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The wildfire season has already been intense, with over 15,000 structures either damaged or destroyed in Western U.S. wildfires and over four million acres burned in the recent wildfires across Northern California, Oregon, and Washington State. From recent RMS® industry loss estimates, insured losses for these events are in the range of US$6-US$10 billion. There have sadly been 31 confirmed fatalities in California from the recent fires.

Seeing images from communities that have suffered both recently and in past seasons—images of what seems to be total destruction—just begs the question how can this be happening and what are the reasons for it, before assessing whether wildfire risk can really be manageable. You feel, a priori, as if there is an inevitability about these events, and given the ferocity and unpredictability of wildfire, that it wouldn’t matter what an individual householder or community could do to mitigate against such a threat.

But this is not the case. For the Northern California mega-complex wildfires, such as the CZU Lightning Complex Fire, the detailed damage inspection (DINS) reports from CAL FIRE, show that between 30 to 60 percent of the structures within the fire footprints survived the fire - they were not damaged or destroyed. When faced with the same threat, why do some structures come through the other side, while others are totally consumed?

Impact of Embers

Among the many innovations supporting the RMS® U.S. Wildfire HD Model™ is a substantial amount of research to understand the role of embers in wildfire spread and structural ignitions that can lead to urban conflagrations. Recognizing their importance, especially in triggering house-to-house urban conflagrations, the model is obsessive in getting a complete perspective of ember contribution, spatial coverage, and distribution of the hazard.  

RMS modelers took advantage of being a few hours away from the 2017 and 2018 Northern California wildfires. We were able to gain access to the most-impacted areas shortly after the fires happened, to investigate the reasons of how and why certain houses survived. 

RMS research into the impact of embers has been instrumental. We worked with our partner, the Insurance Institute for Business and Home Safety (IBHS) and used their exceptional resource – its South Carolina test chamber, which simulated the effects of embers engulfing a typical duplex house.

The duplex house was built and landscaped on one side as a wildfire-resistant structure, and on the other side with common materials used when wildfire resistance is not a consideration. As the IBHS demonstration showed, the wildfire-resistant side did not burn. These advances in building science and the development of innovations such as wildfire-resistant vents are making a difference, as seen by the 30 to 60 percent of structures that survived the recent fires.

As Daniel Gorham, IBHS wildfire researcher, makes it clear in his statement, “It’s all about the embers and making sure they have nothing combustible to land on.” The IBHS “Suburban Wildfire Adaptation Roadmap” (available to members) gives practical advice on how to mitigate wildfires from an individual building to community level.

WIldfire risk mitigation
Figure 1: Nine focus areas for homeowners to help mitigate against wildfire risk. (Source IBHS)

For an individual property, mitigation needs to focus on nine key areas, from roofing materials, vents and eave overhangs that are not flammable, through to decks, fences, and outbuildings. One very important mitigation factor is the first five feet of space around a property. In this zone, it is critically important to remove anything that can be ignited by embers, to reduce the potential that embers landing near a building will burn the home down. More importantly, the improved fire resistance of the building elements often delays ignition and incentivizes fire fighters to prioritize making a stand at that property.

Taking Action to Reduce Risk

The insurance industry needs to do all it can to encourage the widest adoption of these mitigation measures, and policyholders should be incentivized to take action to reduce the risk. To start this process, insurers need to capture the details of mitigation efforts and understand the lowered risk.

The good news is that mitigation measures taken by householders or a community can be incorporated into RMS risk modeling to reflect the lowered risk, and many modifiers that align with the suggested measures from National Fire Protection Association (NFPA) and IBHS. If you can capture details of the mitigation measures taken—the type of roof, clearing the five-foot ignition zone—it can be included, modeled and priced accordingly.

As insurance companies figure out how to adapt to the growing threat of wildfire, it should not only be about cancelling policies in high-risk areas. Mitigation can increase survivability. The RMS U.S. Wildfire HD Model has already been used to assess the impact of adopting mitigation measures. Initial work with the Center for Insurance Policy Research using RMS modeling for three communities in California has shown that by implementing IBHS mitigation strategies, average annual wildfire losses can be reduced by 30 to 70 percent.

“Home hardening” against wildfire is also now gaining traction in California, as the Department of Insurance looks to incorporate regulatory actions to develop mitigation standards and encourage incentives to recognize householders mitigating their wildfire risk.

By working together now, to build awareness and promote action on mitigation, we want to see the percentage of structures that survive a wildfire event continue to grow. Wildfire—with the right mitigation—is a manageable peril.

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Michael Young
Michael Young
Vice President, Model Product Management, Moody's RMS

Michael leads a team that establishes requirements and features for all of the Moody's RMS North and South America climate models. Michael's responsibilities include overseeing the submission of Moody's RMS products to regulatory reviewers, such as the Florida Commission on Hurricane Loss Projection Methodology (FCHLMP).

Michael has led studies of insurance mitigation programs for the state of Florida, as well as the World Bank. In his past 14 years at Moody's RMS, Michael has also worked as a lead wind vulnerability engineer, a director of claims and exposure development, and as the head of the mitigation practice. He has worked in commercial wind-tunnel laboratories doing studies on wind loads for a variety of buildings.

Before joining Moody's RMS, he was involved in the development of Federal Emergency Management Agency (FEMA) HAZUS-MH software for hurricane risk assessment, and he taught courses on the use of HAZUS hurricane and flood components. Michael has also led studies on mitigation cost effectiveness for building codes such as the 2001 Florida Building Code and the North Carolina Building Code.

Michael holds a bachelor's degree in Civil Engineering and a master's degree from the University of Western Ontario in Canada in Wind Engineering.

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