Electric Vehicle Charging – Design and Risk Considerations
Written by Laurence Kwong
With the current energy crisis causing petrol and diesel prices to soar, more people than ever are looking to electric vehicles to see them through the period ahead. While EVs present clear benefits, they also introduce different fire risks that need to be considered in building design and operation. These become critical in buildings where there is an enclosed carpark and disruption to occupation must be avoided such as in apartments and hospitals where displaced occupants may not have anywhere else to go.
An EV battery comprises of multiple cells that utilise a lithium-ion chemistry which are electrically connected to produce the high voltage traction battery that runs the car. The cells themselves have combustible elements, such as the anode (carbon/graphite), the electrical separator, and the electrolyte, and when they break down under high temperatures these elements can produce:
Heat – leading to a cascading breakdown of adjacent cells, often referred to as thermal runaway
Flammable gases – a mixture of hydrogen gas, carbon monoxide, and other flammables which have been likened to propane. This often presents as a white cloud of smoke that can hang around the bottom of the car during an initial runaway event. Eventual ignition of these gases may result in fire, a vapour cloud explosion, or a jet fire.
Toxic gases – carbon monoxide, carbon dioxide, and hydrogen fluoride
These hazards may occur in addition to those associated with internal combustion engine (ICE) vehicle fires and can present a challenge for property, to life safety, and for firefighters who must inevitably come and address the fire. These are not the only factors; the battery chemistry, the form factor (shape) of each battery cell, and how much/how fast it’s charged can all affect the degree to which these hazards are created. These hazards could affect the fire resisting performance of the building leading to the building not being occupiable in whole or in part, the availability of safe evacuation pathways, and the ability for firefighters to contain and extinguish the fire safely.
Importantly, the risk profile of electric vehicles is more nuanced than headlines often suggest. Data tracking from EV FireSafe has shown that these kinds of fires are currently rare when compared to conventional car fires and there is guidance material out there from the Australian Building Codes Board, Australasian Fire Authorities Council, and an imminent Practice Guide from the Society of Fire Safety. Studies from RISE have also shown that there are many similarities between EVs and conventional ICEVs when it comes to fire, particularly when the source of fire ignition is not from the battery itself. The risk of an EV fire in an enclosed carpark can be reduced through careful siting, ensuring chargers are adequately separated from exits and escape paths, fire services infrastructure, and combustible hazards such as gas services or plant. Appropriate structural fire resistance, sprinkler protection where provided, and clear signage also support firefighting and emergency response.
As EV charging becomes more common in buildings, understanding these risks early can help avoid costly design changes and provide safer outcomes. CORE Engineering Group provides advisory services for EV charging installations and lithium-ion battery risk. Contact us to discuss your project.