Lawrence Webster Forrest
Tel: +44 (0)20 8668 8663 Fax: +44 (0)20 8668 8583
Lawrence Webster Forrest
Tel: +44 (0)20 8668 8663 Fax: +44 (0)20 8668 8583
LWF PROFESSIONAL BULLETIN
Fire engineering, in relative terms is a new discipline and is growing faster than ever before. The benefits that fire engineering can bring to projects is becoming increasingly understood and enjoyed by design teams and end clients.
It is our belief that fire engineering can bring significant benefits to a wide range of projects, from small domestic developments to large public buildings. However, it is clear that the role fire engineers play is not always understood.
Whilst it may seem a strange question, there are professionals within the industry that have knowledge of fire engineering, have heard of its benefits but have yet to be involved on a project where fire engineering has been embraced. Other professionals have had experience with fire engineers, but this has often taken a ‘stable door’ approach, whereby a problem has arisen and fire engineers have been consulted in order to assist in finding a justifiable solution.
In the main, the primary objective of our role is life safety. This can be achieved by advising design teams on the implementation of given codes of practice, Approved Document B and the like or by undertaking a performance based, first principles approach setting design objectives, benchmarked acceptance criteria and a clear engineering methodology and accompanying report.
Whilst life safety is often a fundamental element, increasingly clients are aware of the negative effects a fire can have on Corporate Governance issues such as business continuity and seek advice on methods of achieving robust fire protection. Business continuity is not the only area requiring specialist advice, heritage, business reputation environmental impact amongst other factors may be very relevant. A fire engineer should always state the objectives of a design so all parties understand what will be achieved. A fire engineering design that satisfies life safety only may be significantly different to one that encompasses objectives of property and asset protection also.
Whist prescription has served us well and has been greatly influential in reducing fires, fire deaths and consequences of fire, it does not necessarily produce a fool proof solution, this was noted in the Cullen report which investigated the Piper Alpha disaster: “Many regulations are unduly restrictive in that they are of a type that impose “solutions” rather than “objectives” and are out of date in relation to technological advances. There is a danger that compliance takes precedence over wider safety considerations…”
This above statement was made in late 1990 and is very reflective of fire safety today.
How do we do it?
Our works often follow a prescribed format which is referred to as a Qualitative Design Review (QDR). Our initial works will normally take the form of a plan review and collation of project objectives. Plan reviews and subsequent discussions will ensure an understanding of the building and often more importantly, the occupation and associated uses. Whilst reviewing plans, a prescriptive assessment and logical review of fire safety will be considered. Where schemes are naturally in compliance with given codes of practice, little further action is required. However, where compliance is not achieved a method of assessment for acceptability will be chosen. Acceptability should always follow referenced data, for example, it may be acceptable for occupants to have smoke 2.5m above floor level (allowing a clear zone in which to walk), whereby the temperature is less than 200oC and these will form the design parameters. Any solution will strive to meet this criteria, if it does, the solution is deemed to be acceptable and the opposite is also true.
A fire engineering QDR report will almost always be produced and will be a formal report that can be utilised by the design team, the enforcing authorities as well as the end user. Fire engineering reports are commonly the starting point of any fire engineering design that will be taken forward into detailed design and installation often by others. Fire engineers have the knowledge and expertise to set required performance, but other members of the design team will usually take these forward. A clear example of this is smoke control. A fire engineer will set the design criteria, e.g. inlet and vent areas required to provide a desired objective, but the actual detailing will be undertaken by other disciplines as it will fall into their expertise and natural remit, albeit with constant reference with the fire engineer.
The output from a fire engineer will often depend on the clients requirements. A clear, concise report should always feature often accompanied by a set of floor plans identifying key components of the fire strategy.
When do we do it?
As early as possible. From our experience, the earlier our involvement with a project the greater the influence we can have, or the more likely the design aspirations of the team / client can be achieved. A common mis-conception is that early involvement will have an adverse impact on consultancy fees, however this is unlikely to be the case and the opposite may even be true. Our early involvement often means that we are able to produce a fire engineering ‘options’ document. As is true with most problems there is usually more than one solution. If we are able to identify a problem in its infancy we have a number of methods of dealing with it. Firstly, the problem will be raised to the design team, this will offer the simple solution of ‘designing out’. However, this is not always possible, the layout may have taken a given shape in order to meet a client brief, or some other external influence. At this stage, as fire engineers, any potential solutions would be proposed. It is not uncommon to achieve three or more solutions to the same problem, which could range from increased fire compartmentation to complex smoke control. As fire engineers we are not always best placed to determine which solution is best as this will be greatly influenced by factors which we are not always explicitly aware. Cost is always a consideration with any project, however is not always the overriding factor. A good fire engineer will recognise his/her limitations and only make decisions that they are best placed to do so. LWF, typically, in this instance distribute the options report to the design team recognising that fire engineering impacts on multiple disciplines. It is noted that a solution that may be viable for the structural engineer may pose an adverse implication to the mechanical design, hence communication between all parties is encouraged to ensure the right solution is provided to the client and the project and not the right solution for the fire engineer.
In fact, when we are introduced into a project at the latter stages it is often difficult to produce fire engineered solutions that do not have adverse impact on other services. Sometimes, unfortunately, the features we have to introduce into a project can be both costly and problematic. For example, if late in the design, possibly following consultation with the approving authorities it is discovered that there are areas of non compliance, additional fire precautions (often termed compensation features) may have to be introduced. Whilst not necessarily the case, often the more serious problems require complex solutions. Should the area of non compliance relate to life safety concerns, e.g. means of escape, then the compensation features will be fundamental to the overall design and are likely to have an increased level of impact. Features that may be required to justify non compliances related to life safety include suppression systems (commonly sprinklers), smoke control and possibly pressurisation. Enhancement to existing proposed features such as the automatic fire detection system is also likely to be considered, depending on the nature of the problem. These features may be the only solutions to given problems, but create significant problems for other disciplines. If the non compliances are discovered late on in the project, introducing new or major fire precautions will be costly as well as impacting on programme and the overall design. Often, the late introduction of sprinklers will be structurally difficult due to the significant ‘new’ loading of a sprinkler tank often at roof level. Similarly, pressurisation causes mechanical and electrical engineers significant problems in retrospective design. These features are commonly difficult architecturally. Finding space for additional plant and vent shafts always presents a challenge and may have an impact on planning, requiring additional consultation.
Using the services of a fire engineer often has positive implications on the approvals process. LWF strive to ensure that the approving authorities are constantly informed of the project and the fire engineering proposals. All complex fire engineered solutions are agreed with the authorities in principle prior to full engineering assessment, this prevents any abortive work and false expectations.
Fire engineering reports should always clearly state areas of non compliance and give full justification of solutions. This logical procedure demonstrates to any approving authority that the design has been appraised fully and non compliances are highlighted. Non compliances in themselves do not pose a problem provided that sound justification is provided and any proposed solution continues to meet with the primary objectives.
Fire engineering is constantly evolving, embracing technology and experience. Fire engineering should not be seen as a method of reducing fire precautions, but getting the right fire precautions for the building.
Our experience has shown, that utilising the services of a competent fire engineer can bring numerous benefits to a project, including design flexibility, uncomplicated approvals and cost savings.
The LWF Bulletin is designed to give general information on fire safety risk management. Readers should take specific advice when dealing with particular situations. LWF accept no responsibility for action taken as a result of information contained in the document. The information in this document is correct at the time and date of the publication.
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