A Guide to Fire Safety Engineering Dr S D Christian A Guide to Fire Safety Engineering First publ ished 2003 © Dr S D Christian, 2003 BIP 2007 ISBN 0 580 41 896 0 The right of Dr S D Christian to be i[.]
A Guide to Fire Safety Engineering Dr S D Christian A Guide to Fire Safety Engineering First publ ished 2003 © Dr S D Christian, 2003 BI P 2007 I SBN 580 41 896 The ri ght of Dr S D Christian to be identified as the author of this work has been asserted in accordance with the Copyright, Desi gns and Patents Act 988 A catal ogue record for this book is avail abl e from the Briti sh Library Copyright subsi sts in al l BSI publ ications Except as permitted under the Copyright, Designs and patents Act 988 no extract may be reproduced, stored in a retrieval system or transmitted in any form or by any means – el ectronic, photocopying, recording or otherwise – without prior written permission from BSI I f permi ssion is granted, the terms may i ncl ude royal ty payments or a l icensing agreement Detail s and advi ce can be obtained from the Copyright Manager, Bri tish Standards I nstitution, 89 Chiswick H i gh Road, London W4 4AL Great care has been taken to ensure accuracy in the compil ation and preparation of this publ ication H owever, since it is intended as a guide and not a defi nitive statement, the author and BSI cannot in any circumstances accept responsi bil ity for the resul ts of any acti on taken on the basi s of the information contained in the publ icati on nor for any errors or omissions This does not affect your statutory ri ghts Typeset by Progress Services and Design Limited, Essex Printed by Pims Digital , Essex 34 The The The The A Guide to Fire Safety Engineering Contents iii Construction (Design and Management) Regul ations 994 The Stationery Office Fire Precautions Act 971 , Chapter 40, The Stationery Office Fire Precautions (Workpl ace) Regul ati ons 997, as amended The Stationery Office Fire Precautions (Workpl ace) (Amendment) Regul ations 999 The Stationery Office Contents Foreword 1 What are fire precautions? 2 What is fire safety engineering? 3 Benefits of fire safety engineering Background 13 Using standard guidance – code-based solutions 18 Using fire safety engineering 20 Good questions for those dealing with a fire safety engineering design 26 Conclusion 27 Appendix A – Terms and definitions 28 Appendix B – International and European standardization activities for fire safety engineering 29 Bibliography 32 Figure 4.1 17 Table 6.1 25 iv A Guide to Fi re Safety Engineeri ng Bibl iography 33 Fire safety engineering Part 1: Application of fire performance concepts to design objectives Part 2: Design fire scenarios and design fires Part 3: Assessment and verification of mathematical fire models Part 4: Initiation and development of fire and generation of fire effluents Part 5: Movements of fire effluents Part 6: Structural response and fire spread beyond the enclosure of origin Part 7: Detection, activation and suppression Part 8: Life safety – Occupant behaviour, location and condition BS I SO/TR 3 87, Other publications BeneFEU Report ‘The potential benefits of fire safety engineeri ng in the European U ni on’ DG Enterprise Contract ETD/01 /503 480, 2002 BR 86 Revision of design princi pl es for smoke venti l ation in encl osed shopping centres BRE, 990 BRE Report 68 Desi gn methodol ogies for smoke and heat exhaust ventil ation BRE, 999 Buil ding Control Performance Standards CI C/LGA/ACAI /N ational Assembl y for Wal es/DETR, 999 Buil ding Standards (Scotl and) Regul ati ons 990 (as amended) Techni cal Standard E – 6th Amendment 2001 CI BSE Technical Memoranda TM1 9: 995, Rel ati onships for smoke control cal cul ations The Chartered I nstitution of Buil ding Services Engineers, 995 Directi ve (89/1 06/EEC) on the approxi mation of l aws, regul ations and admi nistrative procedures of the Member States rel ating to construction products (Construction Products Directive) European Communities (O.J N o L 40 1 February 989) Directi ve (89/3 91 /EEC) on the introduction of measures to encourage improvements in the safety and heal th of workers at work (H eal th and Safety Framework Directive) European Communities (O.J N o L 83 29 June 989) I nterpretati ve Document N o Safety in case of fire, September 991 DRYSDALE, D.D An introduction to fire dynamics 2nd Edition Wil ey, 2000 FI RECODE H TM 81 Fire precautions in new hospital s (N H S Estates) The Stationery Office, 996 FI RECODE H TM 83 Fire safety in heal th care premises – General fi re precautions (N H S Estates) The Stati onery Office, 994 FI RECODE H TM 86 Fire risk assessment in hospital s (N H S Estates) The Stationery Office, 996 Fire Safety – An Empl oyer’s Guide The H ome Office, Scottish Executive, The Department of the Environment (N orthern I rel and) and the H eal th and Safety Executive The Stationery Office, 999 H eal th and Safety at Work etc Act 974, The Stati onery Office The Bui l ding Act 984, The Stati onery Office The Bui l ding Regul ations 985, The Stationery Offi ce The Bui l ding Regul ations 2000, Approved Document B Fire safety 2000 Edition The Stationery Office The Bui l ding Regul ations (N orthern I rel and) 2000 Technical Bookl et E, as amended The Stationery Office 32 A Guide to Fire Safety Engineering Foreword Bibliography This bibl iography is intended to direct readers to the regul atory guidance, standardization and to basic fire safety engineering guidance, handbooks and fire sci ence/engineering textbooks I t is l imi ted to a sel ection of the guidance most rel evant to the U K and is not intended to be comprehensi ve BSI publications Fire tests on building materials and structures Part 3: External fire exposure roof test Part 4: Non-combustibility test for materials Part 6: Method of test for fire propagation for products Part 7: Method of test to determine the classification of the surface spread of flame of products Part 10: Guide to the principles and application of fire testing Part 11: Method for assessing the heat emission from building materials Part 12: Method of test for ignitability of products by direct flame impingement BS 476, Fire precautions in the design, construction and use of buildings Part 0: Guide to fire safety codes of practice for particular premises/applications Part 4: Code of practice for smoke control using pressure differentials Part 5: Code of practice for firefighting stairs and lifts Part 7: Code of practice for the incorporation of atria in buildings Part 8: Code of practice for means of escape for disabled people Part 9: Code of practice for ventilation and air conditioning ductwork Part 10: Code of practice for shopping complexes BS 55 88, BS 7974:2001 , Application of fire safety engineering principles to the design of buildings – Code of practice PD 7974, Application of fire safety engineering principles to the design of buildings Part 0: Guide to design framework and fire safety engineering principles Part 1: Initiation and development of fire within the enclosure of origin (Sub-system 1) Part 2: Spread of smoke and toxic gases within and beyond the enclosure of origin (Sub-system 2) Part 3: Structural response and fire spread beyond the enclosure of origin (Sub-system3) Part 4: Detection of fire and activation of fire protection systems (Sub-system 4) Part 5: Fire service intervention (Sub-system 5) Part 6: Evacuation Part 7: Probabilistic fire risk assessment Fire safety engineering in buildings Part 1: Guide to the application of fire safety engineering principles Part 2: Commentary on the equations given in Part DD 240, Eurocode Actions on structures – Part 1-2: General actions – Actions on structures exposed to fire BS EN 991 -1 -2:2002, I n preparation DD 240 has been superseded by BS 7974 and is withdrawn Foreword This document aims to provide an introduction and initial understanding of the principl es of fire safety engineering and its rel ati onship to fire precautions I t al so suggests why such engineered sol utions might be offered in achieving the objective of satisfactory safety l evel s in case of fire This document does not aim to provi de a detail ed understanding of fire safety engineering I t is a basic guide for those who are new to the subject and al so provides a guide to where further, more detail ed information can be found Such detail ed gui dance is avail abl e from many different sources, some of which are l isted in the bibl iography A Guide to Fire Safety Engineering Appendi x B 31 Approved Document B – European Supplement What are fire precautions? The term ‘fire precautions’ is generally accepted to include matters that are the subject of legal requirements under specific fire precautions legislation These include The Building Regulations 2000, The Fire Precautions (Workplace) Regulations 997 (as amended) and The Fire Precautions Act 971 (as amended) In Northern Ireland the Fire Services (Northern Ireland) Order 984 (as amended) is in use More generally, there exists health and safety legislation including the Health and Safety at Work etc Act 974 and regulations made under that Act Fire precautions l egisl ation deal s with general fi re precautions These incl ude: • • • • • • • means of detection and giving warning in case of fire; provision of means of escape; means of fi ghting fire; training of staff in fire safety; l i nings that inhibit the spread of fire; means to provide structural stabil ity; and means to resist the spread of fire within and between buil di ngs The Fire Precautions (Workpl ace) Regul ati ons 997 al so incl ude a requirement for empl oyers to undertake an assessment of the fire ri sks The term ‘fire risk’ is general l y accepted to col l ectivel y describe both the risk of fire occurring and the risk to peopl e in the event of fire The ‘ri sk assessment’ is an organized assessment of the work activities and associated hazards in the workpl ace that coul d cause harm to peopl e I t is intended to assess whether adequate precauti ons to avoid or reduce the risk of harm have been taken or whether more acti on i s necessary I n this context, ‘hazard’ and ‘risk’ are defined in I SO/TR 3 87-1 as fol l ows • • A ‘hazard’ is the potential for l oss of l ife (or injury) and/or damage to property by fire A ‘risk’ is the potential for real ization of an unwanted event, which is a function of the hazard, i ts probabil ity and its consequences The present statutory duty imposed upon empl oyers requires that the empl oyer carry out a fi re risk assessment of the workpl ace Consideration must be given, amongst other things, to the needs of al l empl oyees and al l other peopl e who may be affected by a fire i n the workpl ace Adequate provision must al so be made for any peopl e with disabil i ties or with special needs who may use or be present on the premises The Fire Precautions (Workpl ace) Regul ations 997 require that the assessment is kept under review and is revi sed as necessary The Regul ations pl ace a statutory duty on the empl oyer, which wil l be rel ated to the provisions of any fire safety engineered sol ution provided in his buil ding Approved Document B, Fi re safety, 2000 edition, refers to and uti l izes within its gui dance a l arge number of British Standards – typi cal l y the BS 476 series of documents I n order to facil itate harmonization and the adoption and use of new European technical specifications and supporting standards under the auspices of the Construction Products Directive (see above), it has been necessary to amend the 2000 editi on of Approved Document B The amendment to Approved Document B ensures that constructi on products tested by the European harmonized fire test methods can be used in Engl and and Wal es as requi red under the Constructi on Products Directive I n practical terms thi s wil l tend to require increased performance for products tested to BS 476 30 What is fire safety engi neering? A Guide to Fire Safety Engineering The Constructi on Products Directive, through the use of harmoni zed technical specifications and supporting standards, aims to break down the technical barriers to trade, associ ated with the movement of construction products between Member States At the present time, CEN TC/1 27 has now publ ished al l the necessary technical specifications to enabl e the Commission Services to publ ish thei r formal Commission Decision on the cl assification of construction products according to their reaction to fire and fire resi sting properti es The Technical Committee is stil l addressing the need for further harmoni zed technical standards under a direct standardizati on mandate from the Commission These technical standards now provide the means of impl ementing the Essential Requirements of the Directive in respect of reaction to fire and fire resistance testing of construction material s, thereby providing the harmonized European Standards that are needed to make possibl e the impl ementation of national l aws, regul ati ons and administrative procedures Any formal European positi on woul d take into consi deration al l publ ished documents on the subject These woul d incl ude I SO/TR 3 87, BS 7974 and PD 7974 They woul d al so incl ude consideration of any other documents publ ished by any other Member State I t is probabl e therefore that once the Fire Regul ators Group, with the approval of the Standing Committee, have establ ished a ‘European’ posi tion, CEN TC/1 27 may be asked to prepare the European version of I SO/TR 3 87 under the existing mandates What is fire safety engineering? Fire safety engineering is the provision of adequate fire safety precautions in a compl ex buil ding or structure that accommodates a departure from the prescribed performances in any specific area by taking other higher or compensatory measures in another area There coul d be trade-offs between passive and acti ve fire protection measures that ei ther al l ow the designer to use material s in a novel appl i cation or al l ow the buil ding user to make optimum use of the space avail abl e Fire safety engi neering can be considered under several headings • Essential Requirement ‘Safety in case of fire’ I n a document (I nterpretative Document 2) descri bing the provisions of the Essential Requirement, ‘Safety in case of fire’ publ ished in 991 , the question of an engineering approach in the fi el d of fire safety was addressed According to this document, fire safety engineering covered the way in which fire safety i n a construction works is eval uated by the means of cal cul ation methods, taking account of the performance and effect of products, i.e passi ve and active fire protection measures I t was al so made cl ear that fire safety engineering incl uded a number of activities of wi de scope, which infl uenced fire safety in use of construction products This incl uded the use of cal cul ation methods for determining the devel opment and spread of fire and smoke, the time for untenabl e conditi ons to be reached and evacuati on time I n a ful l y integrated approach, fi re safety engineering was al so judged to incl ude the compl ex i nteracti on between the performance of passive and acti ve fire protection measures and the construction works For exampl e, the devel opment of l i fe-threatening atmosphere and human behaviour to achieve safety in the most fl exibl e and cost-effective way must be consi dered Thi s engineered approach required that the rel evant characteri stics of products are provided and cal cul ation and design procedures are val idated on an agreed and harmonized basis • • • • The process of fire safety engi neering is about measurements and rel ationships, backed by scientific study, for engineering appl ication to the required probl ems, but where experience and judgement can contribute, as in other engineeri ng di scipl ines The context of fi re safety engineering is the need to eval uate fire hazard and risk and to offer fire safety strategi es and designs based on performance not prescription The tools supporting fire safety engineering are the cal cul ation methods (someti mes cal l ed model s) that describe the measurements, rel ationshi ps and interacti ons and any necessary test resul ts The inputs are the physical data for the cal cul ation methods, derived from measurement methods (tests, etc.) The framework of fire safety engineering comprises the essenti al core, and transfer, of knowl edge, which permits an engineeri ng approach, the education and training of users and the professional recognition of the discipl ine As a resul t of the substanti al increase in fire research during the l ast decades, many components and systems are becomi ng more amenabl e to anal yti cal and computer model l ing Consequentl y, many national bui l ding regul ators, parti cul arl y in the U K, have moved from a prescriptive approach to a performance-based approach The fire safety engineering approach may have benefits over the prescriptive approach It takes into account the entire fire safety package and provides a more fundamental and sometimes economic sol ution than traditional approaches to fire safety It may be the onl y viabl e means of achieving a satisfactory level of fire safety in some large and complex systems For most buil dings the prescriptive recommendations on design i n existing codes and guides, as given in BS 5588-0, may be found to be adequate H owever, BS 7974 is intended for use to devel op and assess fire safety engineering proposal s The use of a fire safety engineeri ng approach enabl es a more precise design necessary for the assessment of new and compl ex projects I n addition, al though prescriptive regul ations have served us wel l in the past, it is widel y recogni zed that they are infl exibl e in certain circumstances and therefore unabl e to evol ve quickl y enough to meet the modern chal l enges of new material s and i nnovative design A Guide to Fire Safety Engineering BS 7974 defi nes fire safety engineering as ‘the appl icati on of scientific and engineering principl es to the protection of peopl e, property and the environment from fire’ I n practice, fire safety engineering invol ves the use of scientifical l y based or stati stical l y based cal cul ations to demonstrate an adequate l evel of fire safety for a specific buil ding, structure or instal l ation Often, it wil l be appl ied to a specific part of a project whil e other parts fol l ow standard guidance or codes BS 7974 is derived from DD 240 (now withdrawn) prepared by BSI Technical Committee FSH/24 The Draft for Development was prepared with the support of the government departments concerned with fire safety (Department of the Environment and the Home Office – now the Office of the Deputy Prime Minister) BS 7974 therefore provides a framework for an engineering approach to fire safety, which may be applied to both the design of new buildings and the appraisal of existing buildings, and to show that regulatory requirements can be, or are, satisfied BS 7974 is also intended to provide a framework for a flexible but formalized approach to fire safety design that can also be readily assessed by the approvals bodies BS 7974 is supported by a series of Publ ished Documents (PDs) that contain gui dance and information on how to undertake detail ed anal ysi s of specific aspects of fire safety engineering This does not, however, precl ude the use of appropri ate methods and data from other sources PD 7974, Appl ication of fire safety engineering pri ncipl es to the desi gn of bui l dings, i s structured as fol l ows: • • • • • • • • Part 0: Guide design framework and fire safety engineering procedures; Part 1: Initiation and development of fire within the enclosure of origin (Sub-system 1); Part 2: Spread of smoke and toxic gases within and beyond the enclosure of origin (Sub-system 2); Part 3: Structural response and fire spread beyond the enclosure of origin (Sub-system 3); Part 4: Detection of fire and activation of fire protection systems (Sub-system 4); Part 5: Fire service intervention (Sub-system 5); Part 6: Evacuation (Sub-system 6) (i n preparation); Part 7: Probabilistic fire risk assessment (Sub-system 7) (in preparation) BS 7974 can be used to identify and define one or more fire safety designs to be addressed using fire safety engineering The appropriate part(s) of PD 7974 can then be used to set specific acceptance criteria and undertake detail ed anal ysis Within the international and European arena, there has been detail ed consi deration of the need for guidance and standardizati on The I nternational Organization for Standardizati on (I SO) has produced a comprehensive Technical Report that has now been publ ished by BSI as BS I SO/TR 3 87, I n eight parts, the Technical Reports were prepared by I SO Technical Committee TC/92, Fire safety This series of I SO documents offers a sl ightl y different approach to that of BS 7974 and the PDs that accompany it N either approach can be regarded as the ‘definitive’ view As each separate approach offers an al ternative and given the consideration now required of both the BS Publ ished Documents and the I SO Technical Reports, it is hard to say which approach wil l be formal l y adopted Whil e it coul d be one or the other, the more l ikel y outcome woul d be an amal gamation of both Specifi cal l y within the European arena, the European Commission has recentl y funded a feasibil ity study on the benefits of fire safety engineering within the European U nion N OTE: Further information is given on both international and European acti vities in Appendix B Fire safety engineering Appendi x B 29 Appendix B – International and European standardization activities for fire safety engineering International Standards (ISO) With no action at the European l evel , work started at the international l evel to produce a seri es of documents covering the subject BS 7974 was used as the basis of the earl y work, but was substantial l y extended I t quickl y became cl ear, that considerabl e work was needed to make this document useabl e The work was undertaken by I SO TC/92, Fire safety and I SO publ ished a mul ti-sectioned I SO/TR 3 87: Parts to and the documents have generated considerabl e interest European Standards (CEN) Since the publ ication of the British and international documents, i nterest has been generated at the European l evel Whil e al l the earl y preparation for the subsequent documents was underway, CEN and the European Commission were content to await the outcome Given that the Constructi on Products Directi ve (89/1 06/EEC) and the Essential Requirements both make di rect reference to fire safety engineering, the Commission Services funded a feasibil ity study on the appl ication of fire safety engineering principl es in al l of the Member States Al so, in preparati on for beginni ng work at the European l evel , CEN TC/1 27, Fire safety in buil dings, has formed a new Working Group to cover the issue The present position is brought into sharper focus as the European Commi ssion have recentl y funded extensive Research on the Benefits of Fire Safety Engineering in the European U nion (BeneFEU ) I t is cl ear from the concl usions of this study that a European position wil l have to be formal ized and adopted Once the decision has been made by the EU Fire Regul ators Group as to what form the European interest wil l take, CEN wil l deci de who wil l undertake the work Given the basi c remit of CEN TC/1 27, it wil l probabl y be incl uded in its work programme Construction Products Directive (89/1 06/EEC) Council Directi ve 89/1 06/EEC on the approximation of l aws, regul ations and administrative procedures of the Member States rel ating to Construction Products was publ ished i n 989 This Di rective contained a number of Essential Requi rements; one of which was ‘Safety i n case of fire’ U nder the Construction Products Directive (89/1 06/EEC), the Commission Services have establ ished a Standing Commi ttee on Construction Reporting to this Standi ng Committee, the Group of EU Fire Regul ators has discussed the i ssue of fire safety engineering several times Once a ful l consideration has been given to the BeneFEU Report, the Fire Regul ators Group wil l need to consider their future options 28 Benefi ts of fire safety engineering A Guide to Fire Safety Engineering Appendix A – Terms and definitions available safe egress time (ASET) cal cul ated time avail abl e between ignition of a fire and the time at which tenabil ity criteri a are exceeded in a specified space in a buil ding complex analysis consideration of a design proposal and the appl ication of the statistical data in order to come to an agreed posi tion deterministic study methodol ogy based upon physical rel ationships deri ved from scientific theories and empirical resul ts, which for a given set of initial conditions wil l al ways produce the same outcome escape time cal cul ated ti me from ignition until the time at whi ch al l of the occupants of a specifi ed part of the buil ding are abl e to reach a pl ace of safety equivalence provision by other means of a l evel of safety providing the same l evel of performance as that referred to in guidance rel evant to that requirement evacuation time interval between the time of warning of fire being transmitted to the occupants and the time at whi ch al l of the occupants are abl e to reach a pl ace of safety fire hazard source of possibl e injury or damage from fire fire risk product of probabil ity of occurrence of a fire to be expected in a given technical operation or state in a defi ned time and the consequence or extent of damage to be expected on the occurrence of a fire Fire safety engineering can have many benefits; the use of a code of practice such as BS 7974 wil l facil itate the practice of fire safety engineering and in parti cul ar wil l : • • • • • of peopl e, property and the environment from fire • • performance of the fire safety system referred to • • prescriptive requirement expression of a safety requi rement by the means of a detail ed • probabilistic risk assessment methodol ogy to determine statisti cal l y the probabil ity and • qualitative identification of constituents of an eval uation of a proposal science observation, identification, description, experimental investigati on and theoretical • of descri ption of the provisions required which shoul d not be varied outcome of events expl anation of phenomena simple calculation first or initial consideration of data in order to come to a first impression on the val idi ty of the proposal trial fire safety design package of fire safety measures, which in the context of the buil ding may meet the specified fire safety objecti ves provide the designer with a discipl ined approach to fire safety design; al l ow the safety l evel s for al ternative designs to be compared; provide a basis for sel ection of appropriate fire protection systems; provide opportunities for i nnovative design; provide information on the management of fire safety for a buil ding The structure of the BS 7974 is given bel ow This code of practice: • fire safety engineer person suitabl y qual ified and experienced in fire safety engineering fire safety engineering appl i cation of scientific and engineering princi pl es to the protection functional requirement expression of a safety requirement in terms of the required l evel Benefits of fire safety engineering provides a means of establ ishing acceptabl e l evel s of fire safety economical l y and without i mposing unnecessary constrai nts on aspects of buil ding design; provides guidance on the design and assessment of fire safety measures i n buil dings; gives a structured approach to assessing the effecti veness of the total fire safety system in achieving the design objectives; provides a framework for, and describes the phil osophy of, fire safety engineeri ng; outl ines the princi pl es invol ved in the appl icati on of the phi l osophy to the fire safety engineering of particul ar buil dings; can be used to identify and defi ne one or more fire safety design issues to be addressed using fire safety engineering; provides some al ternative approaches to existing codes and guides for fi re safety and al so al l ows the effect of departures from more prescriptive codes to be eval uated; recogni zes that a range of al ternative and compl ementary fire protection strategies may achieve the design objectives I n PD 7974: Parts to the fol l owing steps in the fire safety design process are i dentified: • • • • • definition of the safety objectives and the scope of the study; setting of the acceptance criteria; characteri zation of the buil ding, occupants and environment; undertaking a qual itative design review; and conducting quantified anal ysis The eval uation of the fi re safety design of a buil ding i s broken down, to si mpl ify the process, into the separate components of the overal l system (the sub-systems, see bel ow) bel onging to either the tool s for fire safety engineering eval uation or the fire safety objectives