Prescriptive_V_Performance

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The ancient Code of Hammurabi arguably represents one of the earliest articulations of legal standards for building control. Held within the code it is evident that life safety as well as property protection has been highlighted. If a builder builds a house for some one, and does not construct it properly, and the house which he built fall in and kill its owner, then that builder shall be put to death: If it kill the son of the owner the son of that builder shall be put to death: If it kill a slave of the owner, then he shall pay slave for slave to the owner of the house: If it ruin goods, he shall make compensation for all that has been ruined, and inasmuch as he did not construct properly this house which he built and it fell, he shall re-erect the house from his own means: If a builder build a house for some one, even though he has not yet completed it; if then the walls seem toppling, the builder must make the walls solid from his own means.(1) The prologue of the Code of Hammurabi on a clay tablet in the Louvre Reading these code it clearly shows a “performance based” code aspect, since it does not specify how the builder is to build the house, it simply describes the performance requirements and highlights a set of consequences of failure to perform to requirements, also embedded within the code it employs strict liability rather than negligence. What is the difference between Prescriptive codes of practice and Performance based design in the strategy of fire safety in UK buildings' We must look at these concepts individually to grasp what impact they have had and will have in the development of fire safety within UK buildings. An article in the Fire Safety Journal 34 (2000) describes prescriptive regulations as. “Through trial and error, the evolutionary process in prescriptive building "re safety regulations has adjusted to balance the various perceived risks and benefits of building innovations. For example, as catastrophes have occurred, the prescriptive building code system has been pressured to adjust code requirements to reflect new social mandates”(2) Although this was targeted for the American industry it is very much inline with the UK legislation, this will be covered in more detail in a separate section. Before we try to answer the question on the differences and merits between Prescriptive and Performance driven code and practices an understanding of there background should be demonstrated below is my potted background synopsise. I have described in the introduction that some form of building safety codes have been with civilisation for some considerable time, it is not my intention to give a full history of every piece of legislation which has been introduced since King Hammurabi introduced his version. Pre 1707 at the creation of the United Kingdom, both England and Scotland already had some legislation in place which dealt with issues of Fire Safety. One of the key pieces of legislation enthroned in our history is the Fire Services Act 1947. Prior to 1947, issues of fire safety were in the hands of the local authority and the legal enforcement of issues under the Factories Act and Office Shops and Railway Premises Act, were dealt with by the local authority having usually devolved this down to the Fire Brigade. The introduction of the Fire Services Act 1947 gave the Fire Brigade its first responsibilities for fire safety. Section 1 of the Fire Services Act defined the duties of a fire brigade and further went to say under section 1, sub-section 1 paragraph F, commonly referred to as 11(F), that a fire brigade must give advice and assistance on matters of fire prevention if so requested by any person. The Act did not however give any other powers to the fire brigade in terms of inspection and enforcement. Various pieces of legislation were added over the years but in 1972 the “Fire Precaution Act 1971” came into force when hotels and boarding houses were the first class of premises to be designated. Under the Fire Precautions (Hotels and Boarding Houses) Order 1972, Statutory Instrument (SI) 72 /238) any premises where there was sleeping accommodation for more than 6 persons (staff or guests) or sleeping accommodation above the first floor required a fire certificate issued by the local fire authority. Prescriptive codes and standards of the day provided measures to provide safe means of escape, means of raising the alarm, along with a raft of other measures to ensure the safety of persons within the building The major problem with the Act was that it was that it only applied to the designated premises. Places of public entertainment such as cinemas, theatres and night clubs were never designated so the powers of inspection and enforcement remained with the local authority licensing department. In many areas, the fire brigade carried out the inspections on behalf of the licensing department, but had no powers other than these granted by the Section 10 - Prohibition Notice. The Building Standards and other code of practice documents were key to the construction of building in this time span, although it was possible to build to the standards but still require further work before a fire certificate was issued by the Fire Authority, possibly due to changes in occupancy or something similar. Prescriptive codes had been for years moulded by some of the legislation shown above, enforced by fire authorities throughout the country. Various changes, made only as the result of major failings of the codes or regulations. Below is a short introduction to some of the failing that lead to the changes in legislation on fire safety throughout the UK; The Factories Act 1961 stemmed for a fire at the Eastwood Mills, Keighley, Yorkshire in February 1956 in which 8 people died resulted in the Act being further amended in 1959 giving the fire brigades the power to inspect factories for fire safety, finally in 1961 the Act was re-written to consolidate all the changes. The fire certificates were also updated to include not only means of escape but also provision for fighting fire and structural fire separation. On 1 May 1961, a fire occurred at the Top Storey Club in Bolton, Lancashire which resulted in the deaths of nineteen people. Fourteen died in the building and five were killed attempting to jump out of windows into the canal that ran alongside the building. The Licensing Act 1961was almost immediately amended to update the requirements for safety in case of fire. In June 1960, a fire broke out in the William Henderson & Sons, Liverpool department store. Ten people were trapped in the fourth floor and one man fell to his death whilst assisting others to safety from a window ledge. This fire prompted the Government to amend the Office Shops and Railway Premises Act (OSRA) in line with the Factories Act 1961 and in 1963 a new OSRA was introduced On Boxing Day 1969, fire at the Rose and Crown Hotel, Saffron Walden killed eleven people whilst seventeen were rescued. The fire prompted the Government to look at the whole structure of fire safety legislation and in 1971; the Fire Precautions Act was passed into law. This act combined the fire sections of the Factories Act and the Office Shops and Railway Premises Act and brought in new premises like hotels. The Act was an open designating act, in other words, the Secretary of State could designate any premises he wanted to be covered by the Act. In the early 1990s the government was required to implement several EC directives including one on fire safety. It was at the height of deregulation and the government, architects, commerce and industry considered that fire brigades were too inflexible and demanded belt and braces solutions. They and the directive called for a new approach to fire safety and demanded a cheaper and more flexible system. They decided the prescriptive method used by the fire service should be replaced by a more flexible fire risk assessment approach and consequently the Fire Precautions (Workplace) Regulations 1997 (SI 1997/1840) was placed on the statute books using section 12 of the 1971 Act. They also wanted the responsibility of implementing the legislation to be removed from the fire service and placed on the employers, but the fire service would be the enforcing authority and police the legislation. It was implemented using the Management of Health and Safety at Work Regulations, 1992 (MHSAW) amended 1999. These regulations differed from the previous fire safety legislation in that they introduced the concept of risk assessment in a style similar to the Heath and Safety at Work Act 1974.The Fire Precautions (Workplace) Regulations were amended in 1999, due to introduction of the European Communities Act 1972 which set new directives in standards in fire safety throughout the European Community. Unfortunately they did not revoke sections 5 to 9 of the Fire Precautions Act, which required fire certificates; consequently the legislation now ran in parallel with the Workplace Regulations but secondary to it, with prescriptive codes still being dominant, within the system particularly in Scotland. The following pieces of legislation have been the final nail in the coffin of prescriptive codes. The Fire & Rescue Services Act of 2004, the Regulatory Reform (Fire Safety) Order 2005, the Fire (Scotland) Act 2005 (Part 3) and the Building (Scotland) Act 2003, heralded a new chapter within the standards of fire safety assessment in the UK. The history of our countries prescriptive fire safety codes and legislation had been mostly brought into force through a catalogue of serious fires or disasters, which have been listed in various documents over the years, the exception being FRSA 2004, RR(FS)O 2005 and F(S) A 2005 above. This has been a progressive movement to fundamentally change from prescriptive to performance based codes of fire safety within UK buildings. Many eminent scholars in the field of Fire Engineering have written articles, papers and thesis on performance based design method for controlling fire risk in buildings I will not insult your intelligence in claiming that I can enhance there work, instead I have illustrated some of their work namely; Fredrik Nystedt describes performance based method as;” The performance-based design method uses an engineering methodology to approach the design problem. An engineering solution is developed and analyzed to determine whether it achieves the fire safety objectives. The keyword is to “verify” that a satisfactory level of safety is achieved. Risk-based methods may be used for this analysis”.(4) Engineering has been the backbone of the modern age using tried and test method to determine the outcome of fire modelling a way forward in designing and as Nystedt states to “verify” that a satisfactory level of safety is achieved. Armin Wolski goes on to provide an alternative view stating; “Building fire safety regulations, both performance-based and prescriptive based, establish a standard for design that is intended to provide an acceptable level of risk from fire. In order to provide an acceptable level of risk that meets the public mandate, a building fire safety code should accommodate social perceptions of risk. It seems as if the representative, evolutionary nature of the prescriptive code indirectly addresses the issue of risk perception”.(5) We all have our own perception of risk that is a fact this was evident in the old prescriptive codes were after an major incident or loss of live codes and legislation was changed will this be similar with performance base criteria, will it be possible to adjust the risk based design to accommodate change or will this be a progressive evolution. In the Fire safety Journal V.R. Beck describes the fire safety in buildings based on engineering methodologies as a way to save money; “Fire safety and protection facilities to satisfy current regulatory requirements are a significant component in the cost of many buildings. With the development of systematic approaches to building fire safety and protection, designs based on a fire safety engineering methodology can offer substantial cost savings while achieving satisfactory levels of life safety”. (6) Could it be that simple that this new dimension of fire engineering expansion is driven by money, perish the thought. D.J. Rasbash in an article in the Fire Safety Journal hints that using a performance based approach makes it difficult to evaluate risk perception; “Because the performance-based approach is based on quantification methods, accommodating risk perceptions can be much more difficult”.(7) Again this bring to the fore risk perception, when undertaking a risk assessment within a premise it will be down to your perception of the risk based on your understanding and knowledge of the building, its contents , management structure, use and personnel, life safety design built it the structure or added later, the list goes on and on. At the design stage of the build most of the issues covered above may or may not be known so the dedicated fire engineer’s methods work out by tried and tested engineering and scientific principles may or may not be correct! The performance based method within the UK has been progressive for a number of years starting from the introduction of the Fire Precautions (Workplace )Regulations 1997 where it was indicated that a suitable and sufficient risk assessment should be carried out in any workplace, it went on to explain the finer details of how, when and what requirements had to be met, this was achieved through various publications including a “Employers guild to Risk Assessment” which was available from the governments publication section, or in the case of Scotland was one of the key documents handed out to employers via the Fire Brigades. One of the main problems with this regulation was that Fire certificated issued under the “Fire Precautions Act 1971” or similar. As a serving Enforcement officer with Strathclyde Fire Brigade at the time of the transition from prescriptive to risk based we were in the main left to fend for ourselves and use both pieces of legislation where best fitted. In the main a selection of prescriptive guidance documents and the guidance for risk assessments were used to determine the best solution for each premise. This may or may not have been standard practice throughout the UK as England and Wales had take a slightly different stance with regards the Risk based assessment and were more actively pursuing this agenda. Some of the mainstay documents used within the industry was the technical handbook, building standards and a variety of codes, guidance and best practice documents which assisted in producing a code compliant building. In the mid 1990’s the representatives of the main government department with interests in fire were aware that the legislation relating to fire precautions in buildings was going to a risk based approach, where the responsibility would be placed on those responsible for creating the risk – occupiers, owners, etc. up to this time overall fire safety design for buildings had been directed through various standards and guidance throughout the UK one of the main set of standards used was BS 5588, these originated in 1970’s and originally replaced the CP3: Chapter 4: Code of Practice, which themselves were based on Post War Building Studies. The BS 5588 suite of standards had grown somewhat haphazardly with problems being highlighted including; * Duplication of text between parts * Variation of guidance both within BSI documents and with other published guidance * A lack of overall focus * Much of the guidance was based on out of date building practices and fire service operating procedures. Therefore the concept was agreed that technical guidance on fire safety is provided at three different levels; Basic – ADB, Tech Standards; Advanced – BS 9999; Fire Safety Engineering – BS 7974. This permits a design approach to be adopted that corresponds to the complexity of the building and to the degree of flexibility required. BS 9999 is provided for the Advanced Approach. Guidance provided in this document gives a more transparent and flexible approach to fire safety design through use of a structured approach to risk-based design where designers can take account of varying physical and human factors. The history of how , why and when we have progressed from prescriptive to performance based fire safety methods have been illustrated above, the question is what are the benefits if any these changes have made, has it reduced fire deaths in designed buildings where this method of fire safety strategy is used' Remembering that 74% of all fire deaths in the UK are within domestic properties, which means that 26% have died in non domestic premises, With the total deaths by fire in 2006 being 491 out of a population of 61million, 128 died in non domestic property (8) that is not bad odds, so something must have been working in the prescriptive codes. Will performance based fire safety design method it in the future lower or increase this number' Only time will tell on that score. What we have is the opportunity to progress solutions to new designs and construction techniques/methods to provide hopefully a safer place to live and work. From book by Jane I. Lataille on “Fire Protection Engineering in Building Design” where she says that older prescriptive codes may have been over engineered, inflexible and costly and performance based are not; “Older prescriptive-type fire protection codes could sometimes be overly conservative and therefore unnecessarily expensive. Newer prescriptive codes have alleviated some of the inefficiency, but they still might not provide the most effective designs for very specialized buildings. Performance-based designs allow maximum flexibility while achieving a specified level of protection. With this newfound freedom from prescriptive requirements comes the responsibility for setting goals, selecting appropriate levels of protection, and determining the performance available from the fire protection design options being considered. This requires extensive knowledge of both fire science and fire protection engineering”. (9) Have we achieved this extensive knowledge or is this to come in the future with the information that has been published over the years there still is some uncertainty in the effects fire will have on a structure ( the World Trade Centres) or the way people will react to fire (Bradford City Football Ground) (Kings Cross Station) Brian Meacham Ph.D. PE in an article in the Fire Protection Journal points out; Performance based fire protection engineering is gaining momentum in the United States and throughout the world. Reasons for this includes the slow but steady maturation of the fire protection engineering discipline, the ongoing global transition from prescriptive to performance based building regulations, and the development of fire protection engineering guideline for the use by practicing engineers. As this momentum grows, so do the opportunities to apply engineering principles to a wide range of fire safety concerns, from estimating the time at which a structural member will fail, to estimating the time available for safe egress”. (10) Over the past 3 years myself and others on this course have had many pieces of information imparted on us, one of the key points that I remember was given at the start of the degree course by Douglas Hillhouse, were he stated when making assumptions on inputs to fire engineering solutions “it may be this or it may not be that”(11), to say we are working with exact science would be slightly miss leading, on the other hand we are expanding our knowledge and understanding of fire risk and its consequences, if you are to compare some of the prescriptive concepts handed down i.e. the 21/2 minutes allowed to evacuate a theatre was devised from the time it took to play the national anthem, where did the travel distances come from' Not what you would call an exact science. The last part of this essay should have some input from one of the tutors so it is interesting to note the comments made by Mr Kilpatrick in a piece on fire safety requirements for the European Union where he describes; “Within the international fire engineering community there is a general perception that society is, or should be, moving towards the adoption of ‘performance based fire safety codes’. While there are differences over precise definition, performance based fire safety codes allow designers to claim that a building has a certain quantifiable level of fire safety which can be determined as a statement of ‘engineering fact’. Prediction based on fire experience, whether it is incorporated in deterministic or nondeterministic models, does not necessarily ensure fire safety when applied to new design Concepts”,(12) Just who in society says we should be moving towards “performance based fire safety codes” is it to meet new expectation of building design, to improve life safety in buildings, or could be driven by financial gain or constraints. I have not got the answers to that question. I conclude with this piece, “what I wrote” (13) “The world is a circle ever rotating some things change and some stay the same, it could be in years to come that the codes handed down from King Hammurabi may just come back into vogue”. I hope I don’t have to do another essay on it!!!!! References; (1) Reference; L.W. King (2005) “The Code of Hammurabi: Translated by L.W. King (2) Reference; Hall J. America's "re problem and "re protection. Fire protection handbook, 18th ed. National Fire Protection Association, Quincy, MA, 1997, Section 1 [Chapter 1]. (3) Reference; Hall J. America's "re problem and "re protection. Fire protection handbook, 18th ed. National Fire Protection Association, Quincy, MA, 1997, Section 1 [Chapter 1]. (4) Reference; Fredrik Nystedt “ A Quantified Fire Risk Design Method” Fire Protection Engineering Journal (2001) pp 41 (5) Reference; Armin Wolski, “The importance of Risk Perception in Building and Fire Safety Codes” Fire Protection Journal 10 (2001) pp33 (6) Reference; V.R. Beck Fire Safety Journal 23 (1994) pp133 (7) Reference; Rasbash, D.J., “Criteria for Acceptability for Use with Quantitative Approaches to Fire Safety”, Fire Safety Journal, 8 (1984/85) pp. 141-158. (8) Reference; Based on UK Fire Statistics 2006 taken from Government wed site.2008 (9) Reference; Jane I. Lataille “Fire Protection Engineering in Building Design” PP 2 (10) Reference; Brian Meacham Ph.D. PE (Fire Protection Journal) No 10 (2001) (11) Reference; Douglas Hillhouse 2008 (12) Reference; Tony Kilpatrick: Analysis of statutory fire safety requirements in the European Union (Cobra 1996) (13) Reference; Ernie Wise (Morecambe and Wise Show 1970)