Professor Luke Bisby's expert presentation on fire science fundamentals, explaining flammability, flame spread, and the material properties of Grenfell Tower's cladding system.
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00:06:04 good morning everyone and welcome to today's hearing we're going to hear further presentation from one of the inquiries experts yes mr. millet good morning mr. chairman
00:06:15 yes mr. millet good morning mr. chairman this is the final day of the experts presentations for this week today Professor Luke Bisbee who sits on your right will be explaining certain
00:06:27 your right will be explaining certain key scientific concepts relevant to flammability and to flame spread and he will be describing the material properties of certain materials present
00:06:39 properties of certain materials present in the facade and in the windows of grenfell tower he will also set out the preliminary evidence which assists in understanding the pattern of flame
00:06:52 understanding the pattern of flame spread out of flat 16 and over the exterior of the tower on the night of the fire before I call professor Bisbee formally I should give certain trigger
00:07:04 formally I should give certain trigger warnings about the content of his presentation his presentation and particularly this afternoon will include a large number of images and videos and
00:07:16 a large number of images and videos and audio depicting the external flame spread on the night of the fire that will include the playing of his composite flame spread video which was
00:07:29 composite flame spread video which was played during my opening and the detailed consideration of that and other flames spread material which shows the building burning and on fire some of the
00:07:42 building burning and on fire some of the videos include the audio of people witnessing the fire and their distress at the unfolding events the presentation will also contain a number of images of
00:07:53 will also contain a number of images of the burnt-out tower after the fire and the playing of the first 999 call by mr. kabedon so mr. Chairman I will now call
00:08:05 kabedon so mr. Chairman I will now call professor Bisbee thank you
00:08:18 I do solemnly sincerely and truly declare and affirm that the evidence I shall give shall be the truth
00:08:32 thank you Thank You professor Bisbee could you please give the inquiry your full name Luke Alexander Bisbee and you have provided to the inquiry a written
00:08:44 have provided to the inquiry a written report which is data the 2nd of April 2008 een as correct and that report addresses the ignition of the facade materials and your preliminary
00:08:55 materials and your preliminary conclusions on the fire spread to and on the exterior of the building yes it does and as you indicate in the declaration in Section 1.6 of your report you have
00:09:08 in Section 1.6 of your report you have provided it in the same way as you would have provided a report to a court that's correct
00:09:15 correct in Section 1.4 and appendix D to your report you have outlined your background and your experience relevant to the matters in this inquiry yes I'm not
00:09:27 matters in this inquiry yes I'm not going to ask you to repeat the detail of that today we can take that as read but in terms of key points would you agree you are a professor of fire and structures within the School of
00:09:38 structures within the School of Engineering at the University of Edinburgh in Scotland that's correct and its proprietor taking on your expert witness role for this inquiry you are also head of the
00:09:49 inquiry you are also head of the research institute for infrastructure and environment at the University of Edinburgh yes you are a co editor-in-chief of the technical and
00:10:00 editor-in-chief of the technical and scientific publication Fire Safety Journal that's correct and and you are I think chartered structural engineer with the institution of structural engineers and a licensed professional engineer in
00:10:12 and a licensed professional engineer in Ontario in Canada Australia you are also an active member of the UK standing committees on structural safety or scoffs and confidential reporting on
00:10:25 scoffs and confidential reporting on structural safety cross and a fellow of both the institution of fire engineers and the institution of structural engineers that's correct are the factual matters set out in your
00:10:36 are the factual matters set out in your report true to the best of your knowledge and belief yes there and does your report accurately set out your opinions on matters relevant to this inquiry yes it does thank you very much
00:10:49 inquiry yes it does thank you very much professor Bisbee please do now go ahead and give your presentation thank you and
00:11:02 and give your presentation thank you and good morning the green Fault our fire initiated in the early hours of Wednesday 14th June 2017 and continued for many hours with tragic effect this
00:11:13 for many hours with tragic effect this catastrophic event resulted in 71 fatalities on that night and continues to cause immense trauma to the bereaved survivors and affected community I'd like to begin my presentation by
00:11:25 like to begin my presentation by acknowledging this central continuing and human aspect of the fire during the preparation of my report I've reviewed harrowing evidence from victims survivors and emergency services and I
00:11:39 survivors and emergency services and I extend my deepest sympathies to those whose lives and loved ones were and continue to be caught up in this tragic event as an instructed expert witness to the rental tower inquiry with a specific
00:11:50 the rental tower inquiry with a specific and technical remit my phase 1 report necessarily focuses on scientific and physical information and analysis related to the construction of the building and its external cladding it is
00:12:03 building and its external cladding it is my hope that my phase 1 reports along with the presentation and subsequent phase 1 evidence will help you sir as well as experts and laypeople alike to begin to understand particularly in
00:12:16 begin to understand particularly in physical and scientific terms how and why the grenfell tower fire of 14th June 2017 spreads so rapidly and so extensively with devastating effect my
00:12:29 extensively with devastating effect my phase 1 report is intended to serve two purposes first to provide an initial understanding of the ignition of the cladding materials of MPhil tower and second to set out preliminary conclusions on fire spread to
00:12:41 conclusions on fire spread to on the exterior of the building during my presentation today I will focus on presenting the preliminary evidence that I've gathered rather than on my hypotheses and conclusions with respect
00:12:52 hypotheses and conclusions with respect to that evidence although I will touch on these where necessary at this early stage of the inquiries hearings during
00:13:04 stage of the inquiries hearings during my presentation today I will focus on presenting sorry my preliminary evidence includes images and video submitted by members of the public I'm particularly grateful for these as without them my
00:13:16 grateful for these as without them my task would have been even more challenging my preliminary evidence also includes evidence collected by the London Fire Brigade and the Metropolitan Police Service information obtained from my own site investigations of Grimm felt
00:13:28 my own site investigations of Grimm felt our testing undertaken by various organizations including the University of Edinburgh on behalf of the inquiry and information obtained by or provided to the inquiry from a range of
00:13:41 to the inquiry from a range of organizations including core participants to the inquiry I've also drawn on my own background knowledge and on that of a core of my specialist colleagues at the University of Edinburgh specifically dr. Angus law dr.
00:13:54 Edinburgh specifically dr. Angus law dr. rory Hadden and emeritus professor Dougal Drysdale in addition I've drawn on the academic literature and in a limited number of cases information
00:14:05 limited number of cases information which is publicly available via the World Wide Web all of this information is referenced within my phase 1 report and has been made available to the inquiry support participants for the
00:14:19 inquiry support participants for the benefit of yourself and the wider participants to the inquiry I'd like to place my work for the inquiry within the context of the work being undertaken by the inquiries other instructed experts
00:14:31 the inquiries other instructed experts as mr. Miller has previously explained phase 1 of the inquiry is intended to investigate the development of the fire itself where and how it started how it spread from its original location to
00:14:42 spread from its original location to other parts of the building and the chain of events that unfolded during the course of the hours until it was finally extinguished for burned out phase one is also examining the response of the emergency services and the attack
00:14:54 emergency services and the attack of the residents for phase one you asked me to provide a report on a subset of these issues the first of these is ignition of the building's cladding materials and if I may paraphrase how
00:15:06 materials and if I may paraphrase how did the fire get from inside the building out and on to the exterior cladding my second task is to provide preliminary evidence on fire spread to and on the exterior of the building and
00:15:18 and on the exterior of the building and again if I may paraphrase how and why did the fire spread so rapidly and so extensively over all four phases of the building my focus is therefore on the
00:15:30 building my focus is therefore on the cladding materials products and systems at Greenville tower and the rapid and extensive external fire spread I will not comment extensively on the fires origin it calls the emergency service
00:15:42 origin it calls the emergency service response the spread of fire and smoke within the building or the building's evacuation these are of course all critically important topics part of being addressed by the inquiries other
00:15:53 being addressed by the inquiries other experts I will also avoid commenting on the regulatory compliance of the materials products and systems used at Grenville tower as regards the applicable building regulations and guidance documents in line with your
00:16:07 guidance documents in line with your instructions my phase one work has been concerned with identifying what aspects of the building design and construction played a significant role in enabling the disaster to occur it is only by
00:16:18 the disaster to occur it is only by understanding the specific makeup of the cladding and the physical processes by which the fire spread over the building that you will be able to evaluate the relative rolls of materials products and
00:16:29 relative rolls of materials products and systems during the fire to address the relevant issues my presentation is structured in three parts first fire
00:16:40 structured in three parts first fire science I will provide a brief overview of the fire science that is necessary to adequately understand the factors influencing fire spread to and on the clouding this will also help to explain
00:16:53 clouding this will also help to explain the potential contributions of different materials to exacerbating the speed and extent of the external fire spread second cladding materials and products I will describe in considerable detail the
00:17:06 will describe in considerable detail the various materials in products used within the external cladding system and briefly how each of these responds to heating from a fire the third and final part of my presentation will focus on fire spread -
00:17:19 presentation will focus on fire spread - and on the cladding on the night of the fire
00:17:21 fire I will revisit the video shown during opening remarks by mr. millet and I will use this along with other evidence to provide a detailed summary of both the
00:17:32 provide a detailed summary of both the timelines and the physical mechanisms of fire spread
00:17:48 so Part one deals with fire science the first part of my presentation deals with two particular aspects of fire science that are central to what occurred at
00:17:59 that are central to what occurred at Greenville tower flammability and flames spread together these will help us to understand how the fire spread to the cladding and on the cladding both
00:18:10 cladding and on the cladding both flammability and flame spread are intuitively understood by most people in general terms however I believe it's important to begin my presentation of my preliminary evidence by discussing their more precise technical meetings as well
00:18:23 more precise technical meetings as well otherwise developing a deep understanding and unpicking the causal roles associated with cladding materials products and systems is impossible
00:18:38 flammability refers to the ease of ignition of a material and the manner in which it burns the flammability of a material is governed by the physical
00:18:49 material is governed by the physical properties of the material its chemical composition sorry and to some extent the manner in which its flammability is evaluated a range of different
00:19:01 evaluated a range of different flammability tests are used both in the UK and internationally flammability is not a yes/no proposition there is a gradation of performance amongst materials and products flammability is
00:19:15 materials and products flammability is governed by materials properties its immediate environment and its geometry or sorry flammability is not a yes/no proposition yes flame spread however is governed by materials properties its
00:19:28 governed by materials properties its immediate environment and its geometry as with flammability a range of different tests can be used to assess the flame spread on different materials and products to interpret and understand the evidence of fire spread a Greenville
00:19:40 the evidence of fire spread a Greenville tower it's necessary to have a basic understanding of the physical mechanisms that govern both flammability and flame spread I will avoid technical language and jargon to the extent possible
00:19:52 and jargon to the extent possible however this is science and the matter is rather complex indeed highlighting the complexities of the science is one of the key things that I hope to accomplish today the topic
00:20:05 hope to accomplish today the topic therefore demands a certain level of technical terminology over fire we all have a sense of what fire is in a sense
00:20:16 have a sense of what fire is in a sense of which materials will burn and which will not but fire is not in reality a single and simple process rather it is the result of a sequence of interrelated
00:20:28 the result of a sequence of interrelated processes that may occur when fuel oxygen and an ignition source are combined under the correct conditions fire is the visible flame smoke and heat
00:20:40 fire is the visible flame smoke and heat produced by an uncontrolled combustion reaction this results from a chemical reaction between flammable gases and oxygen which makes up 21% of air the
00:20:51 oxygen which makes up 21% of air the combustion reaction occurs rapidly and is exothermic by which I mean that it releases energy and we perceive this as heat and light in the case of burning of
00:21:05 heat and light in the case of burning of solid materials such as wood plastics or indeed insulating foams the flammable gases which enter the flame are produced by a process of thermal decomposition
00:21:17 by a process of thermal decomposition this process is referred to as pyrolysis gas is produced by pyrolysis of the solid are flammable when they react with oxygen in the air and form gaseous
00:21:28 oxygen in the air and form gaseous products such as carbon dioxide and water vapor in addition very small solid particles are generated these form the visible components of smoke or soot in
00:21:39 visible components of smoke or soot in order for flaming to occur the fuel must be in the form of a gas this means that it's able to mix and react with oxygen from the surrounding air and critically
00:21:51 from the surrounding air and critically this means that solids do not burn directly instead it is the gaseous fuel produced by the thermal decomposition of the solid that is burning this
00:22:02 the solid that is burning this distinction may at first seem unimportant but I hope that my reasons for making it becomes clear during the course of my presentation the combustion of solids
00:22:13 presentation the combustion of solids can be readily illustrated using the familiar example of a flame produced by the burning if it wouldn't matchstick as I've shown here here I should like to say sir that while I'm going to use a
00:22:24 say sir that while I'm going to use a matchstick to illustrate some of the key concepts of flammability and flame spread in reality the processes at play in the ignition and burning of a match are even more complex than I will be able to describe in my limited time
00:22:35 able to describe in my limited time today the solid in this case is the wood from which the matchstick is made wood as we all intuitively understand is a
00:22:46 as we all intuitively understand is a combustible material when wood is heated in this case by the flame from the match itself the molecules that make up a solid wood thermally decompose and are released as flammable gases by this I
00:22:59 released as flammable gases by this I mean the wood undergoes pyrolysis these flammable gases are transported into the flame by a point flow due to the fact
00:23:10 flame by a point flow due to the fact that hot gases rise as the flammable gases are transported into the flame they mix with oxygen which is available from the surrounding air we say that the
00:23:22 from the surrounding air we say that the surrounding air is entrained into the flame provided that sufficient heat is present within the flame and that the mixture of flammable gases and oxygen is in the correct proportions the gases and
00:23:34 in the correct proportions the gases and oxygen will react this reaction releases energy which heats up the gases which then sorry which heats up the gases
00:23:46 then sorry which heats up the gases which then radiates energy this reaction also produces combustion products such as carbon dioxide water vapor and tiny sip particles as I've already mentioned
00:23:57 sip particles as I've already mentioned it is the glowing by which I mean the emission of thermal radiation and light of these heated soot particles that produces the characteristic yellow flame we associate with fire the flame can
00:24:10 we associate with fire the flame can therefore heat objects by two processes of heat transfer convection of buoyant hot gases typically above the flame as I've shown here and by radiation to
00:24:23 as I've shown here and by radiation to any materials that are within sight of the flame in the case where the match is held horizontally as shown here it is radiation from the flame shown
00:24:34 it is radiation from the flame shown there and conduction along the matchstick shown by that arrow which heats the unburned wood conduction
00:24:45 heats the unburned wood conduction refers to the transfer of heat within the solid this heating of the wood causes further release of flammable gases and so on in a self-sustaining process that we call fire
00:25:04 as I've just outlined the process of thermal decomposition of a solid material is called pyrolysis this process is endothermic meaning that it requires a supply of energy from an
00:25:15 requires a supply of energy from an external source in order to occur pyrolysis is fundamental to determining how or rather if a solid material will ignite and continue to burn and the
00:25:27 ignite and continue to burn and the conditions under which this can occur pyrolysis like any chemical reaction is strongly temperature-dependent in that higher temperatures result in faster pyrolysis this means that the rate at
00:25:40 pyrolysis this means that the rate at which a solid can be heated will depend on its rate of pyrolysis the rate at which pyrolysis occurs will then influence whether a flammable mixture of pyrolysis gas and air will form and
00:25:51 pyrolysis gas and air will form and sustain a flame by this I mean that the rates at which pyrolysis occurs will dictate whether a material ignites and whether it will continue to burn not all
00:26:02 whether it will continue to burn not all mixtures of flammable gas and oxygen can burn the gas and oxygen have to be in the correct proportions and in the presence of an appropriate ignition source those mixtures that can burn are
00:26:15 source those mixtures that can burn are called flammable mixtures furthermore both the thermal properties of a material and its geometry play important roles in determining both its ignition
00:26:26 roles in determining both its ignition and it's burning behavior and both are central to developing a physical understanding of what occurred at grenfell tower I'd now like to discuss
00:26:37 grenfell tower I'd now like to discuss some particular technical concepts and terminology which relate to the heating of a solid material when discussing the fire behavior of materials it is conventional to differentiate between
00:26:48 conventional to differentiate between materials that are known as thoroughly thick and thermally thin materials this distinction is based on the physical dimensions of the material the material properties and the thermal
00:27:01 properties and the thermal characteristics of the surrounding environment essentially a thoroughly thin fuel is one which heats uniformly and become and can be characterized by one temperature in this case the
00:27:12 one temperature in this case the response of the material is limited by the transfer fee from its surroundings a thermally thick fuel is one which heats non-uniformly and exhibits an internal temperature
00:27:23 and exhibits an internal temperature gradient as energy is transferred into the body of the material by this I mean that the surface of the material gets hot but the interior stays relatively
00:27:35 hot but the interior stays relatively cool in this case the response of the material is influenced by the rate of heat transfer within the material the other process of heat conduction as I've already mentioned thermally thin feels
00:27:46 already mentioned thermally thin feels ignite more readily than thermally thick fuels all other factors being equal a familiar example of thermal thickness can be understood by comparing the ease
00:27:59 can be understood by comparing the ease of ignition of wood shavings versus a solid block of wood both are composed of the same material wood however the wood shavings are thermally thin and can be readily heated
00:28:11 thermally thin and can be readily heated such that ignition occurs the large block of wood however is thermally thick and when exposed to a flame the heat is conducted into the block and away from
00:28:22 conducted into the block and away from the surface thus making it harder to ignite the difference between these two cases as regards both ignition of a material and the chances that it will continue to burn are shown in these
00:28:33 continue to burn are shown in these side-by-side videos of wood shavings and the block of wood in both cases ignited by a match and I'll play this now
00:28:53 and you can see actually multiple attempts to ignite the block of wood with subsequent matches
00:29:10 you get the point I hope for thermally thick fuel when exposed to a heat source the surface temperature of the solid material will begin to increase the rate
00:29:21 material will begin to increase the rate of increase is determined in part by the physical properties of the material the key parameters in this situation are first the thermal conductivity of the material this is a measure of the
00:29:32 material this is a measure of the ability of the material to transfer thermal energy internally by conduction second the density of the material and this is a measure of the materials mass
00:29:43 this is a measure of the materials mass per unit volume and third the materials specific heat capacity and this is a measure of the amount of energy required to increase the temperature of one
00:29:54 to increase the temperature of one kilogram of the material by one degree Celsius a heat transfer analysis can show that the product of these three parameters thermal conductivity
00:30:05 parameters thermal conductivity multiplied by the density multiplied by the specific heat governs the rate at which the surface temperature of a solid material increases when exposed to a heat source this is called the thermal
00:30:18 heat source this is called the thermal inertia of the material and it represents if you like the ease with which the surface temperature of a material will change when exposed to heating materials with a high thermal
00:30:32 heating materials with a high thermal inertia such as metals for example are comparatively slow to heat at the surface all other factors being equal conversely the surface temperature of material with low thermal inertia such
00:30:43 material with low thermal inertia such as polymer foam insulation for instance will increase rapidly when heated as I've already stated pyrolysis is a temperature dependent process thus there
00:30:57 temperature dependent process thus there is a strong coupling between heating of the solid and pyrolysis consequently materials with a low thermal inertia where the surface will heat more rapidly will initially experience more rapid
00:31:09 will initially experience more rapid pyrolysis than materials with higher thermal inertia it's very important to understand this because it helps us to understand and hopefully eventually to quantify
00:31:20 quantify the potential roles of the various materials and products that made up the clowning at grenfell tower as a result of the factors that I've now described it's common to assume a pyrolysis
00:31:32 it's common to assume a pyrolysis temperature at which pyrolysis will occur for a given material all other factors being equal materials with higher pyrolysis temperatures are more difficult to ignite than those with
00:31:44 difficult to ignite than those with lower pyrolysis temperatures let me now turn my attention to the issue of flammability on a day to day basis we
00:31:56 flammability on a day to day basis we tend to we tend to think of materials as either being flammable or not or as being either combustible or not indeed the word combustible has received
00:32:08 indeed the word combustible has received a great deal of attention of use in the media since the Grenfell tower fire in reality for materials that have the potential to burn by which I mean those materials that are combustible
00:32:21 materials that are combustible flammability is a relative rather than absolute property depending on the circumstances therefore combustible materials can either be more or less flammable and this distinction is
00:32:34 flammable and this distinction is actually very important in a regulatory context material flammability quantifies the degree to which a material will burn with a flame under specified conditions
00:32:45 with a flame under specified conditions material flammability tests sorry material flammability tests therefore allow different materials to be ranked as regards their suitability in certain
00:32:56 as regards their suitability in certain applications based on results from tests in standardized test apparatus it should be noted however the material flammability parameters are not fundamental material properties this is
00:33:09 fundamental material properties this is precisely because they depend on the method of evaluation flammability testing outcomes may be influenced by a range of phenomena and I believe it's worth taking a bit of time now to
00:33:20 worth taking a bit of time now to discuss these in general terms before moving on to look at the specific materials products and systems that were installed in the clouding at Granville Tower
00:33:32 first ignition in the context of most fire safety applications the ignition is defined as the initiation of what is known as gas phase combustion by this I
00:33:45 known as gas phase combustion by this I mean sustained flaming or birding of pyrolysis gases in the manner I described earlier using the photo of the wood matchstick ignition is the moment that the visible flame first appears
00:33:57 that the visible flame first appears whether ignition of a solid material occurs in a given situation is strongly time-dependent this means that ignition only occurs after a period of heating of the solid
00:34:08 after a period of heating of the solid such that its surface temperature reaches the pyrolysis temperature and flammable gases are produced by pyrolysis in sufficient quantities to sustain a flame common ignition tests
00:34:21 sustain a flame common ignition tests used in practice apply a radiant heating source to heat a material the magnitude of the heating is defined in terms of what's called the incident
00:34:39 you
00:36:30 - the wood would actually be insufficient to continue to generate the necessary pyrolysis gases and the flaming combustion would stop the flame would go out higher heat flux is
00:36:42 would go out higher heat flux is therefore lead to more rapid ignition all other factors being equal as I've already discussed the rate of heating for thermally thick fuels depends
00:36:53 for thermally thick fuels depends strongly on the thermal inertia of the material the time to ignition under a given heat flux exposure is therefore also strongly dependent on the thermal inertia of the material materials with
00:37:05 inertia of the material materials with low thermal inertia for example polymer foams heat rapidly at their exposed surfaces generally resulting in short times to ignition materials with higher
00:37:16 times to ignition materials with higher thermal inertia for example example common synthetic polymers which we more commonly call plastics have longer times to ignition it follows from the
00:37:27 to ignition it follows from the preceding discussion that there is a level of heating by which I mean a level of heat flux below which ignition will not occur for a given material when
00:37:38 not occur for a given material when tested in a given configuration this is called the critical heat flux for ignition materials with low values of critical heat flux for ignition are in general easier to ignite than those with
00:37:51 general easier to ignite than those with high values of critical heat flux for ignition understanding how materials ignite is essential for instance in order to confidently suggest how the
00:38:02 order to confidently suggest how the fire at grenfell tower spread from within the kitchen of flat 16 onto or into the cladding adjacent to the kitchen window the ignition properties of the material are also critical in
00:38:13 of the material are also critical in evaluating their ability to spread flame for reasons that I will discuss in a few minutes before doing so however I'd like to discuss heat of combustion
00:38:27 once a material has ignited the primary variable of interest is the rate at which energy continues to be released since this is what drives the growth and
00:38:39 since this is what drives the growth and spread of a fire the total amount of energy that is available to be released from a material is known as its heat of combustion this is a measure of the total energy that can be released per
00:38:52 total energy that can be released per unit mass of a material under optimal conditions for combustion the rate at which energy is released however and the fraction of the total available energy
00:39:03 fraction of the total available energy that actually is released under a given set of circumstances is a function of its heating conditions its geometry and its orientation this distinction is critically important because as I've
00:39:15 critically important because as I've already suggested just because a material can burn under some circumstances doesn't necessarily mean that it will burn under a particular set of circumstances and this idea will be
00:39:27 of circumstances and this idea will be familiar to anyone who has attempted to start a log fire without using kindling just because wood can burn doesn't mean it always will the heat of combustion of a material is measured by burning a unit
00:39:39 a material is measured by burning a unit mass of material in an atmosphere of pure oxygen this increased reactivity of this atmosphere compared to air which as I've already noted is only 21 percent
00:39:51 I've already noted is only 21 percent oxygen results in complete combustion of the material and the conversion of virtually all of the stored chemical energy into thermal energy the heat of
00:40:02 energy into thermal energy the heat of combustion thus provides an upper limit on the amount of energy that can be released by the burning of a material however the heat of combustion on its own does not give any information
00:40:13 own does not give any information regarding the rate at which energy is released after a material is ignited nor does it account for the heat transfer processes that lead to ignition the material geometry or the physical
00:40:26 material geometry or the physical changes that may occur all of which also affect a materials burning behavior to give you a sense of the variability of heats of combustion amongst materials
00:40:38 of heats of combustion amongst materials this chart shows the heats of combustion of a number of familiar and not so familiar but relevant materials on this chart materials with gray bars are
00:40:51 chart materials with gray bars are common and in some senses familiar but are not considered significant as regards mark for eliminate evidence related to the ground felt our fire these are shown because these materials
00:41:02 these are shown because these materials may be familiar to you you may have some understanding of how they react to heating whereas materials in red are less familiar aside from wood of course but we're present in significant quantities within
00:41:14 present in significant quantities within the cladding system at Greenville tower you may note the broadly similar values for the synthetic polymer or plastic materials polyethylene and polystyrene as compared with diesel fuel for
00:41:27 as compared with diesel fuel for instance I'll return to this point later on next heat release rate as I've mentioned the rates at which energy is
00:41:38 mentioned the rates at which energy is released from a material by which I mean whether the available energy is quickly is released quickly or slowly in a given set of circumstances is described by the
00:41:49 set of circumstances is described by the heat release rate the heat release rate describes the rate of energy release per unit time as an object burns objects made from materials with the same heat of combustion may burn in very different
00:42:01 of combustion may burn in very different ways once ignited at a material level the heat release rate behavior is dictated to a large extent by the
00:42:12 dictated to a large extent by the pyrolysis behavior of the solid material if the material melts such as in the case of the synthetic polymer material polyethylene for example then after
00:42:23 polyethylene for example then after ignition the heat release rate will increase to an essentially steady value until virtually all of the material is consumed and this is illustrated schematically in the left-hand figure shown here this is a key point and I'll
00:42:37 shown here this is a key point and I'll return to it I'll return to burning of polyethylene which I abbreviate in some cases PE later in my presentation if however the
00:42:48 later in my presentation if however the material chars such as in the familiar case of wood or the less familiar case of a thermosetting polymer foam insulation which I will also return to later then under most conditions there
00:43:00 later then under most conditions there will be an initial period of high heat release followed by a period of lessening heat release rate this is due to the formation of a protective char layer on the surface of the material and
00:43:11 layer on the surface of the material and this is illustrated in the right-hand figure shown here the formation of the char layer decreases the rate of energy transfer into the material and hence
00:43:23 transfer into the material and hence reduces the rate of pyrolysis and therefore the quantity of flammable gases produced the heat release rates of
00:43:34 gases produced the heat release rates of a material also depends again on its physical geometry and surrounding conditions and on the presence of any external heat sources the heat release rate of an object burning in the presence of an external heat source such
00:43:46 presence of an external heat source such as a large fire will be a strong function of the magnitude of the external heat source for the reasons I've already discussed the heat release rate is therefore important for
00:43:57 rate is therefore important for evaluating the fire hazard associated with an object this is because it determines the energy released from a material that is available to be transferred back to the fuel thinking
00:44:09 transferred back to the fuel thinking again about my match thus creating a feedback loop which may sustain the flaming materials with a high heat release rate therefore typically result
00:44:21 release rate therefore typically result in more rapid fire growth and/or fire spread and sir the growth and spread of fire are obviously of fundamental importance to this inquiry
00:44:37 so finally having discussed these foundational concepts of fire science I will turn to flame spread flame spread occurs when sufficient heat is
00:44:49 occurs when sufficient heat is transferred from a burning region to an adjacent unburnt material region the rate at which a fire will grow depends in part on how on how rapidly flame can spread on the surface of the material
00:45:01 spread on the surface of the material flame spread is strongly influenced by the physical configuration of the system such as its material geometry and orientation the process of flame spread is most easily thought of very helpfully
00:45:14 is most easily thought of very helpfully in my opinion as a series of localized ignitions and the process required to sustain flame spread are thus the same as those that I previously used to describe ignition so as already
00:45:28 describe ignition so as already discussed for ignition sufficient energy must be supplied to the combustible solid ahead of the flames to heat the material such that pyrolysis occurs and flammable gases can be released as the
00:45:40 flammable gases can be released as the area where the pyrolysis is occurring advances so too does the flame that we can visually observe this is flame spread it's common to distinguish
00:45:52 spread it's common to distinguish between what is known as concurrent flame spread and opposed flow flame spread concurrent flame spread occurs when the flame spreads in the same direction as the flow of air I'll show
00:46:04 direction as the flow of air I'll show examples in a moment opposed flow flame spread occurs when the flame spreads in the opposite direction to the flow of air these two extremes are commonly commonly observed when a flame spreads
00:46:17 commonly observed when a flame spreads upwards which we call concurrent flame spread or downwards which is a case of opposed flow flame spread because of the importance to my phase 1 scope of work
00:46:28 importance to my phase 1 scope of work and to the preliminary evidence that I will present later today I'm now going to describe in some detail the key processes associated with upward and downward flame spread I will also
00:46:41 downward flame spread I will also describe
00:46:43 describe horizontal or lateral flame spread this is in fact a special case of a post flow flame spread as I'll explain in a few minutes my discussion of flame spread
00:46:55 minutes my discussion of flame spread draws on many of the fundamental concepts that I've already described and hopefully you can see this is all building the rate of flame spread is dependent on the heat transfer to the material and the materials thermal
00:47:07 material and the materials thermal inertia this is because the rate of flame spread is governed by the rate at which the material adjacent to the burning region can be heated to its pyrolysis temperature upward flame spread is generally faster than downward
00:47:20 spread is generally faster than downward flame spread this is because an upward flame spread the flames and hot gases which rise due to the effective buoyancy as I've already mentioned will preheat the material ahead of the advancing flames this preheating does not occur in
00:47:35 flames this preheating does not occur in downward flame spread which is therefore slower when considering the flame spread on synthetic polymers which are more commonly called plastics as I've mentioned it's important to consider the
00:47:46 mentioned it's important to consider the effects of melting and deformations associated with their softening melting and dripping significantly complicate flame spread processes by removing material from the system and with it some of the available energy to drive
00:47:58 some of the available energy to drive flame spread and I'll demonstrate this in a moment so in a moment I'll show a short video that shows ignition and upward flame spread on a vertically
00:48:09 upward flame spread on a vertically oriented matchstick I will use this simple familiar example again because if it's intuitive value in demonstrating the relative physics or the relevant physics are in awkward flame spreads the
00:48:20 physics are in awkward flame spreads the heat transfer to the unburnt material ahead of the burning region increases the size of the burning zone and hence the flame spread rate the flame and pyrolysis products produced by the burning of the material rise due to
00:48:31 burning of the material rise due to buoyancy and heat the surface of the material and this results in high rates of heat transfer to the surface of the material as the unburned material ahead of the burning region is heated it
00:48:42 of the burning region is heated it begins to pyrolysis and generate flammable gas as the gas ignites the visible flame spreads rapidly typically but not always the rate at which the
00:48:53 but not always the rate at which the wallace's front advances is faster than the rate at which fuel is consumed this is an important point consequently the burning region becomes larger producing
00:49:04 burning region becomes larger producing flammable pyrolysis products at an increasing rate this can be seen in my video in a moment as the bottom of the match you'll see is still burning as the topic nights the flame becomes larger
00:49:17 topic nights the flame becomes larger and thereby increases the height of the heated material which further increases the burning area this positive feedback loop results in a self accelerating process and rapid upward spread of flame
00:49:30 process and rapid upward spread of flame the sequence of events is showed in this short video
00:50:02 my next short video shows downward or opposed flow flame spread on an otherwise identical vertically oriented matchstick in the case of downward flame spread the rate of heat transfer to the
00:50:15 spread the rate of heat transfer to the unburned material is much less than an upward flame spread as I've already described consequently the length of the preheated zone is much smaller resulting in a smaller pyrolysis region a smaller
00:50:26 in a smaller pyrolysis region a smaller volume of evolved pyrolysis gases and a much slower rate of flame spread indeed in this case flame spread eventually extinguishes rather than continuing to
00:50:37 extinguishes rather than continuing to spread downwards this sequence of events is shown in this short video
00:50:51 and you can just see the flame creeping down the matchstick very slowly
00:51:21 and then you can see insufficient pyrolysis gases being released to sustain the flame a further special case of opposed flow flame spread is horizontal or lateral flame spread this
00:51:34 horizontal or lateral flame spread this is similar to downward flame spread and my next video shows the flames spreading from right to left in this case the rising hot gas draws air into the flame from left to right
00:51:45 from left to right hence referring to this as opposed to flow flame spread as in the case of downward flame spread the heat transfer from the flame to the match is higher than in the hot in the downward case as evidenced by the spread of the flame horizontally along the match in this
00:51:59 horizontally along the match in this case the rate at which but the pyrolysis front advances is approximately equal to the rate at which the solid fuel is consumed as evidenced by a steady movement of the flame from right to left and a flame with a reasonably uniform
00:52:11 and a flame with a reasonably uniform size and I'll show this here
00:52:42 and that flame just continues to the left and off the screen now of course matchsticks don't melt and drip this is not the case unfortunately
00:52:54 drip this is not the case unfortunately for all materials rapid downward vertical fire spread may occur due to melting and dripping in particular for certain synthetic polymer materials when
00:53:05 certain synthetic polymer materials when heated in a vertical orientation molten possibly burning material may flow downwards flames spread by this mechanism is governed by the viscosity of the molten material if heated
00:53:17 of the molten material if heated sufficiently the molten material may also form burning droplets which may fall downwards both of these processes are clearly visible in my next video clip and both may contribute to the
00:53:29 clip and both may contribute to the formation of pool fires below and in front of the burning material as is also clear from my next video this slide shows a vertically oriented sheet of a
00:53:42 shows a vertically oriented sheet of a white colored polymer in fact the particular polymer used here is polyethylene and the sheet is three millimeters thick and I should point out this is a demonstration not a scientific
00:53:54 this is a demonstration not a scientific test the sheet has been ignited as it's based using a pad at its base using a butane torch and this butane torch is just barely visible as a blue flame to
00:54:05 just barely visible as a blue flame to the bottom left of the sample and it's quickly withdrawn out of frame and I'll play this clip in three segments in the first segment we see that a few seconds
00:54:16 first segment we see that a few seconds after ignition the molten material is already beginning to fall down and burn on the floor beneath the sample at this point the flames on the polyethylene are relatively small
00:54:49 in the second segment which begins about three minutes later we see that the sample is burning on both sides and that there is an almost constant flow of molten burning polyethylene falling from
00:55:02 molten burning polyethylene falling from the sample to the floor
00:55:19 now I should point out that the vertical streaks are rivulet civ melted burning polyethylene in the third segment which begins about six minutes later still the
00:55:30 begins about six minutes later still the sample has been significantly consumed and molten polyethylene continues to fall
00:55:56 the fact that polyethylene burns in this manner is not at all surprising this behavior has been well known and documented in the scientific and technical literature for decades this
00:56:09 technical literature for decades this particular issue will become very important later in my presentation when I discuss the fire spread that was observed on the exterior of Granville Tower I've not spent considerable time
00:56:23 Tower I've not spent considerable time discussing the most important fundamental fire science concepts and terminology relevant to developing a physical understanding of the circumstances of external fire spread during the Granville Tower fire it is
00:56:36 during the Granville Tower fire it is very important to note that my presentation of concepts such as ignition burning and flame spread relate primarily to single materials rather than to composite products by this I
00:56:50 than to composite products by this I mean products that are composed of a combination of materials all of which may display substantially different flammability and flame spread properties I should also note that very little
00:57:01 I should also note that very little useful fundamental experimental data are available in relation to flammability and flame spread on composite products since most of these products violate the
00:57:12 since most of these products violate the basic assumptions of many of the existing experimental and compliance testing methods and this issue is of particular relevance to this inquiry not
00:57:23 particular relevance to this inquiry not least because of the large number of other buildings in the UK and internationally that are apparently clad using similar materials and products to those used at Grenville Tower despite this disclaimer a series of
00:57:35 despite this disclaimer a series of useful conclusions can be drawn on the basis of the discussion provided in this first section of my presentation today and these are as follows ignition
00:57:46 and these are as follows ignition flammability flame spread and fire growth are all influenced by numerous factors including material properties chemical composition orientation
00:57:57 chemical composition orientation geometry and interactions with other materials upward flame spread on a solid fuel is rapid because the hot flame in gas is preheat
00:58:08 gas is preheat material ahead of the birding zone downward and horizontal flame spread is generally slower because preheating of the fuel ahead of the flame front is critically reduced almost all of these concepts are important in order to
00:58:20 concepts are important in order to understand even my most basic matchstick demonstrations of some of the relevant flame spread mechanisms on this slide I've placed all three of the matchstick
00:58:32 I've placed all three of the matchstick videos and I'm going to run them concurrently so that you can see just how important the relevant phenomena are as regards both the rate and the extent of flame spread
00:59:27 however as I've just mentioned downward flames spread may also be significantly influenced by melting and dripping of burning material as I showed a few moments ago with reference to polyethylene in all cases of upward
00:59:40 polyethylene in all cases of upward downward and horizontal flame spread the spread is dominated by the heat release rate of the existing fire how the resulting fire transferred transfers
00:59:51 resulting fire transferred transfers heat to the unburnt material and the thermal properties of the material itself sir that concludes my summary of the key fire science concepts and
01:00:02 the key fire science concepts and processes to which I'd like to draw your attention at this early stage of the inquiry all of these concepts must be kept clearly in mind when considering the rest of the preliminary evidence
01:00:13 the rest of the preliminary evidence that I will present today and indeed during phase one thank you very much mr. chairman I wonder if that's a convenient moment for the break I think it would be a good maybe a break now and resumed at
01:00:25 a good maybe a break now and resumed at ten past eleven please
01:00:36 you
01:12:22 [Music]
01:13:42 [Music]
01:16:26 [Music]
01:17:32 yes professor this video ratings thank you
01:17:39 [Music] as I've already described the orientation thermal properties and chemical composition are all important
01:17:50 chemical composition are all important in understanding how materials and products may respond to fire during the second part of the preliminary evidence that I will present today I'll describe the materials and products used in the
01:18:01 the materials and products used in the refurbishment cladding system at Greenville tower I'll describe where they can be found on the building and how they're arranged I will also describe how they burn the summary of
01:18:14 describe how they burn the summary of materials and products presented in this section is based on a range of sources of evidence as follows for post fire inspections of Greenville tower that I've conducted prior to submitting my phase 1 report a range of documentation
01:18:27 phase 1 report a range of documentation and photos made available to the public inquiry inquiry via formal disclosures and materials and products samples taken from Greenville tower by the Metropolitan Police Service and provided
01:18:39 Metropolitan Police Service and provided to me for small-scale materials testing at the University of Edinburgh before I describe the materials in detail I'd like to ensure that I'm clear about the
01:18:50 like to ensure that I'm clear about the terminology that I will use to describe different parts of the building I will do this by presenting a number of annotated photographs and drawings to identify the terminology for parts of
01:19:01 identify the terminology for parts of the exterior of the building that are relevant to my preliminary evidence this image shows a portion of the West face
01:19:12 image shows a portion of the West face of the building following the fire this photo was obtained by the Metropolitan Police Service using a drone on the 25th of July 2017 during my presentation when I
01:19:24 July 2017 during my presentation when I refer to columns these are the areas of building indicated on this image I should like to point out that the East and West faces of the building each have four column lines as shown here whereas
01:19:38 four column lines as shown here whereas the north and south faces of the building each have five column lines as noted by mr. millets during his opening when I refer to spandrels this is a generic term that I use for the parts of
01:19:49 generic term that I use for the parts of the building between the windows as indicated on this image I also use the terminology spandrel section to refer to
01:20:00 terminology spandrel section to refer to the building exterior between the column lines the sections shown here when I refer to rain screen cassettes these are the external panels as indicated on this
01:20:13 the external panels as indicated on this image for example here here here are spandrel section rain screen cassettes and here and here on the column sections
01:20:26 and here and here on the column sections of the building it's worth noting that these are gray in color from level four upwards when I refer to the window sections of the building these are the
01:20:37 sections of the building these are the sections of the building as shown indicated on this image within the window sections there are several individual components including windows
01:20:48 individual components including windows extract fans and mounting panels and window infill panels I'll describe these in a moment when I refer to window infill panels these are as indicated
01:21:00 infill panels these are as indicated here in yellow these are unglazed sections of the window units it's worth noting that these are white in color from level four upwards the kitchen
01:21:13 from level four upwards the kitchen windows are indicated on this image and here I'd like to draw your attention to the fact that the kitchen windows are actually made up of three separate areas and I'll describe each to each of these
01:21:24 and I'll describe each to each of these in more detail in a few moments when I refer to cavity barriers which would be very rarely these elements are running vertically and horizontally within the cladding on the building as indicated on
01:21:37 cladding on the building as indicated on this image and visible only where the rain screen cassettes have been damaged or removed during the fire you can just see them as the ragged lines underneath the yellow bars and when I refer to the
01:21:49 the yellow bars and when I refer to the floor slabs I'm referring to the structural reinforced concrete floors within the building and these are the levels approximately indicated by the yellow lines on this image I will now
01:22:04 yellow lines on this image I will now describe the cladding system and its geometry in more detail by zooming in on one specific part of the building specifically the section shown of the
01:22:16 specifically the section shown of the building's exterior we start showing here this part of the exterior has the same arrangement of windows sorry in
01:22:28 same arrangement of windows sorry in this part of the building has the same arrangement of windows as those around the external east wall of flat 16 which is acknowledged by at least three of the inquiries experts as the room of fire origin the internal layout of this
01:22:41 origin the internal layout of this particular flat is also the same as that in flat 16 approximately so that the this is a kitchen window on the other the kitchen windows on the left and the
01:22:53 the kitchen windows on the left and the two rooms to the right of the kitchen window are associated with the living room I'll now zoom in even further to look only at the region around the kitchen window which is shown as
01:23:04 kitchen window which is shown as highlighted there here I've highlighted one of the kitchen windows in the vertical line of flats in the tower ending with the number three these are flats positioned in the southwest corner
01:23:15 flats positioned in the southwest corner of the building I will now zoom in even further to the kitchen window specifically
01:23:25 the window comprises a large glazed window pane which operates in both an inward tilting or inward turning by which I mean swinging manner and hinged
01:23:36 which I mean swinging manner and hinged on the right when observed from outside the building an extract fan which is mounted within an infill panel and this infill panel appears to be made from the
01:23:47 infill panel appears to be made from the same materials and construction as the window infill panels that I noticed that I noted previously and I'll come back to these in a moment and a small glazed
01:23:58 these in a moment and a small glazed windowpane beneath the extract fan and mounting infill panel which operates in an inward turning manner and is hinged on the left when observed from outside the building I'd now like to look in
01:24:12 the building I'd now like to look in some detail at the composition and geometry of the cladding in various locations around this kitchen window which has the same design as a kitchen window a flat 16 as I've mentioned to do
01:24:25 window a flat 16 as I've mentioned to do this I'll use my own hand-drawn sketches of the relevant sections through the building these are based on my own post fire investigations of Grenville tower and I'll do this in the hope that my sketches will be more easily understood
01:24:37 sketches will be more easily understood by you and by the other parties to be inquiry it will necessarily I'm sorry I will necessarily be covering some of the ground already covered by dr. Lane and professor Nick day however I believe
01:24:49 professor Nick day however I believe that this is a useful repetition and that a detailed focus on the cladding materials in geometry is warranted under the circumstances it should be noted
01:25:01 the circumstances it should be noted that my sketches are only indicative and are not scale I should also like to note that my post fire inspections at grenfell tower have confirmed that there is local variation of the refurbishment
01:25:13 is local variation of the refurbishment cladding geometry due to the geometry of the existing building and the presence of the original window openings I've carefully considered this variability in examining the available evidence and drawing my preliminary conclusions in my
01:25:27 drawing my preliminary conclusions in my sketches I will not show the location of cavity barriers within the cladding and this point has already been discussed in some detail by dr. Lane and I don't consider it critical to my own cope of work so let me look now in
01:25:40 cope of work so let me look now in detail at the cladding immediately above and below the kitchen window opening
01:25:48 please imagine if I were to cut through the cladding along a vertical line as shown here and then look inside the cladding to see the various layers that I cut through I would look specifically
01:26:00 I cut through I would look specifically at the cladding materials in geometry here above and below the kitchen window
01:26:09 this slide the four-story the following slide sequence shows the buildup of the different cladding materials starting with the pre-existing or original
01:26:20 with the pre-existing or original cladding construction and adding the various components of the refurbishment cladding as I go this slide shows a sketch of the original concrete construction at the location of the kitchen window and remember this is over
01:26:31 kitchen window and remember this is over a vertical slice through the building the left-hand side of this image shows the outside of the building and the right-hand side is inside the flat please note that I've removed the window
01:26:43 please note that I've removed the window pane and brought these two sections closer together vertically in this drawing than they actually are in reality the original concrete structure can be seen in gray the concrete slab
01:26:55 can be seen in gray the concrete slab that forms the ceiling is shown top right and the concrete wall below the windows is shown below there were also original timber battens
01:27:06 there were also original timber battens and window framing board and pearl board foam insulation both on the ceiling in a band and on the interior wall I'll describe these more in more detail
01:27:18 describe these more in more detail shortly the original windows were located approximately as shown here below the windows the parole board
01:27:29 below the windows the parole board insulation was covered by a sheet of gypsum plasterboard as an internal finish within the flat during the 2012 through 2016 refurbishment program the original windows were removed and
01:27:41 original windows were removed and installed over top of this original construction was the refurbishment over cladding system this comprised supporting aluminium rails and fixings which were anchored
01:27:53 rails and fixings which were anchored into the pre-existing reinforced concrete floor slabs and spandrel beams the polymer foam thermal insulation was applied in two layers on this section of
01:28:05 applied in two layers on this section of the building each 80 millimeters in thickness and the aluminium composite material were ACM rainscreen cassettes were then applied
01:28:17 rainscreen cassettes were then applied between the ring screen cassettes and the foam insulation was an open ventilated void hence the terminology ventilated rainscreen cladding system to describe
01:28:28 rainscreen cladding system to describe this particular type of Claddagh i'm referring to the voids shown with writing they're the new aluminium frames double glazed windows extract fan units
01:28:39 double glazed windows extract fan units and window infill panels were fitted into the openings and mounted on the aluminium rails as shown here you can
01:28:50 aluminium rails as shown here you can see here how I've cut and reduced the vertical or the vertical size of the window inside the building was placed some additional polymer foam insulation in approximately those locations and a
01:29:03 in approximately those locations and a finishing detail of a uPVC window which was bonded in place using a polymer adhesive as shown there any
01:29:14 polymer adhesive as shown there any small visible gaps were then filled with a silicone sealant uPVC stands for unplastered polyvinyl chloride and is a
01:29:26 unplastered polyvinyl chloride and is a specific type of polymer ie a plastic material that I will describe in more detail later in this presentation we will look at each of these materials and products in more detail in a moment
01:29:37 products in more detail in a moment but for now I simply wanted to show their locations within the cladding please note that the location of the glazing has been removed outwards or
01:29:48 glazing has been removed outwards or sorry has been moved outwards as a consequence of the reclining and that the windows themselves now sit some distance outside the original reinforced concrete construction
01:30:02 I'd now like to take a horizontal slice through the building and look at the cladding build up immediately to the left of the kitchen window when viewed
01:30:13 left of the kitchen window when viewed from outside the building at this location here when viewed from out from inside the building this slice is across
01:30:25 inside the building this slice is across the window as shown in this image shown in this image please note that the dark material on the windowsill in this photo is debris from the fire this is a
01:30:37 is debris from the fire this is a partially fire damaged flat in this photo the uPVC windows are clearly visible as are the lines of silicone sealant used to fill the gaps between
01:30:48 sealant used to fill the gaps between them here please also carefully note this thin strip of uPVC window now highlighted in yellow this has been
01:31:00 now highlighted in yellow this has been installed in order to fill what would otherwise be a gap between the new refurbishment window window frame rather and the pre-existing window opening within the original reinforced concrete
01:31:12 within the original reinforced concrete facade as I'll show in a moment this appears to be held in place with a bead of silicone sealant cutting through the
01:31:24 of silicone sealant cutting through the wall of the building at this location and looking from the top down you can see a portion of the octagonal shaped reinforced concrete column on the left side of this sketch inside the building
01:31:42 side of this sketch inside the building is at the top of this slide and outside the building is at the bottom again the original construction included timber battens and timber window framing board
01:31:53 battens and timber window framing board and the original single glazed windows with in aluminium frames here the line showing the glazing fades at the right and this is to indicate an indefinite
01:32:05 and this is to indicate an indefinite distance in this direction in my sketch for the window ten years off to the right as before the original windows were removed and the
01:32:18 original windows were removed and the new double glazed windows were installed on the horizontal aluminium rails which I showed previously but which are not shown in this view in this location to
01:32:31 shown in this view in this location to the left of the window on ie on the column the over cladding comprised the polymer foam thermal insulation in this case a single layer one hundred
01:32:42 case a single layer one hundred millimeters thick and the ACM rain screen cassette as highlighted a moment to go in this location there was a gap between the edge of the new window frame
01:32:53 between the edge of the new window frame and the pre-existing reinforced concrete column sorry there's a void in the rain screen and that is the gap that I'm referring to a weather proofing membrane
01:33:06 referring to a weather proofing membrane made of EPDM rubber sheet was positioned across the gap formed in this location foam insulation was present both on the inside and outside of this gap as shown
01:33:20 inside and outside of this gap as shown there and the uPVC window was again applied as an internal finish as shown there I should like to note at this point that the specific geometry of the
01:33:32 point that the specific geometry of the small section of polymer foam insulation directly outside the kitchen window sorry that's the strip of uPVC windows board that I highlighted a moment ago
01:33:45 and the small section of polymer foam insulation directly outside the kitchen window which is now highlighted appears to have varied over the building in some cases the insulation boards were cut
01:33:57 cases the insulation boards were cut differently at this location and in some cases the smaller pieces of foam insulation immediately outside the EPDM rubber membrane appear not to have been installed at all this is important as
01:34:11 installed at all this is important as regards potential routes for fire spread from inside the building to the cladding as I will discuss later today this is an ongoing item for investigation
01:34:24 moving lower down to the spandrel section of the exterior cladding below the kitchen window I will now take a horizontal slice across this part of the
01:34:37 horizontal slice across this part of the building in this location shown here in this location again looking down at the
01:34:48 this location again looking down at the surface of my slice through the building we can see the original concrete column and spandrel beam here again the spandrel beam spandrel beam fades at the
01:35:00 spandrel beam spandrel beam fades at the right to indicate that in reality it continues to the right there are one or two layers of PIR foam insulation depending on the location on the building on the columns one layer was
01:35:13 building on the columns one layer was present with a thickness of 100 millimeters this is shown here whereas on the spandrel as I've already noted two layers each of 80 millimeters in
01:35:25 two layers each of 80 millimeters in thickness were present aluminium clotting rails support the aluminum cladding rails shown here support the spandrel ACM rain screen cassettes as
01:35:37 spandrel ACM rain screen cassettes as was described in detail by dr. Lane on Monday
01:35:40 Monday these were attached to the refurbishment window frames using a series of metal brackets not shown in this view and here are shown the connection to the ACM rain
01:35:52 are shown the connection to the ACM rain screen cassettes on the cladding rails spray foam was used liberally to fill gaps and small voids within the external cladding system aluminium tape also
01:36:03 cladding system aluminium tape also appears to have been used liberally within the clonic and finally the ACM rain screen cassettes where clung from them were hung from the climbing rails
01:36:15 them were hung from the climbing rails and again please note the void within the cladding between the rain screen cassettes and the PIR foam thermal insulation I'd now like to draw your
01:36:26 insulation I'd now like to draw your attention to a particular feature of the cladding geometry that exists along the vertical line were the spandrel sections of the building meet the column sections of the building
01:36:37 building remembering that the two horizontal sections that I've just taken through this location and where they're positioned in the building both through the window section and through the spandrel section which is shown here
01:36:48 spandrel section which is shown here I've identified that a continuous vertical void exists within the cladding at the locations shown in this figure this void is continuous on all columns
01:37:00 this void is continuous on all columns from level 4 all the way to the top of the tower if I show the location of these voids on the column to the left of this particular kitchen window I should
01:37:11 this particular kitchen window I should know that it's the same on all columns as far as I can tell at this point they are as shown here if I show these voids on a section of the full west face of
01:37:22 on a section of the full west face of the tower there is shown here the final part of the clouding that I'd like to examine in detail is it the location
01:37:34 examine in detail is it the location that I have called the column tip in my phase 1 report this is highlighted in yellow in this figure I wish to
01:37:46 yellow in this figure I wish to highlight this both for completeness and because of another particular feature of the cladding geometry at this location that location just there
01:37:59 this image shows a sketch of a horizontal slice across the column tip as shown by the dashed line in the previous slide and again looking down at
01:38:11 previous slide and again looking down at the surface of my slice the tip of the original concrete columns external precast concrete surface is seen in gray the over cladding in this location
01:38:24 the over cladding in this location comprises the aluminium fixings and rails shown here the single layer of full foil faced PIR foam insulation of 100 millimeters in thickness and the ACM
01:38:38 100 millimeters in thickness and the ACM rain screen cassettes again with a ventilated rain screen cavity within the cladding rail at the column tip I've
01:38:49 cladding rail at the column tip I've identified that there is another uninterrupted void that spans the entire heights of the building this location the location of this void rather is illustrated here again if I show these
01:39:03 illustrated here again if I show these additional column tip voids on a section of the full west face of the tower they are as shown here combining these with
01:39:14 are as shown here combining these with the continuous vertical voids discussed previously here we can see that the column lines in particular provide numerous vertical voids and channels that run uninterrupted from at least
01:39:26 that run uninterrupted from at least level four right the way to the top of the building sir I've now described my key preliminary evidence with respect to the geometric arrangements of the
01:39:37 the geometric arrangements of the cladding
01:39:55 having dealt with the geometry I will now describe the various materials and products that were present within the cladding system of Grenfell tower at the time of the fire
01:40:07 time of the fire before I begin I believe it's important to make clear a distinction between materials and products materials are comprised of well a single material
01:40:19 comprised of well a single material products on the other hand can be comprised of multiple materials for example aluminium is a material and polyethylene is a material however raina
01:40:35 polyethylene is a material however raina bonds PE shown here for instance is a product consisting of two aluminium sheets separated by a gap which is filled with polyethylene even at this
01:40:47 filled with polyethylene even at this early stage of the inquiry Rena bong PE will no doubt be familiar to you and I will discuss this product in more detail in a few minutes it has been common to
01:40:59 in a few minutes it has been common to refer to Rena bond PE and similar rainscreen products as aluminium composite materials or a CMS the use of the word material in this context is in some ways a misnomer however because the
01:41:13 some ways a misnomer however because the word composite precedes the word material the name tells us that this is actually a product consisting of multiple materials another example of a product is Celotex RS 508 o which is
01:41:26 product is Celotex RS 508 o which is shown here this product is composed of several materials polyisocyanurate or PIR foam which is highlighted here a
01:41:38 PIR foam which is highlighted here a thin aluminium foil facing which is shown here and is on both sides of this material and a glass fiber mesh which sits within the PIR foam as indicated by
01:41:51 sits within the PIR foam as indicated by the lines shown here I will also return to the product Celotex Rs 508 o which is part of the Celotex Rs 5000 range of
01:42:02 part of the Celotex Rs 5000 range of insulation products later in my presentation with this distinction between materials and products made I will now move on to describe the different cladding materials and products used on
01:42:14 materials and products used on Greenville tower and their respective locations within the cladding system and I apologize this does get a bit repetitive in this section of my presentation
01:42:28 ACM rainscreen cassettes were provided on both the spandrels and columns of Greenville tower as highlighted here in yellow
01:42:42 ACM products were also used to form the ornamental architectural crown at the top of the building as shown here with
01:42:55 top of the building as shown here with substantial fire damage from a drone photo taken after the fire on the 25th of July 2017 with much of the crown now missing
01:43:05 missing the crown elements would have been configured approximately as I've shown them here before the fire the specific geometry and materials of the architectural crown are discussed in detail in my phase 1 report and will be
01:43:18 detail in my phase 1 report and will be the focus of considerable additional work at phase 2 for my presentation today it's sufficient to note that the architectural crown was comprised largely of closely spaced vertically
01:43:29 largely of closely spaced vertically oriented C shaped channels formed from ACM panels these were mounted on closely spaced aluminium rails which were
01:43:40 spaced aluminium rails which were supported off the original reinforced concrete parapet beams at roof level as we heard on Monday the ACM is at
01:43:51 we heard on Monday the ACM is at Grenfell tower were a product scauldron avant PE where the PE stands for polyethylene this was and is manufactured and sold by our Connacht
01:44:02 manufactured and sold by our Connacht architectural products this image shows the corner of a Rena bond PE panel taken from grenfell tower after the fire and provided to me by the Metropolitan Police Service it is comprised of a 0.5
01:44:16 Police Service it is comprised of a 0.5 millimeter thick aluminium outer surface which is bonded to a 3 millimeter thick polyethylene filler material and appointment and 0.5 millimeter thick
01:44:27 appointment and 0.5 millimeter thick aluminium inner surface to form the product into rainscreen cassettes flat sheets of the material are cut and folded
01:44:38 folded this image shows various different cuts and folds in a typical ACM rain screen cassette taken from Grenville tower after the fire and again provided to me
01:44:49 after the fire and again provided to me by the Metropolitan Police Service I would like to draw your attention to the exposed edges of black polyethylene material that this image reveals this
01:45:00 material that this image reveals this image is showing the back of a typical rain screen cassette by which I mean it is showing the face of the cassette that would have been looking into the ventilated rain screen cavity the black areas in this image therefore
01:45:13 the black areas in this image therefore present surfaces of polyethylene that would be directly exposed to any flame or heat within the cladding cavity should a fire penetrate by essentially any means into the cladding system two
01:45:27 any means into the cladding system two different colors of polyethylene are present in the Rena bond PE ACMs used on grenfell Tower the black polyethylene that I've shown here or a light light
01:45:38 that I've shown here or a light light colored translucent polyethylene which I've not shown testing will be undertaken at the University of Edinburgh to assess if there are any discernible differences between these two different colors of polyethylene in
01:45:50 two different colors of polyethylene in terms of their reaction to fire next I'd like to look at the PIR foam insulation products that were used at Greenville
01:46:02 products that were used at Greenville tower where PIR again stands for polyisocyanurate some of these products are also visible in this image in the
01:46:14 are also visible in this image in the locations where the ACM cassettes again have been damaged or removed by the fire for instance we can see some insulation here and here
01:46:26 most of the PIR foam in this photo has had its external aluminium skin removed and has been charred on its outer surface during the fire thus having a darkened cracked blackened appearance
01:46:38 darkened cracked blackened appearance this charring behavior is significant as regards the manner in which PIR foams may burn and I will return to this point later in my presentation just to remind
01:46:51 later in my presentation just to remind you the locations of the PIR foam on my sketches of vertical slices through the building are illustrated in yellow here where you can see where PIR foam is
01:47:03 where you can see where PIR foam is located both above and below the window and within the window surround and again here around the column to the left of
01:47:15 here around the column to the left of the window in my horizontal slice
01:47:23 this image shows a piece of the PIR foam taken from one of the columns at Grenville tower and again provided to me by the Metropolitan Police Service visible in this photo are the PIR foam
01:47:36 visible in this photo are the PIR foam which is yellow in color and one of the foil faces I should note that the bottom surface of this product also has a foil face but it's not visible in this photo this insulation product is manufactured
01:47:49 this insulation product is manufactured by Celotex under the generic product name rs.5000 the specific product name is Celotex RS 5 1 0 0 where the last 3 digits 1 0 0 correspond to the thickness
01:48:03 digits 1 0 0 correspond to the thickness of the product in millimeters this image shows a piece of PIR foam insulation that was taken from one of the spandrel sections at credit felt tower again
01:48:15 sections at credit felt tower again visible are the PIR foam again yellow in color the foil faces again top and bottom and in this particular product a glass fiber weave within the PIR in two
01:48:27 glass fiber weave within the PIR in two layers as noted earlier this product is also from the Celotex RS 5000 PIR insulation product range and a grenfell tower this product was anchored to the
01:48:38 tower this product was anchored to the concrete spandrels in two layers each of 80 millimeters thickness as I've mentioned a specific product rate the specific product name is therefore Celotex RS 500 804 again the 800
01:48:50 Celotex RS 500 804 again the 800 represents a product 80 millimeters thick also on this photo we can see some of the polyurethane polymer spray foam that was present in comparatively small
01:49:01 that was present in comparatively small volumes I should say in many locations within the cladding in addition to the PIR insulation identified during post fire inspections at Grenville tower phenolic foam or PF insulation has also
01:49:15 phenolic foam or PF insulation has also been found on some areas of Granville Tower
01:49:20 sorry this product the phenolic product is not shown here has been identified as kingspan cool therm k15 and based on the available evidence accounts for only a
01:49:32 available evidence accounts for only a very small proportion of the insulation and only on a small number of spandrel sections of the building to further PIR foam insulation products have been identified during my post fire
01:49:43 identified during my post fire investigations of the undamaged and partially damaged sections of the building these were located around the window framing of the refurbishment windows as I've mentioned and are shown
01:49:55 windows as I've mentioned and are shown in this photo again provided to be by the NPS a 25 millimeter thick foil faced PIR polymer foam insulation board manufactured by Celotex this is shown
01:50:07 manufactured by Celotex this is shown top right on this slide and has yet to be definitively identified and a 25 millimeter thick foil faced polymer foam insulation board manufactured by kingspan this is shown bottom left the
01:50:20 kingspan this is shown bottom left the specific product name is yet to be confirmed although based on its markings it is likely to also be PIR thumb and from the kingspan Therma product range i've previously mentioned an insulation
01:50:33 i've previously mentioned an insulation product called pearl board this appears to have been part of the original construction of Granville Tower and was located inside the building both above
01:50:44 located inside the building both above both above the window on the ceiling as shown here and in a continuous band around the perimeter of all flats and below the window on the inside face of
01:50:57 below the window on the inside face of the reinforced concrete spandrel beams
01:51:01 these locations are indicated here in my vertical slice through the cladding
01:51:10 the pool board insulation is a polyurethane foam board the product is approximately 13 millimeters thick and is based on both sides with a paper
01:51:22 is based on both sides with a paper covering the pearl board on the internal wall of the spandrel sections was as already noted adhered to a layer of plaster board as shown in this photo
01:51:34 plaster board as shown in this photo with the pearl board being the top portion of this sandwich and the plaster board being the bottom I've not yet been able to determine if the pearl board on the ceiling was also faced with a layer
01:51:45 the ceiling was also faced with a layer of plaster board as I've been prevented from disturbing this product due to an apparent asbestos risk associated with the artex plaster on the ceilings around
01:51:57 the artex plaster on the ceilings around the windows are uPVC window framing boards that form the final internal finish of the refurbishment cladding system the location of these uPVC boards
01:52:08 system the location of these uPVC boards is indicated in this image here here here here and importantly as I've already mentioned here in a thin strip
01:52:25 this image which I've shown previously shows a portion of a uPVC horizontal windowsill and the vertical uPVC windows am by which I mean the side of the
01:52:38 am by which I mean the side of the window enclosure after the fire this is shown in my vertical slice again in yellow above and below the kitchen window as shown here and again here in
01:52:57 window as shown here and again here in my horizontal slice at the side of the kitchen window this slide shows a
01:53:08 kitchen window this slide shows a close-up image of one of the uPVC boards taken from Grenville tower these had a smooth surface and were approximately nine point five millimeters thick as
01:53:19 nine point five millimeters thick as already discussed there is an EP DM rubber weatherproofing membrane that extends between the edge of the refurbishment cladding window frame and the original reinforced concrete column
01:53:32 the original reinforced concrete column this is illustrated in this photo looking up at the building during the forensic deconstruction of the cladding that occurred following the fire such
01:53:43 that occurred following the fire such that the rain screen cassette and insulation boards have been removed from the column at the left-hand side of this photo the EPDM membrane is the material
01:53:54 photo the EPDM membrane is the material highlighted here in yellow as you can see this is a flexible sheet which was which was adhesively bonded to the existing reinforced concrete structure
01:54:06 existing reinforced concrete structure the EPDM rubber membrane is highlighted in yellow in my horizontal slice drawing to the left of the kitchen window here
01:54:21 this image shows a role of the EPDM rubber membrane and a single sheet of the material both taken from Grenville Tower and provided to me again by the Metropolitan Police Service this product
01:54:33 Metropolitan Police Service this product used the section the product used in the sections of Granville Tower that I have inspected is one millimeter thick as shown
01:54:50 the window infill panels as I've already discussed are the non glazed sections of the window units and are highlighted in yellow in this image these are comprised
01:55:09 yellow in this image these are comprised of two sheets of aluminium each with a thickness of two millimeters and a polystyrene foam insulation core 25 millimeters in thickness and this is
01:55:21 millimeters in thickness and this is shown here the smaller window infill panels that house the kitchen extract fans were similar to these if not identical in terms of materials and construction that concludes my
01:55:36 construction that concludes my presentation of preliminary evidence as regards the geometry and materials of construction of the refurbishment cladding at Greenville tower in the final section of my Part C presentation
01:55:48 final section of my Part C presentation I'd like to briefly describe the burning behavior some of these materials
01:56:11 in discussing specific material burning behavior which includes flammability ignition etc I will focus on those materials which I consider to be most
01:56:23 materials which I consider to be most important with respect to the Grenville tower fire please note that i'm using the word materials intentionally here at this stage of the inquiry I will avoid
01:56:34 this stage of the inquiry I will avoid commenting on the burning behavior of products other than to reiterate my previous statement that very little useful fundamental experimental data are
01:56:45 useful fundamental experimental data are available in relation to the burning behavior of composite products since most products again violate the basic assumptions of many of the existing experimental and compliance methods the
01:56:56 experimental and compliance methods the discussion below is therefore based on samples of pure material by this I mean a single material in the absence of coatings protective layers or incorporation into composite products
01:57:08 incorporation into composite products and this is actually a very important point this is because this is part of my preliminary evidence or sorry this part of my preliminary evidence gives a very brief introduction to the reaction to
01:57:19 brief introduction to the reaction to fire of materials that have been identified to date as being present in the refurbishment external cladding of Grenville Tower I will present selected
01:57:30 Grenville Tower I will present selected information based on data available in the scientific and technical literature rather than based on the specific materials themselves however in most cases the information available in the
01:57:42 cases the information available in the technical literature has a strong dependence on the exact material formulations and test methods used so at this point these properties and values are provided simply for the purposes of
01:57:54 are provided simply for the purposes of illustration I expect to study the burning behavior of a range of relevant products in considerable detail as part of my work ongoing work for the inquiry and also to comment in some detail at
01:58:07 and also to comment in some detail at some stage on compliance testing methods which are currently used to assess the burning behavior of materials and products both of in the UK and in European regulatory environments again I
01:58:19 European regulatory environments again I will try to avoid technical language and jargon
01:58:23 jargon ever again the subject matter demands a certain level of technical terminology
01:58:31 most of the materials of interest in this discussion are polymers polymers are synthetic or naturally occurring compounds that have large molecules made
01:58:43 compounds that have large molecules made up of many relatively simple repeated units called monomers polymers are created by joining together the short monomer molecules to form long molecular chains as already mentioned a generic
01:58:56 chains as already mentioned a generic term to describe synthetic polymers is plastics polymers can be grouped importantly into two main types thermosetting polymers and thermoplastic
01:59:08 thermosetting polymers and thermoplastic polymers the differences between these two classes of polymers are in my opinion very important as regards the events that occurred at Greenville tower a thermoplastic polymer will melt and
01:59:23 a thermoplastic polymer will melt and can be deformed on heating and in some cases can be returned to its original form if heated under the correct conditions the polymer will also undergo pyrolysis and will directly produce flammable gases a thermosetting polymer
01:59:37 flammable gases a thermosetting polymer will not melt on heating but instead will thermally decompose by which I mean undergo pyrolysis these contrasting behaviors strongly affect how these
01:59:48 behaviors strongly affect how these different classes of polymers burned
01:59:52 upon exposure to heat a thermoplastic polymer will soften and melt once in a liquid state the polymer may break down into constituent monomer parts these may
02:00:03 into constituent monomer parts these may evaporate or pyrolyze to generate a flammable gas mixture it is also possible for the solid to undergo direct pyrolysis to generate flammable gases thermoplastics may spread fire by
02:00:16 thermoplastics may spread fire by burning as they flow or burning as droplets as I've already mentioned since thermoplastic polymers will melt and flow their reaction to fire is strongly dependent on their orientation when
02:00:28 dependent on their orientation when burning in a horizontal orientation a thermoplastic will melt and form a pool of
02:00:33 of liquid which will burn at a relatively steady state in the vertical orientation as I've already shown in part 1 of today's presentation melting and dripping will likely dominate the
02:00:44 dripping will likely dominate the burning behavior of a thermoplastic and as noted previously contribute to the formation of a pool fire at the base of or in front of the material
02:00:57 or in front of the material conversely thermosetting polymers do not melt and instead chemically decompose by which I mean pyrolyze when exposed to heat in this case the pyrolysis process
02:01:10 heat in this case the pyrolysis process produces a flammable gas and leaves behind a solid char the formation of this char means that some of the potential fuel is effectively locked up in the solid charm and is therefore not
02:01:23 in the solid charm and is therefore not available for releasing heat in the flame the formation of the char also reduces the rate of heat transfer into the material and as I've already mentioned the pyrolysis rate
02:01:35 mentioned the pyrolysis rate subsequently decreases consequently the gases may not be released at a sufficient rate to sustain a flame without some additional external source of heat and therefore the flame may go
02:01:48 of heat and therefore the flame may go out the heat release rate of a burning thermosetting polymer is therefore typically characterized by a high initial value as I've already mentioned which rapidly decreases due to the
02:01:59 which rapidly decreases due to the formation of a char layer I will now describe the burning behavior of some of the key materials found at Greenville tower in more detail both thermoplastic
02:02:10 tower in more detail both thermoplastic and thermosetting polymers were present within the cladding system in significant quantities as we have seen polyethylene was present within the Rena
02:02:23 polyethylene was present within the Rena bond PE ACM rainscreen product which was used extensively at grenfell tower both in the rain screen cassettes and in the architectural crown
02:02:35 architectural crown the polyethylene is highlighted here in yellow polyethylene is a highly flammable synthetic thermoplastic polymer upon exposure to heat
02:02:46 polymer upon exposure to heat polyethylene will melt and drip possibly flowing while it's burning or generating flaming droplets as I showed in part 1 of my presentation its melting
02:02:57 of my presentation its melting temperature is around 130 to 135 degrees Celsius and it's heat of combustion which to remind you is a measure of the total energy that a material is capable
02:03:08 total energy that a material is capable of releasing under optimum combustion conditions is about 46 mega joules per kilogram sure you will no doubt have noted in the commentary in the media
02:03:19 noted in the commentary in the media comparing the polyethylene material within the ACM rain screen cassettes Agron felt our two petrol or diesel this is likely to be on the basis as I've already shown that the heats of combustion of petrol and diesel are
02:03:31 combustion of petrol and diesel are similar to the polyethylene used in Renault bond PE ACM products is perhaps worth reiterating here however that the heat of combustion is only one of the
02:03:44 heat of combustion is only one of the important parameters dictating how a material burn as I've already discussed in some detail polyisocyanurate or PIR
02:03:57 in some detail polyisocyanurate or PIR foam materials were also used in significant volumes within the cladding system at grim felt our and this was as part of the for
02:04:08 and this was as part of the for insulation products that i've already discussed and which are shown here the PIR foams again highlighted here in yellow so makes up the bulk of these products PIR is a synthetic
02:04:20 products PIR is a synthetic thermosetting polymer which is primarily produced as a rigid foam it has a very low thermal inertia which you'll remember I discussed earlier it's
02:04:31 remember I discussed earlier it's material properties make it extremely attractive for providing thermal insulation in buildings however the very low thermal inertia of PIR as I've
02:04:42 low thermal inertia of PIR as I've discussed already means that it tends to have a comparatively low to ignition and will support rapid flame spread without protection from an external barrier for instance in aluminium foil facing the very low
02:04:55 aluminium foil facing the very low thermal inertia means that PIR may also accelerate flame spread of adjacent materials by preventing the loss of energy from the system by this I mean by insulating for example the rain screen
02:05:07 insulating for example the rain screen cavity and reducing losses thus possibly accelerating flame spread sorry if the supposedly accelerating fire spread the difference in terminology is actually
02:05:18 difference in terminology is actually quite important the precise formulation of PIR foams varies by manufacturer as does the manufacturers use of different fire retardants as a results comparison
02:05:30 fire retardants as a results comparison between products and the available technical literature is not strictly possible nevertheless to give you an idea of comparative hazard the heat of combustion of PIR is about 26 mega
02:05:41 combustion of PIR is about 26 mega joules per kilogram or about 60% that of polyethylene but this comparison must must clearly be considered in light of my previous comments noting the
02:05:52 my previous comments noting the potential importance of other burning behaviors I have already noted that phenolic foam insulation has also been identified in comparatively small quantities during post fire
02:06:04 quantities during post fire investigations at Grenfell tower phonology excuse me phenolic foam is also a synthetic thermosetting polymer and is also primarily produced as a
02:06:15 and is also primarily produced as a rigid foam with a cellular structure
02:06:19 like PIR phenolic foam has a very low thermal inertia and consequently it happy will have a comparatively low time to ignition and will support flame
02:06:30 to ignition and will support flame spread again when it's surfaces are unprotected as for PIR PIR the precise formulation of phenolic foams varies by manufacturer as does the manufacturers
02:06:41 manufacturer as does the manufacturers use of different fire retardants
02:06:44 specific properties of phenolic foam are given in my phase 1 report but there's limited value in discussing them in this presentation due to the comparatively small quantities that appear to have
02:06:55 small quantities that appear to have been used
02:06:56 been used vil tower polystyrene foam is used within the core of the window infill panels at grenfell tower as highlighted
02:07:08 panels at grenfell tower as highlighted here polystyrene foam is a low thermal inertia thermoplastic polymer and therefore rapidly melts at its surface
02:07:19 therefore rapidly melts at its surface when exposed to heat or flame once melted polystyrene foam typically forms burning droplets or burns as a liquid pool its melting temperature is about
02:07:30 pool its melting temperature is about 230 degrees Celsius and its heat of combustion is about 14 mega joules per kilogram again compared with polyethylene at about 46 mega joules per kilogram
02:07:46 polyvinyl chloride or PVC is a synthetic thermoplastic polymer with relevance to Grenville tower I am discussing rigid PVC commonly referred to as u PVC or PVC
02:08:00 PVC commonly referred to as u PVC or PVC u the you simply stands for unplastered meaning that the PVC is rigid at room temperature upon exposure to fire you PVC may char however its particular
02:08:13 PVC may char however its particular chemical nature means that its heat of combustion is lower than for many other synthetic polymers as a result its ability to spread flame is also comparatively less than many other
02:08:25 comparatively less than many other polymers its heat of combustion for instance is only about 18 mega joules per kilogram however the temperatures at which you PVC will soften and experience
02:08:37 PVC will soften and experience significant reductions of mechanical properties are very low in comparison with other construction materials as a result typical day to day upper service
02:08:48 result typical day to day upper service temperature limits for you PVC are in the range of about 50 degrees Celsius its melting temperature is between 75 and 105 degrees Celsius this is
02:09:01 and 105 degrees Celsius this is significant highly significant in my view in the context of printful Tower because as I've already explained you PVC windows boards form the initial
02:09:12 PVC windows boards form the initial barrier for flames to prevent fire spread from the kitchen of flat 16 into the cladding cavity beside the kitchen window this issue receives considerable
02:09:23 window this issue receives considerable attention in my phase 1 report
02:09:30 ethylene propylene diene monomer or EPDM rubber shown here is an elastomer or synthetic rubber the chemical
02:09:42 synthetic rubber the chemical composition of EPDM rubber means that it will burn no specific details were available regarding the combustion properties if the EPDM rubber used at Grenfell tower at the time of writing my
02:09:54 Grenfell tower at the time of writing my phase 1 report these will be studied by laboratory based testing you know on an ongoing basis thus far today I've presented quite a large volume of
02:10:06 presented quite a large volume of technical information I'd like to summarize the key points that I think are most important when considering the evidence as regards fire spread to and
02:10:17 evidence as regards fire spread to and on the exterior cladding of Grenville Tower with regard to materials and geometry the refurbishment external
02:10:29 geometry the refurbishment external cladding system at grenfell tower has an extremely complex geometry and incorporates a number of different materials and products many of the
02:10:40 materials and products many of the materials and products installed within the cladding system are combustible predominantly synthetic polymer materials particular features of the cladding geometry which I have described
02:10:52 cladding geometry which I have described during my presentation resulted in the presence of a number of vertical cavities and channels within the cladding and running the full height of the building from level 4 from at least
02:11:04 the building from level 4 from at least level 4 up to the architectural crown at roof level as already noted the architectural crown itself was formed largely from vertical channels of highly
02:11:17 largely from vertical channels of highly combustible rena bond pd ACM panels with regard to flammability and fire spread whilst all of the polymer bits Wells to
02:11:29 whilst all of the polymer bits Wells to all of the polymer materials present are combustible different polymer materials as I've explained can burn in very different ways and therefore prevent very different fire hazards
02:11:41 very different fire hazards under a particular set of conditions the total amount of energy available for combustion is described by the heat of combustion but there is no guarantee that all of this available energy will
02:11:52 that all of this available energy will be released under particular fire conditions a materials thermal inertia relates to how quickly its surface will increase in temperature when exposed to heating this has consequences for
02:12:04 heating this has consequences for ignition and surface spread of flame in particular in the materials with a very low thermal inertia such as PIR foam insulation are likely to spread flame rapidly particularly when their external
02:12:16 rapidly particularly when their external surfaces are not protected by a metal facing thermosetting polymers like PIR will char on heating whereas thermoplastics like polyethylene
02:12:27 whereas thermoplastics like polyethylene and polystyrene will melt this again has important consequences for the extent to which the total energy available is actually released during a fire and I've
02:12:41 actually released during a fire and I've Illustrated that again here with respect to the non charring and charring behavior of various polymer solids all of these ideas become will become important during this inquiry as we try
02:12:54 important during this inquiry as we try to unpick the respective effects both of the geometry and of the materials and products present within the cladding system at Grenfell tower these issues are central to understanding what
02:13:05 are central to understanding what happened at Grenfell tower and to ensuring that it can never happen again and that concludes section 2 of my presentation mr. chairman thank you very
02:13:16 presentation mr. chairman thank you very much professor this might be a convenient moment to take the midday break I know that part three fire spread will take a large portion of the afternoon so it may be convenient to
02:13:28 afternoon so it may be convenient to take an earlier lunch now whatever you're happy with well you've been on your feet for quite a long time would you like a break no sure yes yes right well we'll have a rather extended
02:13:40 right well we'll have a rather extended lunch break if we resume it too clock that'll give you plenty of time to finish your presentation minute city yes good well that's what we will do that will rise now and resume at 2 o'clock
02:14:03 you