Fire Science Show

263 - Developments in modelling WUI fires with Arnaud Trouvé

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 spread. The state of the art models for fire spread are lacking in here, due to how they perceive a fire front as a "line", whereas in cities we are looking at collection of compartment-household fires that may last for hours, and create a burning area kilometre wide. Therefore, we need new modelling approaches, and we need them at three scales - the scale of vulnerabilities of a parcel, a parcel-to-parcel setups and whole community scales. To improve the state of the art, he breaks the problem into the scales that matter: indoor fire dynamics (where CFD can estimate structure burning), parcel-level exposure (where fire penetration is the missing link), and community-scale fire spread (where reduced order models dominate because fuel and building maps are often coarse). We dig into the practical modeling mechanics behind WUI simulators: 2D spread on gridded maps, simplified radiation and flame shape models, probabilistic firebrand transport, and the limits of one-way coupling where wind is prescribed but not influenced by the fire. We also discuss an important bottleneck: the data. Satellite observations often arrive with poor temporal resolution, and controlled full-scale experiments are rare, which makes validation and scenario selection painfully uncertain. We also discuss why windows and near-structure fuels can be a universal pathway for loss, and why the field needs stronger shared infrastructure and collaboration to move faster.  Congratulations on your plenary talk and thank you Arnaud for representing the fire community at the Combustion Symposium. Once Arnaud's plenary paper is published, I will update the show notes with a link! ---- 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.

262 - Fire Fundamentals pt. 22 - Optical diagnostics in fire with Elizabeth Weckman

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 photography and video as a first diagnostic and as a planning tool  • calibration habits for cameras and why cheap, robust cameras are often a better choice for a fire laboratory  • infrared thermography for surface heating plus emissivity problems and practical coatings  • Schlieren imaging for density and temperature gradients and what it can and cannot imply  • point vs planar vs line-of-sight vs tomographic measurements and how “smearing” happens  • FTIR and absorption spectroscopy for pyrolysis gases, emissions, and toxic species  • chemiluminescence and laser-induced fluorescence to mark combustion and flame fronts  • Raman and CARS for temperature and concentration and why they are technically demanding  • soot diagnostics from light extinction to laser-induced incandescence and aging effects  • PIV basics, seeding challenges in fire, and what velocity fields unlock for validation  The episode is best enjoyed along Beth's paper from the IAFSS: Unravelling the mysteries of fire [https://www.sciencedirect.com/science/article/pii/S0379711226000640] ---- 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.

261 - The story of the Cone Calorimeter with Vyto Babrauskas

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 that created funding, talent density, and the freedom to build new measurement tools. Vyto explains how the field moved from qualitative “widget tests” toward combustion-science thinking, and why oxygen consumption calorimetry was the turning point. We also talk about terminology and standardization, including how “heat release rate” became the key engineering variable for “how big is the fire,” and why that framing still guides modern fire modeling and performance-based design. Then we get concrete: why the specimen is 100 by 100 mm, how the cone heater geometry was modified to keep combustion products flowing where they should, why adding feedback control was so important, and how ignition and smoke measurement evolved into the robust setup many of us take for granted under ASTM E1354 and ISO 5660. We also cover heat flux selection for realism, horizontal versus vertical orientation, and why some promising variants like controlled-atmosphere attachments never became widespread. The closing brings it back to today, including Vyto's critique of fire research (mainly in Li-ON batteries) that stops at plotting heat release rate curves without answering the deeper engineering and forensic questions. If you would like to read more about the cone, I got  you covered: * https://www.nist.gov/nist-museum/cone-calorimeter-most-important-tool-fire-safety-science from the NIST Museum * https://www.nist.gov/news-events/news/2022/03/happy-retirement-cone-calorimeter - a NIST note on the history of the cone * https://www.jstage.jst.go.jp/article/fst/41/1/41_21/_article paper by Vyto Babrauskas on the early history of the cone. Cover image credit: NIST, from the https://www.nist.gov/news-events/news/2022/03/happy-retirement-cone-calorimeter ---- 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.

260 - Fire safety in a carbon budget with Cecilia Wetterqvist and Axel Mossberg

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 Dahlgren Fire Research) and Axel Mossberg (Bengt Dahlgren Fire Research) to connect fire safety engineering with life cycle assessment (LCA), climate declarations, and green building certification thinking. We talk honestly about system boundaries, early design lock-in, why “50-year” assumptions can be misleading, and how reuse projects can be both a climate win and a detailing challenge that changes maintenance and risk. The heart of the conversation is a translation tool: turning fire risk into the same unit sustainability teams already use, kilograms of CO2e per square meter. Using incident statistics and damage categories, the method estimates expected fire-related emissions, including the big driver most models miss: replacement. The result can flip decisions on their head, especially for larger commercial buildings where sprinklers may reduce expected lifecycle carbon rather than increase it. If you are looking here for more resources, you know I got your back: * Mossberg A. et al., A methodology for the integration of fire risk in building life cycle analysis [https://www.sciencedirect.com/science/article/pii/S0379711225002656?via%3Dihub] * Wetterqvist C. et al., Sustainability and fire safety decisions in the design process: Overview and two Swedish building projects [https://www.sciencedirect.com/science/article/pii/S0379711226000354?via%3Dihub]  * McNamee M. et al., Challenges and opportunities for reuse of products and materials with fire safety requirements – A Swedish perspective [https://www.scopus.com/pages/publications/85165132487?origin=resultslist] ---- 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.

259 - Communicating fire science with politicians with Birgitte Messerschmidt

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, and using storytelling so your message sticks. We also unpack the role of media and “sensation” in shaping political priorities, using electric vehicle fire headlines as a real example. Instead of amplifying fear, we talk about framing the issue as a changing fire landscape: new materials, tighter buildings, batteries, and evolving hazards that demand updated fire safety engineering.  Then we go into the hard parts: how experts can get pulled into political fights, how soundbites get cherry-picked, and when the right move is to say less, not more. We also tackle ethical communication after tragedies, focusing on respect for victims and clear intent to prevent repeat losses. Finally, we wrestle with risk communication, why “it could happen” derails risk-based design, and how to acknowledge emotion while bringing people back to facts. ---- 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.