Fire Science Show

Fire safety engineering based on our codes and legislations often stops at life safety and code compliance. However, in the world of insurers, there is much more beyond that - a critical question is “what happens to the business after the fire?” Today I sit down with Gary Howe, Senior Risk Engineer at Zurich Resilience Solutions (Zurich Insurance Group), to unpack how insurance risk engineering evaluates fire risk across property protection, environmental impact, reputational exposure, and the big one: business interruption.

We get concrete about what risk engineers actually do on site and why underwriters rely on them...

Modeling the consequences of a fire is what most of us do day to day. Modeling how a fire actually grows across real materials, under changing heat flux and ventilation, is the part we tend to avoid, hiding behind a prescribed design fire. That gap is exactly what we tackle with Jason Floyd and Jonathan Hodges from UL Research Institutes, the developers of S-PYRO, a new engineering pyrolysis model already included in Fire Dynamics Simulator (FDS).

We walk through the origin story in railcar fire growth modeling, where “traveling fire” assumptions and fixed HRR curves can fall apar...

ASET/RSET is the fire safety engineering idea that sounds almost too clean to argue with: the building must give you more time to escape than you need to get out. But once you try to prove it in a real project, the simplicity could and and the hard questions start. Where does “time zero” actually begin: ignition, detection, or alarm? What does it mean for tenability to fail in a place where nobody is anymore? And are we designing safer buildings, or just winning a seconds-on-a-spreadsheet contest?

I break down the Available Safe Egress Time and Requ...

In this episode I take you into practicality of introducing wind into fire safety engineering considerations, and focus on it's implementation as a part of fire oriented CFD analyses. In here, we dig into why wind is tied to so many catastrophic fires, why firefighter safety is often shaped by sudden wind shifts, and why designing for calm air can quietly turn fire safety into a coin toss.

I walk through what wind actually is from a fire engineering perspective: an atmospheric, turbulent phenomenon full of vortices and gusts, not a tidy uniform flow. We talk about...

Smoke does not just slow people down, it changes what they believe is even possible. That simple idea is why we get so excited about pyFDS-Evac, an open source workflow that connects Fire Dynamics Simulator (FDS) results directly to modern evacuation modeling with JuPedSim. When the fire environment can remove an exit from view, reduce walking speed through extinction and soot exposure, or even incapacitate an agent, you stop “post-processing evacuation” and start modeling decisions that respond to conditions.

We sit down with Mohcine Chraibi from Forschungszentrum Jülich to unpack how their team builds pedestrian dynamics softw...

A tool doesn’t become a global workhorse because it’s clever. It becomes a workhorse when different labs can run it, calibrate it, compare it, and trust it. It is a very long road from the invention to widespread use. And I got the chance to discuss the path of how the Cone took off with Dr. Marc Janssens, who is a key figure in this story - he was even jointly co-awarded the Phillip DiNenno Prize together with dr Vyto Babrauskas, for his efforts on developing, standardizing and promoting the Cone.

Marc takes us back to t...

A fire scene looks like a puzzle, but it’s a puzzle where the pieces melt, burn, and get hauled away before anyone can measure them. On the 25th anniversary of 9/11, I sit down with Professor Vincent Brannigan to ask a questions - does a fire investigation truly use the scientific method, or are we doing something else and calling it science?

Vincent brings a rare mix of experience as a fire protection engineer, a lawyer who has seen cases up close, and a historian of science who cares deeply about how we justify knowledge in court. We...

Critical velocity is supposed to be the clean moment when tunnel smoke control flips from unsafe to safe. But after too many real projects and too many review battles, I am very sure that such a single number cannot be a sole proxy of what is safe or unsafe... So why it has so much power over my design?

In this solo episode I walk through why critical velocity became the world's favorite proxy for tunnel fire safety: it’s simple, it’s calculable, and it gives verifiers something rigid to check. But what is simple at firs...

Pretty CFD flames are something we got used to, but they usually are a product of our design assumptions - the design fire. While they give us a lovely illusion of being "real" fires, predicting real compartment fire growth is a completely different game. We’re joined by Dr. Stephen Welch (University of Edinburgh) to get honest about what “modeling fire spread” actually means, how quickly results can become believable but wrong, and why validation has to be the foundation of any serious CFD fire modeling workflow. 

We walk through the path his group has taken from traveli...

A compartment fire is more than just “a fire in a room.” The moment flames, smoke, and heat are trapped by walls and fed through openings, the physics changes and so do the hazards we design for. We sit down with Dr. Vinny Gupta (University of Waterloo) to rebuild compartment fire thinking from the ground up, from what the enclosure does to airflow and smoke layers to why those effects still anchor modern structural fire safety.

We trace the roots of today’s design tools through post World War II research and the foundational work of Kunio Kawago...

As a kid of 80s and 90s, a lot of the pop culture was around the post-apocalyptic scenarios following a nuclear exchange. I always thought a nuclear winter is a consequence of atomic bombs falling down, but now as a fire researcher I've learnt it is mostly about fires, after all. Today I sit down with Dr Stephen Welch (University of Edinburgh) to trace the fire-engineering-heavy pathway from mass urban ignitions to firestorms, through soot production and its injection into the stratosphere, up to global climate impacts. The uncomfortable twist is that the energy release from the fires can...

A wind-driven ember shower is a key wildfire exposures a building can face, but we have not yet fully understood or accounted for them in making our communities wildfire resilient. Today we sit down with Samuel L. Manzello of Tohoku University and Reax Engineering to unpack how in the last 20 years the firebrand science went from not being able to characterize the features of them well to being able to procur controlled experiments and standardized generators that can actually shape building codes and product design. 

We dig into what firebrands really are, why vegetation embers and structure-generated e...

Wildland-Urban Interface fires are a class of fires that deserves own models, own studies and a lot of research focus. This is what I discuss today with prof. Arnaud Trouvé from the University of Maryland, shortly before he has given his plenary talk at the recent Combustion Symposium in Kyoto. In this interview, Arnaud explains what makes wildland urban interface (WUI) fires and urban conflagrations so hard to predict, also with a focus on the combustion phenomena. 

Arnaud is interested in how the fires spread from the wildlife into the urban areas, and how to model this sp...

In todays episode of fire fundamentals we talk with Professor Elizabeth Weckman from University of Waterloo about advanced optical diagnostics that let fire researchers read temperature, chemistry, soot, and velocity from light without relying only on probes. We break down what cameras, infrared imaging, spectroscopy, lasers, and PIV can reveal, plus the calibration and interpretation pitfalls that can quietly ruin your data. 

Things covered in this episode:
• why optical diagnostics are “non-intrusive” in practice and where they still perturb the flow 
• limits of probe-based measurements in fire including spatial resolution and radiation errors 
• using basic photogr...

The cone calorimeter sits in thousands of labs, shaping what we know about flammability, smoke production, and heat release rate. This essential piece of equipment comes with quite a story of how it was engineered or why its “obvious” design choices were anything but obvious. We wanted that history from the source, so we invited Professor Vyto Babrauskas to walk us through the decisions, constraints, and small breakthroughs that turned an idea into the most practical bench-scale fire test in common use today.

We dig into the 1970s research environment at NIST (then NBS), including the plastics-focused push...

A carbon budget can feel like a hard wall in modern building design, and once you treat CO2 as currency, everything starts competing for a slice of it. The problem is that fire safety systems often show up in those spreadsheets only as a penalty: extra embodied carbon for sprinklers, alarms, and protection. What gets ignored is the payoff. A serious fire can erase years of “sustainable” choices through demolition, replacement materials, repair labor, and lost building value, all with a very real carbon footprint.

We sit down with Swedish researchers Cecilia Wetterqvist (Lund University and Bengt Dahl...

Fire safety is a tough “product” to sell because the best outcome looks like nothing happened. That’s exactly why we sat down with Birgitte Messerschmidt (NFPA) to talk about communicating fire science to politicians, regulators, grant bodies, and other people in positions of power who can approve policies, permits, and funding, often with only a few minutes to spare. We share what changes when your audience is nontechnical, busy, and sometimes driven by incentives that do not neatly match engineering logic. 

We get practical about preparation: mapping who actually holds the decision power, building an elevator speech...

A battery fire on a train is not “just another small fire.” When a lithium-ion battery in an e-scooter or e-bike fails, the rail car can behave like a long pipe that moves smoke fast, limits escape options, and compresses decision-making into minutes.

We sit down with Adam Barowy from UL Research Institutes FSRI to unpack new full-scale passenger rail car burn tests using real micro-mobility devices and realistic storage locations. We talk through what thermal runaway looks like before flames, why that venting phase is a crucial warning sign, and what changes once flaming ignition starts. Adam...

In this episode of fire fundamentals we sit down with Professor Simo Hostikka from Aalto University to cover radiation in fires, both from the angle of physical phenomena and ways to model it. In this episode we cover following topics:

While we can get pretty far with a very simple approximation of what a fire is in our fire cfd, at some point our simplications are not enough. And there is a plenty of features and phenomena, for which we simply need a better tool to handle -  carbon monoxide, soot, extinction, flashover behavior, and what happens when ventilation disappears. At the IAFSS symposium, we sit down with Professor Bart Merci (Ghent University), fresh off delivering the Howard Emmons Invited Plenary Lecture, to talk about what it really takes to model turbulent combustion in real fires without asking practitioners t...

A timber column can survive the heating phase of a fire resistance test and still collapse later, after the flames are gone. We know there is so much more to structures in fires than the test demonstrates, but how much exactly do we know about timber nowadays? In this episode we try to dive deeper and discuss mass timber fire safety, structural fire engineering, and what a fire resistance rating does and does not tell us. 

I’m joined by Dr. Felix Wiesner from the University of British Columbia, this year’s IAFSS Proulx Award recipient, to unpac...

Fire science should have its place at the fireground, yet I've learned how hard it is to communicate it with the key stakeholder - the firefighters. It's not my isolated experience, and that tension drives our conversation with Steve Kerber, Vice President at UL Research Institutes Fire Safety Research Institute (FSRI). Today we dig into the real craft of communicating fire dynamics to firefighters without losing the truth of the science.

We talk about why experience alone can mislead when every incident is full of unknowns, and how repeatable research can “rewind the tape” to test tactics unde...

A national fire statistics system that updates in weeks is not a statistics system, it is a history lesson. We talk with Dr. Craig Weinschenk from UL Research Institutes - Fire Safety Research Institute about NERIS (the National Emergency Response Information System) and why it represents a real shift in fire incident reporting, emergency response data, and fire service analytics across the United States.

We trace the arc from NFIRS, built for paper forms and rigid codes, to a modern cloud based, API driven platform that can scale to tens of thousands of departments and millions of...

Jumping straight to CFD has become the default move in fire safety engineering, but that habit can quietly weaken our work: more inputs, more assumptions, more ways to be wrong, and often no clearer link to the actual design question. We sit down with Craig Hofmeister and Brian Klein to unpack a practical, defensible way to choose the right fire model for the job using the SFPE guideline “Substantiating a Fire Model for a Given Application.”

The broad framework of this work is to define the phenomena of interest and questions at hand, then choose the candidate mode...

“Two people per parking space” is one of those default fire engineering inputs that we are very used to place into a model without really thinking much of it. But it is one of those defaults that show a huge richness once you dig deeper. Are all parking spaces taken? Are people in their cars? What are they doing? How long have they been there concurrently... We take that simple rule and pull on the thread until it turns into a full conversation about evidence, uncertainty, and what “credible maximum” should mean when you are designing for real-world risk.

A fire strategy can be technically correct, but if the team building the building never truly understands it - goals and objectives may be missed. For the 250th Fire Science Show, we slow down and talk about the craft of communicating fire science to construction professionals so that the intent survives real projects, real deadlines, and real handovers. 

This episode is an extended version of my talk I gave recently at the IAFSS Research Sub-Committee Workshop, which we have organised with Felix Wiesner, and I had a chance to talk along my friends - prof. Guillermo Rein, B...

From the SFPE Performance Based Design Conference in Singapore, we sit down with Jonathan Hodges and Mark McKinnon (UL Research Institutes) and Christian Rippe (Jensen Hughes) moments after their case study presentation to break down a modern parking garage fire engineering workflow with a huge does of performance based and probabilistic approaches.

We talk about what changes when today’s vehicle fleet makes multi-vehicle fire spread more plausible, and why picking a single car fire curve can quietly bake bias into an entire performance-based design. The team shares how they use real incident data, vehicle size distributions, ig...

Fire safety in Europe is shaped in a challenging ecosystem - each member country owns its fire safety rules, yet the construction market, standards, and technical language are increasingly shared. I’m joined by Francesca Sciarretta, Scientific Project Officer at the European Commission’s Joint Research Centre (JRC), to explain how the JRC supports EU decision-making with independent research and why that “science behind the policy” matters for every practicing fire safety engineer.

We unpack what the latest JRC work says about performance-based fire safety engineering in Europe and why prescriptive design still dominates. Francesca walks through how the...

You don’t always need a furnace to end up with a fire resistance rating, but you do need to understand what kind of “proof” you’re actually creating. I’m joined again by Dr. Piotr Turkowski from ITB to unpack calculation methods for fire resistance and the real-world chain from engineering assumptions to a Declaration of Performance. We talk about when standards and European Assessment Documents (EADs) explicitly allow Eurocode-based assessment, and how different methods will lead you to your resulting class in a different way.

We spend a lot of time on the practical heart of structu...

In this episode of fire fundamentals with the ITB fire resistance expert Piotr Turkowski we break down what a fire resistance rating criteria, and what the letters behind ratings like “REI 60” exactly stand for. We use lab experience to explain where the standards are clear, where they are oddly traditional, and where comparisons between products can mislead. 

• ISO definition of fire resistance as an ability over time 
• What R E I W and M mean in fire resistance classification 
• Load bearing capacity as deformation and collapse criteria 
• How test loads are applied and why load choice matt...

plume_rise_1.fds from the FDS Validation Guide (by NIST)

&HEAD CHID='plume_rise_1',  TITLE='Test plume rise height in stable atmosphere' /

&MESH IJK=50,52,50, XB=-50.,50.,-52.,52.,0.,100., MULT_ID='mesh1' /
&MULT ID='mesh1', DZ=100., K_UPPER=1 /
&MESH IJK=50,52,50, XB= 50.,250.,-104.,104.,0.,200., MULT_ID='mesh2' /
&MULT ID='mesh2', DZ=200., K_UPPER=1 /
&MESH IJK=50,50,50, XB=250.,650.,-200.,200.,0.,400., MULT_ID='mesh3' /
&MULT ID='mesh3', DX=400., DZ=400., I_UPPER=3, K_UPPER=1 /

&TIME T_END=900. /

&MISC TMPA=20.36 /

&WIND SPEED=5., LAPSE_RATE=-0.0048 /

&S...

When one takes a decision to evacuate and starts moving, this is not the end of their decision-making process. 

Which route to take? Who to contact? How to arrange a place of shelter? Where to go first? Have I forgotten anything? 

I previously discussed the decision-making with Erica Kuligowski from RMIT, and today we're meeting again to follow up on decision-making for large-scale evacuations. We focus on choices and uncertainties that make many of the evacuees take additional trips, and those trips become background traffic that interferes with your escape. In this episode, we dive de...

A fire in an informal settlement is not just another small building fire. It can be the first domino in a fast-moving neighborhood event, and the little details like the wall material, roof material, door location, even a light breeze, can decide what happens next. I’m joined by Dr. Sam Stevens from Kindling to unpack a massive FSRI funded experimental program carried out in South Africa that burned twenty different informal and humanitarian shelter types to measure real heat flux, flame extension, and fire spread potential. 

We start repeating the uncomfortable gap: humanitarian guidance often relies on...

Being a part of broader civil engineering and built environment sciences, we have the unique opportunity to learn from other "sister" disciplines, rather than coming up with everything on our own. Especially, when those disciplines have 100+ years of experience in investigating stuff that has recently emerged as one of the leading challenges in our field.

The other discipline is Earthquake Engineering.

The interesting stuff - community resilience and managing safety across tens of thousands of buildings exposed to the same hazard.

Our field of application - Fire Safety of WUI communitites.

...

Is it too late to start with the AI in 2026? It wen't so far, does it still make sense to get interested in this technology?

Absolutely. Today we sit down with MZ Naser of Clemson University to map a clear, useful path for engineers who want results without the hype. We start with the basics - clean data, the right algorithm, and a realistic mindset - and climb toward explainability, causality, and even philosophy to show where AI informs decisions and where it can quietly mislead.

We dig into the limits of our experiments: when...

I’m not stressed by AI itself. I’m stressed by the insatiable greed of those who profit from it, even if it means sacrificing large parts of the population. I'm also stressed about how ruthlessly it can be abused to cause deliberate harm.

In this episode I'm not taking you into world of fire science, but rather into my own thoughts on how the AI revolution influences our lives. And I was influenced it just last week - through a phishing attack on the IAFSS, and through reading a very disturbing piece of fiction I found on t...

A tunnel can ride out a fire without collapsing (or even critical visible structural damage), but a question whether it is safe for operations, and what is its long-term residual fire resistance remains. With repair bills being in high seven-eight figures, this is more than just a theoretical question... In this episode we dig into the hard middle ground of fire damage post mild/large fires, and cover where modeling and fire science can help reducing the uncertainty and guiding decisions. With Professor Negar Elhami-Khorasani from University at Buffalo, we map how ventilation settings, tunnel slope, and fuel push...

Welcome to another fire fundamentals episode! Today we dig into how to place a fire in a model so results reflect real physics. From plume inputs to FDS burners, we show where HRRPUA, radiative fraction, and D* make or break smoke your calculations. Things considered in this episode:

• why defining the design HRR is separate from placing the source
• what a flame is and why we cannot resolve its chemistry
• plume models compared by inputs: perimeter, Q, Qc
• entrainment, virtual origin, and effective diameter
• realistic HRRPUA ranges for building-scale fires
• radiative vs convective f...

Welcome back to Fire Fundamentals! Today with prof. Ali Rangwala from WPI and dr Lorenz Boeck from Rembe and WPI we take the world of explosion protection engineering. 

In this episode we touch:

• distinguishing fires and explosions by time scale and damage mode
• taxonomy of explosions by energy density and deposition time
• hybrid mixtures in coal mines and turbulent burning velocity
• severity metrics for gases and dust deflagration index for reactivity
• explosion sphere testing, ignition positioning, and model limits
• ignition sensitivity minimum ignition energy and hot surface risks
• prevention via ventilation...

A tight, historic cellar. Arched ceilings. Long corridors. Tiny shafts. We faced a design wall: to keep routes tenable, we needed twice the extraction that the building could carry. At that point, I've failed as an engineer - I've reached my limit and could not find a solution.

Some time later, a solution appeared in my head from nowhere —what if the fan changed with the fire? Not in a crude on-off way, but by tracking temperature, exploiting density changes, and chasing constant mass flow instead of fixed volume.

We unpack the moment this clicked, th...