Creating an Above Ground Fire Shelter
Following the disastrous bushfires of 7 February 2009 I was shocked at the significant loss of life. 173 persons lost their lives. The impact of the fires extended far beyond the immediate loss of life to include those who survived the fires and to the relatives and friends of those killed and injured. I think most of the Victorian community was collectively traumatized.
As somebody who has spent a lifetime in the fire profession I wondered if there was more that could be done to protect those directly in the path of a bushfire. When I was contacted by the Victorian Centre for Advanced Materials Manufacturing (VCAMM) requesting my support for project to see if there was a better way to protect people living and working in bushfire prone areas. I willingly offered my support.
VCAMM were successful in getting a government grant and put together a group of people to look at the problem. The people included in the group came from very diverse backgrounds. They included representatives from:
- Diver Industries (manufacturer of heat shields for the automotive industry).
- EXOVA (Fire Testing Laboratory).
- Frankston Concrete Products (manufacture of concrete products).
- Pyropanel Fire Doors (fire door expertise; joined later in the process).
- Swinburne (Faculty of Science, Engineering and Technology).
- VCAMM (provided facilitator and secretariat).
It was an interesting exercise as each participant brought something different to the table. What was surprising was how quickly we decided on an above ground shelter. As professionals in the fire profession know it is not uncommon for a fire refuge/fire separation to be part of a fire protection design. They are included in super high-rise buildings and long tunnels. Hospitals separate floor areas to facilitate horizontal evacuation. Why could we not use these principals in creating a safe place for people caught out in bushfires?
Other reasons for an above ground shelter included the psychological impact of going underground into a “tomb” has a significant effect on some people. Access by a ladder is very difficult for the elderly or people with disabilities. Entering our shelter would be like entering a garden shed. It also avoids the significant drainage/flooding issues of an underground shelter.
From the start we decided to use “off the shelf” components where possible to help keep the price down and to facilitate easy replacement of parts over the life of the shelter. We also wanted to make the shelter as simple as possible with very few moving parts. We all understood the shelter was likely to be in place for decades before being required for use but it had to be able to perform its task at a moments notice.
The next task was design. Following the fires there were people coming out of the woodwork to sell “fire shelters”. These ranged from a hole in the ground with a lid to metal shipping containers and a wide array in between. The Victorian Building Commission quickly saw the evolving problem and issued a set of guidelines and (Private Bushfire Shelter Construction) Interim Regulations 2009, which required anybody installing a shelter to obtain a building permit. They also accredited an underground shelter.
In 2010 the Australian buildings Control Board (ACBC) produced a standard titled “Performance Standard for Private Bushfire Shelters” The latest addition is 2014 and is available free from their website http://tinyurl.com/p6g54l9 The standard outlines acceptance criteria and some specific requirement.
A suggested design was proposed by Jim Griffin from Diver Industries based on designs they used to minimize the transfer of heat from car exhaust systems to the body of the car. Peter Zigouras from Frankston Concrete Products (FCP) http://www.sanctuaryshelter.com.au and has over forty years experience in the concrete business under took research and came up with a concrete mix which he thought would satisfy our needs and comply with the requirements of the Code.
Sample panels were constructed and independently tested by Exova. To our delight the exterior face of the panels were exposed to high temperatures for an extended time and the heat transference was minimal. The design had exceeded our expectations. We then proceeded to design and construct a full size shelter. Where possible “off the shelf” components were sourced and consisted in the main of two hour rated components such as door sets and, door hardware including locks fittings and closers. . The biggest challenge was the door. After exploring a number of options we found a two hour rated fire door, which had a very low heat transference rating. We contacted the manufacturer and Pyropanel joined our group.
All of the members worked cooperatively adding their own area of expertize. E.g. Swinburne University considering the ergonomics and psychological impact on potential users. A final design was created that consisted of two separate chambers; an inner and outer, each fitted with a two hour fire rated door.
Whilst it is not a requirement of the Standard there was a need to ensure the shelter would be safe for occupants when the shelter was not in use during a bushfire. As the shelter would be gas tight when sealed there was a need to develop and install a ventilation system for use at other times. A number of different designs were considered but finally an under shelter system with inlet and exhaust from both chambers was adopted. The vents are locked in the open position and only sealed when a fire is threatening.
A prototype of the full size shelter was produced and prepared for testing. The shelter could not fit inside Exova’s largest test furnace so an innovative solution was found. The shelter was fully assembled on a low loader and the whole system was driven up to the furnace. Construction was then undertaken to seal the furnace to the shelter. The full scale test was undertaken whist the shelter sat on the low loader.
The results of the first test were very encouraging with minimal temperature rise inside the shelter. The doors and all of the hardware continued to function after the test. There were some issues regarding gas levels in the outer chamber which needed to be addressed.
A new prototype utilizing lessons learnt was produced and the tests repeated. We now had the data we needed to support our case for accreditation by the Building Regulatory Control Board. Exova produced the Fire Engineering Report and Swinburne provided the Air Quality Test Report.
Accreditation was granted in July 2014. The Shelter was first shown to the public at an engineering open day held at Swinburne in November 2014. From the very little media coverage we have now received interest from within Victoria, Tasmania, South Australia and Western Australia. A new hydraulic assisted mold will be utilized to manufacture the shelter in large quantities.
In a small way we hope to contribute to the options available for people who live in bushfire prone areas.
For more information, go to www.sanctuaryshelter.com.au