A QUT study of buildings lost to bushfire on Queensland's Scenic Rim in the 2019/20 Black Summer has identified key vulnerabilities of homes in bushfire-prone areas and ways communities could increase their homes' resilience.
- More than two million Australians live in extreme bushfire-prone areas
- Scenic Rim multi-disciplinary study of ways to improve buildings' passive resilience to bushfire
- Study looked at three areas where resilience could be improved with simple measures: siting of buildings, design and materials, and landscaping.
The team from Wind and Fire Lab in QUT's School of Civil & Environmental Engineering and QUT Centre for Robotics in QUT's School of Electrical Engineering and Robotics and the Research Engineering Facility used advanced drone-based technologies and computational heat transfer models, bushfire flame and radiant heat experiments and field studies to forensically identify features that contributed to building loss and vulnerabilities of existing buildings.
The project investigators, Dr Sahani Hendawitharana, Dr Anthony Ariyanayagam, Professor Mahen Mahendran, Professor Felipe Gonzalez, Dr Dmitry Bratanov and Gavin Broadbent, worked with the Scenic Rim Regional Council, the Queensland Fire Department Live Fire Campus, the Beechmont Rural Fire Service and local residents.
The two-year, community-focused study received grant funding from the Australian Government as part of the Black Summer Bushfire Recovery Grants Program.
Dr Hendawitharana, who led the study, said more than two million Australians lived in extreme bushfire-prone areas and the study's focus was on improving passive resilience of buildings.
"Our project aimed to strengthen the resilience of existing buildings by identifying factors that contribute to building losses and providing actionable recommendations to raise resilience," Dr Hendawitharana said.
"We looked for cost-effective, retrofitting strategies to improve the safety and survivability of homes."
Dr Hendawitharana said the siting of buildings, and the buildings' design and construction materials used, were areas of risk open to improvement in the short and long term.
"The safest thing to do is to evacuate early according to emergency services' advice but the idea is you want buildings that are able to protect themselves," she said.
"For instance, in the short term, homeowners in bushfire-prone areas can:
- use non-combustible materials on the exterior of the building
- put a non-combustible barrier such as concrete paths around the house to reduce radiant heat on the building
- park vehicles, which are highly flammable, away from the house
- grow vegetation away from the building and mulch with stones.
- remove overhanging trees, clear roof gutters and install 2mm ember-proof gutter guard."
The study modelled the lost buildings under flame-zone and radiant heat conditions with fire approaching from each direction to identify vulnerable areas, Dr Hendawitharana said.
"The actual flame front is about two minutes, but it is the build-up of radiant heat and embers that make more buildings vulnerable," she said.
"Our models predicted the most likely point of entry for embers was through glass windows which crack as the fire's heat approaches.
"Our previous experimental studies have shown that double-glazed and insulated windows with steel-clad, insulated shutters protect windows for longer.
"While we understand that people who live in bushfire prone areas are attracted to being close to nature and many know the risks, there are other important siting and design features that can improve bushfire resilience:
- "Those who want to rebuild must be aware that living on a slope brings beautiful views but also a risk of faster spreading fire as every 10 degrees in slope doubles the speed of the fire uphill.
- "Decks and verandas built on a slope amongst trees are risky. Class 1 timber is more fire resistant than most but using non-combustible materials such as lightweight steel, aerated concrete, and stone would increase resilience.
- "Also, new builds should be sited with alternative routes to get out or for turning of emergency vehicles."
"Our bushfire experiments demonstrated the advantages of using steel sheeting on surfaces of the exterior of the building as a protective measure against radiant heat. We thank the commissioner, QFD for the support to our fire tests at the Live Fire Campus, Port of Brisbane.
Dr Hendawitharana said the study used a novel methodology for assessing bushfire risks as a real-world application.
"It combined drone-based data capture, 3D heat transfer models of the buildings, including temperature-dependent materials data, to simulate heat transfer through the building and fire experiments," she said.
"These simulations highlight the importance of bushfire preparedness by visually identifying potential failure points and vulnerabilities.
"Our method provided detailed physics-based assessments and graphical outputs, emphasising the strong potential for enhancing community risk awareness during the pre-bushfire season."
Consultation and engagement with the local community was an integral feature of the study.
MAIN IMAGE, front: Dr Sahani Hendawitharana; back from left: Dr Dmitry Bratanov, Professor Mahen Mahendran, Dr Anthony Ariyanayagam, Professor Felipe Gonzalez, Gavin Broadbent.
