Comparison IFEG 2005 vs BS 7974 2001

BS7974 and the International Fire Engineering GuidelinesAnthony Ferguson Arup Fire Ove Arup & Partners Ltd 13 Fitzroy Street, London W1T 4BQ July 2006 Summary This report was commissioned by the Scottish Building Standards Agency to compare BS 7974: 2001 ‘Application of Fire Safety Engineering principles to the Design of Buildings’ with the ‘International Fire Engineering Guidelines’ and to assess whether both documents should be cited in the Technical Handbooks. The Technical Handbooks in support of the Building (Scotland) Regulations 2004 state that fire safety engineering can provide an alternative to the fire safety measures contained in the Technical Handbooks. It refers to BS 7974: 2001 as an appropriate framework to identify one or more fire safety design issues to be addressed using fire engineering. This is however, only one method of achieving compliance with the standards. Fire engineering is a continually developing field with a large degree of international cooperation. A document that aims to embrace the best practise worldwide is the ‘International Fire Engineering Guidelines’, jointly published by the Australian Building Codes Board, the National Research Council of Canada, the International Code Council of the United States of America, and the Department of Building and Housing, New Zealand. Fire engineering designs can be complex and generally require extensive use of engineering judgement. Therefore, to assist Local Authority Verifiers and Fire and Rescue Services in carrying out an assessment of alternative fire engineered solutions, the report assess the commonality and differences between the two documents to ensure that the guidance we give encompasses best practice worldwide. Scottish Building Standards Agency BS7947 and the International Fire Engineering Guidelines Review for Scottish Building Standards Agency Contents 1 2 Executive summary Introduction 2.1 2.2 2.3 3 Brief Format of the report Study method Page 1 2 2 3 3 4 4 9 10 11 12 The significance of differences between the BS and the IFEG 3.1 3.2 3.3 Procedural issues Methodology Data 4 5 Functional standards Conclusions and recommendations Appendices Appendix A Process and Methodology Appendix B Data and numerical methods Scottish Building Standards Agency BS7947 and the International Fire Engineering Guidelines Review for Scottish Building Standards Agency 1 Executive summary The brief for this study is to compare the BS and the IFEG to assess whether both documents should be cited in the Technical Handbooks. The study has been conducted in two phases. This report covers the second phase, assessing the significance of differences identified between the two documents in the first phase. It also presents the results of the first phase in Appendices A and B. The general approach advocated by both documents is very similar, and would not present conflicts if both were cited. The IFEG tends to provide less specific technical detail than the BS. There are also a few detailed technical differences concerning data and methodology. The IFEG handles procedural issues more graphically and more comprehensively, and might therefore be regarded as more ‘user-friendly’ for those less experienced in fire safety engineering. The IFEG puts forward a fire service intervention model, based on Australian practice, which the SBSA may wish to review. In the UK it is unusual for fire service intervention to be considered when developing fire safety strategy for a building project. Each of the four different regulatory bodies that support the publication of the IFEG, has written its own introductory section in Part 0 of the IFEG. They explain how the guidance is intended to be applied in their particular jurisdiction. The following points could be addressed by the SBSA in a Scottish part 0 to the IFEG:• Regulatory objectives that should be addressed by a fire engineering brief – the IFEG list issues such as environment protection which may not be relevant under the building regulations [see 3.1.2] The importance of sensitivity analysis and the way that assumptions need to be tested in a fire engineering analysis. There are some differences in data and analytical methods [see appendix B] between the BS and the IFEG. These apparent conflicts can be addressed if users appreciate the importance of exploring the effect of different assumptions or methods. Specific instances are:o o o Fire load density and the use of fractiles [see 3.3.1] Burning rate [see 3.3.2] Ignitability [see 3.3.3] • An issue that the SBSA will need to consider is whether the guidance of a ‘Scottish’ Part 0 to the IFEG will have to be in place before the IFEG is cited. The recommendation of the study’s authors is that this is desirable but not essential, since similar issues arise from citing the BS, which has already been done without the benefit of such clarification. F:\FINAL REPORT WORD COPY FOR WEBISSUE REV A A4.DOC Page 1 Ove Arup & Partners Ltd Rev A 3 July 2006 highlighting areas not covered and identifying alternative approaches. with an Executive Summary clearly identifying what the differences between the two documents are. If this is not possible the areas of conflict need to be highlighted and resolved. New Zealand. the International Code Council of the United States of America. jointly published by the Australian Building Codes Board.DOC Page 2 Ove Arup & Partners Ltd Rev A 3 July 2006 . Therefore. A document that aims to embrace the best practice worldwide is the ‘International Fire Engineering Guidelines’. it would be prudent to assess the commonality and differences between the two documents to ensure that the guidance we give encompasses best practice worldwide. This is however. and to examine and offer views on whether the SBSA could ‘joint badge’ the document with the International Fire Community and reference it in the Technical Handbook as an appropriate framework for addressing fire safety design issues.Scottish Building Standards Agency BS7947 and the International Fire Engineering Guidelines Review for Scottish Building Standards Agency 2 Introduction 2. Fire engineering designs can be complex and generally require extensive use of engineering judgement. It refers to BS 7974: 2001 ‘Application of Fire Safety Engineering principles to the Design of Buildings’ as an appropriate framework to identify one or more fire safety design issues to be addressed using fire engineering. The contractor should discuss any particular weakness identified in either document and make appropriate recommendations. and the Department of Building and Housing. The specific tasks required as part of this project are: • • • to determine the differences between the two documents. Desired Business Outcome The output from this research will be a report. F:\FINAL REPORT WORD COPY FOR WEBISSUE REV A A4. to highlight areas where the documents may give conflicting guidance. Fire engineering is a continually developing field with a large degree of international cooperation. only one method of achieving compliance with the standards. The report should identify any critical areas that need to be addressed to allow both documents to be referenced in the Technical Handbooks. The key issue is to determine if it is appropriate to cite both documents in the Technical Handbooks to assist verifiers and the Fire and Rescue Authorities in determining whether the aims of the functional standards have been met. Aim and Objectives The aim of this project is to compare BS 7974: 2001 ‘Application of Fire Safety Engineering principles to the Design of Buildings’ with the ‘International Fire Engineering Guidelines’ and to assess whether both documents should be cited in the Technical Handbooks. the National Research Council of Canada. to assist Local Authority Verifiers and Fire and Rescue Services in carrying out an assessment of alternative fire engineered solutions.1 Brief The Scottish Building Standards Agency’s brief for the Arup study which is the subject of this report was as follows:The Technical Handbooks in support of the Building (Scotland) Regulations 2004 state that fire safety engineering can provide an alternative to the fire safety measures contained in the Technical Handbooks. F:\FINAL REPORT WORD COPY FOR WEBISSUE REV A A4. PD 7974-1 to -7 associated with the British Standard. as well as the fire engineering knowledge required to carry out the comparison.a comparison of the data and numerical methods given in the two documents. and the aim is to identify possible conflicts that would arise if the IFEG was also to be a reference document.Scottish Building Standards Agency BS7947 and the International Fire Engineering Guidelines Review for Scottish Building Standards Agency 2. codes and regulations in the UK. this report presents the assessment and conclusions first. Arup colleagues in the other two countries.DOC Page 3 Ove Arup & Partners Ltd Rev A 3 July 2006 . The study was conducted in the UK and involved consultation with. Throughout this report the International Fire Engineering Guidelines are referred to as the IFEG. Appendix B . • Throughout this report British Standard 7974:2001 “Application of fire safety engineering principles to the design of buildings – Code of Practice” is referred to as BS7974 or the BS. The emphasis is on the IFEG document.2 Format of the report The study has been conducted in two phases. In examining and comparing the two reference documents Arup was able to apply its knowledge of the background and development of both documents. In phase one the two references were examined and the differences between them were noted and analysed. These deal with:• Appendix A .the procedures and methods. This led to an interim report being submitted to the SBSA by the contractor for comment. and input from. The term ‘verifier’ is used in this report to indicate the body responsible for checking or approving proposals. This title includes the set of ‘Published Documents’. has fire engineering staff with experience of writing fire safety standards. Because the key issue is the question of whether or not both references could appropriately be cited in the technical handbooks. Arup. USA and Australia.3 Study method The contractor. In phase two of the study the implications of the identified differences were assessed so that this final report could be prepared. 2. The detailed comparison of the two documents is contained in appendices to the report. Text in italics indicates a quotation from the document being referred to. because BS7974 is already referred to in the guidance on the Building Standards. including BS7974 and the International Fire Engineering Guidelines. to the extent that some of the factors suggested for consideration are unlikely to be known at the earlier stages of a construction project. called the Qualitative Design Review by the BS. and both documents break the subject down into sub-systems. In both cases the process begins with an appraisal of the task. Fire engineering is not as mature as some other branches of engineering. it has allowed some structure to be imposed on a very diverse field. The Scottish term Verifier is used in this report to refer to the ‘approval’ function.1.2 reproduced from the IFEG shows a process for developing a Fire Engineering Brief. in the opinion of the authors. noting that the role of enforcement is carried out [at present] by the same Local Authorities who have been appointed as verifiers. than in some other disciplines. deletion when applied to any specific project. iteration. It will be important for the verifier to understand that it is not always essential that all the elements listed against FEB development in the IFEG should be fully determined. These issues raise questions of training. While this somewhat mechanical view of the process is not entirely realistic. Originally the sub-system concept grew from the analogy of a computer processor in which many items of data were passed around and processed under the control a central mechanism. change the existing situation. 3.DOC Page 4 Ove Arup & Partners Ltd Rev A 3 July 2006 . The reference to BS7974 in the Technical Handbooks has already presented these issues. they do not prevent the IFEG being cited in the Technical Handbooks. The BS generally provides rather more detailed information while the IFEG handles procedural issues more graphically and more comprehensively. However. F:\FINAL REPORT WORD COPY FOR WEBISSUE REV A A4. Fire engineering embraces a wide range of phenomena. both for the design professions and for the verifiers. The less detailed guidance in the BS does not raise this issue. the Fire Engineering Brief [FEB] is very comprehensive. Within this generalisation lie a very few detailed differences which are discussed in the following section. As described. design features and systems. and inclusion of the IFEG should not.1 AHJ’s and Verifiers The term Authority Having Jurisdiction [AHJ] is used in the IFEG to embrace the roles of approver / enforcer.Scottish Building Standards Agency BS7947 and the International Fire Engineering Guidelines Review for Scottish Building Standards Agency 3 The significance of differences between the BS and the IFEG As a general summary the British Standard and the IFEG are essentially equivalent in concept. Neither the BS nor the IFEG cling relentlessly to the process analogy. Figure 1. experience and qualifications. and the Fire Engineering Brief by the IFEG.1 Procedural issues The two documents use a very similar approach. In a regulatory context there are therefore likely to be more issues of professional judgement made by engineers that have to be assessed by the appropriate authorities. and both make it clear that the illustrations they give are subject to variation. the results of one process often feeding into another. 3. in our opinion. DOC Page 5 Ove Arup & Partners Ltd Rev A 3 July 2006 .Scottish Building Standards Agency BS7947 and the International Fire Engineering Guidelines Review for Scottish Building Standards Agency F:\FINAL REPORT WORD COPY FOR WEBISSUE REV A A4. F:\FINAL REPORT WORD COPY FOR WEBISSUE REV A A4. The following procedural issues could be addressed in a Scottish Part 0.1.2 IFEG Part 0 Part 0 in the IFEG document contains introductory sections for each of the national regulatory authorities jointly responsible for publishing these Guidelines. This aspect of the IFEG clearly provides an opportunity for any particular considerations relevant to Scotland to be described or highlighted. the International Codes Council of the USA. are identified as ones which could be addressed using commentary in a Scottish Part 0. Section 1. They are the Australian Building Codes Board. This would entail the Scottish Building Standards Agency preparing a Scottish Part 0 for the IFEG. assuming that they would wish to become joint participants in the publication of the IFEG. It lists some questions to elicit the relevant information. They have not been reviewed in detail for this report because none of them specifically address the circumstances found in Scotland.2. New Zealand.1 and .Scottish Building Standards Agency BS7947 and the International Fire Engineering Guidelines Review for Scottish Building Standards Agency 3.2. Later in this report other issues.5.2 of the IFEG notes that the regulatory framework for the design must be understood from the outset. Section 1. and the Department of Building and Housing. A Scottish Part 0 to the IFEG could make it clear which of these objectives were relevant for purposes of the Scottish Building Standards. concerning methods and data. And some other possible regulatory objectives:• environmental protection • occupational health and safety • fire services • dangerous goods • land use and other planning matters. the National Research Council of Canada.2 identify possible building regulatory objectives for inclusion in a FEB:• protecting building occupants • facilitating the activities of emergency services personnel • protecting the property in question • preventing the spread of fire between buildings. Each introductory section explains how the Guidelines are intended to be applied in that jurisdiction.DOC Page 6 Ove Arup & Partners Ltd Rev A 3 July 2006 .1. DOC Page 7 Ove Arup & Partners Ltd Rev A 3 July 2006 .Scottish Building Standards Agency BS7947 and the International Fire Engineering Guidelines Review for Scottish Building Standards Agency Figure 1. examples from IFEG of acceptance criteria F:\FINAL REPORT WORD COPY FOR WEBISSUE REV A A4. 1.2. although it is clearly desirable that it should. It does give some examples in section 1. Arguably the need already arises with BS7974.8.2. 3. section 1.Scottish Building Standards Agency BS7947 and the International Fire Engineering Guidelines Review for Scottish Building Standards Agency Given the functional nature of the standards set in the Scottish building regulations.1) omitted {bold ed. rather than simply identifying non-compliances. This situation may occur where the relevant codes comprise objectives or performance requirements only or when general objectives. have been agreed to during the FEB process. other than those covered by recognised codes.” The verifier will need to be able to identify the underlying objectives or performance requirements of the Functional Standards.DOC Page 8 Ove Arup & Partners Ltd Rev A 3 July 2006 . This process will identify the issues that need to be addressed in the analysis of the trial design.2. A Scottish Part 0 to the IFEG could be used to give assistance here by giving examples of the selection of relevant performance requirements. in a functional-based system. The SBSA may wish to consider whether this kind of modification has to be made to the IFEG before it can be called up for use in Scotland.2. and given the range of possible cases it is not possible to do so.8 of the IFEG reproduced above was to draw attention to the importance of determining acceptance criteria.8. Factors of safety are also discussed in this section. so that acceptance criteria can be agreed.10 of performance parameters relevant to certain common fire safety objectives. the relevant objectives or performance requirements need to be identified directly (see 1.2.8 of the IFEG is significant:“In order to determine the specific objectives or performance requirements it is necessary to determine where the trial designs do not comply with the relevant deemed-to-satisfy or prescriptive provisions. By Arup}. F:\FINAL REPORT WORD COPY FOR WEBISSUE REV A A4. and therefore incorporation of Scottish examples in the IFEG does not have to precede it being cited in the guidance. The passage emboldened in the extract from 1. In cases where there are no deemed-to-satisfy or prescriptive provisions. which is already cited. at a very general level.3 Acceptance criteria The IFEG does not set acceptance criteria.2) and the determination of non-compliance issues (Section 1. However this makes the IFEG more dependent on outside sources and gives the publishers less control.DOC Page 9 Ove Arup & Partners Ltd Rev A 3 July 2006 . while the IFEG presents the Australian Fire Brigade Intervention Model as a method for quantifying this intervention. and development of new analytical methods. while various facilities are expected to be provided to assist the firefighters to access the building.2 Changes in the state of the art Fire safety engineering is a relatively new branch of engineering and advances in understanding of fire phenomena.2. The IFEG reduces its exposure to content becoming out of date by giving less detailed technical information. F:\FINAL REPORT WORD COPY FOR WEBISSUE REV A A4.Scottish Building Standards Agency BS7947 and the International Fire Engineering Guidelines Review for Scottish Building Standards Agency 3.2 3. should they decide to write a Scottish Part 0 to the IFEG.1 Methodology Sub-system on fire service intervention The BS reflects British practice in a largely qualitative way. it is not customary to reduce some aspect of a building’s performance in fire in recognition of fire brigade activity. happen frequently. In England and Wales there has been reluctance to take fire service intervention into account when the fire strategy for a building has been put forward for regulatory approval. and calling up other sources. The SBSA may wish to consider including some reference to the account that may or may not be taken of fire service actions. 3. Similarly in Scotland. unless they choose to add material specifically to address new developments. The BS was set up with the detailed technical material in a set of Published Documents because this makes it easier to revise parts of the whole body of knowledge and information as necessary.2. 3.g.Scottish Building Standards Agency BS7947 and the International Fire Engineering Guidelines Review for Scottish Building Standards Agency 3. The 95% fractile is very conservative when compared with other fire loads recommended elsewhere. Fire loads are given as ranges.1 Data Fire load Both the BS and the IFEG refer to the CIB W14 report on fire loading. EuroCode1. BS7974 An effective fire duration of 20 minutes can be assumed in houses. such as release rate. and measured in real fire tests such as the Cardington office series.3 3. The SFPE reference called up by the IFEG discusses these complications. References are made to Babrauskas’ section in the SFPE handbook and Sardqvists “Initial fires”. F:\FINAL REPORT WORD COPY FOR WEBISSUE REV A A4. the essential point.2 Rate of heat release The guidance in the two documents on the subject of heat release or burning rates in fuel bed controlled conditions [i. Topic Fuel bed controlled HRR IFEG No equations are suggested. Law and O’Brien on external steelwork. This should not be considered as a weakness of the IFEG. where the rate of burning is not restricted by a limited air supply] is different. The time to reach burnout after flashover is shown as two times the mass of fuel left when flashover occurs.DOC Page 10 Ove Arup & Partners Ltd Rev A 3 July 2006 . The BS guidance is an engineering approximation to a complex situation. e. which applies to any aspect of fire engineering analysis where assumptions are being made. If one is following the guidance in BS7974 to calculate a post flash-over fire then it would be inappropriate to use the 95% fractile in favour of the recommended 80% one. such as fire load. is that sensitivity studies should be carried out to ensure that a solution's acceptability is not critically dependent on some assumption. While the SBSA might consider addressing this question if they prepare a ‘Scottish’ Part 0 to the IFEG. as summarised in the table below. However the BS recommends that the 80% fractile of the range of fire load should be used while the IFEG recommends that the 95% fractile should be used. 3. for various types of occupancy. is that sensitivity studies should be carried out to ensure that a solution's acceptability is not critically dependent on some assumption.3. It is recommended that “appropriate engineering judgement” should be applied when setting fire rates. offices and shops. which applies to any aspect of fire engineering analysis where assumptions are being made. The fundamental point. Burning rate is based on the assumption that the total initial fire load burns in 1200 seconds Another equation for fuel bed controlled fires is presented with no reference to its origins.e. but it requires a higher level of understanding of fire dynamics to make use of the advice given. divided by peak mass burning rate. Scottish Building Standards Agency BS7947 and the International Fire Engineering Guidelines Review for Scottish Building Standards Agency 3. without attempting to summarise a complicated topic. They reflect the fact that this is a very complex subject. The spontaneous ignition criterion for wood is set to 250-400°C.DOC Page 11 Ove Arup & Partners Ltd Rev A 3 July 2006 . It might have been better if the BS had adopted the IFEG approach of simply referring to other sources.. 4 Functional standards The Scottish building regulations identify 15 functional standards. such as the nature of the heat transfer mechanism.3 Ignitability In data associated with sub-systems 3 ‘structural response’. It is obviously essential that the two documents. the specimen thickness and period of exposure to heating. the two references give different advice on spontaneous or auto-ignition temperatures for timber elements.6kW/m is mentioned as a criterion. do address all of the Functional Standards. Some data on ignitability limits under radiant heat flux. The IFEG gives less data and relies more on other references. Topic Heat flow by radiation IFEG Various references to publications regarding external fire spread. It is suggested that this is a relatively trivial issue in the overall question of whether the IFEG is a suitable reference. giving “some factor of safety” It is possible to base analysis on the increase of surface temperature of the object exposed. and 300-410°C for ignition by flying brands under a radiative heat flux. The measurement of specimen surface temperature is technically difficult. For organic solids a surface temp. BS7974 Standard radiation relationships shown. criterion of 600°C is suggested for spontaneous ignition. In Appendix A section 4 the scope of both the BS and the IFEG have been compared to the Functional Standards. 2 12. This confirms that the functional standards are capable of being addressed by following the guidance in the two reference documents. The value depends on many variables. The range of values offered by both documents overlap. BS7974 and IFEG. F:\FINAL REPORT WORD COPY FOR WEBISSUE REV A A4.3. 1] Burning rate [see 3.1. and therefore incorporation of a ‘Scottish’ Part 0 in the IFEG does not have to precede it being cited in the guidance. In the UK it is unusual for fire service intervention to be considered when developing fire safety strategy for a building project. has written its own introductory section in Part 0 of the IFEG. Each of the four different regulatory bodies that support the publication of the IFEG.2] The importance of sensitivity analysis and the way that assumptions need to be tested in a fire engineering analysis. They explain how the guidance is intended to be applied in their particular jurisdiction. The study has identified a difference in the general character of the IFEG – it tends to provide less specific technical detail than the BS – and a few detailed technical differences concerning data and methodology. F:\FINAL REPORT WORD COPY FOR WEBISSUE REV A A4. and might therefore be regarded as more ‘user-friendly’ for those less experienced in fire safety engineering. The following points could be addressed by the SBSA in a Scottish part 0 to the IFEG:• Regulatory objectives that should be addressed by a fire engineering brief – the IFEG list issues such as environment protection which may not be relevant under the building regulations [see 3.3. which the SBSA may wish to review. which is already cited. Normally the safety of building occupants in case of fire is regarded as a matter of ‘self-help’ without reliance on outside intervention.Scottish Building Standards Agency BS7947 and the International Fire Engineering Guidelines Review for Scottish Building Standards Agency 5 Conclusions and recommendations The brief for this study is to compare the BS and the IFEG to assess whether both documents should be cited in the Technical Handbooks.3] • An issue that the SBSA will need to consider is whether the guidance of a ‘Scottish’ Part 0 to the IFEG will have to be in place before the IFEG is cited. The IFEG puts forward a fire service intervention model.DOC Page 12 Ove Arup & Partners Ltd Rev A 3 July 2006 . Arguably the need already arises with BS7974. The general approach advocated by both documents is very similar. and would not present conflicts if both were cited. based on Australian practice. Specific instances are:o o o Fire load density and the use of fractiles [see 3.2] Ignitability [see 3.3. There are some differences in data and analytical methods [see appendix B] between the BS and the IFEG.3. These apparent conflicts can be addressed if users appreciate the importance of exploring the effect of different assumptions or methods. The IFEG handles procedural issues more graphically and more comprehensively. n Appendix A Process and Methodology . engineering methods are used to evaluate the potential solutions identified in the QDR 3. The document structure with the sub-systems is illustrated in figure 1. in which the scope and objectives of the fire safety design are defined.DOC Page A1 Ove Arup & Partners Ltd Rev A 3 July 2006 .Scottish Building Standards Agency BS7974 and the International Fire Engineering Guidelines Review for Scottish Building Standards Agency A1 BS7974 BS7974 is in effect a headcode under which sit a set of Published Documents [PD’s]. 2. Assessment against criteria. It is intended to be applied in three main stages:1. property and the environment from fire”. performance criteria established and one or more potential design solutions proposed. The sub-systems in the PD’s provide data and analytical methods for tackling the relevant quantitative analysis. F:\FINAL REPORT WORD COPY FOR WEBISSUE REV A A4. This study embraces the PD’s along with the BS7974. The BS code of practice: “provides a framework for developing a rational methodology for design of buildings using a fire safety engineering approach based on the application of scientific and engineering principles to the protection of people. Quantitative analysis. the output of the quantitative analysis is compared to the acceptance criteria identified in the QDR The BS7974 provides guidance on these procedures. Qualitative design review [QDR]. and advice on acceptance criteria and suitable design approaches. It may be applied to new or existing buildings. to show that regulatory requirements can be met. the engineering approach described in BS7974 F:\FINAL REPORT WORD COPY FOR WEBISSUE REV A A4.DOC Page A2 Ove Arup & Partners Ltd Rev A 3 July 2006 .Scottish Building Standards Agency BS7974 and the International Fire Engineering Guidelines Review for Scottish Building Standards Agency BS7974 Code of Practice – Application of fire safety engineering principles to the design of buildings BSPD79740 Guide to design framework and fire safety engineering procedures BSPD79741 Initiation and development of fire within enclosure of origin BSPD79742 Spread of smoke and toxic gases within and beyond the enclosure of origin BSPD79743 Structural response and fire spread beyond the enclosure of origin BSPD79744 Detection of fire and activation of fire protection systems BSPD79745 Fire service intervention BSPD79746 Evacuation BSPD79747 Probabilistic risk assessment Figure A1 structure of sub-systems in BS7974 Note that 0 and 7 are not sub-systems as such. both being applicable to any of the other subsystems. Qualitative Design Review Quantitative analysis Assessment against criteria Figure A2. PD0 provides guidance on procedure and PD7 provides guidance on risk assessment techniques. ie they do not address characteristics of fire or safety systems. omitted or an iterative process introduced. were in contact with members of the team who were working on the first edition of the Australian Fire Engineering Safety Systems code at the same time. In the early 1990’s the original consultant team commissioned to draft the document that eventually became BS7974 in the UK.2 may be re-ordered. The process follows the following sequence:- Prepare FEB Carry out analysis Collate and evaluate results Draw conclusions Prepare report FigureA3. There was cross-fertilisation between these groups.Scottish Building Standards Agency BS7974 and the International Fire Engineering Guidelines Review for Scottish Building Standards Agency A2 The International Fire Engineering Guidelines The guidelines document and approach uses a very similar sub-systems break-down of the subject to that used in BS7974. F:\FINAL REPORT WORD COPY FOR WEBISSUE REV A A4. The structure of the IFEG after the ‘national’ introductory sections. The IFEG notes that the FEB for an analysis to evaluate a simple departure from some prescriptive guidance in a code or standard.1 IFEG Process The first stage in the Guidelines is the preparation of a Fire Engineering Brief [FEB]. methodologies 3. process 2. The UK group picked up the Australian sub-system concept and the Australian group adopted the UK QDR concept (though some of the terminology was altered).1. These criteria are likely to be more detailed than the Functional Standards of building regulations.2 see below] of a process for developing a FEB. since key components of the FEB include acceptance criteria. data A2. have to be involved. in a similar fashion to the other regulatory authorities who have “adopted” the IFEG. Clearly this is only illustrative as the particular characteristics of a project will determine its content to some extent. This section of the IFEG gives an illustration [fig. including the Authority Having Jurisdiction [AHJ]. is in three parts: 1. The guidelines are derived from an earlier Australian document [the draft National Building Fire Safety Systems code]. sequence of the fire engineering process in the IFEG The “Process” section of the IFEG offers guidance on what issues should be addressed in the Fire Engineering Brief [FEB]. It is assumed that Scotland would prepare an introductory section [Part 0] for a new edition of the IFEG. The present study does not examine Part 0 of the IFEG document as these are written for other ‘national’ jurisdictions. The steps shown in fig 1. should they wish to cite the IFEG. may be a much shorter document than the FEB for a major project with many departures from Code. and the basis on which that analysis will be undertaken. The FEB is a process as well as a document. It defines the scope of the fire engineering analysis.DOC Page A3 Ove Arup & Partners Ltd Rev A 3 July 2006 . All interested parties. Scottish Building Standards Agency BS7974 and the International Fire Engineering Guidelines Review for Scottish Building Standards Agency F:\FINAL REPORT WORD COPY FOR WEBISSUE REV A A4.DOC Page A4 Ove Arup & Partners Ltd Rev A 3 July 2006 . once the design has been further developed.2.1.2 identify possible building regulatory objectives for inclusion in a FEB:• protecting building occupants • facilitating the activities of emergency services personnel • protecting the property in question • preventing the spread of fire between buildings. it may be appropriate to revise the FEB.2.Scottish Building Standards Agency BS7974 and the International Fire Engineering Guidelines Review for Scottish Building Standards Agency A practical criticism of the FEB principle is that it is generally impossible to follow in a real project. including fire safety features. It notes that each of these should be clearly identified and all its features.DOC Page A5 Ove Arup & Partners Ltd Rev A 3 July 2006 . Section 1. should be recorded.1 and . And some other possible regulatory objectives:• environmental protection • occupational health and safety • fire services • dangerous goods • land use and other planning matters. Typically there may be some exploratory ‘hand calculations’ before the fire engineer advises the design team to take a particular approach. The IFEG acknowledges this in noting that there may well be iterative loops in its development. adopting the same consultative approach as with the original.2 of the IFEG notes that the regulatory framework for the design must be understood from the outset. The 'final' FEB will be incorporated into the overall report” A2. This is essentially because there are many unknowns in the early stages.2 list the types of feature to be included. A2.1 Regulatory requirements Section 1.2. Sections 1.6. and in accepting that there may be preliminary ‘test’ calculations/analyses to establish the likelihood of success before trial designs are defined ready for fuller analysis. as the analysis of a design proceeds or as a project develops. after which a more time-consuming analysis may be carried out to test the approach.1.3 and 1. F:\FINAL REPORT WORD COPY FOR WEBISSUE REV A A4.14]:“Sometimes.2. It lists some questions to elicit the relevant information.7 describes activity during the development of trial designs.2. The FEB is not necessarily fixed [1.1.2.2 Trial designs Section 1.5. 1.3 Given the functional nature of the Scottish Standards section 1. This process will identify the issues that need to be addressed in the analysis of the trial design.DOC Page A6 Ove Arup & Partners Ltd Rev A 3 July 2006 .Scottish Building Standards Agency BS7974 and the International Fire Engineering Guidelines Review for Scottish Building Standards Agency A2. F:\FINAL REPORT WORD COPY FOR WEBISSUE REV A A4.2.8 of the IFEG is significant:- “In order to determine the specific objectives or performance requirements it is necessary to determine where the trial designs do not comply with the relevant deemed-to-satisfy or prescriptive provisions. section 1. both options would be available. Another issue raised by this section is whether the FEB has to show equivalent performance to the solutions given in guidance/codes. and certainly goes into more detail than the somewhat cursory section 6.2) and the determination of non-compliance issues (Section 1.1. the IFEG gives examples of the selection of relevant performance requirement in Australia.8. but is not a substitute for experience and training in fire engineering. other than those covered by recognised codes. It does give some examples in section 1. if so-desired. F:\FINAL REPORT WORD COPY FOR WEBISSUE REV A A4.9. A2. Arup}. From our understanding of the Scottish regulatory system. have been agreed to during the FEB process” .6 in the BS. although similar information can be gleaned from other parts of the BS and its PD’s.8.1. the relevant objectives or performance requirements need to be identified directly (see 1. USA. See illustration Figure A4. Reflecting the importance of this section. The SBSA will need to consider whether it is necessary for this kind of modification to be made to the IFEG before it can be called up for use in Scotland.4. This situation may occur where the relevant codes comprise objectives or performance requirements only or when general objectives.DOC Page A7 Ove Arup & Partners Ltd Rev A 3 July 2006 .10 of performance parameters relevant to certain common fire safety objectives.4 Selection of analytical approaches The Process section includes a discussion of the selection of the approaches and methods of analysis. Factors of safety are also discussed in this section. Canada and New Zealand. It gives useful advice on the principles involved. at a very general level.2. or whether it is acceptable to demonstrate compliance with the functional/performance standard. Presumably an example under the Scottish regulatory system could be included as part of the process of ‘adopting’ the IFEG.2. so that acceptance criteria can be agreed.2.1) omitted {bold text ed. A2. It is probably more helpful than BS7974 in this area.Scottish Building Standards Agency BS7974 and the International Fire Engineering Guidelines Review for Scottish Building Standards Agency In cases where there are no deemed-to-satisfy or prescriptive provisions.2.5 Acceptance criteria The IFEG does not set acceptance criteria. and given the range of possible cases it is not possible to do so. The verifiers will need to be able to identify the underlying objectives or performance requirements of the Functional Standards. examples from IFEG of acceptance criteria F:\FINAL REPORT WORD COPY FOR WEBISSUE REV A A4.DOC Page A8 Ove Arup & Partners Ltd Rev A 3 July 2006 .Scottish Building Standards Agency BS7974 and the International Fire Engineering Guidelines Review for Scottish Building Standards Agency Figure A4. Scottish Building Standards Agency BS7974 and the International Fire Engineering Guidelines Review for Scottish Building Standards Agency A2. and its control Subsystem C Spread of fire beyond the enclosure of origin. The following quote from IFEG 1. Enables suppression effectiveness to be estimated Subsystem E Occupant evacuation and control. it is the responsibility of the fire engineer to plan the analysis for the particular project. to set down detailed guidance on how the fire safety analysis should be undertaken.2 is important in that it qualifies the importance of the whole sub-system principle:“Typically.” Subsystem A Fire initiation and development and control of fire within enclosure of origin as well as enclosures to which fire subsequently spreads Subsystem B Development and spread of smoke within the building. Figure A5.1 of the IFEG document. F:\FINAL REPORT WORD COPY FOR WEBISSUE REV A A4.6 Sub-systems The sub-system approach is introduced in section 1. Instead. Effectiveness of intervention including suppression. It is not sensible. the BS7974 sub-systems repeated for ease of comparison The point is made that the sub-systems actually used will depend on the non-compliance issues identified and the specific objectives established in the FEB. therefore. They are set out in figure Figure A5. impact on structure and how spread and impact may be controlled Subsystem D Fire detection warning and suppression.3.3. the IFEG subsystems BS7974 Code of Practice – Application of fire safety engineering principles to the design of buildings BSPD79740 Guide to design framework and fire safety engineering procedures BSPD79741 Initiation and development of fire within enclosure of origin BSPD79742 Spread of smoke and toxic gases within and beyond the enclosure of origin BSPD79743 Structural response and fire spread beyond the enclosure of origin BSPD79744 Detection of fire and activation of fire protection systems BSPD79745 Fire service intervention BSPD79746 Evacuation BSPD79747 Probabilistic risk assessment Figure A6.2.DOC Page A9 Ove Arup & Partners Ltd Rev A 3 July 2006 . The FEB is therefore integral to the overall process. each building project is unique and similarly. based on the decisions taken during the preparation of the FEB as discussed in Chapter 1.1. each fire engineering evaluation is unique. Enables estimate of time to reach place of safety Subsystem F Fire services intervention. As noted the IFEG sub-systems bear a very close resemblance to those used in BS7974. 1.Scottish Building Standards Agency BS7974 and the International Fire Engineering Guidelines Review for Scottish Building Standards Agency A2.1 notes that these charts are only for guidance.4. and do not necessarily cover all the factors which may be relevant to a particular case. F:\FINAL REPORT WORD COPY FOR WEBISSUE REV A A4.DOC Page A10 Ove Arup & Partners Ltd Rev A 3 July 2006 .7 Sub-system Flow charts Each sub-system description includes flow charts indicating how analysis may be undertaken. IFEG Section 1. An example from sub system 1 ‘fire initiation and development’ is shown as an illustration in Figure A7 below. Scottish Building Standards Agency BS7974 and the International Fire Engineering Guidelines Review for Scottish Building Standards Agency Figure A7: flow chart from IFEG for sub-system on fire initiation and development F:\FINAL REPORT WORD COPY FOR WEBISSUE REV A A4.DOC Page A11 Ove Arup & Partners Ltd Rev A 3 July 2006 . do address all of the Functional Standards. SS5. or is an enclosed shopping centre. Sub-systems relevant to this functional standard BS7974 SS1.Scottish Building Standards Agency BS7974 and the International Fire Engineering Guidelines Review for Scottish Building Standards Agency A2. BS7974 and IFEG.1. as they may be employed in any sub-system. SS2. The procedures defined in the two documents are applicable to dwellings and to other buildings.15 applies only to a building which is an enclosed shopping centre. The IFEG and BS7974 do not discriminate between domestic and other types of building work. A comparison of the data and methodologies is provided in Appendix B. It is obviously essential that the two documents.1 and n.1 Functional standard 2.11 only applies to a building which is:. Standards n. A4 Functional standards The Scottish building regulations identify 15 functional standards. reproduced below.a dwelling. in the context of probabilistic approaches generally.1 Every building must be designed and constructed in such a way that in the event of an outbreak of fire within the building. is a residential care building.8 Preparation of the Fire Engineering brief The IFEG gives more information about the documentation of the fire engineering work than the BS. A3 Methodologies Part 2 of the IFEG is devoted to methodologies that may be appropriate for the preparation of the FEB and for the analysis in each subsystem It touches on the:• • Identification and definition of fire scenarios Use of event trees for scenario identification. SSC. Standard n. SSB. SSE. or is a residential building. SS3. SS6 IFEG SSA. PD7 of the BS has a section on these techniques. is a high rise domestic building. Limitation This standard does not apply to domestic buildings. SS4. fire and smoke are inhibited from spreading beyond the compartment of origin until any occupants have had the time to leave that compartment and any fire containment measures have been initiated.13 do not apply to domestic buildings and Standard n.DOC Page A12 Ove Arup & Partners Ltd Rev A 3 July 2006 . SSD. The BS lists information that may be appropriate to include in the report. SSF F:\FINAL REPORT WORD COPY FOR WEBISSUE REV A A4. This section is to confirm that all the Functional Standards are capable of being addressed by following the guidance in the two reference documents A4. or forms the whole or part of a sheltered housing complex. SS4 SSB. SSB. SS2. SSA.Scottish Building Standards Agency BS7974 and the International Fire Engineering Guidelines Review for Scottish Building Standards Agency A4. the development of fire and smoke from the surfaces of walls and ceilings within the area of origin is inhibited.3 Every building must be designed and constructed in such a way that in the event of outbreak of fire within the building. SS6 IFEG SSA.3 Functional standard 2.2 Functional standard 2.5 Every building must be designed and constructed in such a way that in the event of an outbreak of fire within the building. SS3. SSB. SSF A4. SSC. SS3. the load-bearing capacity of the building will continue to function until all occupants have escaped. SSD. SS5. SSD A4. must be designed and constructed in such a way that in the event of an outbreak of fire within the building. SS2. SS4. Sub-systems relevant to this functional standard BS7974 SS1. SS4. Sub-systems relevant to this functional standard BS7974 SS1.4 Every building must be designed and constructed in such a way that in the event of an outbreak of fire within the building. fire and smoke are inhibited from spreading beyond the area of occupation where the fire originated. SSD IFEG F:\FINAL REPORT WORD COPY FOR WEBISSUE REV A A4. SSC.4 Functional standard 2. which is divided into more than one area of different occupation.DOC Page A13 Ove Arup & Partners Ltd Rev A 3 July 2006 .2 Every building. Sub-systems relevant to this functional standard BS7974 SS2. SSD IFEG A4.5 Functional standard 2. SSC. SS3. or been assisted to escape. from the building and any fire containment measures have been initiated. Sub-systems relevant to this functional standard BS7974 SS1. SS4 IFEG SSA. SSE. the unseen spread of fire and smoke within concealed spaces in its structure and fabric is inhibited. the spread of fire to neighbouring buildings is inhibited. SSB. Sub-systems relevant to this functional standard BS7974 SS2. before being affected by fire or smoke. the spread of fire on the external walls of the building is inhibited. the occupants.6 Every building must be designed and constructed in such a way that in the event of an outbreak of fire within the building. SSB. or from an external source. SS4. SS2. SSF F:\FINAL REPORT WORD COPY FOR WEBISSUE REV A A4. SS4. SSF A4. Sub-systems relevant to this functional standard BS7974 SS1.9 Every building must be designed and constructed in such a way that in the event of an outbreak of fire within the building.9 Functional standard 2. SS5 IFEG SSA.Scottish Building Standards Agency BS7974 and the International Fire Engineering Guidelines Review for Scottish Building Standards Agency A4. SSC. SSD.8 Functional standard 2. SSF IFEG A4. SSC. SSC. Sub-systems relevant to this functional standard BS7974 SS1. SS5 IFEG SSA. SSF A4. once alerted to the outbreak of the fire. SS2. SSE. the spread of fire to the building is inhibited. SS5 SSC.DOC Page A14 Ove Arup & Partners Ltd Rev A 3 July 2006 . Sub-systems relevant to this functional standard BS7974 SS1. SS4. SS3. SS3. SS5. SSD.7 Functional standard 2. SSD. SSB.8 Every building must be designed and constructed in such a way that in the event of an outbreak of fire in a neighbouring building.6 Functional standard 2. SS6 IFEG SSA. SS3. are provided with the opportunity to escape from the building.7 Every building must be designed and constructed in such a way that in the event of an outbreak of fire within the building. SS2. SS3. SSD. Limitation This standard applies only to a building which: (a) is a dwelling.10 Functional standard 2.10 Every building must be designed and constructed in such a way that in the event of an outbreak of fire within the building. Sub-systems relevant to this functional standard BS7974 SS5. SSB. Sub-systems relevant to this functional standard BS7974 SS5 SSF IFEG F:\FINAL REPORT WORD COPY FOR WEBISSUE REV A A4. SS4. SSD. SS4. SSE A4. the occupants are alerted to the outbreak of fire. Sub-systems relevant to this functional standard BS7974 SS2. SS6 SSE.11 Functional standard 2.13 Functional standard 2. SS2. Limitation This standard does not apply to domestic buildings.12 Every building must be accessible to fire appliances and fire service personnel. Sub-systems relevant to this functional standard BS7974 SS1.Scottish Building Standards Agency BS7974 and the International Fire Engineering Guidelines Review for Scottish Building Standards Agency A4. SS6 IFEG SSA. (b) is a residential building. or (c) is an enclosed shopping centre. SSF IFEG A4.12 Functional standard 2. SSE IFEG A4.DOC Page A15 Ove Arup & Partners Ltd Rev A 3 July 2006 .13 Every building must be provided with a water supply for use by the fire service. illumination is provided to assist in escape.11 Every building must be designed and constructed in such a way that in the event of an outbreak of fire within the building. SS6 SSB. 14 Functional standard 2. SSE. SS4. SS6 IFEG SSB. SS2. (b) is a residential care building. SS5. Sub-systems relevant to this functional standard BS7974 SS1. (c) is a high rise domestic building. Limitation This standard applies only to a building which: (a) is an enclosed shopping centre. SSB.15 Every building must be designed and constructed in such a way that. fire and smoke will be inhibited from spreading through the building by the operation of an automatic life safety fire suppression system. or (d) forms the whole or part of a sheltered housing complex.14 Every building must be designed and constructed in such a way that facilities are provided to assist fire-fighting or rescue operations. in the event of an outbreak of fire within the building. SSD. SSF A4.Scottish Building Standards Agency BS7974 and the International Fire Engineering Guidelines Review for Scottish Building Standards Agency A4.15 Functional standard 2. SSC. SS3. SS4 SSA. Sub-systems relevant to this functional standard BS7974 SS2. SSD IFEG F:\FINAL REPORT WORD COPY FOR WEBISSUE REV A A4.DOC Page A16 Ove Arup & Partners Ltd Rev A 3 July 2006 . Appendix B Data and numerical methods . Initiation and development of fire within the enclosure of origin. Data is provided on ignitability limits for common fuels for both piloted ignition and spontaneous ignition. it is recommended the 95% fractile value should be taken as the fire load. The use of event trees to determine fire ignition and spread is recognised. Both use the same equation for fire load density. Where the CIB W14 workshop figures are utilised. it is recommended that in the UK the 80% fractile value should be taken as the fire load. Extensive references to Babrauskas “Ignition Handbook” A list of common ignition sources is provided. Some information is provided on ignition characteristics. The time to flame contact is given as a conservative value. it is also reproduced in WarringtonBCC’s “Fire resistant barriers and structures (2000)” The CIB W14 workshop report is also referred to. The IFEG is more detailed and also provides more references for additional information. Where the CIB W14 workshop figures are utilised.3 of the main report. Design Calculations-Pre-flashover Fire load densities IFEG Allowed to be assessed by surveys. Potential conflicts identified below are discussed in section 3. NA.Scottish Building Standards Agency BS7974 and the International Fire Engineering Guidelines Review for Scottish Building Standards Agency B1 Data and numerical methods The following series of tables compares the guidance given on input data for each subsystem in the two documents under review [BS7974 including PD’s. For fire spread through radiation Babrauskas relationship between mass loss rate and ignition distance is shown. Generic data-Swiss data collected 1967-1969. and the IFEG] The object of the assessment has been to identify possible conflicts that might arise if both the reference documents are afforded equal status as sources of guidance for satisfying the Scottish Building Standards. F:\FINAL REPORT WORD COPY FOR WEBISSUE REV A A4. Time to ignition of second object is discussed. Generic data-The CIB W14 workshop report is referred to.DOC Page B1 Ove Arup & Partners Ltd Rev A 3 July 2006 . Sub-system 1. Conclusion Identical. IFEG provides more information. Similar. Contradicting Ignition It is appreciated that in most cases a deterministic approach is utilised and a fire initiation is a presumption for the fire engineered analysis. 7974-1:2003 Allowed to be assessed by surveys. Flame length according to Cox and Chitty. Flame temperature Flame radiation & flame emissivity Equation developed by Quintere et al. “Growth times” referenced to NFPA 204 Occupancy related fire growth times referenced to NFPA 204 7974-1:2003 Data for convective heat release fractions rates refers to SFPE handbook Q*-Dimensionless heat release rate as described by Zukoski.DOC Page B2 Ove Arup & Partners Ltd Rev A 3 July 2006 . The smoke mass conversion factors are referenced to the SFPE handbook. F:\FINAL REPORT WORD COPY FOR WEBISSUE REV A A4. Fire growth parameters as described in NFPA92B Picture gallery-slow Dwelling-medium Office-medium Hotel reception-medium Hotel bedroom-medium Shop-fast Industrial storage or plant roomUltra-fast 2 Shops-550kw/m Offices-290kw/m2 Hotel rooms-250kw/m2 Industrial (excl. A basic equation is shown. No recommendations Identical Identical. 1981 recommended. (1982). “Corner room fires are likely to increase flame heights by 75% and wall fires by 32%” this is referenced to Zukoski. (1982) Walton & Thomas (2002) equation for heat release rates needed to induce flash-over.Initiation and development of fire within the enclosure of origin. Walton & Thomas (2002) equation for heat release rates needed to induce flash-over. Emissivity = 1 Standard radiation calculation with view factor. It is suggested that the influence of air flow should be taken into account Smoke mass conversion factors for flaming and non-flaming combustion. No recommendation on an appropriate heat release model. No recommendations If the flame length is over 1m and the flame is luminous it is common to assume black body behaviour. 1980. Conclusion NA Characteristic fire growth curves-t² Similar/Identical Similar/Identical Heat release rates per unit area No recommendations on peak heat release rates NA-More info in 7974 Smouldering fires Heat release within enclosure for flashover Temperature within enclosure prior to flashover Flame length for axi-symmetric fire source. Equation presented by McCaffrey et al. Design Calculations-Pre-flashover Heat release rates IFEG Convective fraction is approximated to 70% of total heat release. (0. storage) – 90620kw/m2 Equation developed by Quintere et al. but not contradicting NA-7974 provides more information NA-7974 provides more information Heskestad (2002) equations Standard radiation calculations.2*Q^(2/5)) The equation shown is referenced to DD240-1. Flame length for line sources Flame lengths for corner room and wall fires. NA-7974 provides more information.Scottish Building Standards Agency BS7974 and the International Fire Engineering Guidelines Review for Scottish Building Standards Agency Sub-system 1. Noted misprint in IFEG on definition of terms NA Flame length is estimated with the McAffrey and Heskestad equations No recommendations No recommendations Dissimilar. The emissivity can be conservatively set to 1 NA-IFEG provides greater detail Identical Smoke yield No relationships are given for mass conversion factors. referred to Drysdale-An introduction to fire dynamics. or the temperature remains below 550°C. No recommendations for thermal effects of enclosures.Scottish Building Standards Agency BS7974 and the International Fire Engineering Guidelines Review for Scottish Building Standards Agency Sub-system 1. McCaffrey for when thermal effects of enclosures is considered. is referenced to the SFPE handbook. NA-7974 provides more information NA-7974 provides more information NA-7974 provides more information Design Calculations-Fully developed fire Time to flashover 7974-1:2003 “Flashover can be assumed to occur when sustained flaming from combustibles reaches that ceiling and the temperature of the hot gas layer is between 550°C and 600°C. flashover can be assumed to be unlikely. IFEG Uses Drysdales’ equation for mass flow. Relations for mass optical density for different fuels is shown. Optical density given in dB/m. Conclusion Similar Heat release rate at flashover When 80% of the fuel has been consumed the fire can be assumed to decay either: -linearly -at rate determined experimentally -at any rate than can be justified Thomas (1981) for no consideration of wall thermal properties. Mass optical density No discussion on mass optical density. This value. D=optical density db/m If a sign is back illuminated its visibility distance can be increased by a factor of 2. 7974-1:2003 Uses Thomas.Initiation and development of fire within the enclosure of origin.013mf. and other conversion factors.5 The mass conversion factor for CO is given as 0. Mass production of CO and other species CO yield factors referenced to “part three of these guidelines” no data is however found in the appendices. Kawagoe and Sekine equation for linear decline. Similar Identical for cases where no consideration is taken for thermal effects of enclosures. 7974 provides further information. equation for the mass flow in an underventilated fire or an unreferenced equation for fuel mass flow (it is identical to the one in Drysdale 1999). S=visibility distance. It is however shown in the fire detection section 7974-1:2003 The light depletion equations is Bouguer’s law. Referenced to SFPE handbook S=(10/D).” For design purposes it may be assumed that heat release rates remain constant until 80% of the fuel has been consumed and the decay phase starts. Walton & Thomas (2002) for no consideration to wall thermal properties. IFEG Flashover occurs when the hot layer temperature reaches approximately 600°C or when radiation at floor level from the hot smoke layer reaches 20kW/m2.DOC Page B3 Ove Arup & Partners Ltd Rev A 3 July 2006 . Conclusion Similar Steady state fires Mass burning rate in ventilation controlled conditions F:\FINAL REPORT WORD COPY FOR WEBISSUE REV A A4. The equations shown are basic concentration equations. Conclusion Identical Optical density data required for smoke detector activation is expressed in dB/m. If flames from the combustibles do not reach the ceiling. Design Calculations-Pre-flashover Optical density IFEG The light depletion equations is Bouguer’s law.1973. with a reasonable and referenced assumption regarding underventilated fires.. Visibility No discussion on visibility of signage etc. Burning rate is based on assessment that the total initial fire load burns in 1200 seconds Another equation for fuel bed controlled fires is presented with no reference to its origins. Design Calculations-Pre-flashover Mass burning rate in fuel bed controlled conditions IFEG No equations are suggested. in accordance with BS 476-20 Temperature curve in accordance with BS EN 1991-12:2002 Two heating curves for slow heating fires.Initiation and development of fire within the enclosure of origin. NA-The 7974 provides many equations and data whilst the information found in IFEG is very limited. Conclusion Different Standard temperature-time curve Hydrocarbon temperature-time curve Short discussion on the existence of empirical timetemperature curves. 7974 recognises the ISO and BS 476 temperature-time curve Large pool fire. Equation referenced to M.law 1978 Kawagoe and Sekine equation dependant on opening factor. References are made to Babrauskas section in the SFPE handbook and Sardqvists “Initial fires”. F:\FINAL REPORT WORD COPY FOR WEBISSUE REV A A4. Reference given to Lie (1994).Scottish Building Standards Agency BS7974 and the International Fire Engineering Guidelines Review for Scottish Building Standards Agency Sub-system 1. Slow heating curve Maximum temperature curve Ventilation controlled temperature-time curve Summary Both documents provide quite comprehensive quantitative guidance on the subject. Reference to BS 1363-2:1999. Time to reach burnout after flashover is shown as two times the mass of fuel left at flashover divided by peak rate mass burning rate. 7974-1:2003 An effective fire duration of 20 minutes can be assumed in houses. BS7974 however provides the most information.DOC Page B4 Ove Arup & Partners Ltd Rev A 3 July 2006 . It is recommended that “appropriate engineering judgement” should be applied when setting fire rates. offices and shops. Evaluate effect on FF operations Conclusion Identical Similar – both outline advantages of controlling temperatures. Identical Techniques Containment mentioned. IFEG SS-C Qc=0. fuel controlled fire creates a plume. Fans pull air out of designated spaces rather than supplying it. Smoke clearance – removal of smoke after smoke has finished being produced. smoke rises to ceiling. 7974-2:2002 Protection of MoE – clear layer solutions Temperature Control – protects materials within the smoke zone Assist fire fighting operations – prevent hot smoky layers occurring in certain situations.Scottish Building Standards Agency BS7974 and the International Fire Engineering Guidelines Review for Scottish Building Standards Agency Sub-system 2. environmental effects. Uses pressure differences over openings.7Q 7974-2:2002 Building Characteristics Occupant characteristics Design fire – sub system 1 Environmental influences – wind. Fire growth may be limited by limited ventilation. Conclusion Similar/Identical Similar. H2O. Further preamble of smoke dangers. Most fire deaths from smoke inhalation. “CO. Smoke Dynamics Dissimilar. Similar N/A – depressurisation not mentioned in IFEG Design Procedure Inputs IFEG SS-C Building characteristics. Similar Zone pressurisation mentioned. stack effect. N/A – No mention in IFEG of limiting heat fluxes. internal air movement. 7974-2:2002 Qp=XQ where X is the fraction of heat Conclusion Identical. then radially spreads. CO2 and HCN are often considered for life safety criteria”. Air entrainment increases volume and decreases temperature. time to smoke detection. but not contradicting. smoke yield.Spread of Smoke and toxic gases within and beyond the enclosure of origin.DOC Page B5 Ove Arup & Partners Ltd Rev A 3 July 2006 . Similar Natural ventilation mentioned. Initial flow influenced by air currents. Smoke Control Design Objectives IFEG Evaluate effect on Means of Escape [MoE] Temperature control mentioned with regards to fire spread. Influence of buoyancy and combustion generated products. Property Protection – limiting heat flux on structure through exhaust. heat release rate profile. but not F:\FINAL REPORT WORD COPY FOR WEBISSUE REV A A4. Smoke exhaust ventilation – natural or mechanical means of removing smoke from top of layer. Smoke containment – physical measures to prevent the spread of hot and smoky products – smoke curtains. CO2. Depressurisation – limiting smoke movement by pressure differentials. 7974-2:2002 ‘airborne’ products of combustion. Amount of air entrained greatly exceeds mass flow of fuel burned. CO. Smoke Dilution – mixing smoke with clean air to reduce the concentration of toxic products and increase visibility. characteristics of smoke management equipment. solid or liquid particulates within a gaseous mass. Analysis Heat content Conclusion Dissimilar. Active systems activation time. Hazards of smoke IFEG Visible and non visible products of combustion or pyrolysis and entrained air. walls etc. Similar Dilution mentioned. HCN. Pressurization – effectively contains smoke. Similar Extraction mentioned. BS 7974 has greater detail and commentary. depth of smoke layer and the profile correction factor. More detail in BS 7974. N/A – BS 7974 has more information. intermittent flame region and buoyant plume. Identical references – BS 7974 goes into more detail. More detail in BS 7974.Spread of Smoke and toxic gases within and beyond the enclosure of origin. (Alpert 1972). Fire induced winds: Inlet air velocity causes the flame jet to move away from opening. but not contradicting. but not contradicting – BS 7974 goes into more detail. N/A –not mentioned in IFEG References the use of reflection (Mowrer and Williamson 1987). Axi-symmetric plumes: Discussion about the movement of smoke and air entrainment. Not mentioned. Not mentioned. Equations outline the maximum temperature rise and maximum gas velocities and is dependant on the radial distances and height of ceiling above the fire source. Dissimilar. Dependant on temperature and height of rise.4 – 0. Effect of Adjacent Walls: the reduction of entrained air from the perimeter causes the flame height to lengthen. Ceiling jet mentioned in Detection sub system. but not contradicting. Equation given for vertical smoke flow rate (kg/s). Maximum velocities and temperatures occur in first 1% of fire source to ceiling height. No calculation given. IFEG of plume Smoke plumes above fire source Mean flame height and virtual origin mentioned.9).DOC Page B6 Ove Arup & Partners Ltd Rev A 3 July 2006 . Flow from enclosure openings Rockett (1976) and Edmonds (2002) equation given for mass flow out of an opening.Scottish Building Standards Agency BS7974 and the International Fire Engineering Guidelines Review for Scottish Building Standards Agency Sub-system 2. F:\FINAL REPORT WORD COPY FOR WEBISSUE REV A A4. The velocity and temperature rises are dependant on the width of the corridor and the distance to a point which wants to be found. Dependant on density of smoke and opening. (Alpert 1972). Axi-symmetric ceiling jet: temperatures and velocities in unconfined spaces discussed. Dissimilar. the velocity and temperature rises will be different to unenclosed spaces. McCaffrey Model – equations given for mass entrainment rate for flame region. Equations outline the maximum temperature rise and maximum gas velocities and is dependant on the radial distances and height of ceiling above the fire source. air density. but not contradicting. Axi-symmetric ceiling jet: temperatures and velocities in unconfined spaces discussed. Luminous flame height – Cox and Chitty or Heskestad – whichever is more onerous. Ceiling jets are typically 5-12% of fire source to ceiling height in depth. Dissimilar. mass flow of smoke. Flame height. (Delichatsios 1981) Calculation of mass flow of smoke from a vertical opening before the onset of flashover is considered (Thomas 1992). Depth of smoke layer is presented based on a constant of proportionality. Short explanation. 7974-2:2002 as convection (0. Mass flow of smoke can be calculated. Dissimilar. Ceiling Jets Stack effect makes reference made to Klote and Milke (2002). More information in 7974. Dissimilar. Plume impingement on ceiling. but not contradicting. Dissimilar. Flame height and mass floor of smoke given for fire against wall and in corner. Conclusion contradicting. Identical. but not contradicting. Line Plume: Where L=5W of fire base. This is based on the temperature rise. table provided for different fuels. Stratification of Smoke: two equations for stratification of smoke rise (m). Dependant on length of side and HRR. Two-dimensional ceiling jet: Where beams or corridors inhibit plume spread. Calculations outlined for flame height and mass flow rate of smoke and entrained air. References Delichatsios 1981. N/A – BS 7974 goes into more detail. Consideration required for certain toxins when related to life safety. Evans and Klote (2003). 2600m for powered 2 and 3000m for property. but not contradicting. Gas species mass concentrations: discussion about the means by which the mass concentration of a particular species can be found. Klote and Milke (2002). Calculations for mass flow of smoke presented. Optical density of smoke: expression given on the way light is attenuated in respect to source intensity and optical density of smoke. Dissimilar. Not mentioned. N/A – BS 7974 goes into more detail.Spread of Smoke and toxic gases within and beyond the enclosure of origin. Smoke volume flow rate: well mixed smoke layer volume flow rate represented by temperature and mass flow of the smoke. Large uncertainties can be involved. but not contradicting. 7974-2:2002 Spill Plumes: discusses the effect of large spill areas. N/A – BS 7974 goes into more detail. Temperature of the hot gases: represented by the relationship between fire size and mass flow of smoke. Visibility through smoke: visibility through the smoke is one over the optical density per unit length (Tewarson 1995). Not mentioned. IFEG Smoke spread from other than the enclosure of fire origin is stated as being difficult using hand calculations are rarely used although SFPE handbook has some calculations. Optical density of smoke: expression given on the way light is attenuated in respect to source intensity and optical density of smoke. references made to. Minimum number of exhaust Ventilators Interactions of sprinklers and smoke ventilation Free hanging smoke curtains No mentioned. Referes to NFPA92B and NFPA 204. Conclusion Dissimilar. but not contradicting. The phenomenon of plug holing is discussed and the calculation for critical exhaust rate of ventilators away form a wall is given from BRE 368. SFPE Handbook (DiNenno 2002). Smoke Reservoir Size No information given. Flow through a horizontal vent references Klote and Milke (2002). 7974 allows calculation of species concentration by mass. N/A – BS 7974 goes into more detail. Replacement Air Properties of Smoke BS 7974 provides more detail. The number of vents can be found from the mcrit and the mass flow entering the layer. materials in room and fire size. F:\FINAL REPORT WORD COPY FOR WEBISSUE REV A A4. Not mentioned. Not mentioned. Curtains containing a smoke layer: the deflection of the smoke curtain N/A – BS 7974 goes into more detail. Dissimilar. Greater detail in BS 7974. Flow of hot gases through natural horizontal vents: calculation given to determine the mass flow rate through a horizontal vent (Thomas et al 1963). Gas volume concentrations: dependant on the density of species. Similar – Different equations with same basis used. Optical density per unit length can be found.DOC Page B7 Ove Arup & Partners Ltd Rev A 3 July 2006 . Similar – BS 7974 goes into more detail. Upper temperature of layer from McCaffrey. Refers to NFPA92B and NFPA 204. Dependant on openings. Short discussion on the use of gas species concentrations. The optical density of smoke is a function of the total volume of smoke and the mass optical density of the fuel.Scottish Building Standards Agency BS7974 and the International Fire Engineering Guidelines Review for Scottish Building Standards Agency Sub-system 2. References BRE 368 to determine whether sprinklers will affect the designed smoke control system and the effect the temperature control will have on the sprinkler system. Dissimilar. Equation given for vertical smoke flow. Limits for smoke reservoir sizes in the absence of computer modelling to 2 2 2000m for MoE. maximum speed 5m/s. Briefly mentioned. BS 7974 provides greater discussion and provides hand calculations. Drysdale (1999). N/A – BS 7974 goes into more detail. Discussion on the problems associated with free hanging smoke curtains and horizontal deflections. Visibility through smoke is not given. but not contradicting. N/A – BS 7974 goes into more detail. The mass flow rates include the effect of the width of the opening. Essential for inlet to be provided. Conclusions IFEG SS-C Where calculations and concepts are not given. no advice given. thermal radiation etc. Data Convected fractions Mass optical density 7974-2:2002 Convected fractions for various materials Mass optical densities and CO yield of various products.Spread of Smoke and toxic gases within and beyond the enclosure of origin. Curtains closing an opening: deflection of curtain and length can be found. Conclusion N/A – BS 7974 goes into more detail. Not mentioned. Some details are brief. Computer Modelling IFEG SS-C Mentioned as a means of analysis. Conclusion IFEG goes into more detail. Length of curtain required is iterative. Means of determining via use of extinction coefficient. zone models. although only BS 7974 provides them within the document. 7974-2:2002 Provides defined areas to provide smoke ventilation and smoke control in enclosures and large spaces. F:\FINAL REPORT WORD COPY FOR WEBISSUE REV A A4. Conclusion Not mentioned. 7974-2:2002 Defines the use of BS 9999: 4 to determine frequency of maintenance. Mass optical densities and CO yield of various materials. N/A – BS 7974 goes into more detail. CFD. IFEG 7974-2:2002 can be calculated from the parameters of the curtain and projected smoke layer. Fire Safety Management Management IFEG SS-C Suggest management procedures for active systems particularly and consideration required for passive systems.7 referred to as standard. Conclusion N/A – BS 7974 goes into more detail. some widely-used calculations are not present. N/A – BS 7974 goes into more detail. 7974 references a management document. Good flow chart of procedures.DOC Page B8 Ove Arup & Partners Ltd Rev A 3 July 2006 .Scottish Building Standards Agency BS7974 and the International Fire Engineering Guidelines Review for Scottish Building Standards Agency Sub-system 2. N/A – BS 7974 goes into more detail. IFEG references other document heavily. Conclusion Both provide the answers. reference one of a number of books/papers. IFEG SS-C 0. 7974-2:2002 Discussion of model types. Some information in other sub-systems. Section factors from BS 5950-8 and temperature rise within a steel member is calculated from DD ENV 1993 1-2. Concrete Empirical equations based on the standard time temperature curve to predict temperature profiles within concrete members Information given on thermal elongation and shrinkage. NA-IFEG provides a fair bit of information on existing standards. They do however differ from the EC1.Structural response and fire spread beyond the enclosure of origin IFEG 7974-3:2003 Information from standard tests is reasonably well understood. Simplified design processes for reinforced concrete members are referenced to a number of national standards from Australia. The EC1 suggests a kb ranging between 0. Time equivalence Recognises and shows the Eurocode1 approach.DOC Page B9 Ove Arup & Partners Ltd Rev A 3 July 2006 . Dissimilar.Scottish Building Standards Agency BS7974 and the International Fire Engineering Guidelines Review for Scottish Building Standards Agency Sub-system 3. Fire severity Determination of fire conditions through engineering calculations 7974-3:2003 Maximum temperature equation shown.09-0. The recommended kb value (0. ASCE/SFPE 29. Conclusion Dissimilar. Timber Protection to external steel member is referenced to Law and O’Brien (1981) and EC1 and EC3 Short discussion on the possible fire protection measures available for steel structures. IFEG references to other sources and only provides a rough commentary. kb is set in a range of 0.07. but not contradictory- F:\FINAL REPORT WORD COPY FOR WEBISSUE REV A A4. Conclusion NA-7974 provides more information. The recommendations given are similar between the two publications. as well as a similar equation for through draught conditions. No practical guidance is found in the document. Information given on thermal elongation. New Zeeland. thermal conductivity. Conclusion NA-7974 provides more information. Detailed recommendations of calculation methodologies for protected steel.080. thermal conductivity. This is referenced to Kirby (1999) IFEG Basic heat balance and references to simple relationships. Steel Eurocode 3-Design of Steel structures is recommended as a suitable guide for steel design. This is higher than the values found in EC1. The charring rate is estimated Identical NA-7074 provides more practical guidance.05 with a recommendation for UK for 0. Guidance is given on when FEM methodology should be used over simpler methodologies. density and emissivity. NA-7974 contains a lot of practical guidance. Recognises and shows the Eurocode1 approach. Structural Performance General IFEG Much of the information given on this subject seems to be taken from a standard presented by the American Society of Civil Engineers. density and emissivity. Confirms a charring line equal Protection to external steel member is referenced to Law and O’Brien (1981). Transient fire conditions equations shown from DD ENV 1991-2-2 7974-3:2003 Very detailed on the structural performance of different construction units in fire conditions.07. BS7974 provides more data and guidance in the document but other sources will still need to be studied to perform an analysis. 1999. specific heat capacity. In most cases this allows a rapid appraisal of an element’s ability to resist fire spread and maintain structural function. Eurocode. but not contradictory General Recognition of fire tests It is appreciated that the standard fire test curves do not represent a real fire timetemperature curve.045) is however higher than the recommendations given in EC1.04 and 0. specific heat capacity. Information given on thermal elongation and shrinkage. emissivity. mostly on the thermal heat capacity. -Monte Carlo analysis is recommended to evaluate combinations of openings Designer should take “great care” if deciding to use a criterion of a surface temperature on the unexposed side in Conclusion NA Heat flow by conduction No information given NA-7974 provides quantified guidance.Structural response and fire spread beyond the enclosure of origin IFEG to the 300°C line of heating. Information given on thermal elongation and shrinkage. No information given Information given on thermal NA-7974 provides more elongation and shrinkage. 7974 provides a great deal of information on the structural performance of most the common building materials. Collier (1996) and others. No information given General description on the fire performance of these constructions. Some guidance on structural stress behaviour in raised temperatures. F:\FINAL REPORT WORD COPY FOR WEBISSUE REV A A4.1. specific information. The structural performance is referenced to BS 5268. NA-7974 provides information that is more related to thermal properties rather than structural design. mostly on the thermal heat capacity.Scottish Building Standards Agency BS7974 and the International Fire Engineering Guidelines Review for Scottish Building Standards Agency Sub-system 3. specific information.1 and DD ENV 1995-1-2 is shown. Lightweight steel frame guidance is referenced to Gerlich et al. Masonry Reference for methodologies given to Australian Standard AS 3700 Lightweight Timber/ Steel Frame assemblies Plastics Aluminium Summary of information on structural performance Information given on thermal NA-7974 provides more elongation and shrinkage. density and structural performance. thermal conductivity. References given to thermal calculations on lightweight timber walls performed by Clancy (1999). NA-IFEG does not provide any data or practical guidance but refers to a number of sources. BS7974 provides more data and practical guidance. that charring rates to columns should be increased by 25% compared to a beam. Fire spread General IFEG The recommended approach to determining the appropriate fire resistance of barriers is to utilise the time equivalence model and then use a barrier that can achieve the resulting fire period. thermal properties but some also on conductivity. thermal conductivity.DOC Page B10 Ove Arup & Partners Ltd Rev A 3 July 2006 . specific heat capacity. density and emissivity. IFEG appreciates that there is not much guidance available but still references a national standard for some guidance. but studies of external sources is still necessary for a complete analysis. 7974-3:2003 Design guidance on openings into fire enclosure: -doors should be assumed open if enclosure has no other openings -doors should be assumed closed if the enclosure has other openings -all enclosure surfaces (including glazed openings) may be assumed to be imperforate for the duration of fire provided analysis hasn’t proved otherwise. in accordance with BS 5268-4. EC 5 is mentioned as a source of charring rate equations 7974-3:2003 using Hadvigs (1981) equations. emissivity. with references to external sources. thermal properties but some also on conductivity. Charring rates from BS 5268-4. Conclusion IFEG only provides a very short commentary of timber behaviour in fire. It is suggested. Equations for time to maximum charring rate and time dependant charring rates shown. IFEG is very limited in its guidance and refers to other sources. density and emissivity. density and structural performance. specific heat capacity. Refers to White (2002) and an Australian Standard. Only very brief exposed. 7974 does not flow of burning liquids.. the design process. NA-7974 provides quantified Standard radiation relationships shown. Any part of continuous combustible construction that extends outside the enclosure the enclosure should be viewed as permitting fire spread beyond that enclosure. IFEG is more qualitative and often only suggest other sources for where the information can be found. NA-IFEG provides a very Presence of flying brands hard to short commentary. It is recommended that the floor area should be sub-divided into smaller grids (10-50m²) and that fire spreads from one grid to another. 60°C saturated air is mentioned as intolerable. F:\FINAL REPORT WORD COPY FOR WEBISSUE REV A A4. whilst 7974 severity and that a fire in a large only provides a qualitative compartment is more likely to be fuel bed comment. Piloted ignition is assumed to be probable in the region 400-450°C Some criteria given for human tolerability levels. The spontaneous ignition criterion for wood is set to 250-400°C. For organic solids a surface quantified guidance on temp. involved in the fire. and what one should keep in mind when utilising computational modelling. provide any quantified guidance. criterion of 600°C is suggested for ignitability. No guidance in enclosure will at some point become IFEG. The models discussed are zone and field models used to establish fire severity.6kW/m is mentioned as a criterion. spontaneous ignition. 2 guidance. criteria for ignition of solids. ignition due to convection only. Provides information on the No information NA.Structural response and fire spread beyond the enclosure of origin IFEG Heat flow by convection No information given 7974-3:2003 Conclusion excess of 200°C Criteria of 500°C can be used when NA-7974 provides quantified establishing likelihood of spontaneous guidance. surfaces exposed to flying Design care should be taken to mass brands. It is recognised that the size of the Similar-The IFEG suggests a enclosure influences the potential fire quantified value. It seems that 7974 provides comprehensive quantified guidance to many aspects of structural performance in fires. Some data on ignitability limits under radiant heat flux. The section regarding thermal properties is extensive but the information is effectively very simple physical properties. Heat flow by mass transfer BS 476-3 is recommended for a methodology assessing the ignitability of roof coverings subject to radiative heat fluxes and flying brands Heat flow by direct pyrolysis and reaction to fire No information given Fire spread in large enclosures Computer models Summary It is recognised that assuming simultaneous combustion in enclosures over 150m² leads to unrealistically high temperatures in the enclosure.. Heat flow by radiation Various references to publications regarding external fire spread.DOC Page B11 Ove Arup & Partners Ltd Rev A 3 July 2006 .IFEG provides more use of computer models in information. Should be reference a test method for considered as piloted ignition leads to assessing ignitability of lower necessary surface temperatures. but does determine with any certainty. giving “some factor of safety” short commentary and Possible to base analysis on the increase references to other guidance of surface temperature of the object documents. IFEG provides a 12. A reasonable design approach is to NA-Some practical guidance assume that all combustibles within from 7974. The use of FEM models is also discussed. controlled than fires in smaller compartments.Scottish Building Standards Agency BS7974 and the International Fire Engineering Guidelines Review for Scottish Building Standards Agency Sub-system 3. and 300-410°C for ignition by flying brands under a radiative Some dissimilarity in the heat flux. Alpert (1972) ceiling jet model for gas temperature and gas velocity predictions. BS EN 54-5 is referenced for tables showing detector response times Dissimilar. It should be noted that the equations shown for heat detector activation are quite dissimilar. but not contradicting. It is stated that calculations of the optical density should be performed for the plume or preferably the ceiling jet. NA Identical F:\FINAL REPORT WORD COPY FOR WEBISSUE REV A A4. EN 54-12 Aspirating detectors Manufacturers specifications and SS-B “smoke development and control” parameters Each sampling point can be modelled as an individual point detector. It does also require the detectors specific sensing threshold. This is referenced to an EN standard in draft. but this does not seem to be the case. Heat detectors The concept of RTI is described. Quintere et al. especially on the heat detector equivalence.Scottish Building Standards Agency BS7974 and the International Fire Engineering Guidelines Review for Scottish Building Standards Agency Sub-system 4-Detection of fire and activation of fire protection systems. (1982) model for temp. It is therefore unclear if the references used in the two guides are interchangeable. and a simple correlation between light depletion and detector threshold. Conclusion Identical Smoke detectors is assumed to activate when the temperature is raised 13°C above ambient. When considering location of smoke sampling points.DOC Page B12 Ove Arup & Partners Ltd Rev A 3 July 2006 . Qualitative commentary on cases where smoke spread is confined by beams and narrow corridors etc. This is suggested as a worst case scenario for combined fixed-temperature/ heat-rise detectors. but not contradicting. A relationship for the obscuration is shown. Identical Dissimilar. Long detection time delays in Similar-The equations shown are almost the same. DD 240-1 is referenced for the equation showed for smoke detector activation time. (Heskestad 1981) For the optical density detection model only brief information is provided. Beam detectors An unreferenced equation is shown for the optical density required to cause activation of a beam detector. 7974 provides more practical information. Additional equations shown for special applications such as high ceilings or partially confined ceilings. the best analogy is to consider them as individual point detectors.15m/s to be able to detect fire. One would think that 7974 would therefore be expressed in bel rather than decibel. IFEG does not really provide any calculations on the activation of smoke detectors. These are referenced to NFPA 92B. IFEG General 7974-4:2003 Extensive References to BS 5839 and BS EN 54 Conclusion Type of detectors Smoke IFEG Two models mentioned: Optical density and Heat detector equivalence 7974-4:2003 Mentions the research performed regarding the temperature rise needed to activate a smoke detector. Point-type smoke detectors need a surrounding air velocity of at least 0. it is however hard to determine how much of an impact this has on the estimation of activation time. rise in the hot layer. Long detection time delays in large British Fire Protection Systems Association “COP for Category 1 Aspirating Detection Systems” (1996) is referenced for information. For non-flaming fires alternative method will have to be sought The concept of RTI is described. For flaming fires. 13°C above ambient is mentioned. but they differ by a factor 10. The SFPE refers to standard curves for fire size and distance. such as the impact of fire growth. Bs 5306-2 is referred to for engineering guidance Conclusion Similar Water mist Referred to applicable national standard. NA-7974 provides more information. Activation of fire barrier system IFEG No information given F:\FINAL REPORT WORD COPY FOR WEBISSUE REV A A4. such as the impact of fire growth. 7974-4:2003 Evans (1993) NIST relationship between heat release and spray density. Conclusion NA-7974 provides more information Flame detectors Gas detectors It is recommended that normal radiation and view factor equations should be utilised to calculate the radiation impinged on the detector. Conclusion NA-7974 provides more information. An extended radius is recommended to incorporate a degree of conservatism in the detection time equations. No information 7974-4:2003 large systems. 7974-4:2003 It is recognised that siting and spacing of detectors to a standard template (BS 5839-1 mentioned) is not likely to provide the optimum performance and that engineered layouts can provide a more effective system. A threshold value of 40 ppm is mentioned.DOC Page B13 Ove Arup & Partners Ltd Rev A 3 July 2006 . No acceptable methodology available for detection times. No information given General discussion on the subject. The BS EN 54-10 standard is mentioned. NA-7974 provides more information. NA-7974 provides more information Manual detection No information NA-7974 provides more information Conclusion NA Spacing of detectors IFEG No information given Automatic suppression Sprinklers IFEG Madrzykowski and Vittori (1992) relationship for heat release after sprinkler initiation. Dissimilar. Reference to NFPA 750 for more information Gaseous suppression system Foam system Referred to applicable national standard.Scottish Building Standards Agency BS7974 and the International Fire Engineering Guidelines Review for Scottish Building Standards Agency Sub-system 4-Detection of fire and activation of fire protection systems. SFPE handbook relationship for the level of radiation impinged on the detector. Linear heat detectors IFEG systems.7974 provides quantitative guidance. Reference to BS ISO 14520 for more information General discussion on the subject. General discussion on the subject. such as the impact of fire growth. This is presented as a conservative estimate. including failure modes. low or medium pressure systems. Evans (1993) NIST relationship between spray density and heat release. Reference to SFPE handbook for more information 7974-4:2003 General discussion on the subject. with a relationship for the mass flow of CO as a function of total mass flow. NA-7974 provides more information. It is stated that manual call points should be provided to aid in raising an alarm. mostly qualitative but with some guidance on high. A brief discussion of the applicability of linear detectors. but not contradicting. The most practical way of assessing their performance is recommended to be by regarding them as a continuous line of heat detectors. Carbon monoxide detectors mentioned.. The fire service operation is split up into 16 flowcharts. NA-7974 provides more including failure modes information 7974 provides more practical information and quantified guidance. It is however suggested that the quantitative guidance in FBIM can be used as a semi-quantitative utility in other locations. The FBIM employs a structured decision-based framework necessary both to determine and measure fire service activities on a time-line basis. The IFEG effectively refers all of its recommendations to the FBIM. F:\FINAL REPORT WORD COPY FOR WEBISSUE REV A A4. It also addresses issues such as choosing the right detection system with regards to false alarms. It is also appreciated that the guidance given in FBIM is developed with Australian conditions in mind.DOC Page B14 Ove Arup & Partners Ltd Rev A 3 July 2006 . and a table of recommended time limits is shown for different areas depending on the areas risk classification. IFEG The Australian FBIM (Fire Brigade Intervention Model) Model) is presented as an appropriate method for quantification of fire service intervention. The only details to support a quantified analysis are the recommended time limits and a notation that the initiation of fire tackling will take “upwards 10 minutes from the time of arrival” A detailed description of what is expected of fire service provisions installed in a building. 7974 provides more information. and the reader can find more information IFEG does not cover any about quantified analysis of fire technical details of fire service service operations. Conclusion NA-IFEG provides a model or a framework for fire service intervention. 7974-5:2002 The time for fire service attendance is referenced to the Home Office. and that the guidance given in the document may not be directly applicable to other countries. but their respective relation to fire service operations is not thoroughly explained. Summary The description of the FBIM is Very little information on where the very much an overview. It also appreciates that the FBIM is a unique document as Australia is the only country that has produced such an extensive quantified guide. provisions and operations. The IFEG keeps the quantified guidance to a minimum. Sub-system 5-Fire service intervention.Scottish Building Standards Agency BS7974 and the International Fire Engineering Guidelines Review for Scottish Building Standards Agency Sub-system 4-Detection of fire and activation of fire protection systems. and the equations shown are often very basic physical relationships. 7974-5 is highly qualitative and does not provide any model for setting up a quantified model for fire service intervention. but this is qualitative to a great extent. The FBIM (2004) is referenced for quantified estimates for each flowchart. Some quantified guidance on the likely fire service response times as a function of the areas UK risk category. IFEG IFEG No information given Summary 7974-4:2003 Conclusion Activation of smoke control systems 7974-4:2003 Conclusion General discussion on the subject. A model for travel times is referenced to Nelson & Mowrers’ work presented in the SFPE handbook. given in appendices.5m and a smoke layer temperature not exceeding 200°C. most of the figures originates and relates from the UK. F:\FINAL REPORT WORD COPY FOR WEBISSUE REV A A4. 7974 provides a mainly qualitative commentary on many different aspects of evacuation times and evacuation behaviour. Very little quantitative guidance on the subelements of the escape time. evacuation times etc.Scottish Building Standards Agency BS7974 and the International Fire Engineering Guidelines Review for Scottish Building Standards Agency Sub-system 6-Occupant evacuation. It is recommended that Fire engineered Solutions should be based on data in publications such as the SFPE handbook and other scientific publications. Summary The IFEG provides only qualitative guidance and refers extensively to other sources for guidance on several subjects in regards to evacuation. A tenability criterion is given for zero exposure. Conclusion NA. General IFEG The Required Time for Escape (RSET) is divided into a detection phase and a movement phase. and guidance is given on quantified values for the time needed in the different subelements. behaviour and condition. separating RSET into sub-elements. but 7974 provides more information in regards to the different parameters. This is given as a clear layer height of 2. A quantified strategy is proposed.the two documents are similar in such that they both appreciate the basic model for evaluating egress time. 7974-6:2004 A description of Available Safe Escape Time (ASET) and Required Safe Escape Time (RSET). A list of information sources is however presented. Some quantified guidance is provided. travel speeds. Extensive quantified guidance on time to detection.DOC Page B15 Ove Arup & Partners Ltd Rev A 3 July 2006 . An event tree technique is utilised to show different fire scenarios and establish the risk parameters. It is recognised that the acceptable risk can be of absolute type or comparative type. Fire Cost Expectation is mentioned.DOC Page B16 Ove Arup & Partners Ltd Rev A 3 July 2006 . One method of probabilistic risk assessment is shown. General IFEG The use of a probabilistic approach is recognised and described in the Overview section of Part 1. This method is based on Beck and Yung’s work. A similar methodology is shown for estimations of monetary risk. F:\FINAL REPORT WORD COPY FOR WEBISSUE REV A A4. such as ignition frequencies. . In general the 7974 provides “better” quantitative guidance as the guidance for several parameters is shown as a distribution rather than a point estimate or a mean value. Conclusion NA. A number of examples of criteria is shown but it is highlighted that there is not a generally accepted criteria for fire risk in the UK. both qualitative and quantitative. behaviour and condition. on the subject of risk analysis. IFEG provides some information on setting up a fire risk assessment and the results of such an analysis. Data and information given on many of the parameters needed in a Probabilistic Fire Risk Assessment. but it is clear that 7974-7 provides more detail than IFEG Acceptance criteria are shown as absolute or comparative. An example of cost-benefit analysis is shown. presented in1994. It is appreciated that risk analysis can be used to estimate financial loss. A brief discussion on the financial aspects of probabilistic risk assessment.Scottish Building Standards Agency BS7974 and the International Fire Engineering Guidelines Review for Scottish Building Standards Agency Sub-system 6-Occupant evacuation. Different techniques are described and the probability of different aspects of fire scenario models is discussed. Some quantitative guidance is provided on some parameters of fire scenarios. 7974-7:2003 Three method categories are described in some detail: -simple statistical analysis -logic tree analysis -sensitivity analysis A section also discusses complex analysis tools. Summary 7974 provides the most guidance. fire loads and detection/suppression system reliability. No information given on the cost-benefit side of fire protection or any target values for acceptable fire risk. For life safety the result is shown as Occupant safety and Occupant number of deaths. 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