Jack Cohen, retired research physical scientist with the Rocky Mountain Research Station's Fire, Fuel and Smoke science program, is renowned for his research on wildfire and home ignitions. Findings from Cohen's research using modeling, experiments, and wildland-urban interface case studies shows that a home's ignitability during extreme wildland fires depends on the characteristics of the home and its immediate surroundings. This is why, in a post-fire area, you often see totally destroyed homes surrounded by homes that survived the wildfire. This area around the home that primarily determines home ignitions is called the home ignition zone (HIZ). The HIZ includes the home and vegetation, outbuildings and neighboring houses in the immediate surroundings within 100 feet of the home. Research shows that most home destruction is associated with burning embers [firebrands] and low intensity surface fires contacting the home, not the big flames of intense wildfires. It is more likely that a shower of firebrands lofted into the air ahead of the wildfire and landing on homes or the immediate surroundings results in home destruction. Thus, reducing home ignition within the HIZ is the most effective homeowner action for preventing home ignitions during wildfires.
The Washington, D.C. National Building Museum featured Cohen's research in their Designing for Disaster exhibit that ran from May 11, 2014-September 13, 2015. The museum featured the following video stating: "No one has done more to define the wildland-urban interface problem and empower homeowners to reduce their risk of wildfire than Jack Cohen. His post-fire field examinations and laboratory-based research on fire dynamics led to the concept of the home ignition zone, a phrase he coined. Cohen also co-developed the U.S. National Fire Danger Rating System and contributed to the U.S. fire behavior prediction systems."
In this next video, "Radiant Heat Versus Firebrands(embers)" produced by Seidler Productions, Cohen clearly demonstrates why most home destruction is caused by burning firebrands [embers] rather than the radiant heat from the flames.
For complete information on how to create an HIZ go to www.FIREWISE.org and click on the Wildfire Preparedness tab.