Flame Zone (BAL-FZ) product testing requires successful completion of the AS1530.8.2 test. This test has a 30-minute furnace cycle and a 60-minute cooling down cycle in which the product still has to keep its integrity. Part of the test is also a radiant heat requirement of a maximum of 15kW/m2 on the inside. Paarhammer BAL-FZ products showed a heat flux on the non-fire side of between 1kW/m2 and 2kW/m2 in the test, depending on the product. This is just 1/10th of the allowed heat flux.
To put this into perspective, naked skin can tolerate 5kW/m2 for approximately 10 seconds only.
Some companies offer windows and doors, which are tested to -/30/- for use in a BAL-FZ area. This test is AS1530.4 and does not take heat transfer into account. So while it may legally be possible to use a 30-minute window, the transferred heat may reach 200+ degrees inside the building, which is not compatible with human life.
New Australian Standards were introduced following the devastating Black Saturday fires in 2009; however, there were no window products, which were tested to, and found to comply with AS 1530.8.2 that were available for purchase at the time. Therefore, a line was inserted in the AS3959-2009 (Sec 9.5.2, (b) (i)) allowing a 30-minute window.
Fire barriers need to be made from materials that insulate the fire and keep the non-fire side cooler. These elements have to maintain both integrity and insulation. Insulation is measured as the last number in the equation, e.g. -/30/- has no heat insulation, or -/30/30, which would provide 30 minutes of time before the temperature inside reaches untenably high results.
If there is fire on the outside of a window or door, you want the inside to stay cool and not create temperatures that might ignite furnishings, and cause the fire to spread, or reach temperatures harmful to life. If you are building in a BAL-FZ area, please ensure that your windows and doors are tested to the correct Australian Standard 1530.8.2 for bushfire safety.
Be aware of products that allow radiant heat inside and can therefore cause harm to inhabitants. Be aware of products being sold as BAL-FZ although they require another product (like a shutter) to achieve the BAL-FZ rating.
Always get a copy of the Flame Zone test AS1530.8.2 performed by an independent NATA-accredited testing facility for the windows and doors you would like to purchase before ordering. And check with your council and/or certifier for the BAL ratings that apply to your particular block of land.
For more information on the Paarhammer Bushfire Safe Range see http://www.paarhammer.com.au/bal-FZ-windows.