Approved Document 3 of 3 Bushfire Management Plan Dec 2020 OPW20-0145 · OPW20/0145

                                                                                          Noosa Civic | Page 11




                                     Figure 6

4.1.1. Direct Flame Contact
Direct flame attack refers to flame contact from the main fire front, the flame that engulfs burning
vegetation is the same flame that contacts the building. It is estimated that only 10 to 20 percent of
buildings lost to bushfire occur as a direct result of flame attack.

4.1.2. Ember Attack
CSIRO research has shown that ember attack is the cause of up to 80% of house loss in Australia.
The convective forces of bushfire raise burning embers into the atmosphere on prevailing winds and
deposit them to the ground ahead of the fire front. Typically, ember attack occurs approximately 30
minutes prior to the arrival of the fire front and continues during the impact of the fire front and for
several hours afterwards.

Building loss via ember attack relates largely to the vulnerabilities and peculiarities of each building,
its distance from the classifiable vegetation and whether someone is present to actively defend the
building.

4.1.3. Radiant Heat
Measured in kilowatts per m2, radiant heat is the heat energy released from the fire front which
radiates to the surrounding environment, deteriorating rapidly over distance. In terms of impacts on
buildings, radiant heat can pre-heat materials making them more susceptible to ignition. Radiant heat
can also damage building materials such as window glazing, allowing openings into a building
through which embers may enter.

4.1.4. Fire Driven Wind
The convective forces of a bushfire typically result in strong fire-driven winds, which can lead to
building damage. The typical effects of fire driven wind include conveyance of embers, damage from
branches and debris hitting the building, as well as direct damage to vulnerable building components,
such as lifting roofs and the breakage of windows.




                                                          Bushfire Planning Specialists | qldbushfireplanning.com.au