Fire evacuation from office buildings

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Alan Field examines the importance of reviewing the technical aspects of fire evacuation strategies in office buildings. All aspects of life safety fire risk assessments should always be considered in terms of how operational routines may aid or compromise the assumptions made within those assessments.

Too many assumptions

As with all fire safety in the workplace, particularly in comparatively low risk buildings such as offices, complacency can set in at all levels from landlord to individual office worker. If individuals incorrectly assume that a fire is most unlikely to take place, then they may not give due attention to evacuation procedures.

The facilities management professional can help provide a focal point between the different parties to ensure that up-to-date awareness carries through into any emerging limitations in the life safety fire risk assessment, and can liaise with the fire service to help ensure any incidents are managed effectively in terms of evacuation.

With the tragic events at Grenfell Tower in mind, many individuals now consider life safety issues more critically in relation to high-rise buildings. Yet working in a high-rise building is, of course, very different from being resident in one. Equally, each high-rise building presents different safety challenges just as each building use will present its own risks, eg an office building with one commercial tenant will present different risks from one with multiple tenants or short-term licensees.

Just one example

A modern office building with multiple fire protection measures may present a better range of risk controls to manage life safety than an older building. However, as with all building systems, there must be an awareness of any limitations — both actual and future. The facilities management professional is often in the best place to have the overview of the practical issues that may impact on all evacuation strategies based on the building systems present.

For example, pressurisation of staircases is a common approach to minimise risk to occupants from smoke and other toxic gases spreading, especially while evacuating the building or moving certain occupants to a safer area. It can have a particular impact on the decision to have a single (or simultaneous) evacuation compared to a phased one. It can also enable a safer environment for the fire service to deploy its initial attack or establish a Fire Control Centre (FCC), which may be established on the ground or first floor in the event of an incident.

However, has the life safety fire risk assessment taken into account that, with pressurisation, there could be issues with any assumptions made? For example, if the pressurisation needs any particular maintenance routines to ensure it works effectively these need to be carried out regularly. Also, there may be circumstances that would compromise the pressurisation, eg a certain combination of fire doors left open. If so, then the operational routines should reflect the importance of the education of tenants and contractors to minimise the risk of these critical doors being left open.

Similarly, if a refuge area has been designed into the building, could the effectiveness of this be compromised, especially if pressurisation is always assumed to be in place? Are there any contingencies that could be deployed if this happened?

There can be many similar scenarios where the dependence on fire detection and fire alarm systems to progress evacuation needs to be considered in terms of reality rather than assumptions, eg the zonal accuracy of fire alarm panels, which might be used to detect priority areas for evacuation.

The other consideration with life safety is with regard to the structural integrity of the building itself. The author has seen examples where older office buildings, especially from the 1960s, were not always built fully to the architect’s plans of the time. These variances might only relate to the construction method itself, eg the particular type or quantity of pilings, or the drainage layout. Especially with phased evacuations — and even with normal fire spread — unexpected structural differences can prove to be inhibitors to timely egress if the fire spread might create barriers or other unplanned delays. So, if this is a risk with the building concerned then it should always be evaluated in relation to life safety strategies. This would include areas immediately outside the main structure of the building if these are part of the evacuation route to the muster point(s).

Saved by the bell

One key area a facilities management professional can influence is the relationship with the fire and rescue services. As well as the topography of the site and other key matters, the facilities manager (FM) can provide added value by explaining the building systems and using the fire safety officer (or local fire station watch manager, as will often be the case today).

A part of this dialogue could include how the M and E systems of the building operate, how they can be isolated (where desirable in the event of fire) and how they will influence evacuation, eg ventilation systems; redundancy (or, occasionally, lack of them) in terms of a Building Management System. Such changes might may not have been fully considered at fire risk assessment stage, especially where comparatively minor upgrades have taken place since on things like software, Wi-Fi controls or physical wiring in the building. All of these might — in certain circumstances — have an influence on drifting smoke or early detection of a fire.

The fire service will then be better informed as to how the building systems will impact on the structural protections designed to support evacuation and any refuges within the building. This is where the facilities management professional’s knowledge and experience can supplement what the fire risk assessments may have determined.

Conclusion

  • Fire risk assessments need to be kept under regular review, especially for buildings with multiple tenants; this is especially true for life safety fire risk assessments.

  • Life safety risk assessments should always to consider any operational changes to the use of the building, including fire protection systems.

  • For example, where assumptions are made about pressurised staircases or refuges, what contingencies are in place if they are partially compromised?

  • If the building is not modern, how clear is the FM as to the structural integrity of the building, including areas immediately external to the main building if these are going to be used as egress or muster points?

  • Fit outs or minor structural changes will have their own fire risk assessments but was there adequate consideration given to wider changes to traffic within a building?

  • Consider minor changes to M and E systems, including where there is a BMS, where they may influence existing fire evacuation decisions, eg changes to software controls over ventilation systems, the isolation of electrical systems and other possible scenarios.

  • Always consider discussing changes with the fire service — the more real time information they have gives them the opportunity to plan strategies to facilitate safer evacuation and a more effective attack on any fire situation.

Last reviewed 22 January 2019

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