How our bushfire proof house design could help people flee rather than risk fighting the flames
By 2030, climate change will render one in 25 Australian homes ‘uninsurable’ if greenhouse gas emissions continue unabated, with river flooding posing the greatest insurance risk, a new Climate Council analysis finds.
As an architecture professor, I find this analysis dark, but not surprising. One reason is that Australian housing is largely unsuited to the challenges of climate change.
In the past two years alone, we’ve seen over 3,000 homes razed in the 2019-2020 megafires, and more 3,600 housing units destroyed in the Northern Rivers region of New South Wales during the recent floods.
Building homes that are more resilient to the impacts of climate change is one way to protect us for the future catastrophic conditions. I am part of a research team that has developed a new bushfire resistant system house designwho won a international price last month.
We hope its ability to withstand fires will encourage homeowners – who would otherwise stick around to defend their homes – to flee when bushfires encroach. Let’s take a closer look at the risk of bushfires and why our housing design should one day become a new Australian standard.
Today’s houses are easy to burn
Climate Council analysis finds that among the 10 Australian voters most at risk from climate change impacts, one in seven homes will be uninsurable by 2030 under a high emissions scenario. This includes 25,801 properties (27%) in the Victoria electorate of Nicholls and 22,274 properties (20%) in Richmond, NSW.
Bush fires are among the worsening hazards making homes uninsurable and particularly high risk for many thousands of homes in eastern Australia.
For example, the Climate Council found 55% of properties in the electorate of Macquarie, NSW, will be at risk of bushfires in 2030, if emissions do not come down. This increases to 64% of properties by 2100.
The typical Australian house was not designed with bushfires in mind, as most were built decades ago, before bushfire planning and building regulations. came into force.
This means that they incorporate combustible materials, such as wood and plasterboard, and have characteristics like the gutters which can trap the embers.
Additionally, gaps between building materials are often too large to keep embers out, which means spot fires can start inside the home. And many houses are located too close to fire-prone grasses and trees.
Indeed, at least 90% of houses currently in bushfire areas are at risk of being destroyed in a bushfire.
How our new design can withstand fire
The prototype bushfire-resistant house we designed won jackpot in the new housing division of the Solar Decathlon of the United States Renewable Energy Laboratory.
The House would be made from a locally sourced recycled steel frame. It would be mounted on reinforced concrete pilings to minimize its disturbance on the pitch, touching the ground only lightly. We thus contribute to preserving the biodiversity of the site.
The main building material is rammed earth – natural raw materials such as earth, chalk, lime or gravel – which is not combustible.
The roof and some coverings are made of fire-resistant corrugated iron. Its glazed facades are equipped with fire shutters made of fiber cement sheets, an incombustible material that can be closed to seal the house.
How a bushfire can destroy a house
It is important to note that the gaps between these construction materials are 2 millimeters or less.
Pitched roofs slope inward to capture rainwater. And since the roofs are made of corrugated iron, which has channels, the house does not need gutters.
These channels guide rainwater into two open retention basins on either side of the entrance and into protected reservoirs under the house. It also helps to protect the house in the event of a bushfire, as it means the fire cannot enter from below.
When bushfires hit, the risk to life is highest when people stay and defend their homes. A design that can withstand fire on its own entices its owners to leave.
But it should be noted that it is not a bunker in which people can take shelter. No matter how well designed a house is, it always will be too dangerous stay when a fire breaks out, especially in the catastrophic and extreme fire conditions that we are increasingly experiencing.
It is also profitable
The estimated cost of construction is between 400,000 and 450,000 Australian dollars. We have deployed several strategies to reduce costs:
the house is designed to be energy and water independent, so it will not need city utilities
it uses common construction techniques and is based on the construction industry standard for sheet metal, so it does not require specialist builders and wastes no materials
Rammed earth is relatively inexpensive as it can be obtained from many places, often for free. We also consider using recycled materials whenever possible.
Aesthetically speaking, the design also presents an elegant home space that is flexible enough to easily adapt to almost any location.
The next step is to build and test a prototype of the house so that we can evaluate its performance and make improvements. We are currently talking with potential funders to make this happen.
As climate change drives more disasters, Australia must prepare for the destruction of thousands more homes. Innovative architecture like ours gives homes and valuable possessions a chance to survive future disasters.