Access and facilities for fire-fighting (Section 6, Clauses 20 - 29) In section 6, the provisions for access and facilities for fire fighting are prescribed without any link to the risk profile. This section is a purely prescriptive design guide and is an updated version of  BS 5588-5:2004 : "Access and facilities for fire-fighting"  which was superseded by BS9999. For larger buildings , clause 25 requires the existence of a fire control centre from where rescue and fire fighting operations can be organised. In Annex I, recommendations are given how to manage the evacuation from that fire control centre. In FRAME, there are no specific requirements for building access, but there is an increase in the potential risk by factor z, for compartments which are less accessible, being very wide or located high up or deep down the access level. A much stronger penalty is given for the area factor g for buildings with narrow frontage. In a future version of FRAME, the provision of fire fighting shafts and of dedicated fire-fighting lift cars could be included as special protection for tall buildings. Building structure design (Section 7, Clauses 30 - 38) Section 7 "Designing the building structure (load-bearing and non-load-bearing elements)" clauses 30 -38 give (prescriptive) requirements for the building construction and installations, in order to prevent the spread of fire inside and outside the building and to guarantee its structural integrity as needed. Clause 30 gives the general principles, clause 31 refers to structural fire safety resistance, clause 32 deals with compartmentation, clauses 33 and 34 with controlling fire and smoke spread through openings and cavities, clauses 35 and 36 consider external fire spread. Structural fire safety resistance  (clause 31) Clause 31 gives three reasons for the safety role of structural fire resistance: minimize the risk to occupants remaining in the building, reducing the risk to fire-fighters  engaged  in rescue operations, and reducing the danger to people in the vicinity, who might be hurt by the collapsing structure. These reasons are not valid, structural fire resistance offers little or no protection at all for the occupants inside a building, because structural fire resistance is not a "safe time" period, but the value for the thermal attack on the structure after flash-over. A 30 min rating corresponds with a room temperature of 842 °C. In such situation nobody can survive or be rescued at all. And the ISO-834 curve temperatures are defined for a test furnace, in the reality of a building it will take much more time to reach them, and by then nobody should still be in a building on fire. A valid reason to require structural fire protection for a building is to avoid damage to adjacent property by the collapsing structure. In this perspective it makes sense to require little structural fire resistance for low buildings and high values for high rise buildings, where the risk of collapse by fire should be nearly impossible. The main benefit of structural fire resistance is compartmentation, proper fire resistive  barriers define and limit the size of the property and the number of people directly at risk in case of a fire. The boundaries of such a compartment are the open air and fire resistive barriers such as walls and floors, with a FR rating of 60-120 min. Needless to say that the structural elements that support these barriers shall also be fire resistive. Property and people outside the compartment on fire are not directly at risk, and will probably never be, when each compartment is adequately protected. Walls and floor with these moderate ratings are adequate to meet the compartmentation goal, and these are used to define the compartments for a FRAME calculation. Insurance companies sometimes require maximum loss limiting fire walls of superior construction and fire rating, but their primary goal is to limit the monetary values to be insured, even in the case of failure of all (active) protection. Fire resistive (non-structural) elements of separations protecting escape routes do contribute to the occupants safety, as they shield them from direct exposure to a fire.  Table 24 gives the minimum requirements for fire resistance for the different parts of the building and follows the set-up of the Approved Document B, with a reference to old BS and newer EN standards. The difference between BS9999 Table 24 and FRAME lay in the way the fire resistance  is handled: The standard imposes minimum performances, FRAME evaluates what is available in factor F, and when the performances are substandard, it will result in an inadequate level of fire protection in most cases, unless compensated by the extra protection evaluated by factors S and U. Structural fire resistance requirements  (Table 25) Table 25 gives recommendations for fire resistance based upon the fuel load density and assuming an unventilated fire. Instead of using the risk profile classification (A1, A2 , etc.) it refers to  the occupancy uses of the prescriptive Approved Document B, and replaces hereby the occupant based risk profile by a fire load based requirements table. No effort is made to "translate" the occupancy classification into risk profiles.  When looking at these requirements for sprinklered and unsprinklered buildings, there is a mere 30 minutes fire resistance "benefit" allowed for the sprinkler protection, which is in contrast with the statement on p.133 that: "The provision of an automatic sprinkler system significantly reduces the severity of a fire". In FRAME, the duration of the  sprinkler water supply can be taken as the fire rating, but not for more than 60 minutes . Indirectly, Par. 32.2 p.146 admits that this is a correct approach:  "A sprinkler system, suitably designed and installed for the hazard to be protected, can be expected to prevent the rate of heat release from significantly exceeding that at the time of sprinkler operation. In most instances it will assist in controlling the fire. The fire resistance of the compartment walls and floors can therefore be reduced in a sprinklered building or compartment."  But it is legally difficult to introduce in BS 9999 a better benefit for sprinklers than is accepted in the APB. The comment on table 25 says that: "Since there are a number of factors to consider, in some cases it is possible that certain combinations of building and occupancy characteristic might initially appear inconsistent."  It might be more logical to leave out of the table the weird combinations like "unsprinklered residential at basements below 10m". Structural fire resistance for ventilated compartments  (table 26) Table 26 gives requirements for fire resistance of elements of structure based upon the ventilation conditions given in Table 27. Contrary to table 25,  the risk profile classification is used here, and it is probably meant to be a "risk based" complement to Table 25. In the comment on table 26 it says : "From the Monte Carlo analysis, the cumulative distributions of time equivalent were subsequently analysed based upon the fundamental premise that risk = frequency × probability × consequence of failure. The frequency was linked with the height of the building following the principles of the Building Regulations 2000 [19], and consequence of failure was linked to both the building height and risk profile of the occupancy taking account of the familiarity and mobility of the occupants within the building and whether there is a sleeping risk. The probability of failure is directly related to the cumulative distribution curves that resulted from the Monte Carlo analysis." An impressive statement that shows that the author(s) have no clear ideas on what risks are. The expression "Risk = frequency (of what ?) x probability (of what?)  x consequence of failure (of what?)” is a mix of undefined concepts.  Frequency of occurrence of an event is basically an observation of the past, e.g. how often is there a fire in an office building, while the probability of that event is the prospect for the future, whereby we usually assume that it will be same as in the past under the same conditions. A better definition for (discontinuous) risks is given in FRAME : risk = frequency (of occurrence) vs. consequence (damage occurred) vs. exposure (to the fire threat). The mathematical expression is a cumulative product of the three values for a series of events. The basis of table 26, is a time equivalent approach based upon expressions of EN 1991-1-2, for post-flashover fires. The variables, which determine the level of heating in a real fire, can be linked to the standard fire resistance test conditions by the concept of time equivalency (t-equivalency). It is true that in a well ventilated room, the fire intensity is less, resulting in a lower equivalent fire duration time, so that in theory the fire resistance requirements can be lower. But in practice, the type of structure (steel, concrete or other) is chosen very early in the design process and the inherent structural fire resistance is defined by that choice. The openings in the façade that can serve for ventilation, like windows, are defined much later and have also to respond to other criteria like providing natural light, energy conservation, and limiting fire spread between floors and external exposure. The designer cannot trust that the conditions of table 27 are met at the time the structural design is fixed, so table 26 is of little practical use. In FRAME,  the distinction between ventilated and non-ventilated compartments is discounted by the ventilation factor v, and the height by the level factor e. The resulting higher values for the potential risk R, can be compensated by a higher protection level D, as factor F will increase where FR building elements are used. Compartmentation (clauses 32, 33, 34) "The spread of fire within a building can be restricted by subdividing the building into compartments, separated from one another by walls and/or floors of fire-resisting construction. The same approach can be applied to prevent fire spread between buildings that are close together. Compartmentation, horizontal or vertical, can also be used as part of an escape strategy to create areas of relative safety." Clause 32 follows the prescriptive requirements of the ADB with reference to the occupancy risk profile. Compartment sizes should be not more than the maximum sizes given in Table 30 for the appropriate risk profile. Compared with what is practised in other countries, these limits are very large. Compartmentation is very important for FRAME, as one of the principles of the method is that the risk assessment is made per compartment.  Construction criteria as in BS9999  clauses 32.5, 33 and 34  will define the boundaries of the compartmentation, or shall be imposed for those walls and floors that are defined as compartment barriers. The size of the compartment is evaluated by factor g of the Potential Risk factor, and is a major contributing factor in the severity of the property risk.  Clause 33 repeats the prescriptive requirements of the ADB for fire doors, ductwork, piping and other openings in compartment barriers and complements these with a number of rules of good practice. Clause 34 is also in line with the ADB requirements for concealed spaces and cavity barriers. Materials and finishes  (clause 35) Clause 35 states:  "In most cases the contents of a building have more influence on the size and growth rate of a fire than the fabric. The choice of materials for walls and ceilings does affect the contribution that the building fabric makes to fire severity, but is more important as an influence over the rate at which flames propagate over the surfaces in question than in determining the magnitude of a fully developed fire … For life safety purposes the surface flame spread and heat release rate characteristics of the lining material should be of a high class in circulation spaces." The clause defines the requirements for materials and finishes, It repeats essentially the rules fixed in the ADB for the classification of linings, for the use of thermoplastics,  lighting diffusers, stretched-skin ceilings, insulating core panels, etc.  Most of these requirements are very specific for the UK only. In FRAME, the presence of combustible materials and finishes is evaluated in the fire spread factor i and the environment factor r, where the sub factor combustibility class M is used to evaluate the fire propagation characteristics of building and content.  A percentage weighed value can be used for a compartment with  various types of surface materials. Any unfavourable situation will yield a high risk value. The most efficient measure to reduce the risk is often to select less combustible surface materials.  External fire spread (clause 36) Clause 36 deals with the risk of external fire spread between neighbouring buildings, and is equally a copy of the prescriptive rules used in the UK.  In most other countries (except for the Netherlands) the separation rules between buildings are very simple , often a minimum distance between buildings linked to some basic requirements  for fire resistance (integrity) of the opposite façades. It s possible that because of other -mainly urban planning- rules fire spread between buildings is not experienced as a real problem.    FRAME does not include specific risk factors to evaluate this risk. The purpose of FRAME is to define an adequate level of fire protection, and when the compartment  or building is well protected inside, the risk of external fire spread becomes minimal. However, a calculated value of R, the property risk, higher than 2, i.e. a damage potential of more than 100 % , is a clear indication that fire spread to adjacent compartments or buildings  is possible. Ancillary Equipment and Engineering Services  (clauses 37 -38) Clauses 37 and 38 gives guidance for the installation of ancillary equipment  such as electrical switchgear rooms, boiler rooms, fuel storage spaces, mechanical ventilation and air conditioning plant rooms, flammable liquid storage, gas services, electrical installations, lifts , escalators, conveyors, etc. In FRAME, the nature and quality of this equipment is considered as part of the activation factor a: Generally speaking they are possible (additional) sources of ignition, certainly when they are not  correctly designed, installed or maintained.  Such additional sources of ignition increase the probability of exposure and as such they reduce the value of the Acceptable Risk A. Special risk protection (Section 8, Clause 39) This section gives general considerations about special systems such as automatic fixed gas, foam, powder, water spray deluge systems or other purpose-designed extinguishing systems, and indicates the design standards for those systems. These systems are used almost exclusively to protect vital parts of a production process, and as such they are effective to reduce the overall risk of business interruption. That is why they are part of the calculation of the salvage factor Y in FRAME, but they are nearly insignificant for the overall property protection and for the life safety of the occupants, and they are very seldom used for these purposes. Managing occupied buildings  (Section 9) "This section is concerned with the management of fire safety, … , addressing the issues that will apply whilst the building is in use or which need to be taken into account when alterations to the building or the use of it are being considered." After instructing the designer in sections 5 to 8, BS9999 addresses now the duties of the fire safety managers. Clause 40 deals with the transition process of commissioning and hand-over, and after that it is the fire safety managers' job to keep things working as the  designer imagined they should, the other clauses deal with management issues following occupation of a building. This section is complemented by a number of  good practice guidelines which  can be found in the  following annexes. Annex M: Operational information (emergency packs) for the fire and rescue service; Annex N: Commissioning and hand-over of smoke control systems; Annex O: Fire safety training; Annex P: Control of conditions in public areas; Annex Q: Recommendations for owners of multi- occupancy residential buildings; Annex R: Advice to occupiers of dwellings in residential buildings; Annex S: Examples of fire instruction notices; Annex T: Audience/crowd control; Annex U: Hot work; Annex V: Routine inspection and maintenance of fire safety installations; Annex W: Routine inspection and maintenance of ventilation and air conditioning ductwork; Annex X: Phased evacuation; Annex Y: Examples of evacuation strategies; and Annex Z: Example messages for use in a phased evacuation. The fire manager is likely to be the owner or a caretaker in smaller premises, and a member of senior staff in larger organisations, eventually with a dedicated team to do all the work. In between, all imaginary combinations are possible, the persons in charge with often combine their fire safety duties with other similar duties like security, safe work conditions or environmental safety duties. In a number of countries, legislation requires these persons to have a certain degree of professional training, and may give them some protection to allow them to inform management without fear of unacceptable situations. It is also necessary that other members of staff are aware of their part in the fire safety plan, be it as origin of possible fires, as user of safety devices, or as participant in evacuations etc. FRAME is first of all a tool for the designer to define the elements required to meet the goal of an inherently fire safe building. The designer has to assume that systems will be kept in good condition by the management. FRAME gives little credit to organisational practices like training, exercises and maintenance programs to reduce the risk level, as they are subject to all kind of  temporary conditions, and thus not "stable during the life cycle" of the building. FRAME can be used by managers to establish the level of fire safety in existing situations, and to define adequate measures in the process of correcting unsafe circumstances.  Inadequately designed or improper maintained or used systems can be evaluated as "inexistent" to show the difference between the risk level in the actual conditions , and what could be achieved by adequate management. Specific occupancies: atria (Annexes B and C) Annexes B and C gives recommendations for atria and replace BS 5588-7:1997: Code of practice for the incorporation of atria in buildings. Annex B explains the particular characteristics of an atrium fire and the problems encountered for the evacuation and fire fighting in that environment, and gives the general requirements  for the construction, the means of escape, evacuation procedures, and active and passive fire protection. As there is a wide variety of situations, Annex C gives a decision tree guidance to what is an acceptable fire safety concept, linked to the occupant classes A, B and C. Each decision tree process is structured to follow a common pattern related to the technical issues that need to be considered. The decision tree guidance is in fact a risk analysis process leading towards a series of standard acceptable solutions to guarantee an acceptable level of fire safety. The decision tree does not consider the total floor area of the compartment as a selection parameter, which is probably the decisive element  for property protection. Some of the design solutions consider "controlling the fire load at the atrium base" as an option. This is a tricky choice for a designer, as there is no guarantee that the strict conditions of par. B.8 can be maintained during the life cycle of the building. The FRAME manual gives guidelines how to define the values  of the sub factors in atrium type compartments. When the adjacent  floor are not separated from the atrium by fire resistive construction, they should be considered as part of the atrium compartment and the floor area of the upper levels shall be used to define the level factor a. In the atrium, the value to be used for the ceiling height is the distance between the ceiling and the highest floor which has to be evacuated by a path inside the atrium compartment. BS9999 makes a distinction between atria of <18m high, between 18 m and 30 m high, and higher than 30 m. FRAME  automatically reduces all ceiling heights to a maximum of 15 m to avoid that unrealistic values should be obtained for the ventilation factor v.  Smoke clearance systems can be entered in the ventilation factor calculation as mechanical smoke venting systems.   Specific occupancies: theatres, cinemas and similar venues (Annex D) Annex D, as replacement of BS 5588-6, is a detailed design guide for this type of places of assembly, which are a very specific occupancy where tailored requirements as those of Annex D are the most convenient working method. Risk assessments by FRAME can be useful to guide the fire safety selection process, where considerations of property protection and business continuity may conclude that following the legal minimal requirements  is not the best overall solution.  Specific occupancies: shopping complexes (Annex E) A shopping complex is for an occupancy type that has a potential for catastrophes: "The modern shopping complex offers a different set of fire safety problems from those that are common to a single shop, and this annex considers these problems and how to mitigate possible fire hazards." The fire safety issues of a shopping complex justify a more elaborate  and comprehensive approach, and therefore BS9999 is not the best place for this subject , as this standard is aimed as an advanced approach between pure prescriptive fire protection design and a "full"  fire safety engineering. Basically, shopping complexes  fall also outside the scope of FRAME, as it is a good tool for situations where prescriptive fire protection becomes restrictive and where full fire safety engineering is too expensive.  It can be useful to use FRAME a part of a full engineering study to define the fire protection concept for secondary compartments, such as storage areas for super markets, car parks, e.a. where more elaborate instruments like fire growth simulation models and egress flow simulation  are used for the malls and other areas open to the public. The main justification of the normative annex E, is that the legislative documents like the ABD still refer to BS5588-10, which is superseded by BS9999.  Section E.4 requires the full load of a fire alarm system (E.4.1),  fire detection systems (E.4.2) , public address (E.4.3), sprinkler systems with duplicate water supplies (E.4.4) and smoke control provisions  (E.4.5).  But in section E.5 it is admitted that  "The recommendations in this annex are, in the main, made in the context of new medium to large shopping complexes with fully or partially covered malls. Although these recommendations can be applied to complexes of all forms and sizes, it might nevertheless be appropriate to consider some variation in the case of uncovered complexes, small shopping developments, refurbishment of existing shopping complexes and covering existing streets … Much will depend on the particular circumstances and a flexible application of the recommendations is therefore needed." So, here we are back at square one, where " Any variations made in accordance with this sub clause should be agreed with the enforcing authorities."  In such cases, a FRAME supported risk assessment may be the easiest way to fix the ideas and to define a fire safety concept that gives a correct level of safety at an acceptable cost. When the FRAME risk assessment  points to the full load of section E.4, then it is time to switch also to a full fire safety engineering study. Specific occupancies: process plant and structures  (Annex F) Annex F gives general design considerations for the fire safety of this type of industrial occupancies, often manned by a small number of persons. The fire protection requirements  here will be defined mainly by the need for property protection and business continuity, the safety of the occupants is to be guaranteed by the existence of fire alarm systems, automatic protection and maximum travel distances for exits.  For those installations which are located in a building, FRAME will give adequate guidance for the selection of the fire protection package. For open air installations, FRAME is not applicable.  Conclusion. BS9999 appears to be a combination of a prescriptive fire design manual based on the provisions of the Approved Document B, with a touch of a risk based approach and a guideline for fire safety management through the life cycle of a building. The risk assessment methodology is just elementary, using only two parameters, the occupant type and fire growth, and offers merely an incomplete generic classification for well known buildings uses, were the traditional prescriptive requirements are used most of the time. Unlike FRAME, it offers no instructions or information to handle uncommon situations where the risk profile approach can be useful both for the designer and the approving authority. Many users, like managers, specialised designers and contractors  will only need some parts of this standard and were better off with a set of sub standards focusing on specific subjects, like fire fighting access, atria, shopping complexes or air conditioning. The idea to replace by one BS9999 standard the BS5588 series may have the benefit of a common approach, but it results in an overloaded document with a "ratatouille" of design concept principles, requirements for a good execution of works, and management guidelines. I liked the dish and the film more than this document. ©  Erik De Smet,  february 2012 PRINT  THIS SECTION  (pdf)