Enhancement of Neighbourhood Impacts

Research into the 2009 Black Saturday bushfires in Victoria highlighted the need to be able to predict the loss of buildings under a wide range of bushfire severity conditions.

This research focused on better understanding the vulnerability of the rural/urban fringe under certain bushfire conditions, and was led by CSIRO’s Justin Leonard.

To try and manage the bushfire hazard in urban areas, buildings constructed in bushfire prone areas must comply with a set of building codes. The current Australian Standard AS3959 Construction of Buildings in Bushfire Prone Areas (2009) sets out prescriptive provisions for dwelling construction in response to specified levels of hazard exposure. The importance of radiant heat as a major source of ignition and subsequent damage to buildings is acknowledged in AS3959, yet the validation of the assumptions upon which it relies has significant knowledge gaps.

The research extended knowledge of AS3959 through improved modelling of radiant heat flux exposure by considering more variables and their respective spatial variability across the landscape.

A spatial modelling approach was developed to determine the time profile of radiant heat – the amount of heat transferred per unit area – experienced by a house during a bushfire and to assess the significance of this modelled radiant heat on house loss in previous bushfire fire events.

This research was applied on three historic fires: the Wangary fire in South Australia in 2005; the Black Saturday in Victoria in 2009; and the Springwood fire in New South Wales in 2013.

These case studies sought to validate the modelling approach and determine specific characteristics of the exposure that are most effective as predictors of house damage. The case studies were also used to investigate the value and limitations of different spatial datasets (e.g. remote sensing imagery, national land-cover databases) when applied to modelling bushfire impacts.

The research significantly increased understanding of both a primary cause of house ignition and damage resulting from bushfire, as well as radiant heat flux modelling. Better knowledge of radiant heat flux modelling could improve building standards for bushfire-prone areas.

PhD studies by Douglas Brown (University of Sydney) explored householders’ perceptions of bushfire risk and whether perceptions change when different building materials or design and architectural features are applied. He found that people view risks as external to their properties, in terms of their surroundings, other properties and bushland.

University of Western Sydney PhD student Grahame Douglas researched the application of extreme value analysis to extreme fire weather conditions. Historically, this approach had been restricted to floods, storms, temperature and wind.