Experimental studies of bushfire resistant window shutters exposed to radiant heat and flame zone conditions

The escalating frequency and severity of bushfires in many countries pose a substantial challenge to the safety of residential buildings. Among the most vulnerable elements of a building's exterior envelope during bushfires are its glass windows, which are highly susceptible to intense heat. This vulnerability can result in large openings in the building envelope, allowing embers, radiant heat, and flames to penetrate the building envelope. This study embarked on a series of fire tests to assess the performance of various window shutters constructed from thin steel sheets, ceramic fibre blankets, and some composites. These shutters were tested under simulated bushfire conditions, including radiant heat, direct flames, and a combination of both. The radiant heat tests adhered to specific curves, simulating varying intensity over 11 and 47 min periods, while the flame zone exposure tests followed the CSIRO/NASH Curve for 47 min. The research findings show that shutters made of steel sheets, or a combination of steel and insulating materials effectively withstand radiant heat and direct flame exposures. They also highlight the superior performance of aluminium foil-backed thin flexible blankets in radiant heat tests. The aluminium foil served as an efficient reflective barrier, redirecting radiant heat towards the fire side. This mechanism significantly lowered the ambient side temperature, maintaining glass temperatures below 50°C in prolonged tests (47 min). The study demonstrates the effectiveness of fire tested window shutters in preventing flame penetration and blocking radiant heat. Enhancing the bushfire resistance of windows offers a crucial layer of protection, substantially increasing the safety of communities in bushfire-prone areas. This research contributes significantly towards developing practical and effective measures for safeguarding houses against the devastating impact of bushfires.