Factors influencing ember accumulation near a building
Stephen L. Quarles A , Christine Standohar-Alfano B , Faraz Hedayati A and Daniel J. Gorham
C *
A Insurance Institute for Business & Home Safety, 5335 Richburg Road, Richburg, SC 29729, USA.
B Haag Engineering, 2224 E 117th Street, Burnsville, MN 55337, USA.
C Fire Safety Research Institute, UL Research Institutes, 6200 Old Dobbin Lane, Suite 150, Columbia, MD 21045, USA.
International Journal of Wildland Fire 32(3) 380-387 https://doi.org/10.1071/WF22132
Submitted: 8 July 2022 Accepted: 31 January 2023 Published: 28 February 2023
© 2023 The Author(s) (or their employer(s)). Published by CSIRO Publishing on behalf of IAWF. This is an open access article distributed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License (CC BY-NC-ND)
Abstract
Background: Embers, also known as firebrands, are the leading cause of building ignition during wildland–urban fires. This is attributed both to direct ignition of material on, in, or attached to the building, and indirect ignition where they ignite vegetation or other combustible material near the building, which results in a radiant heat and/or direct flame contact exposure that ignites the building. Indirect ignition of a building can occur when embers accumulate on and ignite nearby combustible fuel, resulting in radiant heat or flame constant exposure.
Aims/implications: Factors that influence ember accumulation near a building include building geometry, such as flat wall and re-entrant corners, building wind angle, wind speed and the surface roughness characteristics of the horizontal landscape close to the building.
Methods: Experiments conducted at the Insurance Institute for Business & Home Safety (IBHS) Research Center using full-scale buildings with the above-mentioned factors provided a means to quantify ember accumulation on a mass per unit area basis.
Key results: Ember accumulation was greatest at locations immediately adjacent to the building and higher wind speeds allowed more embers to reach the building.
Conclusions: The work presented in this paper provides data and insight on wind-blown ember accumulation near a full-scale building.
Keywords: accumulate, accumulation, building, deposit, deposition, ember, firebrand, structure, wildfire, wildland, wildland–urban, WUI.
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