166 - Bio-based insulation with Patrick Sudhoff

Transcript

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Hello everybody, welcome to the Fire Science Show.

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The modern building environment is going through some sort of sustainability revolution, as you obviously have noticed around, with carbon dioxide becoming one of the enemies.

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One of the goals is to get rid of it or get rid of the carbon footprint, and there's a ton of new things introduced into the market that allows us to actually play with the carbon footprint of our buildings.

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One of such things are new materials, bio-based materials.

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They are made from living plants which grow.

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They take CO2 from the atmosphere, they store them inside and you cut them off and put forever into your building.

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Well, saying forever perhaps is a bit too optimistic, but at least they allow you to store this for quite a long time.

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And they have other benefits too.

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Now, the issue with those is obviously, as you can imagine, they pose new challenges from fire safety engineering perspectives.

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They usually exhibit different fire behaviors than mineral materials.

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And, yeah, because they're novel, because they've never been systematically studied, the amount of knowledge we have is quite limited.

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We can only base on some of our previous experiences.

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But it's not that you can always extrapolate from one material to another, not that we often have a choice, but, yeah, better to have science and experimental knowledge on the material property before you start placing it in your buildings.

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Now to close on that loop.

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As you can imagine, that's exactly what we have for you in today's episode of the Fire Science Show.

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We're going to be talking about experiments and new knowledge regarding bio-based insulation materials.

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My guest is Sudhoff from the DBI.

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This was a subject of his PhD.

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I actually love interviewing PhD students and young PhDs because they are usually very passionate about their subject and actually their knowledge is very, very in-depth, and this is the case as well.

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So, with Patrick, we're going to venture into the world of bio-based insulation materials and we're going to unravel some challenges regarding them.

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I can spoil that smoldering will be a big part of this episode.

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So sustainability revolution is coming to us.

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We need to insulate our buildings.

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We need to reduce carbon footprints.

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Bio-based insulation may be the answer.

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Let's learn.

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The fire challenges related to this solution may be the answer.

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Let's learn the fire challenges related to this solution.

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Welcome to the Firesize Show.

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My name is Wojciech Wigrzyński and I will be your host.

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This podcast is brought to you in collaboration with OFR Consultants.

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Ofr is the UK's leading fire risk consultancy.

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Its globally established team has developed a reputation for preeminent fire engineering expertise, with colleagues working across the world to help protect people, property and environment.

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Colleagues are on a mission to continually explore the challenges that FHIR creates for clients and society, applying the best research experience and diligence for effective, tailored FHIR safety solutions.

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Who would like to collaborate on fire safety futures this year, get in touch at ofrconsultantscom.

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Hello everybody, I am joined today by Patrick Sudhoff from DBI.

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Hello, patrick, good to have you on the show.

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Hi, wojciech, thank you very much for having me.

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We're going to talk about biobased installation materials.

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I don't think I've had that topic on my podcast yet.

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Materials I don't think I've had that topic on my podcast yet.

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So an exciting opening.

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And, of course, the world of sustainability welcomes us.

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So I hope this will be interesting to a large audience.

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And my first question is what made you pick this topic for your research.

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I would say it's quite unique actually.

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Yeah, that's true.

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So it's based on my master thesis, which I did at the University of Applied Sciences in Magdeburg-Stendal, also where the research I present here was carried out.

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And yeah, I was really fascinated by these flameless combustion mechanisms and so I wanted to dig into them because, as you mentioned, it's still a niche, but these materials are getting used more and more and we have to consider the combustion behavior of them, so I wanted to have a look at it.

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For us it was a very similar pathway with the green walls.

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We're doing a lot of external facades and green walls and it also lot of external facades and green walls and it also like felt.

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Oh yeah, this is a.

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This is an obvious direction that everyone is going in, in the world of architecture at least, but no one understands it from the fire perspective and, of course, fire behavior is not very obvious.

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So, uh, was the smoldering because you mentioned flameless combustion, you referred to smolderingering Was the smoldering immediately the direction of the research or was it an outcome of some experiments or work before?

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So in Germany we had quite some research projects regarding biobased insulation materials About eight to 10 years ago.

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There were some initiatives to extend the applic for, let's say, more Than Just Insulation.

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It covered not only fire behavior but also soundproofing, thermal insulation, sustainability, moisture protection and emissions.

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The aim was in general and there was a political will to force the extension of the applicability to examine the behavior of bio-based insulation in general.

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But of course the fire safety is one of the main aspects.

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What were the drivers for it?

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Green deal, eu policy, sustainability.

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Carbon sinks like all of the usual aspects.

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Carbon sinks like all of the usual specifics.

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I mean when we consider that buildings in total have a global CO2 impact of 15% or so and the insulation is one important measure to improve the energy efficiency, we have to consider which type of insulation we want to use, and in these terms, we have also to consider the gray energy, so the energy which is being used to produce the materials, and also the CO2 impact of the insulation itself.

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So when we talk about sustainability with the three dimensions environment, economic and and social aspects One thing is the environment itself, but we also have to consider the social aspect, and that means a fire safe, and the idea was to use more of these materials from an environmental point of view.

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But on the same side, we have to consider then some under safety aspects.

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But the applicability itself is an outcome of the U-factor how well it insulates the energy taken to produce the material and transport and everything and the overall CO2 impact, which I assume can be negative because that's common for biomaterials the insulative properties, how good those materials are, because I guess that would be a driver for many projects.

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You have to get specific EU values.

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You want to have your passive house, you want to have elite certificates and stuff like that.

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Does it match the commonly used natural mineral wool materials or polystyrene and so on, the usual pre-bio era materials?

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Yes, indeed.

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So, for example, if you consider the thermal conductivity, they have comparable values, maybe slightly higher values of 0.04 or 0.038.

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One advantage of the biobased materials is the low thermal diffusivity, so you have a quite high heat capacity and that's good in terms of summer heat protection, so they can prevent the heat to go through the wall for a longer period of time, and that might be important in the future.

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And yeah, other advantages are that they have a quite high moisture diffusivity and when you think about the humidity, the interior climate, it's good to have a material which is able to transport the moisture which is generated inside the building to the outside.

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Besides that, as you mentioned, we have compared to the mineral materials, the carbon storage.

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So during the growth phase we store, for example, wood fiber, co2 equivalent of 1.5 kilogram per one kilogram of insulation, and they also have better recyclability than other materials.

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I am going to be annoying to you, sorry.

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What about biological damage?

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You said they transport moisture pretty well, but wouldn't the moisture transport within a bio-based material be a reason for biological damage to that material?

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yeah, of course there are certain limits for the humidity, so you also have to make sure that the construction is itself is diffusion open, so that you will not collect the humidity inside of the construction, which would then lead to damages.

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But yeah, with, for example, a timber frame construction or also an exterior wall, in general it is possible to build a diffusion opening.

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I think we didn't define the biobased insulation materials, so maybe we can give a list of what type of materials are we using?

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Do you group them?

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How do you subdivide them?

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Yeah, so bio-based insulation materials in general are materials from renewable raw resources, for example, wood, cellulose, straw, hemp, jute, cork, wheat, seaweed, but also some fungal base, so mycelium or textile fibers are a source for the insulation.

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So, yeah, there are lots of different raw materials which you can use, and it depends, of course, on the availability of the material which you should use.

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In the Grand Design series they were using sheep wool.

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I loved sheep wool as an insulation material.

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Perhaps we can get into the carbon footprint of sheep wool at some point, but let's continue.

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Where do you put those?

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Is this like a general insulating material that you would put in normal places in your building?

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Where do you find use for those materials?

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There are different fields for the applicability.

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One is timber framing, so, for example, cavity insulation in load-bearing or non-load-bearing walls or ceilings.

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You can use it as roof insulation, like between-raster insulation, but also for interior insulation or soundproofing, or in terms of facades, when you think about external wall insulation, composite systems, for example.

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There you could also use these insulation materials or even for rear ventilated facades.

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Okay, so far sounds great.

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We have a material, bio-sourced, preferably from waste, negative carbon footprint, fantastic properties.

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It just burns, and that's when you come in with this research behavior.

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First, maybe let's start with ignition, like how prone they are to ignition, are they easy to ignite?

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Have you, have you measured that and have you analyzed any measures to prevent or safeguard them?

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yes.

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So when we talk about ignition we have to think about the scenarios which are likely to ignite them.

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We can maybe distinguish between a facade and a component or a component, for example a timber frame, wall or ceiling.

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The most likely scenario would be an external heat flux, so for example, a compartment fire which would lead to a thermal exposure of the wall and, depending on the cladding, for example a Gibson plasterboard or so you can reach critical temperature or critical heat flux behind them.

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Besides that, you can also think of other hot surfaces.

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So when you think about a chimney, for example, which could be close to an insulation material, that might be also an ignition source.

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And there are certain others, for example electrical fault arcs, which are, according to our research, not so likely.

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Likely scenario is either also a compartment fire, so an exposure from the inside, or maybe a garbage can, a burning garbage can on the ground, but also flying sparks from a neighbor's burning balcony would be a scenario.

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So these are the different scenarios we are talking about.

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Usually the material is encapsulated somehow and this is also then relevant for the ignition itself.

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So when we examine ignition temperatures we can distinguish between an exposed surface and also a long-term exposure.

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For example, we put some samples cubic samples in a hot storage oven overnight and 170 degrees were enough for a thermal runaway of these materials.

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So that might be not a realistic scenario for a wall or a ceiling, because it's three-dimensional and it's uncovered.

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But when you think about a long-term exposure, for example a chimney, the ignition temperature might be relevant.

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For claddings, for example, we have higher ignition temperatures of 300 to 400 degrees.

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With the thermal runaway you mean like onset of some sort of self-ignition.

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Biological or decomposition properties Like we know, like linen and cloth, will give you like self-ignition at some point because of the reactions there.

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So is this a similar mechanism?

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Yeah, it's not a biodegradation mechanism, also not based on the carrier also, but with the higher temperatures you have a certain heat release in your sample and depending on the volume of your sample and the surface, you have a balance between the heat generation and the heat loss to the sides.

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And there's a critical point that's kind of a critical ambient temperature also where you have, depending also on your cube size or on your sample size, have a high heat generation depending on the volume and compared to that, low heat loss on the sides.

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And then you have this kind of ignition, self-ignition, thermal runaway point Going back to your scenarios.

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I'm not sure which would worry me more the flashover compartment fire that eventually transitions to the wall, or a small like arc, or failure in electrical system.

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I think I would be more worried about the small one, you know, because if if my house went through the flashover I'm not sure if the fact if my hemp wall is still there or not is my biggest concern in my life at that point I probably could understand.

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I mean, as long as they don't contribute that much to the fire.

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But I assume that's the reason you encapsulate them.

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That's actually interesting that you've brought them so.

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You would say that in normal, everyday use encapsulation is the typical approach, like unlike wood where architects would like to have them exposed.

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I guess there's not that much sexiness in sheep wool exposed in your room, right?

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Right, that's true.

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So usually with timber framing, where you would use a cavity insulation like loose fill, blown-in insulation or even mats, you would have some kind of planking or cladding and depending on the thickness of your cladding, you have a certain ignition protection.

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For example, two layers of 18 millimeter Gibson plasterboard would protect your insulation for at least 60 minutes with standard fire curve and we also did some experiments with the natural fire curve, which considers structural fire loads, so exposed timber in the projects.

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But what you have to consider is when you have, for example, electrical installations, for example, a socket would be an entry point.

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So even when your cladding would be able to protect it, if you have a light switch or a power socket in your cladding, that's an entry point and that's where the 60 minutes might be, not the time which you can use as an ignition prevention.

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I wonder even, perhaps drilling a hole through the wall could be, in a way, an entry.

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Yes, right, have you tested various scenarios like that Sensitivity to those openings?

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Yeah, and so in the OPRA tech project so that's a project on the optimization of firefighting procedures, the optimization of firefighting procedures, where also the Institute for Fire and Disaster Prevention Heiratsberge and also the fire brigade Hamburg was involved we did experiments with several components and especially at these electrical installations or we could detect smoldering afterwards, and also, like you mentioned, a screw or something which is drilled afterwards into it might be a problem to the ignition prevention.

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So ignition prevention is one point, but you also should then try to limit the smoldering itself, the spread, and to enable firefighting mechanisms, because you cannot totally exclude a smoldering itself, the spread, and to enable firefighting mechanisms, because you cannot totally exclude a smoldering.

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Okay, now we're going to make the addition.

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How do you do that?

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How do you limit the smoldering in the wall?

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First of all, you have your studs, which inside of a timber frame provide some prevention to a spread.

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Of course it can also take over to another frame.

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We observed, especially in combination with OSP boards, that smoldering can also occur at these OSP materials and then that enables a spread from one frame to another.

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In general the smoldowing velocities are quite low, so inside of a component we have about 10 centimeters per hour.

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Of course depending on oxygen supply and the heat transfer mechanisms, but as a rule of thumb inside of a component we have 10 centimeters per hour.

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So it's quite a slow combustion.

00:21:10.190 --> 00:21:39.666
But still when we have undetected smoldering over several hours, that poses a risk not only to the separating function of a wall but also perhaps to the structure where I also can maybe recommend your episodes with smoldering of mass timber from Harry Mitchell or the timber column failure and the decay phase with Thomas Ganey and Jochen Sefus.

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Is this type of smoldering that you observe?

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Is this sufficient to trigger a smoldering in CLT, like you would say?

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It can transition.

00:21:49.744 --> 00:21:56.063
You said it transitions to OSP or the energies, or I don't even know how to define it.

00:21:56.063 --> 00:22:00.340
I'm not sure if you can speak about ignition temperatures.

00:22:00.340 --> 00:22:06.423
I guess there's some minimal energy that has to be to become an onset of smoldering in the CLT.

00:22:06.423 --> 00:22:10.981
So I wonder if smoldering in a bio-installation would have that.

00:22:11.849 --> 00:22:19.430
Yeah, so in experiments with components we observed that it can also affect, for example, a stud.

00:22:19.430 --> 00:22:32.439
So usually you would and that's also a thing to consider usually you would stop a fire resistance test after, let's say, 60, 90 or 120 minutes and then you would end the test and that's it.

00:22:32.439 --> 00:22:37.823
But in terms of smoldering, yeah, that's not the main issue.

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It happens after our primary fire event.

00:22:40.980 --> 00:22:47.104
So we observed after we put out some specimens out of the furnace.

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We put out some specimens out of the furnace.

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We observed then hours, six, eight hours later that the whole component was affected by the smoldering, and also stud between two frames can be affected.

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So that can be an issue.

00:23:03.838 --> 00:23:05.201
Yes, With this test test.

00:23:05.201 --> 00:23:10.371
Is this referring to k2 uh fire resistance glass, or is it something different?

00:23:10.872 --> 00:23:21.094
so yeah, there were k2 capsule criteria is a thing which is used for the building code, but I mean with the k2 criteria.

00:23:21.094 --> 00:23:27.982
You would test it with not the insulation behind, but I think it's OSB or wood.

00:23:28.984 --> 00:23:29.365
Or brook.

00:23:30.993 --> 00:23:41.450
Yes, so we are also doing experiments just with the insulation between the cladding or an ignition protection to give it a value.

00:23:41.450 --> 00:23:55.241
The K2 criteria is used now in Germany to say something about the ignition and in the future we will also have more methods with the upcoming Eurocode, with the charring rate.

00:23:55.241 --> 00:24:00.461
Charring rate or key char to estimate the ignition behind.

00:24:01.390 --> 00:24:03.598
Because K2, I think at a point you can have 180.

00:24:03.598 --> 00:24:08.304
, and you've mentioned earlier a nonsense of smold smoldering at 170.

00:24:08.304 --> 00:24:14.426
So that's awfully close, even though it's just, like you know, a single point and perhaps end of the test and so on.

00:24:14.426 --> 00:24:22.171
But but still I don't have this comfortable margin of safety that I would normally like in my uh fire resistance stuff.

00:24:22.211 --> 00:24:23.534
Right yeah, right.

00:24:23.534 --> 00:24:36.962
So when you want to be sure, then I would recommend for 60 minutes two times 18 millimeters, and yeah, otherwise then you would have to do some more performance based design.

00:24:36.962 --> 00:24:41.781
That would be an alternative to use different setting types.

00:24:42.869 --> 00:24:49.281
And did you observe any transition to flaming after some time, like when you've reached the end of the sample edge?

00:24:49.281 --> 00:24:50.844
Yeah, actually yes.

00:24:51.411 --> 00:25:06.586
So we did experiments, for example with the component at the 1x1 meter furnace with the Gibson plasterboard on the fire-exposed side and the MDF board on the unexposed side.

00:25:06.586 --> 00:25:16.470
We just used 15 minutes of standard ISOCUR for the exposure, so we wanted to facilitate the smoldering inside.

00:25:16.470 --> 00:25:38.902
And then we took out the samples, placed them aside and you could observe with the thermal imaging, but also with thermocouples, that with this spread of about 10 centimeters an hour, sometimes less, the smoldering front reaches, or reached after some time, the outer surface.

00:25:38.902 --> 00:25:53.221
And then there was also smoldering of the MDF and after you had the hole burned through, there was enough air supply so that you have this smoldering to flaming transition phenomenon.

00:25:54.604 --> 00:25:55.105
Interesting.

00:25:55.105 --> 00:25:59.869
I wonder how that will scale to issues at the building scale.

00:25:59.869 --> 00:26:03.575
I mean, it's a difficult discussion.

00:26:03.575 --> 00:26:11.892
You know whether those phenomena are important, impactful or or not and I I I'm undecided yet.

00:26:11.892 --> 00:26:13.234
I I don't know if.

00:26:13.234 --> 00:26:41.769
If this is important at the building level, fire safety, or this is just a feature and we'll have to just live with that and accept that it happens, definitely must be a complication for firefighters to uh to investigate a scene after that, and I think the minimum required to use of materials like that is that the firefighters are informed that there actually is this type of material exhibiting this type of the behavior in your building.

00:26:41.769 --> 00:26:47.185
Regarding those recordings, you just recorded the surface of that, or or you had to cut it to find it, or you can see that there's smoldering happening behind the surface of that.

00:26:47.185 --> 00:26:53.970
Or you had to cut it to find it, or you can see that there's smoldering happening behind the surface board with some FLIR thermal camera easily.

00:26:54.550 --> 00:27:08.844
Yes, so we had FLIR thermal imaging on both sides of the component and additional thermocouples inside so you could really follow the smoldering from the exposed side to the unexposed side.

00:27:08.844 --> 00:27:21.884
But I totally agree that we're testing in a quite small scale and it's a different thing when you have a building and a whole construction, not only a wall.

00:27:21.884 --> 00:27:41.801
So I think we have to do more research in general on these materials, but also on these special phenomena like smoldering to flaming, because it's, in my opinion, still poorly understood what the critical conditions are for this transition.

00:27:42.270 --> 00:27:42.451
This.

00:27:42.451 --> 00:28:02.362
What you said is the part that kind of terrifies me, because you could have a fire onset of smoldering on one side of the wall and the smoldering transitioning into the other side of the wall where there can be a different compartment, different owner, you know, different person, and it could, like literally cross the boundaries between compartments.

00:28:02.362 --> 00:28:05.640
I think that feels very disturbing to me.

00:28:05.640 --> 00:28:10.221
How about the production of like what was produced in those fires?

00:28:10.221 --> 00:28:12.276
Are they very CO heavy?

00:28:12.276 --> 00:28:13.539
Did you measure that?

00:28:14.412 --> 00:28:30.259
So in general the smoldering fires are really incomplete combustion, so the oxidation is not very sufficient, so you have naturally a high CO, carbon monoxide release.

00:28:30.259 --> 00:28:44.057
We measured it in the lab scale where we observed quite a high amount of CO, and also in the larger scale experiments.

00:28:44.057 --> 00:28:49.265
We tried to measure the CO inside and outside of there.

00:28:49.265 --> 00:28:55.115
I mean it was not easy to measure it in a smoldering compartment CO.

00:28:55.115 --> 00:29:21.761
And we also know from different research that usually the cladding like a Gibson plasterboard or other OSB MDS boards that they have a high permeability or CO, so it can permeate through these materials very well.

00:29:21.761 --> 00:29:29.559
However, if it is a problem in a real scenario, it's the same with the smoldering to flaming.

00:29:29.559 --> 00:29:44.082
We would have to do more research on a real scale to see if CO really poses a risk, for example for people at the other side of the wall.

00:29:45.130 --> 00:29:48.621
How generalizable are those conclusions or observations?

00:29:48.621 --> 00:29:53.342
Because at the start you mentioned there are so many types of biobased materials.

00:29:53.342 --> 00:30:01.461
So perhaps let's reemphasize again what have you tested and let's try to think about how we can generalize them to other materials.

00:30:02.289 --> 00:30:19.643
Yeah, so in the more than just insulation research project, we focused on wood fiber, salinos, straw, hemp, jute and seaweed, and they all showed this tendency to continuously smoldering.

00:30:19.643 --> 00:30:27.163
However, there were some differences, for example regarding the smoldering spread rate.

00:30:27.163 --> 00:30:40.056
So you have differences between when you, for example, use the EN 16733 smoldering test stand, which is introduced in Germany, you have, let's say, 10 to 50 centimeters.

00:30:40.056 --> 00:30:48.462
Besides different materials, however, they all showed more or less the smoldering behavior.

00:30:48.462 --> 00:31:00.541
Yeah, I think there's no perfect bio-based material, at least not without modifications where you can say okay, this material doesn't show this behavior.

00:31:01.049 --> 00:31:11.420
I would expect that all like, say, bio-based insulation material is like kind of obvious that it would exhibit smoldering, Like you could expect that.

00:31:11.420 --> 00:31:23.059
Of course, the cases are what's the temperature at which it starts, what's the CO production, what's the smoldering front velocity or however you define that.

00:31:23.059 --> 00:31:26.391
But it's also like not gonna be a massive change.

00:31:26.391 --> 00:31:27.212
I think that would be.

00:31:27.212 --> 00:31:29.740
There would be different drivers for the choice.

00:31:29.740 --> 00:31:36.221
I don't think one would choose one material over another because it has higher smoldering onset temperature.

00:31:36.221 --> 00:31:42.021
I guess there would be different economical and technical factors that would result in in your choice.

00:31:42.021 --> 00:31:44.623
In your work you've also tried modeling that, or that was the the point In your work.

00:31:44.623 --> 00:31:51.061
You've also tried modeling that, or that was the point of your work to create models that allow us to capture those behaviors.

00:31:51.061 --> 00:31:52.596
Please tell me about the models a bit.

00:31:52.971 --> 00:31:53.171
Yes.

00:31:53.171 --> 00:31:59.384
So part of my PhD thesis is modeling of the smoldering behavior.

00:31:59.384 --> 00:32:35.244
And since we already talked about the complexity of this smoldering combustion, I think it's not enough just to do more and more tests, because we need to better understand the are, in the complexity, high enough to account for the transport and reaction mechanisms which will occur during a smoldering.

00:32:35.244 --> 00:32:58.896
My objective was to propose a model which takes into account both transport mechanisms, so speaking of the flow, the convective flow, the heat transfer, but also moisture transport, and they have to be coupled with the reaction model which considers the swoldering combustion itself.

00:32:58.896 --> 00:33:11.343
But of course, that are highly nonlinear mechanisms and it's not easy to have a model which can consider all these nonlinear mechanisms.

00:33:11.343 --> 00:33:13.778
So there's still some work to do.

00:33:14.470 --> 00:33:15.574
What was your basis?

00:33:15.574 --> 00:33:18.637
Like GPyro or you've developed your own model.

00:33:19.410 --> 00:33:49.417
So the basis for the reaction model was models for bulk materials, so for example, stockpiles, because we did some research before at the Ottil von Gehrig University in Magdeburg and the idea was, if this is also a high-porose lignocellulosic material, like when you think about wood pellets, is there a huge difference to wood fibers, for example, or not?

00:33:49.417 --> 00:33:55.275
Because the basic reaction mechanisms, basic transport mechanisms, should be the same.

00:33:55.275 --> 00:33:56.940
So that was the basis.

00:33:56.940 --> 00:34:18.875
But of course you have different properties and also in detail then a different chemical reaction or different kinetics which you have to consider, and I tried to implement this then in a in a console model to combine it with the transport model and this console model?

00:34:18.934 --> 00:34:26.965
do you connect it with, like cfd studies, or it's just a own model that just works on itself for now?

00:34:27.146 --> 00:34:30.375
it's limited to the insulation itself.

00:34:30.375 --> 00:34:42.458
So the idea would be to extend it and that would be also an aim here at the dvi to extend it to a full component or maybe a facade.

00:34:42.458 --> 00:34:52.659
But then you have to consider the surrounding layers, for example the plaster layer or the plasterboard or the studs and so on.

00:34:52.659 --> 00:35:04.342
And during the three years of research in this pure probit project, which was the basis for my phd, we achieved a model for the insulation itself.

00:35:04.342 --> 00:35:13.641
But the complexity is so high that we need models for the surrounding layers with the comparable complexity.

00:35:13.641 --> 00:35:19.041
And of course then you have at some point also convergence issues to deal with.

00:35:19.650 --> 00:35:30.469
Of course it's challenging, but I think this is the interesting part because, as you said previously, even drilling a hole or putting a socket for your electricity changes.

00:35:31.371 --> 00:35:49.005
So finding those critical locations which can be the onset of smoldering hotspot, which then can transition into propagation, and then again going back from the smoldering into flaming, I assume this would be also the pathways through which it can get out easier right?

00:35:49.005 --> 00:35:55.923
So if you have double plasterboard, it's also going to be the weak spots in the world through which it will go back.

00:35:55.923 --> 00:36:08.679
So to systematically study those, I think having a model that combines exterior, interior, the detailing would be a lot of fun and as a fellow modeler, I understand your struggles.

00:36:08.679 --> 00:36:13.561
It sounds easy but it's a lot of work to get that rolling.

00:36:13.561 --> 00:36:15.094
I sympathize with you.

00:36:15.094 --> 00:36:27.614
I hope that you'll achieve it because it would be very, very interesting and, of course, given the diversity of the materials that you're dealing with, having a model tool would also be very interesting for sensitivity analysis.

00:36:27.614 --> 00:36:37.369
Did you do any like modeling of the properties or figuring out the properties for modeling for those bi-based materials, based on some desktop studies perhaps?

00:36:37.871 --> 00:36:38.271
yeah.

00:36:38.271 --> 00:36:44.635
So the parametrization, the determination of the model parameters, was a big task.

00:36:44.635 --> 00:36:55.603
So if you have this transport model, for example, you have to have material parameters such as the porosity, the permeability, for example.

00:36:55.603 --> 00:37:00.987
And the interesting thing is for these materials it doesn't have to be isotropic.

00:37:00.987 --> 00:37:15.041
So, for example, the permeability, when you think of a board, it's a double times the permeability perpendicular to the fiber, so then parallel to the fiber.

00:37:15.041 --> 00:37:30.579
So the fiber direction, especially in boards, can influence not only the permeability but also, for example, the thermal conductivity, and so you have to measure then more than one direction.

00:37:30.579 --> 00:37:39.257
And also for the model it can be important when you have an upward smoldering that your permeability will be much lower, so you have more convection in that side.

00:37:39.989 --> 00:37:40.411
It's interesting.

00:37:40.411 --> 00:37:42.701
I wouldn't think that there would be a directional component to those properties, but very interesting.

00:37:42.701 --> 00:37:53.824
I wouldn't think that there would be a directional component to those properties, but very interesting, yes, and besides that, then you have to consider the chemical mechanisms, the reaction scheme.

00:37:54.250 --> 00:38:01.195
So we tried to figure out some basic reaction mechanisms or to reduce it to some which are necessary.

00:38:01.215 --> 00:38:12.184
Reduce it to some which are necessary, because when you think about chemical reactions there are a gazillion different reactions happening in a real fire.

00:38:12.264 --> 00:38:19.074
But you have to reduce the complexity to simplify it, otherwise you wouldn't have the chance.

00:38:19.094 --> 00:38:26.469
So we tried to use the fact that the material shows a different behavior in inert atmosphere and in air atmosphere.

00:38:26.469 --> 00:38:42.275
So, for example, in inert atmosphere you wouldn't have a self-sustaining smoldering because the heat generation would be neglectable and you wouldn't also have a fully degradation, would just have the pyrolysis in an inert atmosphere.

00:38:42.275 --> 00:38:58.679
But then when you add oxygen in different amounts, you will have oxidative pyrolysis, you will have char oxidation and that changes also the pathway from a chemical point of view and we tried to distinguish it.

00:38:58.679 --> 00:39:21.123
So we did lab experiments, not only thermogravimetric analyzers but also some hot storage, oven experiments, so with larger samples compared to TGA, where we also tried then to elaborate the difference between air and inert atmosphere and to take that into account for modeling.

00:39:21.123 --> 00:39:28.018
Because in a real component or in the facade you won't have your ambient oxygen concentration.

00:39:28.018 --> 00:39:42.050
You will consume oxygen, and so your reaction scheme will change over the time, and that's the thing your model should be able to consider to accurately predict the smoldering.

00:39:42.411 --> 00:39:43.597
Did you have a chance to match it?

00:39:43.597 --> 00:39:51.057
That's actually quite an interesting point because, as you said, gypsum would be to some extent permeable, but perhaps you would have different materials.

00:39:51.057 --> 00:39:56.079
Especially if we're talking about external facade, you probably want to have something not very permeable.

00:39:56.079 --> 00:40:01.530
Have you measured those internal oxygen concentrations and the conditions at which the smoldering is happening?

00:40:01.530 --> 00:40:08.570
Or this is just enclosed within the broad spectrum of the velocity of the smoldering is happening, or this is just enclosed within the broad spectrum of the velocity of the of the smoldering is just going to be slower.

00:40:09.371 --> 00:40:19.543
So, for example, we did experiments in the controlled atmosphere cone calorimeter, where you can adjust your ambient oxygen concentration.

00:40:20.052 --> 00:40:22.869
Ah, you have the expensive calorimeter Envy.

00:40:22.989 --> 00:40:46.885
You have the expensive calorimeter NV, yeah right, so to say, and we figured out that with the lower oxygen concentration, as expected, the heat generation will also decrease and at about 10-12% the heat generated or the oxidation is nearly neglectable.

00:40:46.885 --> 00:40:52.342
So you won't have enough energy to sustain smoldering below a certain point.

00:40:52.342 --> 00:40:59.563
So from lab-scale experiments I would say about 12% oxygen as some kind of limit.

00:40:59.563 --> 00:41:01.815
But yeah, of course that's better.

00:41:01.815 --> 00:41:22.523
Lab-scale experiments and the situation in a real component, component or facade are much more complex and you have not only the permeation through the Gibson plasterboard you have, you will have joints somewhere, maybe cracks, and that's also what might be difficult to consider in simulations.

00:41:22.523 --> 00:41:48.195
But yeah, we have to somehow try to simulate the fire behavior to get a better understanding of what happens inside the material, because during a small week we cannot look inside and the model helps us to better understand it, even though it might not replace a full scalescale test, but it helps to understand it better yeah, absolutely.

00:41:48.835 --> 00:42:04.757
I fully, fully support that and I believe models can be very, very useful things to explore new technologies like there's especially, like so many different choices for those materials, so so many sources.

00:42:04.757 --> 00:42:19.402
If you can have a model, figure out some very fundamental baseline characteristics from a TGA, from cone, from a low oxygen cone fuel this to the model, observe if there are massive changes in the large scale behavior.

00:42:19.402 --> 00:42:21.135
It gives conclusions.

00:42:21.135 --> 00:42:39.485
And fire science is not about assigning a class you have to pass a test for that and there are laboratories for that and you're very welcome to use mine if you want but for just understanding the science behind and the safety, I think I'm highly supportive of efforts like yours developing models to help us with that.

00:42:39.931 --> 00:42:46.284
One thing we have not talked about are the legal barriers to use bio-based materials and bio-insulations.

00:42:46.284 --> 00:42:53.838
Perhaps you can tell me how does it look in Germany in terms of actually using this type of material, where this material would be used.

00:42:53.838 --> 00:42:58.635
We talked that it can be used in walls, ceilings, facades, but in one type of buildings.

00:42:58.635 --> 00:43:04.934
This actually is a technology that is promising, is a technology that is promising.

00:43:04.954 --> 00:43:17.782
Yeah, so in general, we have a limitation in Germany for the usage of combustible and therefore also bio-based insulation materials to an upper floor height of 7 meters.

00:43:17.782 --> 00:43:35.344
So that's where we are now, but we already have one federal country because we have different building codes inside Germany where we also have an extension to 13 meters upper floor height.

00:43:35.344 --> 00:43:52.902
So, yeah, I think in the future the idea is to enable it for multi-story timber buildings, because we need them, we want to use them regarding lightweight construction, urban densification and so on.

00:43:52.902 --> 00:44:03.262
But therefore we have to deal with the fire behavior, and I think it's possible if you consider certain points.

00:44:03.262 --> 00:44:31.000
For example, we've talked about the ignition prevention, we have talked about the smoldering spread itself and some factors to limit it, and another important point is the firefighting techniques, so the fire brigade should be enabled to detect a smoldering and also to have the right tools to extinguish it, and then we can talk about also higher buildings.

00:44:31.889 --> 00:44:36.409
My feelings are that I'm not sure if it's necessary in higher buildings.

00:44:36.409 --> 00:44:52.902
I think if it's a technology that's truly supposed to change carbon footprint of the construction industry, that footprint is, you know, in the thousands of low-rise buildings, not in the Europe's tallest skyscraper.

00:44:52.902 --> 00:44:57.322
And the same goes for structural timber and mass timber and CLT and everything.

00:44:57.322 --> 00:45:08.862
If you want to really change, if that's the true reason you're doing this, you don't have to build the tallest building with the bio-based insulated walls.

00:45:08.862 --> 00:45:16.976
You need to run of a mill, simple, repetitive, boring buildings, building after building after building.

00:45:16.976 --> 00:45:24.454
You're sequestrating tons of carbon, and that's the answer, and I guess legislation today allows to some extent for that.

00:45:24.454 --> 00:45:26.916
And that's the answer, and I guess legislation today allows to some extent for that.

00:45:26.978 --> 00:45:28.259
Seven meters sounds a little low.

00:45:28.259 --> 00:45:30.121
13 meters sounds like small residential units.

00:45:30.121 --> 00:45:33.826
I'm not sure how exactly you could use those materials in Poland.

00:45:33.826 --> 00:45:44.038
I didn't research that, but we also have requirements related to the combustibility of the external walls up to certain heights, so probably would also be limited.

00:45:44.038 --> 00:45:47.652
Definitely something interesting to to observe.

00:45:47.652 --> 00:45:49.695
So what are your next steps?

00:45:49.695 --> 00:45:54.570
I know you just landed at dbi, so you start to feel comfortable.

00:45:54.650 --> 00:46:10.942
And what's next in the dbi, how the research plan is looking yeah, the next steps would be to extend the work on the biobased insulation materials in general and also to continue working on the model.

00:46:10.942 --> 00:46:41.960
So for now the applicability of the model is limited, but with DBI we want to propose, let's say, a tool which you can use for the risk assessment and, as you have mentioned, maybe not every building has to be built with biobased insulation materials, but at least the fire consultancy and the fire brigade and all the participants during the construction should be able to assess the risks properly.

00:46:41.960 --> 00:46:59.639
And I think we need to do more research in general about that, to achieve the shield, to get the knowledge how this material really behaves, and then we can decide where we want to use it and under which conditions we can use it.

00:47:00.081 --> 00:47:00.661
Fantastic.

00:47:00.661 --> 00:47:02.045
Okay, thank you, patrick.

00:47:02.045 --> 00:47:06.739
This was very, very interesting, looking forward to the future findings in the subject.

00:47:06.739 --> 00:47:08.896
Yeah, thanks, it was a pleasure to be here.

00:47:25.590 --> 00:47:29.181
Believe, episodes like this are exactly what the mission is supposed to be, that is, bringing you the fire science as it's being made worldwide.

00:47:29.181 --> 00:47:34.092
From this episode, my takeaways are that bio-based installations are out there.

00:47:34.092 --> 00:47:52.530
They are perhaps a small share of the market yet, but I believe, given the sustainability revolution and the current market drivers, I can only think about their use growing over the years, which means the challenges that they bring will be growing over the years.

00:47:52.530 --> 00:47:59.161
That is the smouldering combustion, of course, but also other things that Patrick mentioned in the interview.

00:47:59.161 --> 00:48:06.820
So good to be up to date on the current state of art regarding fire safety of this type of insulation.

00:48:07.630 --> 00:48:19.481
In the episode, we also went into some pretty decent modeling, pretty hardcore modeling, if you ask me Console modeling of pyrolysis, moldering, trying to apply that for a general model.

00:48:19.481 --> 00:48:38.922
This is something that obviously I or you won't be able to use in practice very soon, but it's great to know that such models are under development and perhaps within the world where there is so much complexity related to the installation, so many choices, so many densities, so many materials, so many ways you can place it.

00:48:38.922 --> 00:48:45.123
Having a modeling support will definitely help us design our buildings better.

00:48:45.123 --> 00:48:49.161
So that would be it for today's 5 Science Show episode.

00:48:49.161 --> 00:48:57.481
I hope you've enjoyed your weekly dose of fire science and if you need more well, there's an episode coming your way next Wednesday.

00:48:57.481 --> 00:48:59.978
So just join me and let's do it again.

00:48:59.978 --> 00:49:01.213
Thanks for being here.

00:49:01.213 --> 00:49:02.239
See you, bye.

166 - Bio-based insulation with Patrick Sudhoff

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