Guidance document on Fire Safety of EV Parking Garages

Electric vehicles (EVs) present unique risks such as the thermal runaway propagation within their traction batteries.

The nature of EV construction is to protect the battery cells from weather, surface water spray, and damage in normal use, and this presents a challenge in delivering extinguishant to the cells. Therefore, it is extremely challenging, if not impossible, to stop in-cell thermal runaway inside the traction battery. or slowing cell to cell propagation.

The increase size of modern cars - to those of the 1970s, including internal combustion engine (ICE) vehicles and modern EVs - is well documented, however the size of most car parking spaces has not retrospectively been changed. The resulting increased proximity and reduction in space between cars, speeds car-to-car fire propagation which is exacerbated by the significantly higher plastic content of modern cars. Increased parking density, such as car stackers and the probable emergence of autonomous parking, compounds this further still. Even with new construction, allowing for larger cars, there has been car-to-car spread evidenced.

This guidance discusses the statistics, research on fire behaviours and safety measures associated with both electric and combustion vehicles, providing an overview for safety professionals, and policymakers.