Development of wildland fire exposure indicator for performancebased design applications

Fire curves provide a simplified yet practical and operational description of a fire over time, and are widely used in engineering applications for building design and risk assessment. They are generally fit for deterministic performance-based applications, where a quantitative description of the reasonable level of hazard associated with the fire is compared against performance metrics to assess the suitability of a particular design. Although the use of fire curves in performance-based applications is now well established for urban developments, its use in the context of wildland-urban interface (WUI) building design remains in its infancy. This paper presents a new fire curve, here referred to as wildfire curve, suitable for applications in the WUI. The curve was derived from more than 20.000 brightness temperature measurement locations acquired during a 150 x 200 m2 prescribed gorse shrub burn using Unmanned Aerial Vehicles (UAV) technology, and 25 in-situ temperature probes evenly spaced inside the experimental plot. The measurements were linked to its local behaviour using an overhead visual video footage and Light-Detection-and-Ranging (LiDAR) data of the vegetation canopy. Furthermore, this paper proposes and discusses a methodology to estimate heat release rate from the proposed wildfire curve, enabling more comprehensive fire engineering design and risk assessment applications.