Since the wildfires in January devastated neighborhoods in Los Angeles, resulting in the displacement of nearly 13,000 households and an estimated $30 billion in losses, many communities across California have sought ways to better protect themselves from future disasters.
A new study led by researchers at the University of California, Berkeley provides evidence that certain mitigation strategies can reduce wildfire damage by up to 50%. The research offers data-driven guidance for lawmakers and residents on how to make communities more resilient.
The study focuses on two main strategies: home hardening and defensible space. Home hardening involves structural changes such as installing fire-resistant siding and roofing materials, covering vents, and upgrading windows. Defensible space refers to maintaining a vegetation-free buffer zone around homes. According to the research, these measures together can double the number of homes that survive a wildfire. Removing vegetation within five feet of homes—a proposal under consideration in California’s Zone Zero regulations—could reduce structure losses by 17%.
“I view this as really powerful evidence that the mitigation measures that are available to us, hardening and defensible space, actually have some real-world effectiveness,” said Michael Gollner, associate professor of mechanical engineering at UC Berkeley and senior author of the study.
Gollner noted that these steps may also help slow fire spread, giving people more time to evacuate and allowing emergency responders extra time to reach affected areas.
“We can’t always change the spacing between structures or the exposure from flames and embers,” Gollner said. “But even within those limitations, we still have the power to cut the destruction in half, if not more. That is very powerful.”
Published August 28 in Nature Communications, the study was supported by grants from CAL FIRE through its Forest Health program as well as funding from the Gordon and Betty Moore Foundation and National Science Foundation.
The research team used advanced wildfire simulation tools alongside real-world data from five major fires before 2022—including events like the Camp Fire—to quantify how different approaches impact survivability. They leveraged CAL FIRE’s detailed inspection database covering structures damaged or destroyed since 2013. This information was combined with other geospatial sources for a comprehensive analysis of building arrangement, construction materials, and surrounding vegetation.
A key feature of their approach was using machine learning techniques on this dataset to create a model predicting whether structures would survive with about 82% accuracy. This allowed them to separate out factors such as spacing between buildings, fire exposure levels, construction details, and defensible space practices.
“We wanted to identify the risk factors that make a structure susceptible to loss,” said postdoctoral scholar Maryam Zamanialaei.
“It’s possible that a well-protected home may have a low chance of survival because of everything around it,” Gollner added. “The model allows us to tune in to see the impact of each factor and how they interplay.”
Their findings indicate that separation distance between buildings is especially important in densely built neighborhoods where fire can jump from house to house; flame length is also significant. Construction features such as siding type and window material were found to affect vulnerability as well.
However, Gollner emphasized that widespread adoption is necessary for these strategies’ maximum effectiveness. Implementation often depends on both individual property owners’ choices and collective action within communities—a challenge highlighted by ongoing debates over proposed Zone Zero regulations.
“Much of what you can do to prevent these fires from spreading through the whole community happens on an individual’s property and depends on what your neighbor does,” Gollner said. “This is a really challenging social, economic and political problem that requires a lot of groups working together.”
He hopes this work will help justify further investments into mitigation efforts: “We need to justify the investments we’re making in mitigation, and I was glad to see that for many of them, we do see significant payback in terms of risk reduction,” he said.
Co-authors include researchers from Universidad Técnica Federico Santa María; University of Maryland; Cloudfire; as well as additional scholars from UC Berkeley.
Related resources note ongoing efforts by UC Berkeley researchers helping Bay Area communities prepare for wildfires (https://news.berkeley.edu/2024/06/14/wildfire-season-is-here-uc-berkeley-scholars-are-helping-bay-area-communities-prepare/) along with work simulating wildfire spread through communities (https://engineering.berkeley.edu/news/2024/08/uc-berkeley-researchers-simulate-how-wildfires-spread-through-communities/).
