Fire Science Show

230 - Wind driven conflagration experiments with Faraz Hedayati

A facility with 105 synchronized fans pushing hurricane-class wind across a full-size house while a live fire... This is not science fiction - this is a real research capacity that helps us re-shape our knowledge on the full scale building ignition, fire spread, and failure. That’s the stage at IBHS, where we dig into how wind-driven fire behave differently to small-scale and how tiny choices around a building can decide its fate. Together with my guest - dr Faraz Hedayati, we go from embers generation and fire spread studies, to urban conflagration research. We start with embers, the quiet culprits behind so many structure losses in the WUI. Embers aren’t a single threat but a spectrum of sizes, temperatures, and lifetimes that ride shifting eddies and stall in stagnation zones. We talk through what full-scale tests reveal: glowing ember lines at the base of walls, roof reattachment zones where deposits spike, and the hard truth that counting particles matters less than controlling where they land. The guidance is clear and actionable—noncombustible vertical clearance, hardened vents, defensible space within the first five feet—because under wind, any component can become the first domino. Then we tackle conflagration: how a spot fire becomes a neighborhood problem. IBHS’s shed-to-structure and fully furnished burns show exposure arriving in pulses, not a smooth curve. Collapse chokes flames and then reinvigorates them, creating multiple peaks where materials succeed or fail on a timer. We compare 30 mph to 60 mph winds and see how plumes lose buoyancy, flatten into the target, soften vinyl frames, and push glazing inward. Separation distance emerges as a decisive lever: around 10 feet, continuous flame contact dominates; at 20 feet and beyond, exposure becomes intermittent and materials can win—unless “connected fuels” like vehicles, fences, and decks bridge the gap. The takeaway isn’t a silver bullet. It’s a layered defense: control embers, clean the near-wall zone, harden openings, choose noncombustible claddings, and increase spacing where possible. Small-scale testing and modeling still matter, but wind-driven fire demands validation at full scale to catch the peaks, the collapses, and the failure modes no bench setup can mimic. If you care about wildfire resilience, urban design, or building safety, this conversation offers a rare, data-rich look at how communities ignite—and how we can change the odds. Learn more about IBHS research at https://ibhs.org/risk-research/wildfire/ [https://ibhs.org/risk-research/wildfire/] Cover picture courtesy of dr Faraz Hedayati. ---- The Fire Science Show is produced by the Fire Science Media in collaboration with OFR Consultants. Thank you to the podcast sponsor for their continuous support towards our mission.

229 - Learning from 900 fires with Björn Maiworm

What can you learn after processing observations across 900 severe fires? A lot. Actually, I will send you to the paper straight away: Evaluating 900 Potentially Harming Fires in Germany: Is the Prescriptive Building Code Effective? German Fire Departments Assessed Fire Safety Measures in Buildings Through On-Site Inspections  [https://link.springer.com/article/10.1007/s10694-024-01560-6] And now let's dissect this. We sit down with Björn Maiworm of the Munich Fire Department to unpack a decade of structured observations from more than 2,000 significant incidents (900 in the paper but the database already grew!) across Germany—and the results may challenge the assumptions of Fire Safety Engineers. Smoke spread shows up as way more common, despite that legislation should prevent it, and is often seen breaching beyond the apartment of origin when doors are left open, self-closers are defeated, or vertical shafts pull hot gases to the top floor. Meanwhile, true flame spread between units is relatively rare, suggesting that basic compartmentation and detailing are quiet success stories. We also talk about people. Injuries appear in roughly a third of these consequential fires and fatalities in 6 to 7 percent, with risk concentrated in prisons, elder care, and dense low-income housing. Building age isn’t the driver; height and social factors are. Where self-closing doors are mandated and maintained, smoke infiltration to stairs drops—just not as far as theory predicts, thanks to behavior and upkeep realities. That gap between paper and practice is where small, targeted fixes make the biggest difference. On emerging risks, the data draws sharp lines. Mass timber’s challenge isn’t fire resistance; it’s the speed and multi-floor spread when exposed surfaces meet window plumes. The result can outpace practical firefighting capacity. By contrast, shifting a typical household to an EV, PV, and home battery can reduce overall fire probability; the true hazards arise from poor products, DIY installs, and dense storage arrangements. The smart response is segmentation and simple physical breaks that buy time, not blanket bans or panic. We close by reframing fire safety as a complex system problem. Instead of chasing perfect proofs, we can use continuous field feedback to find the leverage points: doors that stay shut, shafts treated as priority risks, vulnerable occupancies protected with tailored measures, and dispatch data that points crews to the right entrance first.  If this resonates, subscribe, share the episode with a colleague, and leave a review telling us which finding surprised you most. Your feedback helps more engineers, firefighters, and policymakers turn real-world lessons into safer buildings. ---- The Fire Science Show is produced by the Fire Science Media in collaboration with OFR Consultants. Thank you to the podcast sponsor for their continuous support towards our mission.

228 - Quantifying the expected utility of fire tests with Andrea Franchini

What do you expect from running a fire test? I would hope that it improves my state of knowledge. But do they do this? We often pursue them blindly, but it seems there is a way to do this in an informed way.  In this episode we explore a rigorous, practical way to select and design experiments by asking a sharper question: which test delivers the most decision-changing information for the least cost, time, and impact. With Dr. Andrea Franchini of Ghent University, we unpack a Bayesian framework that simulates possible outcomes before you touch a sample, updates your state of knowledge, and quantifies the utility of that update as uncertainty reduction, economic value, or environmental benefit. First, we reframe testing around information gain. Starting from a prior distribution for the parameter you care about, we model candidate experiments and compute how each would shift the posterior. The gap between prior and posterior is the signal; diminishing returns tell you when to stop. In the cone calorimeter case on PMMA ignition time, early trials yield large gains, then the curve flattens, revealing a rational stopping point and a transparent way to plan sample counts and budgets. The same structure scales from simple statistical models to high-fidelity or surrogate models when physics and geometry matter. Then we tackle a post-fire decision with real financial stakes: repair a reinforced concrete slab, or accept residual risk. We connect Eurocode-based thermal analysis to two test options—rebound hammer temperature proxies and discoloration depth—and compute their value of information. By translating updated probabilities of exceeding 600°C into expected costs of repair versus undetected failure, we show how to choose the test that pays back the most. In the studied scenario, the rebound hammer provides higher value, even after accounting for testing costs, but the framework adapts to different buildings, cost ratios, and risk appetites. Beyond pass-fail, this approach helps optimize sensor layouts, justify added instrumentation, and balance multiple objectives—uncertainty, money, and environmental impact—without slipping into guesswork. If you’re ready to move from ritual testing to evidence that changes outcomes, this conversation maps the path.  Papers to read after this: * Which test is the best? Choosing the fire test that maximizes the information gain [https://iopscience.iop.org/article/10.1088/1742-6596/3121/1/012037/pdf] * Quantifying the expected utility of fire tests and experiments before execution [https://www.sciencedirect.com/science/article/pii/S0379711225002024] ---- The Fire Science Show is produced by the Fire Science Media in collaboration with OFR Consultants. Thank you to the podcast sponsor for their continuous support towards our mission.

227 - The differences between EV and ICEV fires in car parks

A viral clip of an EV igniting was what started my worries about safety in car parks I have been designing. Are we ready for fast growing fires? Since 2019 I've learned and studied a lot, I've relaxed on some aspects of it and was able to identify they areas where a lot more engineering considerations should be placed. In this episode I would like to take you inside the engineering choices that shape outcomes: ceiling height, smoke control, structural details, and how fast systems wake up when seconds matter. Instead of arguing EV versus ICE, we look at what the data shows across 148 vehicle fire tests and why there’s no single “true” car fire curve. Think of a car as a set of compartments—the cabin, engine bay, trunk, wheels, and for EVs the battery pack—each with its own vents and barriers. That lens explains the wildly different heat release profiles you see in experiments and helps you separate worst-case lab setups from realistic design scenarios. We unpack why rapid battery-led growth is so challenging for low garages, how beams can trap and extend flames under the ceiling, and how wind can either help by stripping hot gases or hurt by pushing fire across bays. From there, we focus on consequences and controls. For evacuation, the goal is to avoid early smoke cut-offs and protect crowded egress moments after events. For firefighting, the single most important factor is a clear entry path—no smoke between the crew and the fire—so water can be applied fast to stop spread, even if battery cooling remains lengthy. For structure, isolated car fires shouldn’t be catastrophic in robust frames, but long, multi-vehicle burns can threaten integrity without early control. What works? Height buys time and reduces ceiling flame attachment. Smart smoke control drains energy from the layer and lowers radiation to neighboring cars. Thoughtful layouts keep chargers away from exits and closer to exhaust paths. And suppression systems may not “kill” a battery, but they cut plume temperatures, slash spread potential, and make the entire operation safer. We also surface key gaps: natural battery-initiated growth rates, context-specific risk acceptance, and handling potential explosive gas releases with low-level detection and dilution modes. If you like to learn more, see more here: Miechówka & Węgrzyński: Systematic Literature Review on Passenger Car Fire Experiments for Car Park Safety Design [https://link.springer.com/article/10.1007/s10694-025-01701-5] Zahir & César Martín-Gómez: Evaluating Fire Severity in Electric Vehicles and Internal Combustion Engine Vehicles: A Statistical Approach to Heat Release Rates [https://link.springer.com/article/10.1007/s10694-025-01711-3] * Collection of Fire Science Show episodes on cars and batteries [https://www.firescienceshow.com/categories/batteries-and-evs/] * Episode 6 - my early research on fast fire growt [https://www.firescienceshow.com/006-evs-rapid-fires-and-car-parks/]h * Episode 190 - Review of research on vehicle fires [https://www.firescienceshow.com/190-car-park-fires-review-with-zahir/] * Podcast episode 135 - Contemplating a car park design fire [https://www.firescienceshow.com/135-contemplating-a-design-fire-for-car-parks/] ---- The Fire Science Show is produced by the Fire Science Media in collaboration with OFR Consultants. Thank you to the podcast sponsor for their continuous support towards our mission.

226 - New Swiss fire safety code with Gianluca De Sanctis and Sofia Kourgiantaki

It is a massive effort to rewrite a national fire safety code around measurable risk, explicit targets, and cost-effectiveness. But sometimes, there are great reasons to do so. In this episode, together with Gianluca De Sanctis and Sofia Kourgiantaki we take you inside Switzerland’s sweeping reform, where a new federal law sets a maximum individual risk for life safety, ties property protection to a clear marginal cost rule, and harmonises practice across cantons. Together, we trace how the framework defines acceptance criteria, builds a shared “model code” of probabilistic inputs, and keeps prescriptive pathways for standard projects—only now grounded in risk-optimised measures. You’ll hear how the system replaces vague equivalence with transparent math. Life safety is anchored at 5×10^-5 fatalities per user per year; if a building exceeds that threshold, measures are required until it doesn’t, regardless of cost. Beyond the threshold, optimisation is driven by the marginal cost principle and a nationally defined social willingness to pay, aligning fire with flood, transport, and earthquake risk policy. For property, the rule is simple and strict: do not spend more than the expected damage you remove. While the code was being developed, Sofia put the method to the test in a retail centre case study using Bayesian networks and ASET/RSET. The model compared detection, sprinklers, and smoke exhaust while capturing occupancy, fuel loads, growth rates, system reliability, and fire service response. The surprising result: in a seven-meter hall, detection met the life-safety target on its own, and the most cost-effective optimisation paired detection with sprinklers, while smoke exhaust added little benefit in that geometry. The lesson isn’t that one system always wins; it’s that context and data should decide, not habit. Switzerland didn’t stop at policy. A peer-review approval process, ETH’s advanced training in probability and risk, and a national model code make the approach usable and reviewable. The reform is in technical review ahead of political approval, with mechanisms for minor updates as evidence grows. Direct links to the document: - German Version: https://mitwirkung-vkf.ch/de/ [https://mitwirkung-vkf.ch/de/] - French Version: https://mitwirkung-vkf.ch/fr/ [https://mitwirkung-vkf.ch/fr/] Also, there are 4 short videos in German, French and Italian that describes the new framework of the new codes: https://www.bsvonline.ch/de/brandschutzvorschriften/projekt-bsv-2026/videos [https://www.bsvonline.ch/de/brandschutzvorschriften/projekt-bsv-2026/videos] A part of this shift in culture is also the new MAS in fire at the ETH, which you can learn more about in here: https://mas-brandschutz.ethz.ch/ [https://mas-brandschutz.ethz.ch/] ---- The Fire Science Show is produced by the Fire Science Media in collaboration with OFR Consultants. Thank you to the podcast sponsor for their continuous support towards our mission.