155 - New Guideline for PV Fire Safety with Grunde Jomaas

Two years ago I had Jens in the podcast , who I thought cleared most of the misconceptions about PV panels , especially highlighting the role of the roof construction and treating them as a system . Then , sometime later , I had Radar from Norway , who was talking about building integrated photovoltaics , also reemphasizing some of the same thoughts as Jens did .

So with all this information out there , why there would be misconceptions anymore . And yet they are . Yet you see them every day on LinkedIn and around People not really getting what is the fire issue with the photovoltaic panels .

So here today let's try once again to clear the misconceptions around the fire safety of PV panels , and for that I've invited Professor Grunde Jumas from Frisbee . That's a part of ZAK in Slovenia . Grunde is my good friend , we do some research together and , most importantly , we are figuring linkedin out together .

Since he's 10 times bigger than I am on linkedin , I refuse to call him anything else than grunders and say , but yeah , we're having a lot of fun there trying to get some good communications to the people . And yes , communication , that's the point of today's episode .

I've invited Grunder to talk about PV not just because he has a decade of experience testing and experimenting with photovoltaics and the fire safety , not just because he's a great communicator , but his group , frisbee , has just released a brilliant piece of communication , a guideline on fire safety , photovoltaic panels on flat roofs , and this is the direct reason why

we are here today . We're going to discuss that guideline in depth , but you know not just what's written inside we're going to talk about . Where did all of this come from ? What is the experimental background for all the claims that we discussed ?

From the book and also other guidelines that exist out there , because that's obvious , that it's not just the sole source of knowledge . I think this episode will be very beneficial if you have to deal with PV panels and if you don't , well , perhaps sometime in the future you will , so still worth listening .

It's very good to listen to this episode having a PV in front of your eyes . I know many of you will be jogging or driving , so that's going to be harder , but if you have ability to open up the guideline and just look at the contents as we discuss them , I think it's going to be much better experience for you .

The link to the guideline is in the show notes and the podcast episode is right behind the intro . Let's spin it up and jump episodes . Welcome to the Firesize Show . My name is Vojtěch Vyngřínský and I will be your host . This podcast is brought to you in collaboration with OFR Consultants . Ofr is the UK's leading fire risk consultancy .

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Get in touch at ofrconsultantscom . Hello everybody , I'm here today with Professor Grunde Jumas from Frisbee Project in Slovenia . Hello , grunde , hey , wojciech , good to see you , sensei , on the podcast . Happy that you joined us . And the topic is of great importance , that's the photovoltaics on flat roofs .

The direct reason is a guideline that your group has released something like a month ago . Tomorrow there's a big webinar , from what I've heard , and I know there's a lot of interest on PV panels in the fire science community . Thanks for getting on this important subject , but what made you do the guidelines ?

What was the inspiration to put the knowledge into a guideline actually ? Well , I guess the direct answer was , as you can read in the guideline , it came as a result of a meeting that was held in Brussels last year , hosted by NFPA , fm Global and Rockwool

And also the second part is that we can't escape this in a discussion between the two of us LinkedIn our friend and foe in a discussion between the two of us linked in our our friend and foe , I could see from a lot of debates there's a lot of things that people don't get that say that I take for granted some key concepts that we try to portray in the

guideline , where people think that , oh , it's the bitumen that is the problem , or it's this specific membrane or it's this panel that is the problem .

Science Show , jens was your PhD student . He'd done his PhD on burning the PV panels , basically on different membranes , different settings and what you just said . You know , he kind of cleared that out right . There's paper out of that , many papers out of that , there's his PhD thesis .

You could argue that the information is out there for anyone who is like a Google search away from that information . Yet people would still share the misconceptions . Yet people would still not seek it .

But it also because the the number of times where I've copied jens's googleolar page and put it as an answer to people in questions on LinkedIn . I say just go here , the papers here are telling all of this . Or , similarly , check out these papers by Raida , check out these people by the group in Malaysia and their references , of course , and so on .

But it is amazing how many times you have to say some things . And it's actually interesting because you say Jens is PhD , but Jens actually did also a master's on the topic at BTU that started , and before that we did an industry project and that started it all .

And I talked with another former student just some months ago where I said , oh , can I use this video ? And he said , well , I don't know if it's really in the public domain , I have to check with some people . That probably don't work here , but it's almost 10 years ago and I said because I wanted to show it .

And he's like , yeah , the thing is he said we already had the answer at that point , we just didn't know it . So you know , it just shows how it's a slow process for the messages to get out there and for people to get the details .

And of course there are many stakeholders that also don't necessarily want to have the debate , that want it to be communicated the way it is . So they try to dilute the information pool a little bit . And you know there's nothing wrong with that . So to speak , everybody has the right to promote their own solutions , as long as they're safe , I guess .

So and I say that because I first wanted to complement the guideline it's a great piece of communication and we will come back to this point many , many times . So we know where it came from . Tell me what it's about , what is in the scope and perhaps what important parts are not in the scope of this document .

But the authors , the main authors , are Nick Russ , alessi Huguet and myself that have been writing this and , with all due respect to a lot of it comes from compiling existing information and this is one of the main . You know , I guess we had the three maybe main goal of the guideline .

One was it shouldn't be too long , it should be so people will actually read it . There are other guidelines that are very good . I'm not criticizing them , but we know that people just put them in the drawer because they're too specific , they're too long , too many recommendations , and so we wanted an overview guideline , not an installation guideline .

It's not an installation guideline . We wanted it to be well documented . Hence you can see we have two pages of small font references with links and we wanted it to create an overview , holistic overview that touches from sort of like the start .

So hence we have the figure where we talk about the ignition hazards , the fire dynamics , the roof construction and the firefighting operations . And then we go . We try to be sort of pedagogical about talking about these four aspects .

It's for PV panels that are placed on the roof , so not as a part of the roof , and also for fire hazards that would start mainly in the installations or in its vicinity , not as a part of the building fire that eventually spread to roof right yeah , so so that's why you know we start .

We do have a figure where we explain that you have a fire that can start inside the building and go to the roof and you have a fire that starts on the roof , and predominantly we focus on the ones starting on the roof , because the ones that start in the building technically should be dealt with already through building regulation on the roof , because the ones

that start in the building technically should be dealt with already through building regulation . That is of course , not always the case , but then you can't always then see . You know , it's important also to not blame solar or blame things for things that are are not part of the root cause .

But at the same time , the frontispiece is a picture from the Asko distribution center in Norway and that fire started inside the building and it spread to the roof and because the fire section walls didn't extend up through the wall , it spread along the wall and then into another fire section , so it became a very big fire .

So that is a route and that's where , of course , the PV panels played a significant role , because in other circumstances the energy would just be vented up and you wouldn't have spread across the route . But then we do focus on this new ignition source , this new system on the roof that can lead to fire scenarios there .

And yes , we don't talk about building integrated pv vip , it is building applied photovoltaics . And when you say flat roofs , some people ask me recently oh , is there a big difference with slope roof ? There are some many similarities , so it's not like that's a whole new chapter to do .

You can actually see some of the work that's been done by Rise Fire Research in Norway . We mentioned Reidar . One thing with the slow proof for example , they did some testing with bitumen was that then you had the flowing of the bitumen , but as a system .

They've also published , I think , some things in PV Magazine and some other places where the whole thing with the critical gaps , the ignition , the spreading and so on are on a membrane that otherwise doesn't lead to power spread are

very similar . But there are some nuances .

So perhaps let's use this framework also in this discussion . Let's start with the ignition hazards . Let's start with the ignition hazards . So you've been a part of a team that was investigating the probabilities or the statistics of rooftop fires , so let's perhaps start with that how often those fires happen and how did you figure out a number ?

You know , to some extent we've been lucky that it was very timely and we started way back when I was at DTU 2015 , 14 , almost . There's been 10 years of doing some of this and it's not that we were groundbreaking in that sense , because you have the work done by Backstrom and UL and things going back .

Also , you can see some of the reference we have to Cancellary and SM Global's documents . But anyway , so we did this work with a group from Malaysia you know Saputria , and it's difficult to get good numbers . Yeah , Because a lot of it's based on media reports and does big graze salts , because what's reported in media is maybe just big fires .

Nobody will report a small house fire and so on , but they're , you know they're . What we ended up with in that paper was to say that to a reasonable extent , we said 29 fires per gigawatt per year , per gigawatt installed . And some people say , oh , you know how much is this . And , yeah , what does the number mean ? Actually , possibility ?

Somebody said you know , there was uh , this a few years ago , the fire at uh in bristol that we are the curious museum and somebody going to oh , it's a freak incident , it's only 0.01 chance of a fire . And then somebody in the comments said well , there's about I about I don't know like 2 million solar installations in the UK .

So if you multiply that up , that means that you should have about 200 fires per year , which corresponds quite well to the fire service saying that there are several times a week are called out to PV fires . So it is not a small problem because in risk theory you often want to go to 10 to the minus 6 , not to 10 to the minus 4 , which is 0.01% .

So it is actually a significant problem in many risk aspects and this is what we also see . You know there's a figure there that we took from the Clean Energy Associates , where they had inspected 600 sites worldwide and I think they came with something like 96% of these places had some mistakes and we've shown .

You know the 10 main things related to grounding issues , damage module , cross-mated connectors , the list . You know there's 10 main issues . All of them are as high as 50% and more than 20% . So combined there's a big , very big chance . And people ask you know , but why ? You know , you know , you just have to do it right .

But if you think about it , some of these things have 2000 , 3000 , 4000 panels on a roof , maybe even more . You know more than that and imagine the labor to put all of that together , that all those operations , all those connections , that there's not a faulty connection , that there's no poor workmanship or poor maintenance in all of this .

You have movements due to wind , snow , load , things like this that can create a strain . So there , you know the main , there is a too high of a probability right now .

So this , this is what we also go all to do , this nfpa 550 , fire concepts 3 , where we say we need to work on the consequence , we need to work on and on the probability frequency of the fires . So the frequency , you know , this is the ignition and aspects of that and that is too high . But we in the guideline we tone that down there .

That's done a lot elsewhere and I'm also no electrical engineer , so . So the details of all of these things we defer to other places where people look there are german , you know , from vds and also from fire protection association . They have long things with pictures of all kinds of installations and all kinds of faults and errors people can do .

And if we were going into that detail , I think we would lose the overview , the holistic part , which is the main aspect for us .

But in most of the work jens did , we used even a metal plate and and we even in the experiment I mean where the first , very first approximation experiments I did back in den Denmark 10 years ago or so we actually just used some glass wool and we saw the same thing .

Hence my former students said we knew the answer that it wasn't the panel that was the problem , it's the system , it's this Physics is the problem , the physics , the fire dynamics is the problem . So well , so we knew . So that's what we chased and that's what ended up with all these very nice papers .

Also we have to commend he worked with some very good students Ben Jacobs , farah from IMFSC , where they were doing their master's theses . Working with Jens , we also had Ming Chang from also I'm a C student who recently completed his PhD now at Ghent University . So so we had also other people in in that work .

Just to highlight that that contributed to the knowledge . But that's , you know , the focus . There was the fire dynamics . So if you move into , you know in the guideline , from the ignition where , yes , we , I think what the ignition , where , yes , we're igniting . What we're igniting is typically we're igniting the membrane in the experiments we do with CRIB .

But some people have been , oh , why aren't you not using an arc ? And the reason we're not using an arc ? We have actually done the arc and gotten the same results . The wood curve is more repeatable and we get the same end result . And also , of course , working with high currents and voltages can imply some other risk assessments in a lab environment .

And finally , we can see that when people say , oh , but are you sure you're not making it too big , well , empirically we see the fires on the roofs that we see in media .

So whatever ignited them led to spread to a thousand panels , two thousand panels , so that we are spreading from one panel to another , is empirically shown time and time over in those rooftop fires .

So we're not making an overly big crib , we're actually quite a small that ignites the membrane , creates this feedback system that is again shown with these nice figures . I , you know we have them recreated here , but they're figures made by Jens in his PhD . Again , the whole guideline , as you can see , is type sense . So all the figures .

We have references to many other places where we've done it , but we wanted the uniform expression instead of copy and pasting and then using other figures . And it's the first time I've done that in the sense to have the luxury of working with the typesetter and getting everything uniform , because I , you know , I'm terrible with graphics myself .

But so , instead of having this is the figure from this and it looks completely different than the figure from Canceleri . And here's the figure from Clean Energy Associates . And here's the figure from BRE . And here's the figure from there . We have the benefit of working with a very good typesetter that put this all together .

So we look at this figure in the guideline , figure six , where , if you do a woodgrip , so that you know , let's backtrack a bit when you build a roof you have some insulation typically , and then you have a roofing membrane and before PVs were put on roofs and European Commission told us that we need to put them on the roof , or you know , there's not just

the European Commission saying many people want to do it because energy prices are costing an arm and a leg , as they say . So the tests have been done , that the roofing membranes , if you have a burning brand , if you have a small fire attack , they shouldn't spread the fire across there . So you have these roof tests with the T1 , t2 , t3 , t4 .

Commonly , if you pass T2 , you will also pass all the other ones . It's the one that's most stringent in that . So we show this that , yeah , we use the membrane , we use the builder . With a crib it doesn't show , but then you put the panel above it and then they have an edge . So you gather some small .

There may be a little bit of combustible material on the panel , but you get the heat feedback . You get re-radiation you on the panel , but you get the heat feedback . You get re-radiation . You have a flame that extends also up against a slow panel . So you get a bigger flame area , a bigger radiating area , and that preheats the membrane .

That is then releasing enough paralysis gases that you can have a thermal runaway . You have a progressive set of ignitions , which is fire spread .

know , a flammable material . Yeah , so there's no , there's no surprise that they burn per se , but they're constructed that when they're put flat they don't spread flame . I think similar with carpets if you put the car particularly and ignite it at the bottom , many of those would burn . That don't really spread the fire while lying flat on the on .

put a bunch of steel and then the wool on top of that , which is non-combustible by definition , and suddenly your B-roof approved membrane becomes a hazard . Precisely say that the intended use of that membrane has changed , because it was intended to use in an open air and now it's used under a roof as a part of a mini compartment . To be honest , exactly so .

Hence we need to go to a roof construction and eventually maybe also have different firefighting provisions . But so when we go there it is a key point that you're saying that I don't think you know in that sense that a membrane is a culprit . It's not a panel , that's a go . I said that before .

It's important to point out that it's not this or that or this , it's a system . We just changed the rules of the game . Take a , you know french open is going on .

If we all of a sudden change the height of the net or the length of the of the playing field , or if we say shorten it even more , so they would miss the field all the time because they're programmed to hit this and that's sort of the same .

It's not something you can say blame them for , and that's because you can see also in if we go to figure seven . But those are from experiments .

We also did part of jens's master's thesis , actually , and others have done the same to show that if you spread under the panel , but when you get to the edge , it doesn't spread , because this was the target that the membrane was set up to test for .

I mean , they're tested from fire safety or maybe not creating an arc or having some flame retardant in the cables and a small amount of combustible in the panel . But all of that , this is Senelec , this is electric regulation , and now we bring that in and go into the roof regulation . And now we bring that in and going to the roof .

And a point that somebody is smart pointed out is now that we are requiring or are required in the eu to put pv systems on the roof , shouldn't we then have a test ? Shouldn't we then have some regulations that include this as a part of the building ? And there you go .

And it's interesting because the BIPV , the building integrated , is a construction product and that's tested according to European standards . But for the system we're in now because it's building applied and where it gets . Then you said sloped roofs or even flat roof .

If you were to do a building integrated photovoltaic on a flat roof , you would have to test it according to construction product regulations , you know , according to a building product , but if you lift it up a little bit , you go there by . You know . Similar with facades or a piece of oh , it's a rain screen .

It's not part of the building , so it's like one of these . We know this is a problem . We've seen it in so many places before . The tests are not testing what they should . The test is currently wrong . We need to do something about it .

the wall . The wall is fire resistant and meets all the regulation . It's not spreading the fire . And then I just put a few plants on top of that , like there is no law that forbids me to decorate my wall . And this is kind of annoying because again , the same case as something that's certified for intended use , suddenly the use changes by the user .

One thing if you mentioned the fire spread on the PV arrays , when you mean PV array you don't mean like one bay of PV panels , you mean the entirety of the roof that's discovered by PV panels , because the fire can jump between the smaller arrays , right that's also something when we get to say then the roof construction , or you know chapter three here , we know

flat roof construction with PV systems , construction with PV systems .

When we renovate them , then we're dealing with some of the constraints of the past , potential errors of the past , and so you don't want to go into the facade . But then when you look at an array , an array is a set of panels and on the roof we have it . Even in table , two different insurance companies and guidelines .

They say , oh , it should be 40 by 40 , 45 by 45 is the max . And then you have to also have a separation between these . The separations are one or 1.2 , two meters .

But the reason fires show that those separation , separation distances , the way we build , are too small , because the fire spread , it gets big enough that it just sort of blows by like in a wildfire . You have a too small of a fire gate and then it just jumps across or there's a burning brand or whatever that's going .

It feels like more like an access gap , you know , a space of sufficiency so that a person with a set of tools can walk between them . It doesn't feel like something that would do a big difference in a fire intuitively . And seeing the fires , the images of the fires on the rooftops , you can see those flames extend for many meters .

There's one guy down in BDS that gives you more than five meters and that sounds more like a fire meant separation between the arrays , exactly so .

But of course , as you point out , if you start building separations there , do you lose part of this thing of . Well , I wanted to run a pallet there when I'm installing it and I have thousands of panel .

You know , people are obviously operate with pallets and pallet trucks , or quite often at least , because they don't want to carry them one by one from the edge . So it becomes a practical manner too of how you build it up and maintenance . Well , if you have countries where you have snow load or other things , you want to be able to navigate between them .

So I think you're right . The main driver for this has been to have some distance . But you can see that the VDS or CDS from Germany 2234 , they say more than five meter . I think we didn't put the asterisk , or I think they have the asterisk , that it or engineering solution or something .

If they could prove and then the size of the arrays , so you can see , are typically around 40 by 40 meters , and this is related to spraying distances for hoses . Okay , there there's . Actually was a fire not too long ago in the U S .

To show this completely the the roof was covered all the way to the edge and , all you know , on three sides and the firefighters can only enter the roof from one side and then they're almost like they're on their phone because they're like we can't reach that and we can't . You know the burn , the roof has burned . We can't walk across it .

We don't know the structural stability of the roof at this point .

You know where they have to drop the foam for a very , very long distance and they actually can do that , but it requires completely different equipment than from what you have you would have been using on a building firefighting .

I think it was something like nine , nine thousand square meters involved in the fire . So they actually you , yeah approach it in in a different way there you probably can throw a fireball much further than water and perhaps I see you want to go to the fireballs . I'm not , I'm sure , not sure we're ready about it , but they are .

They're quite quite something , quite something exactly , exactly , um .

If you have a highly combustible I'm going to throw it out there you know a lot of the roofs have EPS and we have shown quite clearly that because of the change scenario with the buildup , that you will ignite the EPS in that situation . So you need a mitigation and that could be . There's many options for the mitigation layer .

There's non-combustible , there's even hard roof , there's even you know , you can do metal plates , you could do insulation types , you can do different thicknesses of insulations that you , uh , you can do . You could do gypsum boards .

In the end , there's many other constraints that will also play in for that , because I've heard a number , like in the uk , that there's 30 percent of the existing roof that can't even afford the weight of a glass , glass panel . Okay , that's , they're so lightweight construction . This is why you also may have the .

You know they're very lean constructions so you're getting down to oh well , we cannot install this . So it comes down to what can you afford ? You know how thick , or because it's a heat transfer problem in the end . So you're like , oh yeah , well , I'll just use a big thick this and that on top and nothing will happen .

And and that could be good from an energy renovation perspective . You can do two things at once , that you improve the energy efficiency of the building at the same time as you're putting the the pv panel on top . But so you know .

So we , we recommend or say that you have to do preferably a non-combustible insulation , but if you do use other solutions , that you should test them . Okay With the panel . Yeah , test . As you know , it's a system , so test it as built .

You know , it's Alliance , axa , risk Control , risk Association , zurich , generali , fm , global . They're very active on this , which is again when people say , oh , why are you talking about this ? It's not such a big problem and it's like well , I don't think the insurance companies are talking very much about things that are .

You know , if they're very interested , I guess they have recognized that there is something that they want to do about it .

But I guess this creates another dynamic with the wind yeah of course you do have these other constraints that come in .

So it's not just like a one-way road because , unsurprisingly , if you have a vertical panel not much happened because you don't have a chain fire dynamics and they're non-combustible , so it doesn't change .

But it's not like you go then to certain angles and it gets worse to the point where you go then to certain angles and it gets worse to the point where you go to the flat , because actually the flat is somewhat better than the angled one , and that has to do with when you have an angled one you have an easier flow route for recirculation , you have some

buoyancy going up , you have a longer flame extension along the panel and then you get to you . We established some critical gap height . But there's very nice work and very nice scientific engineering result .

The problem with it is that everybody then wanted to have a talk . What is it ? Is it 11 centimeter ? Is it 12 centimeter ? And it's the system . Again , it's the system . It depends on ? Which type of membrane do you have ? Which type of panel you have ? Which type ?

I guess you've done that with the green facades , but also all of the work you have done with the car park and ventilation and so on , where I'm sure people say so how big of a ventilation system do I need ? or or which car park will work what height of this then and you're like , yeah well , it's higher .

Yeah well , they can tell you higher with good certainty . But or as I often end up saying , it depends . But it's a case by case . It is engineering that is needed . It is not something you can take off , just the shelf solution , I say , but that's a .

You know , when people have said what we we're getting , to some extent we're getting to the firefighting and maintenance and some of these things that we also discuss .

But on this thing people have said what's next in terms of research and the fire dynamics , the ignition , one of the things that , after the work that Jens did , he focused mostly with PVC membranes . There's a lot of different membranes .

So we're trying testing the different membranes , also getting nuances of the different panels , but basically also trying to really look at , maybe through testing , also get some solutions that we know work , because we , you know we're going to have this unprecedented change of the roofs in Europe and around the world .

They don't have to per se , but it's the natural driving thing because it is a good solution in most asp . So we need to , you know , if we can have a couple of work solutions that we say , if you build it like this , you'll be fine , it may . And then people say , well , but that doesn't work for me because of these and these constraints .

sometimes easiest , is to remove someone's else objective , you know , turn something into non-combustible . The membranes are combustible for a reason because they're damn good waterproofing materials and it's hard to find a non-combustible waterproofing material that creates matrix as good as PVC or vitamin . So there are reasons for those things to be combustible .

It's our job to figure out .

Uh , when you have pv and and the membranes that are like we have them now , that have been perfected for 25 year , whatever lifetime , or and you know all of the conditions that the membrane should do , and they're like , that's very , very difficult because you know it comes down to changing chemical compositions , uh and so on , and and they , they know the

constraints with all the these products , they know which uh parameters to choose . So that's why we need to when we talk again about , you know , a mitigation layer . And I realized I was just at a conference in the Netherlands , at the NIPV , and one question was so what is a mitigation layer ? I said I need to explain that better .

So what is a mitigation layer ? I said , well , it is what you have between the membrane and and whatever you have below .

You know it could be many different things , but if you have , so you only have a mitigation layer if you have , well , for the most part , if you have an existing construction with , say , highly flammable insulation material and again I'm going to say it's eps , and that's when you you really need the mitigation here and and it can be many , many ways to do that

, so you can look it up there's many , many suggestions for how to do that , because it is getting recognition that , yes , the fire will spread across the membrane , but we want to protect the assets which is the building below . Quite a few people can tolerate that you burn some panels and you burn some membrane . That's actually reasonably easy to deal with .

But what we need to understand is what brings the difference of that being a small nuance to that being a big loss in the building . Because , as you mentioned , the membranes function well . The membrane one of the big thing is to keep water out .

If the membrane is burned and you start throwing water on the building uh many situations you have a lot of water entering where it's not intended to come you've segued me to important point , because the last part of your guidance is is related to firefighting . So why did engineers look into firefighting and what did the engineers find in that ?

The main thing is to I mean it goes in . The most quoted firefighter in the world recently is from the Copenhagen Fire Brigade , Jakob , where he said at the SFP conference after the big fire at Burson's like don't make our lives more complicated .

You know the firefighting fires is very complex , very challenging to begin with , and that's why , when we go for the firefighting for the roofs , we you know safe rooftop access , safe operations while on the roof and then a successful application of extinguishing medium . You know that they could do that .

And then you can retract and say you know that they could do that , and then you can retract and say , oh , how can we do that ? Well , so some of the things are related to don't put pv panels across the entire roofing surface . They should be able to enter the room from any of the four sides of a building and they should be able to walk around .

In terms of safe operations , people also , you know it's related to shutoffs or de-energizing the panel , Different ways to do that , and whether it's active application of a medium or whether it's main switches that you turn on and then you have extinguishing medium and that's a selection to what is most effective to do , and that's a selection to what is most

effective to do

. But if we backtrack because this is something I didn't get to before you ask it , do we have any fixed systems ? So one of the quite challenges now for firefighters , I would say it's very manual detection . So detection is somebody seeing a big plume in the sky ? Detection , is somebody seeing a big plume in the sky three kilometers away ?

They see it's a fire , but inside the building they may be unaware that the building is on fire . And and then you know that there's posting on . Linkedin will get you all the solutions in the world . Uh , so so you know there could be , you know cameras .

There's the drones , there's the monitoring of the performance of the system , there's linear line detectors , there's the flame detectors nothing new . All of the systems we know that exist and work in other places and that , of course , with an earlier detection , earlier alarm , maybe the fire can even be dealt by trained personnel on site .

In a big warehouse you will typically have staff that are building superintendents and they can have training to deal with this . And I've heard that maybe the ones with the really big warehouses and so on will deal with that .

And then you also have I've heard you know there are some developments for extinguishing systems and that I think will be , you know , a cost benefit type of interest , Because if you have four panels on your home , a little cottage , I'm not sure you want to necessarily invest in it .

But if you're a big warehouse with 10,000 panels and a billion at risk , if something happens happens , maybe consider actually that the insurance company may , may say that is something that they require , and of course , then you should also focus , as is where we end up is .

You need to work on the maintenance and you need to , you know like , because the maintenance will reduce the probability of this and also the consequences . There's bird's nests that can be growing up , there's poor connections , there's panels that have been moved , you know rodents going One of my favorites actually , recently I heard in the US .

You also need to look at bullet holes on the roofs . Yeah , well , because apparently on the 4th of July and other celebrations , people shoot guns and the bullet needs to land somewhere , and if you have a warehouse that is eight or ten football fields big , you know that very big landing area .

So apparently it's not so uncommon to have bullet holes on warehouse roofs in the US .

Where should people find it to to take a look at it ?

Uh , you will put a direct link , well , to the page but we can also directly exactly just a right link to the pdf document . I've also , you know , linkedin the tough to find , but I have published it on linkedin as well , where you can just click on the document there and people can take it from there .

And for those that can't figure out of those , then they end up emailing me or you to find it . Then we will direct them . Just to recap also , you know we have the so Ignition . So there's installation quality products . There are things also that you can install to minimize it , to protect the arcing or monitoring direct physical systems that you can use .

Then you have the fire dynamics and then the route buildup that you need to take care of and the maintenance and the firefight . So it's a balance of all of them that there are options , many options in all , and I don't think there's one thing that can solve everything . It's a combined effort .

But what we do say is that , from a general fire perspective , to say that we will never have any ignition , that's , I think , been proven in fire science that that is a wrong assumption or a very risky assumption to take , and that's why we recommend to have a robust system that can handle a fire in the case and deliver an outcome that you can live with

instead of facing big consequences . The nuance is that it's very , very little , which is why it required this very careful engineering , interaction by knowledgeable people , because you have a fire like the we Are the Curious in Bristol that museum that was in 2022 .

It's more than two years and it's about to open this summer and you have I've used in the talk and I think I will do in the talk tomorrow when I do the webinar If we look at two fires that , from the outlook , look pretty similar , one is a total loss and the other one opened a few days later .

So there's nuances and people may say , oh , that was lucky , it's resilience , that is resilience . Yeah , it's resilience and it's quite positive base because people know what they're doing To a great extent .

Grund also has his new project , the newsletter called the burning matters . There's , of course , a link in the show notes , and if you sign there every week , you're gonna get a new dose of interesting fire science , perhaps not in the podcast version , but also in a very accessible and nice format . So good job on that , sensei . That's something I don't have yet .

Perhaps I should one day , who knows ? Anyway , back to the content . This episode once again highlighted the role of systematic thinking . It's not PV that's an issue . It's not the building roof membrane that's the issue . It's the combination of both . It's the way how PV panels change the intended use of your roof .

Even though you may not realize that , even though that the testing regime does not account for that , even though that it seems trivial , but yet it does . It does significantly and imposes a ton of challenges for the building , for the firefighters , for their insurers , for the owners .

We have to take that into account and great that resources like the one presented today exist that help us do the job . There's not much more to add .

You really should read up that short guideline , because it simply covers most of the stuff that you need to know about PVs , and if you need more knowledge , there are links and references to more detailed guidelines out there . So a great starting point . If you have to deal with PV installations as a fire safety engineer , I would definitely start there .

And yeah , that's it for today's episode Once again , where I'm still in the mood of celebrating the third birthday of the podcast , still extremely happy that I am still here with you , and I will be here with you next Wednesday . I hope you will be there with me as well . See you there . Thank you bye . This was the Fire Science Show .

Thank you for listening and see you soon .