Fire Science Show
Fire Science Show
217 - Things that go wrong with the smoke control and how we fix them
In my personal view, an alarming truth about building fire safety lies in the gap between what's designed and what actually works in a building. After conducting 1000+ hot smoke tests in 200+ buildings, my experience is that most (maybe even 90%) of buildings had deficiencies in their smoke control systems, with 30% experiencing issues significant enough to potentially endanger occupants during a real fire. But it's not just about the problems. Good news - we have solutions.
Hot smoke testing stands as a powerful, yet underappreciated methodology that reveals what standard commissioning simply cannot. By creating controlled fires using methylated spirits and specialized smoke machines, we can observe how an entire building's safety ecosystem responds under fire conditions. The results are often eye-opening: systems operating in the wrong sequence, air flows disrupting smoke layers, pressurization fighting extraction, and critical components failing to activate when needed.
The most dangerous issue we encounter involves systems that don't "lock" to the first activated detector. This programming error causes safety systems to operate in areas far from the actual fire while leaving the fire location unprotected – a potentially life-threatening situation that's surprisingly common but easily fixable. Other frequent problems include excessive air velocity disrupting smoke buoyancy, extraction systems operating out of sequence, and auxiliary systems working against each other rather than in harmony.
What makes hot smoke testing so valuable is that it bridges the gap between aspirational safety (what designers intended) and actual safety (what the building delivers). Almost all identified issues can be corrected during commissioning, making this one of the most cost-effective safety investments possible. While the process may be disruptive and demanding, the alternative – discovering these failures during an actual emergency – is unthinkable.
Connect with me on LinkedIn to discuss implementing this approach in your projects and ensure your buildings aren't just designed for safety on paper, but truly deliver it when it matters most.
Recommended complimentary podcast episodes:
- https://www.firescienceshow.com/136-fire-fundamentals-pt-6-the-fire-automation-in-a-building/
- https://www.firescienceshow.com/033-science-theatre-or-engineering-polish-take-on-hot-smoke-test-with-piotr-smardz-and-janusz-paliszek/
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Hello everybody, welcome to the Fire Science Show. After gone missing last week, I'm back. Last week I've been in Slovenia for the European Symposium on Fire Safety Science, esfs. It was a really nice conference, very suited towards early stage career researchers and younger people in fire science, giving them an opportunity to present their work in progress, their research, to gain this important experience in doing conferences and prep themselves for upcoming submissions for IFSS, which are due in a few weeks. It was a really pleasurable conference. Big thanks to the steering committee for putting out this nice symposium. Great thanks to Grunde Jumas and his Frisbee team at Zag in Slovenia for being the local organizers of this event. Everything went perfect, so congratulations, big compliments to you all.
Speaker 1:I had a good time, but now it's back to reality and back to my original normal podcast schedule, and this week I have an episode that was supposed to go out last week but I finally finalized it and I'm really eager to share my thoughts with you. Today I am again solo on the microphone and I will be talking about some things that go wrong with smoke control in our buildings and actually multiple, multiple ways that fire engineers can investigate them, diagnose them and fix them. Them, diagnose them and fix them, and this fixing, I believe, is one of the easiest and cheapest ways to truly influence the safety of a building. This is a very strong opinion, but I promise I will argue for it later in the episode. This is really things that can improve safety in a measurable, in a quantifiable way that cannot be disregarded, and they are very cost effective if you compare them with other things that you can do to improve safety of your buildings. So I guess I'll stop now and just invite you to listen to the episode, because just after the intro you will find much more about the topic. Let's spin the intro and jump into the episode, because just after the intro you will find much more about the topic. Let's spin the intro and jump into the episode.
Speaker 1:Welcome to the Firesize Show. My name is Wojciech Wigrzynski and I will be your host. The FireSense Show is into its third year of continued support from its sponsor, ofar Consultants, who are an independent, multi-award-winning fire engineering consultancy with a reputation for delivering innovative safety-driven solutions. As the UK-leading independent fire risk consultancy, ofr's globally established team have developed a reputation for pre-eminent fire engineering expertise, with colleagues working across the world to help protect people, property and the plant, established in the UK in 2016 as a startup business by two highly experienced fire engineering consultants. The business continues to grow at a phenomenal rate, with offices across the country in eight locations, from Edinburgh to Bath, and plans for future expansions. If you're keen to find out more or join OFR Consultants during this exciting period of growth, visit their website at ofrconsultantscom.
Speaker 1:And now back to the episode. So hello again. It's great to see you after the intro, great to see you after the music. Statistically, you already made your mind to listen to this podcast episode, for which I am very thankful to you. There's a low chance that you're going to switch right now. So I can tell you the truth.
Speaker 1:This is a Hot Smoke Test episode and for some reason, when we mention hot smoke testing to our colleagues outside of Poland, they usually make big eyes and they do not really appreciate the method. I sometimes have a feeling this is some sort of alternative medicine of fire or something that people just don't like, or they don't trust it or they don't see big value in it. I always hear things like ah, it's theatrical, it's a demonstration, it's nowhere close to real fire. Some of those things are very true about hot smoke testing but it doesn't mean it cannot provide value to your building. And I think by doing those hot smoke tests in Poland a lot, doing them really a lot, we have found ways to actually make them in such a way that they bring a lot of value. So in the past, my team I think we've done like 200 buildings with hot smoke tests. Really there were years where we would be doing like two, three buildings a month with hot smoke tests. That was a really intense period. Now it's settled down a little bit. Now our hot smoke testing is mostly in critical infrastructure and tunnels. There are other companies that provide those services to buildings at large.
Speaker 1:But indeed it's a wealth of experience, wealth of observations related to performance of the smoke control and auxiliary devices that work together with smoke control and why I think it's worthy of a podcast episode. Because in many buildings, in many cases that we have tested, in many hot smoke tests that we've performed, those systems did not really perform like they were supposed to. I had a statistic. It's not extremely precise, more like a gut feeling, but in approximately 90% of the buildings 9 out of 10, we found some issues, we found some problems and I would say in 3 out of 10,. The issues were quite significant, like if there was a fire that would develop in the same location where we had the hot smoke test and the stuff would go like in the hot smoke test. The outcomes for the people in the building would not be great in terms of what the systems provided them with. So that's quite a staggering statistics, and when I talk with my colleagues who do hot smoke tests, it's not just my opinion. A lot of them share the same view that many of the buildings have different levels of faults in the systems because the systems are so inherently complicated.
Speaker 1:Now, in the beginning of the episode, I also mentioned that it's a cheap way to provide safety. I would like to elaborate on that. If you think about delivering safety to a building, imagine you have your building which has nothing in it in terms of fire safety systems and you want to spend some money to increase the safety in that building. You can purchase some sort of equipment system, smoke alarm systems, smoke control systems. Whatever you put into that, most likely spending that money will lead to an increase of safety in the building that you are designing. But if you want more safety, well, obviously you can put more systems in it and as the number of systems grows.
Speaker 1:One thing that I think is universally true is that you start to see some diminishing returns on safety. Like every another system, every another thing you put into your building is going to provide less and less safety compared to if that solution was used standalone in a building that has nothing. So by simply introducing a smoke alarm system, you will tremendously increase the safety of your building, but if you double the number of sensors, you're not going to increase the safety that much. And if you triple the number of sensors in your building, I'm not sure if you will even gain much safety at all while you keep spending your money to put new stuff in the building. And the other thing that I also think is universally true is that when you design a set of systems, when you design a building, when you design what goes into the building, you probably don't explicitly claim that, but you end up with some level of safety in that building, some level of fire safety in that building, and this is not yet safety that is in the building. This is the level of safety that can be in the building if everything works right.
Speaker 1:So I like to call it aspirational level of safety or perhaps design level of safety. This is level which the building can get to. That's a point at which you can get to if everything in your building works, operates in unison, works as expected and nothing goes wrong with it. Now, in reality, as I mentioned, nine out of 10 buildings have some flaws, which means some of those safety features have not operated to the level they were expected to, which means that this aspirational level of safety is very rarely achieved by the systems in the building. And here we are talking commissioning of the building. Maybe perhaps I should have mentioned that before.
Speaker 1:Here we are talking the final stage of building delivery. The building has just been completed. It's going through delivery process. It's about to be open to public. Everything's fresh, new, everything's fine-tuned, everything's started in it. So this is perhaps the best level, best quality of all the systems they will ever be in their life cycle.
Speaker 1:So if, at this point, you don't reach the aspirational level of safety, there's a fair chance that you will never do that. And also, you know, when you buy a ticket for any concert or venue, you see the tickets start from 20 bucks up. It means they may cost a lot more, but they will never cost less than 20 bucks. With aspirational level of safety, it's the same, just opposite. Like this is the maximum you will get. It's not that your smoke extraction systems will spontaneously achieve double the efficiency. It's not that your sensors will magically get five times bigger sensitivity to fires and will be able to tell them apart from false alarms in a better way. This level of safety will not spontaneously increase. So, basically, here we're talking about what you have designed in your building and that's level of safety will not spontaneously increase. So, basically, here we're talking about what you have designed in your building and that's the max the building can get to, and there will be faults along the way which will prevent the building from reaching that level.
Speaker 1:Now, the difference between the level of safety you have designed the building for the aspirational one, and the true one, the real level of safety you got your building to, is a gap. And here is where host, smoke testing, building commissioning and all the work I'm about to talk to you about is where it takes place this gap. Because in this gap, if you are able to identify what causes the gap, if you can identify how big the gap is and what actions take to close the gap. You start providing a true, real, tangible level of safety in your buildings. If a system is not operating and it's not providing a safety to your building occupants, and through commissioning, through your careful expertise, you fix the system and it starts operating. You've delivered the level of safety like if you just introduced the system to your building. I'm not sure if you follow me, follow my logic, but if a designer designs something and it's broken, it's like they've never achieved their design. You know it's like if the system was not there in the building and if you fix it, it's like they've never achieved their design. You know it's like if the system was not there in the building, and if you fix it, it's like if you put it in the building for the first time. It's the same gain in safety. I'm not saying that commissioner is the only one who did that, it's the design team and everyone else. Of course, I'm not speaking about credit, but I'm speaking about what has finally been delivered in the building, what has finally been delivered in the building. And this is why I so believe in those methods, because this is the point where I can make sure that my buildings are as safe as they have always intended to be.
Speaker 1:Now, how do we do that? We do them with hotspot tests. As I mentioned, this is our tool of choice in the commissioning stage of the building. We have done our own twist on this methodology. A lot of people in different countries use this method in different ways. We have our own twist of it. Actually, there was an episode early in the podcast about hot smoke testing already where I talked with Janusz and Kjotr from InBeppo on how to perform hot smoke tests. You're very welcome to revisit that one. That was like 200 episodes ago. Anyway, poland has its own twist on hot smoke testing and our method is largely focused on qualitative assessments of smoke control system and all the systems that interconnect with smoke control. So stuff that detects fires, stuff that issues electrical signals tos fire, stuff that issues electrical signals to the network, stuff that powers up ventilators and other devices in the building, everything interconnected with smoke control is actually undergoing the hot smoke test. It's not just the test of a fence in your building. No, it's much more. It's everything that consists of the safety layer of the building.
Speaker 1:To start the test, you first have to plan it out, which means you have to build your understanding of the building and the systems that you will be dealing with, which is already stage one of the assessment, because you look into the drawings, you look into technical designs and you can already understand what to expect from the building. Often, in the building, it's very different than what you've expected, but here you can build up some expectation towards how the building. Often in the building, it's very different than what you've expected, but here you can build up some expectation towards how the building will look like and what you will be dealing with. This is also a point in time where you can capture some little errors in the design, if they are still present in the design and perhaps they're fixable by the designer even before you get into the building. Of course, if you went to a solid third party, there should be less and less of those. In Poland we don't have that culture of third party, so perhaps this is the moment when we go through that, perhaps that's we experienced this. But again, this stage allows you to prep for the hot smoke test, plan it, the safety of it, and it's critical, in my opinion, to really do the hot smoke testing well if you have to prepare well for it. As for the setup.
Speaker 1:There are two components to the hot smoke testing. One is your hot smoke generators. So we are using commercial devices produced in the UK by a company called Concept Smoke. They're not an affiliate. I'm not an affiliate, they're not sponsoring this podcast. I am simply using the devices of those people for more than 16 years and I'm very happy with how they work and how reliable they are. We use machines called Vulcan.
Speaker 1:There was another machine called V-Count that we have used in the past and this, basically, is a big industrial generator of smoke. It is a different smoke than you would have from your theatrical generator. So this one is not based on paraffin. This one is based on material which is named smoke mineral oil 180, if I'm not wrong and apparently this is a fraction of oil which gets evaporated. It's turned into aerosol in the machine and it is released as a white smoke, and the benefits of this particular aerosol is that it is very stable in the air. It has a very long life cycle, so you can do your hot smoke test and it's going to stay for hours in the air until it is removed. Therefore, it makes it very suitable for those types of tests which may take an hour, two, three, depends on some of the test data.
Speaker 1:You need a stable source. Paraffin will not give you that. It will disappear in the air. The particles will deteriorate as they age. The smoke produced by the machine is not also very hot itself. It's maybe 30 degrees centigrade. So it's not enough to create this strong effect of buoyancy. But still it's hot enough to basically fly upwards. So you have a chance to control it and the smoke itself is not toxic. This oil is apparently neutral to the human. It has some certificates that you can refer to when the client asks.
Speaker 1:I know that health and safety is sometimes a concern. A big concern in health and safety is the second element of the hot smoke test apparatus, which is the source of heat. So a very efficient source of heat in fire safety are fires and in here to generate a lot of heat, to generate strong, buoyant thermal plumes through which we inject the aerosol. We use open flames, we use pool fires. Of course it's not that we spill anything on the floor and set it on fire.
Speaker 1:We have trays, steel trays. Ours are dimension 0.5 by 0.5 meters, so a quarter of a square meter, and you fill them up with a few liters of methylated spirit methanol, sometimes ethanol, sometimes isopropanol, depends on the scenario that we're testing Basically low-rank alcohols. The benefit of them is that they don't generate tremendous heat release rate per unit area and they are very clean. They lead to very clean combustion, very little soot. If you burn methanol, you basically get no soot at all pretty much in the test, which is very convenient because you do not make the building dirty. With the hot smoke test you get more or less 100, maybe 200 kilowatts per tray, depending on the fuel, and that's the size of the fire that you will end up using them. The caveat is that if you use more altogether, they start interacting with each other. Therefore, it means each of them is going to generate more heat release rate than it would if they were used independently, which you have to be kind of aware of.
Speaker 1:That can be problematic and you don't want to be surprised by your own fire. This, of course, comes with extreme health and safety challenge. To run open flame in a building that's about to be delivered is quite a hazardous thing. So you really need to be mindful of what you are doing, how you are approaching it, how you are protecting things around you from direct flame contact, from heat radiation. You have to shield things up. You have to be very mindful of what's above you, because you are creating a thermal band plume. You may not have flames touching your ceiling you should not have that but you may have a thermal stream of 80, 90, 100 degrees above your source of the fire, which can already be enough to cause damage, especially if you have some fragile plastic elements above you. So you have to be extremely mindful about the space in which you are performing the hot smoke test and you have to prepare that space for those hot smoke tests. In the end, this may not be a real fire, but it's very close to what a real fire will do in the building. So, yeah, we need to be considerate about that.
Speaker 1:The hot smoke test starts by initiating the fire. You release the smoke and basically what happens from that point is something you should not play too much manually. What I mean is that you want to test the building automation, so you want to let the building automation act respond to the fire you've done. You don't want to start a hot smoke test and then trigger a manual alarm and then have a guy run stuff from their computer and operate the things for you. No, you want the building to respond to this, because that's the point of the Hot Smoke Desk.
Speaker 1:You basically sit down and watch, you take photos, you take notes, you look into operation of different devices. You walk around the building. You basically try to see as much as you can. You record it to get additional layers of information from spaces. You were not physically present when you were walking around the room. And after the test finishes, after you conclude the test, after some minutes, you take the logs of the system and you look into the logs. What has operated at what point of time? This is a very critical information that you have to extract after the fire test. So you need to be aware what happened and when to really give an interpretation of the outcomes of the test. This is very important.
Speaker 1:We also do some measurements along the fire tests. We usually would measure extraction rates and at the openings that supply air extraction rate, at openings that extract air and smoke from your building. So those are fundamentally important. We would perhaps measure pressure differences, we would perhaps measure forces on the doors. Those are things that you can do while doing hot smoke tests and they provide you additional level of information and in the end, once you have all of that, you run your analysis level of information and in the end, once you have all of that, you run your analysis. By analysis I mean you look into the plan, you look into the design and you compare the design state of the operation of the systems, the performance, this aspirational performance that was designed for the building, and the performance you really got on your building in the hot smoke test indicating where the safety gap is.
Speaker 1:If you find anything, sometimes they're very obvious when you find an is. If you find anything, sometimes they're very obvious when you find an error, sometimes you have to go through the logs to see that something has not operated like it should have went. So in here we do a lot of work to prepare a final analysis. Unfortunately, this work has to be done very quickly because it's a building undergoing a commissioning stage, so there are no months to write a report. Work has to be done very quickly because it's a building undergoing a commissioning stage, so there are no months to write a report. It has to happen very quickly, almost overnight. You have to deliver those reports extremely robustly and at speed. But we can do that and this is where we can provide value to the building by identifying the gap between the real level of safety and the aspirational level of safety in the building.
Speaker 1:Now, an important thing to understand about hot smoke tests and perhaps this is the source of the confusion why a lot of people don't like them, why they think they're useless is what you cannot get from a hot smoke test. And one thing that you cannot confirm with a hot smoke test is that the performance of extraction, the smoke control system in your building, will be sufficient for your design fire. This is something you are unable to quantify and confirm with a hot smoke test. The reason is that, as I mentioned, the source of heat would be a few hundred kilowatts per a tray that we use. We may use four trays in a large shopping mall. We may use six, eight trays in a tunnel, so our fires could go up to one or two megawatts even, but that's still far below the usual design fires you would use for those spaces in your design stage, which means you're not really exposing your system to the maximum size of the fire you have envisioned in that building for those devices to work at, and it's simply impossible to reach those levels until you make a real big fire in the building, and you don't want to do that. You don't want to damage stuff. So if your system works in a hot smoke test, it doesn't necessarily mean it's going to achieve the level of performance you expect in it in terms of providing sufficient extraction capacity, maintaining smoke layer height, etc. In a full scale fire.
Speaker 1:There were attempts to scale up hot smoke tests to say, okay, if I have smoke layer height of this much in a hot smoke test of this size, what does it mean for a fire of much larger size and a particular hot smoke layer height? What is going to be in the real case? The thing is they are very difficult to apply. I don't really appreciate the scaling with fruit number that people try to do for those. I see too many challenges with this scaling approach, so I don't really feel there's a real value to do this type of confirmation. There are simulations for that. Cfds is a tool that gives you this kind of answer and also, if you want to do that, you are required to run a lot of additional measurements in your hot smoke test, a lot of additional things that are necessary to give you this quantification, which takes a lot of your time, even days of your time, and my choice is that, if I have to spend a few days setting a single hot smoke test to give me this quantification, which I don't even think I need at that point, versus a very robust and quick hot smoke testing routine which allows me to run multiple hot smoke tests in a day of work in a building, I take the second one because it allows me to test so much more and unravel so much more gaps in the safety compared to the precise measurements and attempt to extrapolate the results of the hot smoke test to a full-scale scenario. So, yes, I am absolutely convinced.
Speaker 1:I cannot judge the system performance fully. I cannot tell you, yes, your system is absolutely sufficient for the design fire you have seen, because the capacity is enough in the hot smoke test. No, I cannot say that. However, the opposite is true. If I make a hot smoke test which is a smaller fire than you have designed the building for and the system fails to operate in that hot smoke test, so it does not manage the hot smoke test fire which is smaller, it is to some extent unlikely it's going to work in a full scale. Going to work in a full scale, perhaps in natural ventilator systems, where buoyancy plays a lot of role. This is not 100% true, but in most cases it is true. If the system is insufficient to clean the hot smoke test, it's probably insufficient to clean up a real fire in the real world. So, yeah, these are the things.
Speaker 1:That number one you have to be aware of what you cannot do with hot smoke test. Now let's talk about things that you cannot do with hot smoke test. Now let's talk about things that you can do with hot smoke test. So what kind of errors do we find in buildings and how do we approach fixing them? I would group them into three groups scenarios, performance and maybe ill cooperation between the systems. Yeah, I think that those will be good groups to start with. So we will start with scenarios and the design, operation of the systems in the building, and here we immediately jump into number one biggest issue we find during hotspot testing, which is potentially life-threatening, and unfortunately this issue has been identified in multiple buildings that we were working with. So before I tell you what it is, I need to give you a context.
Speaker 1:When you, as a designer, design a fire safety system in your building, you have to design some way of operation. Basically, we write things in our fire strategies like when the fire is detected in a compartment, number, this, this system should activate, this door should shut, this dampers should close, etc. We give a list of things that shall happen in the fire. This is, let's say, a write-up of what is supposed to happen. Now this has to get translated into technical language, which means if a detector, number A52, operates in zone number 1.7, it means that the dampers on the duct number 1.7.1, 1.7.2 will have to shut and the HVAC will have to operate in this way and the extraction fan number 7.1.A will have to extract at 50 Hz and the other fan will have to extract at 20 Hz. Extract at 50 hertz and the other fan will have to extract at 20 hertz. You know a very technical list of things that precisely define you the state of every single device in the building in case of a fire in particular location.
Speaker 1:We called it the matrix of operation and it's usually a gigantic Excel spreadsheet which contains all of this information. Now, this is not yet the delivery of the system in the building, because now this matrix has to be programmed into the smoke control panel or fire alarm panel or an integration device. Whatever is steering, driving the devices in your building, it has to be programmed to reflect this matrix of operation. So there are multiple steps, you know, from the designer, from the fire engineer, creating the strategy, into building this matrix, into programming in the building. There are multiple steps on the way and during those steps then there could be errors. Unfortunately, one of such errors is that the last person that does it, or perhaps the earlier, but usually it's the programmers, but from my experience it's usually at the programming stage, at the last stage, people do not lock the order of operations to the first instance of fire alarm. What I mean by that?
Speaker 1:If you have a fire is detected by its nearest sensor. Therefore, the first device that finds the fire, the first detector that is triggered by the fire, is usually the one that will be closest to the fire. By definition, it has to be the closest sensor to the fire that is going to operate. So this is your most reliable information. You will ever get in where the fire is located in your building because as more and more sensors get triggered, the information will be happening further and further away from the source of the fire. So you really want those devices to operate at the seat of the fire, and that's why you have to lock your alarm to the first location indicated and then operate for this location and this location only. The issue is we often find that the smoke travels through the building, it triggers different devices and eventually the alarm state could switch to a newly triggered device. So perhaps the smoke has traveled across the boundary between my smoke detection zones and suddenly the operations start for the second zone and the third zone and the fifth zone and eventually I have a building which operates the safety systems far away from the fire and does not operate the systems in the location of the fire. And this is, in my opinion, life threatening because, one, you do not provide any safety at the location of the fire. Two, actually, the performance of those devices for different zones could be adversely affecting your fire. So it's not just you're not providing the safety, you're actively making it worse than if the systems have not operated at all.
Speaker 1:This is a very major flaw. I've talked about it in the communications episode. I attribute this to miscommunication in fire engineering, which is a very major flaw. I've talked about it in the communications episode. I attribute this to miscommunication in fire engineering, which is a very difficult thing, very difficult skill. I don't blame the programmers. I see a reason why they do that and I also understand that fire engineers have to be vigilant about this and have to pick it up and have to fix it, because this is one of the biggest threats you have in your building.
Speaker 1:And it's easily fixable you just apply the lock. Sometimes it's super easy, it's just one click and it's there. Sometimes it takes you to write some complicated scripts and algorithms to fix it, but it is fixable. Another thing is when your scenarios involve a lot of things that have to happen simultaneously at the exact same second. Like it's easy to write after two minutes everything starts. But when we're talking about issuing thousands of signals to thousand different devices, it actually takes time to deliver those signals.
Speaker 1:We had a case where we were commissioning an extremely large car park under a very big building, a rectangular car park, tens of thousands of square meters, four big extraction inlet points in the corners of the car park, and when we were doing those tests the performance of the system was very random, like we really could not understand what the hell is happening, why the system sometimes works, sometimes does not work. It felt very, very odd and on paper everything seemed fine. So as an act of desperation, we've sent people to each of extraction rooms with a stopwatch and they were measuring what happens and when. And then from this exercise we found out that in one test, let's say, northeastern extraction point would activate immediately, south one would activate after two minutes. In another test, the northern would take five minutes and the southern would activate in one minute. The reason was that the system was absolutely overwhelmed by the number of signals to be issued and it took it minutes to send signals to particular elements of the system. And eventually those minutes have created this, you know mismatch in when the devices were operating in the car park, creating an extremely dangerous situation of the system not working. It was good on the paper. It's just that electronics that were used to deliver that have not matched, you know, the expectations.
Speaker 1:The solution was again fairly simple. We had to spread apart sending out the signals, we had to give some priorities and once this was done we could make sure that the critical elements start immediately and then other elements follow. So it was absolutely fixable. But again, I believe it would be not possible to capture that if it was not during the hot smoke deaths, because you could immediately see from the behavior of hot smoke layer and when the hot smoke went that something is very wrong with the system. That looks good on the paper and the measurements confirm that it should be good. Another scenario-based errors that we sometimes capture in hot smokes is that you probably want to subdivide your space into some sort of smoke control compartments where not everything operates at the same time in your building, and we sometimes see issues with those compartments in terms of how they are designed. Sometimes the real building behaves a little bit different than what the designer expected. Maybe there's a mismatch between the CFD and what has been built. In the end it's fixable.
Speaker 1:Usually you can move those boundaries a little bit. You can use different devices to establish new boundaries. You can sometimes split a bigger zone into two smaller ones. You can sometimes combine two smaller zones into one larger one. Those actions are helpful in fine-tuning the system performance. We once had, for example, a very wide balcony in a shopping mall which created an extremely wide spill plume which was problematic for the system. We've cut the balcony into half with a small curtain and it magically fixed the operations of the system because suddenly the spill plume was much narrower, much more narrow and easier to maintain, to contain, by the extraction system, for example. Things like that.
Speaker 1:Sometimes with jet fan systems, people don't appreciate how much momentum the jet fans introduce into your car park. If there is discrepancy between how much momentum you input into the car park and the extraction rate of your system, the jet fans will start moving your smoke around the building beyond the point where it's extracted, which creates some problematic situations where the smoke is just spilled into the building. And you can fix that by changing the zones in which the jet fans operate. You can trigger them off and perhaps fix that. Of course, this is not something that an engineer that runs hot smoke test has a sole, you know ability to do.
Speaker 1:In this stage you really need to work with the designer of the building and the third party. They have to be present at the hot smoke test, they have to be part of the process and if you find a gap, it's up to them to find a solution. You can assist them, you can advise them, but it's their them who have to fix their system and and, together with the designer, you can do those choices If the designer agrees yes, this is better. You can perhaps implement them in the building. Sometimes you have to run some CFD ad hoc for some changes. Sometimes you have to get some other opinions to support the change, but usually it's manageable and we have found that those designers, those people who design the building, are very helpful in the process because they are also very interested that their systems reach this aspirational level of safety they wanted them to reach in the first place. So that would be the scenario problems.
Speaker 1:Now let's talk about issues with performance. Let's perhaps start with performance of passive fire protection. So in general, walls, doors, gates, etc. Hot smoke testing is brutal. If you are supposed to have a fire compartment, which means nothing exits the compartment. If there's a hole, hot smoke test will exit the hole and you will see it on the other side of the wall and you will immediately be able to point out there's leakage in this wall. The fact that there is no leakage does not mean that the wall is perfect or it achieved some class of integrity or whatever. But if there is a hole, the hot smoke will pass through that hole and it will create a problem on the other side of the wall. You can rely on hot smoke test for that. You can trust me on that. It's very good to verify if we really sealed the fire compartments like we say. We are Other problems with performance, perhaps more about the smoke control systems.
Speaker 1:Well, you could say there's either too much or too less of the flow or extraction capacity that you want to have, and both will be problematic For me. If I had to rank the number one cause of failure of smoke control systems, I would say the inlet air supply is the most challenging one. Extraction not that often, but inlets very, very often. And I think people just do not appreciate how much momentum is within the air that you input into your building and how little is needed to disturb why our smoke control systems work in the evacuation phase. How can we protect people from smoke? You want the smoke to be away from the people, right. And because the smoke is hot, it has buoyancy, it will fly up, it will accumulate in a smoke reservoir, which means it is far from people and they can evacuate. This is the basic strategy how our smoke control systems operate, how we want them to operate and how we achieve safety through smoke control systems.
Speaker 1:Now, if you disturb this buoyancy, if you do not allow this layer to form or, even worse, you disturb that layer, you suddenly bring smoke to the people, which is a hazard and you do not want that. So you have to be very mindful of where you inject air so it does not mix with the buoyant hot smoke in a way that the smoke will lose its buoyancy and the smoke will fall, descend into the space where people are and cause hazard. We've seen that a lot of times because it's actually very little that is needed to disturb this. If you have one meter per second flows, you're pretty much safe. But if you have anything above two, two and a half meters per second that's already very strong flows that will cause disturbance in buoyancy. If you have five meters per second, that's a lot, that's really a lot of velocity in the compartment and it will interfere with your layers even far away from the point of injection. You have to be extremely mindful and when you find problems like that there are sometimes fixes to be applied so you sometimes can operate a different inlet point far away.
Speaker 1:The further away from the fire you can supply air and the closer to fire you can extract air. Those are your rules of TAMP, where you want them to be. So sometimes you can move the inlet point far away and it's solved. Sometimes you cannot do that and as a last resort, we sometimes set up ramp up functions on the devices. So basically, the device starts to operate at very low capacity and slowly, with time, builds up the capacity until it reaches the full potential, because the fires grow it's also a transient phenomenon. You probably do not need all of your extraction capacity very early. Therefore, you can build up this capacity within minutes and actually create space for evacuation to happen and yet reach the full potential when you expect the fire to be fully grown.
Speaker 1:Again, this is not the responsibility of the hot smoke engineer. It's the responsibility of the designer of the building, who participates in the process along with you and together you may find out what is suitable, delay time for this to make space for evacuation and get the performance you want. Sometimes you end up with not enough flows and we, as I said, you don't see that through hot smoke test directly, but unless it failed. But you can measure the velocities at your grills and estimate how much air is flowing into and out of your compartment. This is very efficient and you can indicate where the system is lacking the capacity which it should have.
Speaker 1:Sometimes there are issues with how the ducts are made. Sometimes there are programmable issues, like perhaps a wrong frequency on the frequency inverter. Sometimes, actually, in a very sealed spaces, like corridors of high-rise buildings, you may not have sufficient inlet air, which reduces the amount of extraction air you can have because it's a sealed space and it will also manifest itself with a high pressure gradient in that case. So you have to be mindful of that. Usually, if there's a problem like that, it's necessary to investigate and find the reason why the air is missing. Many times, like in the road tunnels when we had long docks, we have found like someone left a hatch open to some space and we lost like 30% of volume to that hatch. So if you measure the capacity and it's not meeting the design, there must be a reason why it is like that and you absolutely have to investigate why this mismatch is present.
Speaker 1:Finally, you may have temporal mismatch. Like I mentioned before, your systems will take time to operate, but sometimes the temporal mismatch, like I mentioned before, your systems will take time to operate, but sometimes the temporal mismatch is also with the sequence of operations. So you must open a damper before you start the fan. That's fundamental. You must close the HVAC dampers before you start the extraction in a very big building, because if your extraction runs to the maximum, it may be very difficult to close them. At that point, if you don't open the damper and operate the fan, you may break the damper. Trust me, we've seen doors being ripped apart from ventilation rooms, mechanical rooms, because something did not work and the damper has not opened when it was supposed to. So this mismatch may cause real damage in the building and, in the case of a real fire, may cause a very big problems in operation of the safety features of the building. You have to observe that. That's why you go through the logs after you've done your hot smoke test and that's how you indicate if everything happened. But it doesn't have to happen. It doesn't only need to happen, it has to happen in the very correct, precise order that you have designed the things to happen in, and this is absolutely critical.
Speaker 1:Finally, we reached the third group of issues ill cooperation of the system, and I would say it's mostly between pressurization systems and smoke control. That's a big challenge to me, the reason for that being, in Poland we use a lot of pressurization PDS systems. I know they are not that popular in the world. Perhaps the things will change in the future, but we use them very commonly in anything taller than 25 meters. I would probably have a pressurization system there. So yeah, it's my bread and butter. The problem is that those systems are very specific and therefore they are kind of designed in a silo independently. So smoke control is being designed independently, pds is designed independently.
Speaker 1:Of course there is some sort of coordination between the projects but it's different design concept, different goals of operation and sometimes those lead to some issues in the building. Perhaps you will have too much airflow from the PDS that extraction cannot take away. Perhaps the extraction will be too strong and it will increase the pressure difference for the PDS system beyond the region in which the system can operate. Both things can lead to excessive forces on the door handles which may prevent you opening the doors. It can cause an extreme air streams like too much air velocity in your building. You lose the buoyancy. You can have an adverse effect of the pressurization.
Speaker 1:In skyscrapers we often have pressurization serving as your main air inlet, as the makeup air, which is a brilliant strategy, very robust, very safe, but it needs to be very mindful how you do that, how you achieve that state, and in that case you are unable to design those systems in silos because they together have to work in a way that provides the performance level that you expect. This is a very big challenge actually, and it sounds simple, but in so many buildings we find problems with that. You indicate those problems by measuring the forces on the doors, by measuring the pressures, by measuring the flows, by observing the response. We've also developed a methodology, eventually, that we not only measure this. You know, you put an anemometer to the grill and you just have a reading. No, we have systems that continuously measure those parameters. We set up the devices in the building and we measure that as a function of time, to observe the temporal evolution of those flows and how they interact in also the time space. It's very important in the very sealed spaces in which you rely on those. So that's one way of ill cooperation.
Speaker 1:Another way is between the passive fire protection and the ventilation systems, especially when we talk about fire doors, which are normally open and they are released close to when the fire is observed, and fire gates that shut down the connections between big fire compartments, especially in car parks. So when you design a system for your fire compartment, what you would do, you would run a simulation for that compartment and that compartment only. The assumption is that the fire cannot exit that compartment, so it's useless to account for what's outside right, and I would agree that this is the standard procedure for fire simulations. However, in reality, there are things that can go wrong with those closing devices so they can be physically inactive, they can be turned off, they can be unpowered, they can be broken, there can be a physical object blocking the operation of the device, there can be a wrong signal sent to the device. There's a ton of things that can go wrong, leading to an opening not be shut when it's supposed to, and in that case you will have a mischievous airstream in your building that may actually completely change the way your smoke control system operates. So this is a very big thing and, again, something very easily identified and found during hot smoke testing and perhaps not that easy. When you are just testing your systems by hand, you know running scenarios manually, etc. Much easier to pick those up in hot smoke tests and those things are big.
Speaker 1:Another thing is sometimes when especially again when the premises are sealed. And sometimes, especially again when the premises are sealed, if you have a sealed compartment in your car park, for example, and you extract too much air from it, you create a big pressure difference between this fire compartment and another fire compartment. If you have this pressure difference across a gate that closes a gap between those buildings, you will end up with a big force acting on that gate, sometimes enough to break the gate. So you have to be mindful of that. Again, you can observe that in hot smoke very easily and it's a very dramatic observation when those things start to bend and move. So you can very quickly identify the problem and there are solutions for that with careful management of air flows and air paths. And where do you inject air in your building to not cause this huge buildups of pressure in your building? But you really have to identify those to be able to fix those. There are more examples like that Ill cooperation between jet fans and extraction.
Speaker 1:I've already mentioned that, but I would say it's a big one. Perhaps jet fans require their own podcast episode. There are so many things that can go wrong in details with jet fan systems and all those things are necessary for the system to operate correctly and provide you the level of safety you aspire to. So maybe I'll make a follow-up just focusing on the jet fan systems, maybe I'll make a follow-up just focusing on the JetVan systems, but in general I think I gave you pretty lot examples of what can go wrong with the systems and how we can fix it. An important lesson is that a lot can go wrong and the second lesson is that we can fix most of that. I said nine out of 10 buildings had some issues in them. I think we fixed all of them, like literally, maybe one or two buildings out of 10 buildings had some issues in them. I think we fixed all of them, like literally maybe one or two buildings out of hundreds where we had real issues fixing them. Most of the buildings we were able to fix the problems within the commissioning period. Sometimes it extended the commissioning but hey, that's safety, you need to have safety. Sometimes it was annoying, sometimes people hated us, but in the end we were able to fix all of that, hopefully bringing the level of safety to the level that the designer aspired for.
Speaker 1:And I think that's the biggest testimony for hot smoke testing and this procedure. You know they're not obligatory by the law in Poland. They are extremely annoying for everyone. Like you know, you have last two weeks before you deliver a building or a last month. Everyone is rushing to finish the job. No one has time and then comes a bunch of guys. They set up fire to your building. No one can work.
Speaker 1:While this is happening, a lot of weird things are operating, there's a lot of noise, everything's shutting down, opening. It's a period of craziness and they do this for two or three days, in the most valuable part of the time you have on your construction, because you're about to finish it. Trust me, it's annoying. They hate us for doing that and it's also costly. You need to hire a lot of people, bring a lot of equipment, a lot of equipment, a lot of materials to run those tests. Precautions, you know, safety, build up the locations for the fire tests, secure the things, clear out things. Have a lot of people to be present at different parts of the building that you want to investigate. It costs a lot, but in the people still pay to do that. People still pay to go through this process because if you do it once and you see how much has improved after this routine, you immediately understand how important it is to have the system tested in a full scale in a scenario as close to the real fire as humanly possible and for a fire safety engineer.
Speaker 1:Now I will talk about my personal experience running those hot smoke tests, being in those buildings in fires, observing firsthand how the building responds to the fire, how the detection systems trigger, how the smoke control behaves, how the flows interact with each other in the building, how different systems operate together or maybe they break each other or maybe it's impossible to make them work together. You know, to see all of those firsthand in a hot smoke test is really enriching to the experience of a fire safety engineer. I have learned tremendously a lot in hot smoke tests. You can also touch things that you would normally not do. We often do power shutdowns during hot smoke tests to see how auxiliary power supply will come into the play. You can test the connection between the building and the fire brigade. Will they receive the correct information, will they come, and they can also test how quickly they may come to the building. You may test so many different things. You would normally not be able to test so many interactions, a rich world of fire automation in the building that you can literally play with in a building that is about to be delivered and to really indicate if there is any gaps in safety in that building. I think it's a beautiful word.
Speaker 1:One of the best parts of my work really is to do hot smoke tests in the building. And a final comment I've said this is a part of commissioning, but you could also run those in the buildings that are working. We had projects where we would come back to a building after a few years to do a hot smoke test in limited scope, to just check up on the building. What has changed? And yeah, it's, it's really good. Usually the buildings that went through hot smoke testing in the first hand they don't show that many errors accumulated over the years. So I would say this level of safety is to some extent maintained over the years uh, the one that we initially increased by doing the hot smoke test in them. But definitely running a maintenance hot smoke test to just see has anything changed in my building and can we fix it Again a very valuable exercise to truly increase the level of safety. So in the end I gave you a promise, a very cost-effective tool to truly increase the level of safety. Hot smoke tests are definitely that and I highly recommend anyone to run them.
Speaker 1:There is another episode on hot smoke tests. 200 episodes ago I mentioned about it. It's in the show notes. You can check it out. There's more technicalities about hot smoke tests in there. There is one more episode of Fire Fundamentals on automation in the building, so all the little things that happen in the building when the fire is detected. I've also linked it in the show notes. I think it's a great complimentary material to this podcast episode.
Speaker 1:I am looking forward to hear what you think about hot smoke testing. Have you ever done it? Do you hate it? Why do you hate it? Where do you see yourself using this method and do you even see using yourself this method to improve the safety of your buildings, your designs? I hope you will have a chance to actually use this method and actually benefit from what this method can bring to real projects. If you have any questions and you would like to talk about how to do hot smoke desks, I'm open. Just send me an email, poke me on LinkedIn, let's talk and I'll try to help you out to build your own safety routine. This is it for this Wednesday Again, I'm very sorry for last Wednesday.
Speaker 1:It was a crazy period. We were delivering a massive, massive project which kind of interfered with the time where I had to travel to Slovenia and in between that massive project and Slovenia I simply ran out of time. I hope that I will have sufficient time to edit this podcast episode and release it for you, and I've failed miserably and I'm so sorry for that. But now I'm back to my normal routine. I already have episodes recorded for the future weeks, so I do not see any hazards related to you not having your source of fire news on Wednesday. So I can promise next Wednesday we will see each other in the same place approximately the same time, I hope. So yeah, thanks for being here with me. I hope you've enjoyed this hot smoke testing episode episode on what goes wrong and how we can fix it, and see you here next Wednesday. Thank you, bye you.