H.L. Mencken (the American 19th century writer) once said: ‘For every complex problem there is an answer that is clear, simple, and wrong.’ This applies to the Bushfire threat in Australia.
In a modern society with developed planning and building laws, communities can often believe that we have tamed the threat of fire. Of course, most of us who work in this area know this can never be true and that changing environmental, climate and demographic factors are having a further adverse influence on the risk of bushfire across communities.
The bushfire risk for buildings can be broadly described in a matrix of four building types as shown in Diagram no. 1.
Building design is a static process and response; we generally consider the worst case and design to withstand that. In relation to bushfire we have a mixed approach, often, but not always, considering the worst-case bushfire day, but measuring it against today’s vegetation even though vegetation is dynamic and ever changing, and using a historical weather dataset that does not include changing climate factors.
Whilst there is significant research and development occurring in Australia to improve these issues, the policy focus is still almost entirely on new dwellings (homes), and not on communities as a whole. This creates challenges for an appropriate building response over entire communities; for example, what type or size of fire in the bush (or in any vegetation) is a ‘bushfire’ that warrants a significant building or legislative response. And should that response include existing buildings, not just new construction. How will vulnerable people cope with the threat of bushfires and how practical is it to evacuate schools, hospitals and aged-care facilities when a bushfire nearby occurs? Should we be evacuating buildings before an ‘extreme’ or catastrophic’ bushfire weather event day?
Not all fires that burn outside are bushfires, and not all bushfires are the same. The conditions under which bushfires become catastrophic and therefore a significant threat to life and property vary significantly across Australia. This has created some difficulty for communities around current thresholds or boundaries of bushfire risk, as described by bushfire-prone areas and bushfire planning controls. The typical ‘in or out’ approach that mapping can create often results in significant policy inconsistencies around those demarcation interfaces and inhibits how a homeowner can establish their own bushfire risk on a site specific basis. The details in the Insurance Council of Australia extract below from the ‘black summer’ event in 2019/20 highlights this challenge.
In relation to construction measures for new buildings, the current Australian Standard for Bushfire (AS3959) applies only to dwellings and is clear it does not yet deal with adjoining buildings, maintenance of bushfire safety systems, wind direction and wind strength (including bushfire tornadoes), egress, access, water supply, appropriate firefighting equipment for occupiers (including protective equipment), and many other good design issues. Whilst some of these are dealt with by current planning controls, these are mostly not dealt with under building legislation.
Governments across Australia have quite rightly regulated for new residential buildings; however, this will not substantially mitigate the bushfire risk for many decades as housing and building stock, particularly in rural and regional Australia, is not replenished quickly.
The greatest challenge for Australia is how to build resilience in existing communities. For example, how bushfire resistant is a typical brick veneer dwelling, or a weatherboard dwelling, and what are the points of weakness to look at, such of location adjoining buildings, window orientation, storage around and under buildings and vegetation management. Is a swimming pool a useful bushfire measure? Can a new garage also be built as a bushfire shelter? What upgrade measures can be easily incorporated into an existing house as part of a family room extension? What are appropriate outdoor furniture materials for the alfresco dining area in a bushfire prone area?
A well-designed new house that can withstand most bushfires, should not be excessively expensive to build, and an appropriate ‘plan b’ should always be considered for extreme event days (i.e. a private bushfire shelter, leave early plan, community fire refuge or neighbourhood safer place.). A staged response approach such as this may provide the most efficient and effective overall response to the risk of bushfire for communities.
Of course, the risk of bushfire applies to all buildings and structures, not just homes. How should we design a nursing home, hospital, school, fire station or even a fuel depot in a bushfire prone area? The design response is obviously very different for each building and there are substantial challenges ahead to assist and educate home owners and other building occupiers that even an Australian Standard building code compliant building will not necessarily survive a bushfire, or all bushfires.
Summary
The solution to the bushfire challenge for Australia lies in supporting sound scientific research and statistical analysis of the risk of bushfire and the circumstances where conditions become challenging and life threatening, and building strong community resilience and awareness.
For example, we know from the evidence that well-defended houses have a much greater chance of survival, but also that on some extreme event days there can be significant loss of life of people trying to defend their homes, even if they are ‘well-prepared’. We also know that these extreme event days will increase in number in the future.
The key is education and awareness that not all bushfires are the same, and that each individual building will have a design bushfire limit and a consequential site-specific human behavioural input and ability response on owners or occupiers.
What next?
The new Australian National Construction Code 2022 edition will be released later in 2022 and will have new requirements for buildings in bushfire-prone areas with vulnerable occupants including schools, hospitals, nursing homes and disability care facilities. Those provisions will be in NCC Part G5 and new Specification 43: Bushfire protection for certain Class 9 buildings.
Many private-sector organisations are also working on resolution of these issues and the Bushfire Building Council of Australia (see Bushfire Building Council of Australia – Inform – Adapt – Reward (see bbca.org.au) has the following free resources:
- For new builds and re-builds after a bushfire event; FORTIS House:
The FORTIS House project provides free architectural drawings, specifications and handbooks to make it easier and more affordable for Australians to build sustainable houses that are resilient to bushfires, floods, storms, heatwaves, cyclones, mould and pests.
- For existing buildings, the Bushfire Resilience Ratings project:
The Bushfire Resilience Star Rating program provides households with a tailored list of actions to measurably improve the bushfire resilience of their home. The free household Star Rating self-assessment app will be released in 2023 but you can register your interest on the website now.
For more information, go to bbca.org.au
About the Author
Stephen Kip is a Director of SKIP Consulting, an engineering consultancy firm. He is an Adjunct Associate Professor at Victoria University, a board member of the Bushfire Building Council of Australia, an Honorary Fellow at the University of Melbourne, and a Fellow of Engineers Australia.
