blog

Fire Engineering for Healthcare Premises – Risk Assessment – Part 57

October 18, 2021 12:01 pm

In LWF’s blog series for healthcare professionals, our aim is to give information on best practice of fire safety in hospitals and other healthcare premises. In part 56 of Fire Engineering for Healthcare Premises, LWF looked at speed of movement, patient dependency and disabilities. In part 57, we discuss the use of risk assessment in fire safety engineered healthcare environments.

Risk assessment is a part of the fire engineering process. Fire engineering works to provide an environment with an acceptable level of safety in a fire situation for a sufficient duration to allow a safe evacuation of any occupants (or affected occupants in the case of horizontal evacuation systems). The process of providing a fire engineered solution involves calculating or modelling scenarios affecting all or a part of the fire system and it is this element in particular that requires risk assessments to be carried out.

Some risk assessment examples are implicit – the comparison of calculation results with threshold criteria, for example ‘smoke layer well above people’s heads’. These can be compared with worst-case scenarios. Lesser worst-case scenarios are considered to have minimal consequence, whereas more severe scenarios will have minimal probability.

There are also explicit risk assessment examples. Explicit risk assessment uses the formula:

Risk = probability x consequence

Each fire safety decision requires a full risk analysis until or unless it can be show that a less comprehensive approach is sufficient. Uncertainty in any area should be quantified wherever possible, rather than relying on conservative assumptions.

While it would be desirable to have a completely safe healthcare building, such absolutes are not possible. It therefore falls to the designer and/or fire engineer to interpret successfully what is considered to be an acceptable level of risk. Acceptability varies depending upon circumstances and perception of acceptability varies depending upon who is asked.

It is most common for it to be decided using one of two methods. The first is that the risks inherent in following prescriptive guidelines (e.g. Firecode) are acceptable and ‘reasonable’. The second is to use quantitative methods in comparative mode and assume that systemic errors and biases cancel out when two similar buildings are compared.

It is not possible to calculate absolute risks without a large degree of uncertainty

This blog has concerned itself with the use of risk assessment as part of a fire engineered design. On an ongoing basis, the Regulatory Reform (Fire Safety) Order 2005 requires the responsible person in a healthcare building to undertake fire risk assessments on a regular/ongoing basis. This form of assessment is qualitative and works on the basis that changes in circumstances may lead to an increase or decrease in fire risk. The working level to be maintained is the one set originally by the design team and which is discussed in these blogs.

In Part 58 of LWF’s blog series, LWF will look at the use of sensitivity analysis. 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 LWF on freephone 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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