Design challenges and risk mitigation for Electric Vehicle fire safety in car parks

In this Insight Paper, Adrian Griffiths and Andy Hudson, from our London Studio provide an analysis of the design challenges for Electric Vehicle (EVs) fire safety, and discuss the role of architects and designers in accommodating EVs while mitigating the fire risks.

The recent incident at Luton airport in the UK (October 2023), where a single car fire led to the loss of an entire car park containing over 1,500 vehicles, has raised concerns about the potential dangers posed by car fires. While the type of car responsible for the fire remains uncertain, initial analyses suggest it may have been a diesel SUV. Regardless of the specific cause, this event underscores the risks associated with car fires. It is important to note that modern-day cars come in many forms, and present a greater fire risk than their predecessors, due to the multiple power options, being fuel, often contained in plastic tanks, Liquefied petroleum gas (LPG), hybrid and electric. To compound this issue, much of the car’s construction is made from plastic, carbon fibre and composites.

Electric vehicles have emerged as a promising solution for reducing greenhouse gas emissions and transitioning to a more sustainable transportation system. However, the spotlight on EVs catching fire in a few high-profile incidents has raised concerns which is clearly demonstrated by a call for EVs to be banned from using ferries with some transportation companies have already banned some small EVs, meaning, e-unicycles, e-skateboards, and hoverboards. It is important to note that e-scooters are banned from being taken on the London Underground and mainline trains which is mainly down to a concern related to faulty batteries.

It is essential to recognise that Hybrid or fully electric cars do not inherently pose a greater risk of catching fire compared to traditional internal combustion engine (ICE) vehicles. In fact, the risk is much lower although there is a view hybrid cars present an even greater risk than both ICE and full EVs, (recent numbers suggest 25.1 fires per 100,000 for EVs, 3,474 per 100,000 for Hybrids, and 1,529 per 100,00 for ICE’s). In fact, EVs offer several safety advantages when it comes to fire risks. However, it is crucial to understand the specific aspects that potentially make EV / Hybrids fires different from ICE vehicle fires which mainly comes down to the fact that they can be harder to extinguish for the following reasons:

• Battery chemistry: EVs use lithium-ion batteries, which are known to be highly reactive when they catch fire. Lithium-ion batteries contain flammable electrolytes, and when they overheat or experience thermal runaway, they can release a significant amount of heat and energy, making the fire more intense.
• Thermal runaway: If a portion of an EV battery pack catches fire, there is a risk of thermal runaway, a phenomenon where the fire can spread rapidly from one battery cell to another. This can cause a cascading effect, making it difficult to control the fire.
• Cooling systems: Many EVs are equipped with cooling systems to manage the temperature of the battery pack. If these systems fail during a fire, it can allow the fire to burn at higher temperatures.
• Containment: The battery pack is designed to contain a fire and prevent it from spreading. However, when the fire breaches this containment, it can become more challenging to control.
• Extinguishing agents: Traditional firefighting agents, such as water and foam, may not be as effective in extinguishing lithium-ion battery fires. Specialized firefighting agents, like dry powder extinguishers, are often needed to control the fire.
• Re-ignition: There is a risk of re-ignition in EV fires. Even after it appears that the fire has been extinguished, the battery may still have smoldering or hot spots that can lead to reignition.

To combat these challenges, firefighters and emergency responders are being trained to handle EV fires safely. Manufacturers are also working on developing better safety features to reduce the risk of fires and improve the ability to control them when they occur. This includes the development of more robust thermal management systems, fire-resistant battery enclosures, and improved materials that can contain and mitigate fires. Additionally, some EVs are equipped with automatic safety systems that can disconnect the battery from the rest of the vehicle in the event of a crash or fire to reduce the risk of fire spreading.

As electric vehicles / Hybrid (EVs) become more prevalent, it is inevitable the potential risk of EV fires increases and extends beyond the road into residential and other building environments. It is imperative to proactively consider the necessary design changes to protect the public from this risk. Anticipating that building regulations will become more stringent to enhance building and public safety, we should pre-empt what these changes will be and future-proof our designs for long-term suitability.

In light of these considerations, it is vital to explore the implications of EV fire risks on building design and outline the changes required to enhance safety measures for occupants and properties.

Building Materials

The materials used in building construction can impact the spread of EV fires. Key considerations include:

• Fire-Resistant Materials: Incorporating fire-resistant materials, such as fire-rated insulation and cladding, to limit the spread of flames from an EV fire to the building.
• Enhanced fire protection of the structure
• Garage Construction: Enhancing the fire safety of attached garages by using fire-resistant construction materials.
• Car Parks. The form of construction should be reviewed to ensure they can survive an intense fire. The original loadings for car parks were based on 1.5t per car and this has just been updated to 2t per car in the Institute of Structural Engineers, Car Park Design Guide, issued in June 2023. This increase in loading is mainly a result of heavier EV cars which will only become more of an issue as their numbers grow. This suggests many older car parks are no longer fit for purpose.

It's important to question the construction materials used. For example, would the Luton airport car park fire have been as catastrophic if it were constructed with concrete? We know that steel construction lacks structural stability when exposed to heat and quickly fails in a fire situation. We can reasonably assume that building regulations related to construction materials will become even more stringent, especially in cases of podium car parking below residential buildings.

Building Infrastructure

Designing buildings with infrastructure to accommodate EVs while mitigating fire risks is crucial. This involves considerations such as:

• Charging Station Locations: Determining safe and strategic locations for EV charging stations, such as positioning them away from building entry points and emergency exits.
• Electrical Safety: Ensuring that the electrical systems of buildings can safely handle increased EV charging loads.
• Fire Suppression: Installing fire suppression systems, such as fire extinguishers and sprinklers in garages and areas near potential EV fire sources.
• Smoke Extraction: Provision of smoke extraction and compartmentation to control the spread.

It is wise to anticipate the need for fire suppression systems within our designs. The idea has been proposed that charging points should be located outside of buildings, which may be challenging to accommodate in some locations.

Emergency Response Procedures

Establishing effective emergency response procedures is critical for building safety:

• Evacuation Plans: Develop clear evacuation plans for building occupants in the event of an adjacent EV fire. Adhering to the principle of always being able to escape by turning away from a fire.
• Communication: Ensuring that building occupants are aware of the risks and know how to respond during an EV fire.
• Firefighting Training: Fighting EV fires can be challenging due to the need for specific firefighting procedures and materials. Firefighters need to be trained on how to handle battery fires, which has led to concerns about emergency response preparedness which requires special considerations for firefighters during rescue operations.

Public Awareness

Public awareness campaigns can educate building occupants about the risks of EV fires and how to respond to them safely.

Regulatory Compliance

Ensuring that building codes and regulations are updated to reflect the increased prevalence of EVs and their potential fire risks is essential.

In conclusion, with the growing adoption of fully electric and hybrid vehicles, the risk of EV fires in proximity to residential and other buildings demands our attention. Incorporating fire-resistant materials, enhancing building infrastructure, developing emergency response procedures, promoting public awareness, and updating building regulations are essential steps in mitigating these risks. Instead of waiting for regulations to change, we should acknowledge that standards will evolve, and we must future-proof our designs to ensure their long-term viability and safety.