Fire Science Show

If we truly want to account for the population at a disadvantage in evacuation, there is only this much we can do with the current approach... Pre-evacuation time distributions, walking speeds, and so on only tell us a part of the story - the story of your average person within an average population, with an average walking speed and average response. While these models are undoubtedly useful in engineering, there is perhaps a better way.
My friend and guest Enrico Ronchi is trying to find this way through his new ERC Consolidator grant, "Egressibility: a paradigm shift in evacuation research". In this grant, instead of following the main path, he is focusing on stuff we do not know - how to characterise disabilities and understand them better (also through the lens of health and medicine), how to quantify the disadvantages at large, and how to solve potential issues for those who those at the largest risk.
In this episode, you will learn about Enrico's ideas and the edge of the knowledge we have today. Some key points covered are:
• Insights on paradigm shifts in evacuation science
• Introduction of the concept of "egressibility"
• Importance of understanding functional limitations in emergencies
• Shift from agent-based models to inclusive data-driven models
• Use of technology, like VR, for immersive research experiences
• Need for changes in regulations for better evacuation safety
You may also like to read the paper by Guylène Proulx, which introduced egressibility as a concept - available here.

----
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.

In this week's series covering experimental fire science, we venture into a recently finished Code Red project by ARUP, led by my today's guest Dr Panos Kotsovinos. The project was carried out in CERIB with the collaboration of the Imperial College London. History will tell if this experiment will change fire science, but I truly believe it is at least worth sharing!
The research was carried out on a large open-plan office (350m2) with a combustible CLT ceiling. It was a continuation of previous X-One and X-Two experiments on travelling fire behaviour carried out by Imperial College London in Poland (referred to here as the "Obora" experiments, listen to episode 27 of the show) but with an important difference - this time the ceiling was combustible. They were looking into how the introduction of the combustible ceiling will change the travelling fire behaviour, investigating variables such as the opening factor, the introduction of a low-pressure water mist system and partial encapsulation of the ceiling. The findings include observations related to fire spread, persistent smouldering fires, effects of the partial encapsulation and many many more which are discussed in detail in the show.
To learn more, please read the press release about the experiments here and most important - the papers:
- Fire dynamics inside a large and open-plan compartment with exposed timber ceiling and columns: CodeRed #01
- Impact of ventilation on the fire dynamics of an open-plan compartment with exposed timber ceiling and columns: CodeRed #02
- The Effectiveness of a Water Mist System in an Open-plan Compartment with an Exposed Timber Ceiling: CodeRed #03
- Impact of partial encapsulation on the fire dynamics of an open-plan compartment with exposed timber ceiling and columns: CodeRed #04
- Review of fire experiments in mass timber compartments: Current understanding, limitations, and research gaps
- Structural hazards of smouldering fires in timber buildings
- Flame spread characteristics in large compartments with an exposed timber ceiling
If you have any further questions to Panos please let me know, and I will gladly pass them on to him!
Fire Science Show is produced in partnership with OFR Consultants.

----
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.

If you have ever learned about the compartment fire dynamics framework, have tried zone modelling or any kind of fire modelling, you have probably noticed that as the compartments get bigger, the less uniform conditions inside are. At some size, the flashover or a "single-zone" model theories just break, MQH equation does not give a reasonable solution and the fire seems not capable of growing to a huge size... But yet, they destroy buildings. Local fire exposure may be damaging to structural elements in the same way as a flashover is. And that is how we considered it for many years...
But there was a gap. Something between a localized fire and a flashover'd fire. For many years we've seen it, but we have not acknowledged it fully untill it was given a name - the Travelling Fire. In today's episode, I have invited prof. Guillermo Rein of Imperial College London, to tell us the origin story, recent developments and future plans related to this methodology. This should be interesting to all - from fire scientists to engineers. IMHO, a well invested hour of your time!
Make sure to connect with Guillermo on socials:
- Twitter
- LinkedIn
and with his group - Imperial Hazelab (also on Twitter).
Guillermo has published 200 research papers, and among them many landmark pieces on travelling fires that I recommend:

• Travelling fires for structural design (2012) with J. Stern-Gottfried
• Improved formulation of Travelling Fires (2015) with E. Rackauskaite et al.
• Improved Travelling Fire Methodology - iTFM (2017) with E. Rackauskaite
• Computational analysis of thermal and structural failure criteria of a multi-storey steel frame exposed to fire (2019) with E. Rackauskaite et al.
• Flame extension and the near field under the ceiling for travelling fires inside large compartments (2020) with M. Heidari et al.
• Fire Experiment Inside a Very Large and Open-Plan Compartment: x-ONE (2021) with E. Rackauskaite et al.
• Thermal Response of Timber Slabs Exposed to Travelling Fires and Traditional Design Fires (2021) with F. Richter et al.

and some many more... You may also be interested in the relevant PhD thesis:
- Jamie Stern-Gottfried (2011)
- Egle Rackauskaite (2017)
And some other work related to travelling fires carried across the world:

• RK Janardhan and S Hostikka When the fire is spreading and when it travels?
• X Dai et. al. Extended Travelling Fire Methodology
• D Hopkin Testing the single zone structural fire design hypothesis
• C Maluk

----
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.

Zone modelling is a technique introduced in 1970's and 80's that has changed fire science. In my personal opinion, along with oxygen calorimetry and the development of FDS it may have been the most impactful tool of fire science. This is why I think its shameful it does not receive the same recognition today.
With Colleen we go deep into the zone models, discussing the tool itself and the ways to adapt it to current needs. You will learn how zone models evolved, and what makes them really useful in the modern world. It is a technology of the past, but certainly one with a bright future.
*** A mandatory download ***
https://www.branz.co.nz/fire-safety-design/b-risk/
This is the zone model largely developed by Colleen, absolutely worth your time to try it out!
--- LinkedIn discussion thread ---
https://www.linkedin.com/feed/update/urn:li:activity:6818412552368771072
--- Useful links ---
https://fireresearchgroup.com/ FRG is the company that Colleen works for, and it is a bunch of great experts solving issues of modern fire science. Excellent resources are available. Keep an eye on them.
Branzfire / B-Risk technical documentation covers the basics of zone modelling, available at: https://www.branz.co.nz/fire-safety-design/b-risk/
The same I can tell about the CFAST documentation, available here: https://pages.nist.gov/cfast/index.html
The paper that made Colleen pursue the career in fire! https://www.sciencedirect.com/science/article/abs/pii/0379711284900067?via%3Dihub
i was wrong in the interview, it is not the one about RSET (that was another by Leo Cooper in the same year, wow, what a brilliant mind he was!)

----
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.

When the flaming combustion stops and the raging inferno disappears, the environment is still far away from a stable, stationary state. The heat emitted by the fire and accumulated by the structural elements is still on the move, travelling through the members until it gets eventually dissipated. As parts of the structure get heated, some processes will occur, that may influence their load-bearing capacity and other properties. This is nothing new, we recognize this as an obvious process within the so-called "decay" phase of the fire.
What is new, though, are some recent observations related to the behaviour of timber elements in this phase of the fire. Today's guests Thomas Gernay and Jochen Zehfuss (along with a team that I call EU Fire All-Star Team) have performed a very precise study in which they have shown on one example the exact conditions in which the load-bearing capacity is lost in the decay phase by a column. If you missed that, they made quite an impression on LinkedIn (check the post and discussion here). In their experiments carried out within a well-controlled furnace environment, the variable they played with was the duration of the heating phase. It allowed them to find out two separate behaviours - one in which the column collapses in the decay phase, and one (not very different) in which the collapse does not happen. To learn more, please join us in the episode, and for sure - read the research paper provided in here.
If you would like a quick insight, I will also steal some text from Thomas's post on LinkedIn, as he did a great job summarizing their research. So here is his short comment:
"Two of the columns were subjected to ISO 834 heating until failure. They failed after 55 and 58 min (-> standard fire resistance).
Two other columns were subjected to 15 min of ISO 834 heating followed by controlled cooling. Flames self-extinguished after 40 min. But the columns still failed during the cooling phase, respectively after 98 and 153 min.
The load on the timber columns was constant throughout the tests. What changes between 15 min (end of heating) and 153 min (failure)? Heat transfer. The temperature of the inner parts of the column section continues increasing. Hence the strength continues decreasing.
Flaming and charring are not necessary for this inner temperature increase. And the absence of flaming is not a good predictor that the column is safe (see video).
By better understanding these phenomena, we can design to account for them - and achieve safe and resilient timber designs, including for burnout resistance when needed. Numerical modelling can support this objective. But simple methods based on charring rate fall short because they don't account for the slow heat transfer processes during the cooling phase."

----
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.