What’s new in the application of fire safety engineering principles?
BSI has just published a long-awaited revision to BS 7974 – the UK’s “go-to” standard on fire safety engineering. This blog post looks at the principles of FSE and at how the standard has changed.
Fire safety engineering is about taking the total fire risk management of a building into account and designing accordingly. It’s seen as an alternative approach to fire safety in buildings but is one which is now well-established. Edinburgh University, for example, is home to the BRE Centre for Fire Safety Engineering (FSE) and has been an important researcher and educator in FSE for over forty years.
For many buildings, the recommendations in existing design standards such as BS 9991 and BS 9999 will suffice. However, FSE is credited as being an approach which can often offer more fundamental, bespoke, safer and economical solutions than more generic approaches to fire safety. Also, in some cases where large, complex and unique buildings are contemplated, it’s seen as the only viable means of achieving a satisfactory standard of fire safety.
FSE applies scientific and engineering principles as well as expert judgement based on an understanding of the phenomena and effects of fire, and the reaction of people. FSE practitioners therefore need to have a holistic understanding of how fire systems, structures, and people respond to fire. Fire safety engineers can then create infrastructures that are inherently safe and at the same time meet the needs of clients, architects, and fire safety regulators. Which brings us to fire safety engineering design – the subject of the new standard BS 7974.
How does BS 7974 help?
BS 7974 was first published in 2001. It supplies a framework which lets users apply fire safety engineering principles to building design and is used to develop and assess fire safety engineered proposals.
The standard describes the philosophy that underpins fire safety engineering and outlines the basis involved. It provides a means of establishing acceptable levels of fire safety without imposing unnecessary constraints on aspects of building design. It allows the effect of departures from design codes to be evaluated. The standard also recognizes that functional objectives can be achieved by a range of alternative and complementary fire protection strategies. It aims to facilitate innovation in design without compromising safety.
For users, the standard gives designers a disciplined approach to fire safety design; it allows safety levels of specific designs to be assessed and quantified where appropriate; and it allows the safety levels for alternative designs to be compared. The standard’s framework also provides a basis for the selection of appropriate fire protection systems and information on the management of fire safety for a building.
The Published document series
The standard is supported by the PD 7974 series: currently seven published documents that contain guidance and information on how to do detailed analysis of specific aspects of fire safety engineering in buildings. The intention is that each summarizes the “state-of-the-art” in its area, and is updated as new theories, calculation methods or data become available. The series comprises:
- Part 1: Initiation and development of fire within the enclosure of origin
- Part 2: Spread of smoke and toxic gases within and beyond the enclosure of origin
- Part 3: Structural response and fire spread beyond the enclosure of origin
- Part 4: Detection of fire and activation of fire protection systems
- Part 5: Fire service intervention
- Part 6: Evacuation
- Part 7: Probabilistic fire risk assessment
The BS is used to identify and define one (or more) fire safety design issue(s) to be tackled via FSE. The appropriate PD is then used to set specific acceptance criteria and undertake detailed analysis.
Fire is a complex phenomenon and there are still gaps in our knowledge of it. However, the intention is that when used by suitably qualified persons experienced in fire safety engineering, this series of Published Documents can provide a means of establishing adequate levels of fire safety economically without imposing unnecessary constraints on aspects of building design.
What’s new in the 2019 version?
2019 sees the first revision of BS 7974 in 18 years. BS 7974:2019 Application of fire safety engineering principles to the design of buildings. Code of practice is not a big departure from the 2001 version, but some important changes have nevertheless been made.
First, for ease of handling, the recommendations that were previously found in PD 7974-0 and PD 7974-8 have now been incorporated into the BS standard, meaning that those two PDs are now withdrawn.
Second, and most importantly, this revision puts a greater emphasis on the competence of fire engineers. Also, additional recommendations have been introduced covering quality assurance and verification of fire engineering reports.
Finally, the drafting committee took this opportunity to simplify and consolidate the terminology used in the standard. It’s important to note that the underlying process of fire engineering based on the qualitative design review has not changed, but every effort has been made to ensure the terms used to describe the process are used consistently throughout the standard.
In addition, four of the PDs – Parts 1, 2, 6 and 7 – have also been fully revised and updated in line with current thinking, technological advances and changes to BS 7974 and other parts of the PD 7974 series. The hope is that BS 7974 and its PDs will now provide robust support to FSE practice for many more years to come.
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