Shack fires usually spread very quickly and lead to loss of life and property in informal settlements. And although there's no magic bullet to preventing these devastating fires, erecting shacks at the right distance from each other and lining them with the correct material could help curb the spread of a fire once it has started.
This is according to Dr Antonio Cicione, a postdoctoral research associate in the Fire Engineering Research Unit (FireSUN) in the Department of Civil Engineering at Stellenbosch University (SU). He obtained his doctorate in Civil Engineering at SU recently. His study forms part of IRIS-Fire, which is an international and interdisciplinary research project between SU and the University of Edinburgh.
To analyse, describe and predict the way fires behave in informal settlement dwellings, Cicione conducted full-scale fire experiments on single and triple shacks that were built specifically for the research. These shacks had steel and timber cladding. He also developed simplified computer simulations to simulate time-temperature curves, and also to predict when fire spread between shacks may occur.
Cicione says the experiments showed that with heat fluxes (the amount of heat transferred per unit area per unit time to or from a surface) surpassing 150-200 kilowatt (kW) per square meter at one meter away from the door, any common material will be ignited within seconds. He also points out that most materials will ignite at 20 kW/m2 and people exposed to a heat flux of 3–5 kW/m2 will experience pain within seconds. This highlights the risk associated with these closely spaced structures.
“For the timber-clad dwellings, the overall spread time (i.e. from the start of flashover ̶ the near-simultaneous ignition of all of the directly exposed combustible material in an enclosed area ̶ in the first dwelling to the end of flashover in the third dwelling) was approximately four minutes. In an experiment consisting of 20 dwellings, it basically took five minutes for all dwellings to be ignited.
“We found that an approximate primary safe separation distance of 3 m (i.e. based on the average heat fluxes emitted during the single dwelling experiments) would be sufficient for fire spread not to occur, although further work is required to consider factors such as wind and ember attack.
“Shacks lined with cardboard for insulation are at higher risk to fire spread compared to those lined with nothing or non-combustibles."
Cicione adds that the experiments have shown that the fire dynamics in dwellings in informal settlements are very similar to that of formal dwellings, i.e. these dwellings also undergo the five stages of fire development associated with enclosure fires (ignition, growth, flashover, fully developed fire and decay period). The decay period is typically when shacks collapse.
He says hopefully the experiments conducted will be used as a benchmark to test and compare future interventions.
“Hopefully, this research will be able to help us identify hotspots in specific settlements and provide a tool for local authorities to simulate fires to provide predictive capabilities that can help in identifying high-risk areas or quantifying the magnitude of an incident that municipalities may need to respond to."
According to Cicione, there is no magical solution to the problem of fire spread and because of the complex nature of informal settlements, those who develop interventions to address this problem face significant challenges.
“It is clear that the solution will have to be a combination of components, across multiple sectors including engineering design, education, firefighter interventions, early warning systems, risk reduction measures and much more."
Cicione says such an approach is important to help the approximately one billion people around the world who live in informal settlements that are often ravaged by large fires. He points out that, according to the Fire Protection Association of South Africa, we have more than 5 000 informal settlements fires yearly and this number is increasing.
He says he hopes his study will help local authorities make better decisions when choosing fire spread interventions and to prevent them from spending large amounts of money on interventions that we know upfront won't work.
Cicione adds that people living in informal settlements, politicians and firefights will benefit from his research.
FOR MEDIA ENQUIRIES ONLY
Dr Antonio Cicione
Fire Engineering Research Unit
Department of Civil Engineering
Faculty of Engineering
Tel: 021 808 4921