Fire Science Show

255 - Timber load bearing capacity in fire from nano- to megascale with Felix Wiesner

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 unpack his review on mass timber load-bearing capacity in fire across scales. We start where most design decisions begin: full-scale furnace tests and the practical reality that many modern timber elements are too large, too new, or too costly to test under load. From there we dig into the reduced cross-section method, charring rate assumptions, and the controversial “zero-strength layer” that turns heated wood into a simplified design allowance, even as uncertainty and code-to-code differences persist.  Then we turn to the decay phase and delayed failure, connecting recent column results to the bigger question of performance-based design for compartment fires that heat and cool. To model that behaviour, we need credible links between temperature, strength reduction, and elastic modulus reduction, and we need to care about how the data were generated: steady-state oven tests versus transient tests where timber is loaded first and heated with steep gradients.  Finally, we go down to the microscale and nanoscale, where moisture migration and even hydrogen-bond changes in cellulose help explain why “loaded while heating and cooling” can permanently reshape capacity. If you work with mass timber buildings, timber fire design, Eurocode approaches, or structural safety in fire, this is a deep reset on what matters most.  Read about the IAFSS Awards here https://www.iafss2026.com/awards [https://www.iafss2026.com/awards] Read the whole paper with a more in-depth view on the subject "From nano-to megastructure: A review of mass timber load-bearing capacity in fire" [https://www.sciencedirect.com/science/article/pii/S0379711226002353] ---- 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.

254 - Communicating fire science with firefighters, with Steve Kerber

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 under controlled conditions. Steve explains how measurements like temperature, heat flux, and toxic gas concentration can clarify what different decisions actually do to survivability and operational time windows. We also get honest about the trust gap between lab work and the messy reality firefighters see every day, especially when buildings and contents evolve faster than training programs. From there, we get practical: how FSRI listens to a more complete voice of the fragmented fire service using advisory boards and fire service technical panels, how to reach line firefighters through the media and training pathways they already rely on, and why “simplify, don’t dumb down” is the way to teach concepts like ventilation-limited fire, flashover, and ventilation control at scale. Steve shares how video, clear visuals, and well-designed props can build the muscle memory crews need under pressure, plus the story of how research challenged the old fear that exterior water “pushes fire.” We also cover a clear win where technical research and health research meet: firefighter exposure and cancer prevention, and why that evidence changed behavior across the profession. If you care about fire protection engineering, evidence-based firefighting, firefighter safety, and turning research into real-world outcomes, this one is for you.  The Fire Science Show was built around the mission to communicate better. This is the kind of episode that is perfect for the occasion... as we are celebrating the 5th anniversary of the podcast today! Thank you all for being with us for the 5 years! If you would like some additional resources: * https://fsri.org/resources [https://fsri.org/resources]All the resources by FSRI. A masterclass on how good communication looks like. * Utilizing Research to Enhance Fire Service Knowledge [https://www.lu.se/lup/publication/a3a3c13b-3882-4d8b-84e2-0b31941b1eeb]- Steve Kerber's PhD Thesis very relevant to the topic we discuss today ---- 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.

253 - NERIS - the paradigm shift for the US fire data collection with Craig Weinschenk

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 records. Craig explains the practical problems that held fire data back: delayed batch uploads, validation errors that return long after the call, fractured “plus one” local codes, and how hard it was to update incidents when outcomes change. Then we get specific about what NERIS enables: easier updates with full change history, consistent unit typing, staffing counts per apparatus, all hazards reporting, and narrative fields that document impediments so the data keeps real world context. We also dig into what departments get back immediately: interactive dashboards, geospatial maps, time of day trends, mutual aid linking, and a clearer view of complex incidents that involve suppression, rescue, and medical actions at once. On top of that, NERIS enriches incident records with external data like parcel information and weather, creating new opportunities for fire safety engineering research, community risk reduction, and smarter resource planning while keeping sensitive operational details controlled. Learn more about the NERIS here: https://fsri.org/programs/neris Check this webinar to see the live demo: https://fsri.org/program-update/now-available-demand-access-neris-version-1-platform-launch-and-national-rollout ---- 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.

252 - Substantiating Fire Models with Craig Hofmeister and Bryan Klein

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 models and evaluate them through set of core qualities, then address the verification and validation of the models, consider uncertainties and user impact, and finally document the whole process. We walk through the framework step by step, starting where good performance-based design always starts: the questions the model must answer. From sprinkler and detector activation to atrium smoke control, pressurization, visibility and tenability, we talk about translating objectives into key physics and required outputs. That sets up a grounded comparison across hand calculations and algebraic correlations, zone models like CFAST, node network tools like CONTAM and Ventus, and field models like FDS built in PyroSim. From there, we get into the part many projects rush past: verification versus validation, how to use published V&V evidence (and when you are outside the validated scope), and how uncertainty and user effects should shape your confidence. We also address real-world constraints like AHJ expectations and contract requirements, plus practical tools like sensitivity studies, bounding analysis, and grid sensitivity checks to keep complexity from turning into false precision. If you want a cleaner way to defend your modeling decisions to reviewers and stakeholders, this conversation gives you a repeatable process you can build into your own practice. ---- 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.

251 - Occupant loads in Car Parks with Mike Spearpoint

“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. Dr Mike Spearpoint from the OFR joins me to explain how occupant load values end up in codes, why they are so hard to interpret, and why “maximum possible” can push designs into unrealistic corners. Then we get practical: we build a static, risk-based method for car park occupant load using distributions for car park utilisation and people per vehicle, run it through Monte Carlo simulation, and talk about selecting percentiles like the 95th or 99th for design. If you work with evacuation analysis, performance-based fire engineering, or fire safety assessment, this is the kind of reasoning you can reuse anywhere. In his consideration, Mike reaches something he calls the dynamic model: people are only briefly “in the car park” as they park, unload, walk to the destination, and leave. Because published data on “around-the-car” activity time is scarce, Mike measures it directly using public CCTV observations and turns it into a usable distribution.  Why did he do this? This is a part of a larger project on adequate fire resistance periods in car parks. We also connect utilisation to vehicle-to-vehicle fire spread and why those assumptions can ripple into design fires and structural fire resistance decisions for open-sided car parks. If you are looking for the report itself with all the details, look here: https://www.gov.uk/government/publications/fire-safety-open-sided-car-parks [https://www.gov.uk/government/publications/fire-safety-open-sided-car-parks] I'll make it easy for you, it starts at page 218 ;) ---- 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.