Large-scale fire events are on the rise, from the flames that raged for days across LA, to the widespread devastation seen in Greece in 2023 and 2024. The blurred line between urban and wildland areas means these events will continue to proliferate.
Scientists dub these types of fires wildland urban interface fires (WUI), and they differ from traditional wildfires. While wildfires are limited to vegetative fuels combusting in uninhabited areas, WUI fires comprise vegetative fuel combustion as well as human-made fuel combustion: gasoline cars; EV battery cells vehicles, and the gas we use to cook or to heat our home exasperate threats not seen in wildfires.
In light of this threat, Tohoku University visiting professor Samuel L. Manzello is working to harmonize international testing standards for large outdoor fires, including WUI Fires.
Details were published in the journal Fire and Materials on December 8, 2024.
"Even though many countries are experiencing a spike in WUI fires, very few have any standards or codes for these fires," says Manzello. "Without better preparation, we can expect greater destruction, as was seen in Maui in 2023."
Harmonizing International Standards
After a spate of fire events in California in the early 2000s, the Office of the State Fire Marshal began to explore WUI fires in more detail. They wanted to develop building codes standards akin to those in urban fire prevention. Yet the limited scientific understanding of WUI fires impeded their efforts, with building codes built on best-guess estimates.
To address this, the ASTM International sponsored a workshop in 2015 that brought together researchers, building code officials, and industry representatives. Likewise, the International Organization for Standardization tasked with fire safety (ISO TC92) and the International Association for Fire Safety Science (IAFSS) sponsored a similar workshop, where they sought to address the growing problem of WUI fires in a more global manner. Meanwhile, the International FORUM of Fire Research Directors issued a position paper focusing on the threat of WUI fires.
The confluence of initiatives spawned a Large Outdoor Fires and the Built Environment Task Group (ISO-TC92/TG03) - where Manzello was appointed convener. Its mandate was to develop international standards and technical documents for ISO TC92, to lessen impacts from large outdoor fires.
"This was a major shift," says Manzello. "Until then, ISO TC92 had been mainly focused on fires occurring inside buildings."
Advancing Fire Safety Through Research
From there, ISO-TC92/TG03 began developing roadmaps to address large outdoor fires, including WUI fires. After a workshop in the Netherlands in 2018, ISO TC92 balloted, creating a formal working group called the Large Outdoor Fires and the Built Environment Task Group, ISO TC92/WG14. Manzello, again, was appointed convener.
In 2022, the group published ISO TR/24188, entitled Large Outdoor Fires and the Built Environment - Global Overview of Different Approaches to Standardization. The report provided an overview of global testing methods to assess how vulnerable buildings are to large outdoor fires. It also offers insights into land-use management practices. The document includes definitions. WUI fires are one type of large outdoor fires, along with other types including, wildland fires, informal settlement fires, urban fires, and fires caused by natural disasters like tsunamis and volcanic eruptions. This February, the second edition of ISO TR/22188 was published, further refining large outdoor fire definitions.
"The spread of large outdoor fires is not limited to well-defined boundaries like in building fires. We must consider the interaction of topography, weather, vegetation, and structures, and factor in that ignition occurs via three ways: direct flame contact, thermal radiation, or firebrands," says Manzello.
These reports have benefited from the ISO Firebrand Generator, a device invented by Manzello and Associate Professor Sayaka Suzuki from the Institute of Science Tokyo. Nicknamed 'the Dragon,' the device produces continuous firebrand showers seen in wildland-urban interface (WUI) fires, wildland fires, and urban fires.
The workgroup is also working on a new standard for post-fire data collection, known as ISO/AWI 24944. This standard will review existing studies on fires in WUI areas, urban fires, post-earthquake fires, and informal settlement fires. The goal is to create a consistent method for collecting data after large outdoor fires, which will help assess and compare fire spread and damage globally.
Another important project is ISO/AWI 25399, which aims to harmonize test methods for thermal flux exposure in large outdoor fires. This includes both direct flame contact and thermal radiation. While different countries have their own methods, this new standard will create a unified approach for better global consistency.
Looking ahead, ISO TC92/WG14 is considering developing firebrand shower test methods for ornamental vegetation, mulch, and construction components. The group also aims to explore performance-based design methods from traditional building fire standards to improve resilience against large outdoor fires.
- Publication Details:
Title: Progress to Develop Globally Harmonized International Testing Standards for Large Outdoor Fires, Including Wildland-Urban Interface Fires
Authors: Samuel L. Manzello
Journal: Fire and Materials
