A system for accurate risk assessments from wildland fires that may lead to future improvements to building codes, standards and practices has been released in a research report from the U.S. Department of Commerce's National Institute of Standards and Technology with the U.S. Department of Agriculture's U.S. Forest Service. The proposed Wildland Urban Interface Hazard Scale measures the expected risks from fire and embers during a WUI fire event for individual locations within a community.

Fire behavior in wildlands and the wildland urban interface is a function of fuel, topography and local weather. According to NIST, the scale accounts for a local and transient variation in these factor,s so each specific location can be rated as to its susceptibility to fire and embers. The range of ratings can be used to create a map of the different levels of risk throughout a community and pinpoint where protective measures or hardening of structures is most needed.

Once risk in a particular zone is determined, the researchers can predict the likely response of structures and components to embers and fire, according to NIST. The WUI Hazard Scale currently considers fire and ember exposure from a single source: wildland fuels. The researchers have designed the scale to easily accommodate additional threats and plan to include exposure from three other sources associated with WUI fires—burning structures, ornamental vegetation and vehicles—at a later date, using the same methodology.

NIST said the next step is to collect the appropriate data to make the scale viable, through field evaluations of exposure characteristics in a wide variety of communities and surveys of areas that have recently experienced WUI fires. The two agencies also will be working with various public and private stakeholder groups toward acceptance and implementation of the proposed scale and building construction classes with the goal of improving standards, codes and practices.