Fire ventilation and electric cars
On the one hand, the risk of potential fires in electric cars in underground garages, and on the other, the lack of clear guidelines on how to effectively design a fire ventilation system in these facilities. Designers do not have an easy task. How to cope with this difficult situation and choose a solution that best guarantees safety? Joanna Marzec, a designer in the Fire Ventilation Systems Department at MERCOR, shares her experience.
How to predict a fire ventilation system that guarantees safety in the event of a fire developing in an underground garage, the source or participant of which is an electric vehicle. What is the biggest design challenge?
Joanna Marzec, designer in the Fire Ventilation Systems Department at MERCOR: In the era of development of electromobility, the topic of electric cars appears in the public space more and more often, usually in the context of ecology, as well as the development of infrastructure that will facilitate the operation of cars with EV engines or plug-in hybrids. In my opinion, these solutions are still too rarely discussed in the context of fire safety, especially in the case of underground garages, where in accordance with the Act of January 11, 2018 on electromobility and alternative fuels (Journal of Laws, 2023, item 875, as amended), the legislator imposes the provision of ducts for electric wires and cables, enabling the installation of charging points, which is interpreted as the possibility of locating the charging points themselves, in an appropriate number, depending on the type of building. For example, in residential buildings with more than 10 parking spaces, this option must be provided in all parking spaces.
On the other hand, the media coverage of electric car fires in Poland and abroad, as well as cases of problems with controlling fires caused by lithium-ion batteries, mean that the topic of advantages and disadvantages of the development of electromobility is constantly brought up. Unfortunately, these discussions do not entail legal regulations when it comes to ensuring fire safety. It is the responsibility of ventilation designers and fire experts to undertake an analysis for each topic individually.
So how can a designer navigate these ambiguities?
JM: When designing a fire ventilation system in underground garages, we must take into account the power and speed of fire development, also in order to verify the design assumptions through CFD simulation. The question is: how to approach this?
In 2024, a Polish institute CNBOP published a publication about fire protection in garages in the context of charging electric and plug-in hybrid cars, giving hope for indicating the direction in this topic. Unfortunately, this study refers mainly to the electrical industry, without indicating specific solutions in the field of fire ventilation.
The only hint for designers in the sanitary industry are the results of scientific research and tests cited in the aforementioned CNBOP study, such as the German SUVEREN research program, the Austrian BRAFA project, or full-scale fire tests from South Korea and many others. Analyzing the results presented in the publication, as well as the fire development curves contained therein, it can be concluded that fires in EV-powered cars develop more dynamically than in conventionally powered vehicles, while generating higher fire power.
This means that fires in electric cars pose a much greater challenge than in conventionally powered cars.
JM: In 2024, another publication was also published by the Fire Academy, concerning the verification of jet ventilation in underground garages using CFD simulations, in which, among other things, fire curves for EVs were published, including according to RISE research. According to data from this publication, in the first phase of development, the fire assumes a gentler growth than in the case of conventional cars (in the context of, for example, the curve from the NEN 6098:2012 standard), which would even indicate that for the analysis of evacuation conditions, such a fire is more beneficial than combustion cars. The total fire power, according to the Academy's publication, is higher than in the case of a conventional car fire. Be wise here, designer!
Despite the lack of guidelines, responsibility for the completed project remains. So what data do MERCOR designers use?
JM: There are voices that for conventional cars, curves from the British standard or Dutch or Belgian standards are outdated due to the fact that when they were created, fires of cars with a lower plastic content than those produced today were analyzed, nevertheless, in our opinion, as MERCOR designers, there is currently no better point of reference in this regard, especially due to the contradictory results of published studies and the prevalence of these curves in the environment of people performing CFD simulations.
Analyzing cases of real fires of electric cars and films published on the web, in our opinion, a definitely rapid development is observed in the first phase of the fire. Many industry sources also state that despite the rapid development of the fire, the total power of the fire is similar to the fire of conventional cars.
In our work, as a starting point, we use the curve of conventional cars according to the Dutch standard NEN 6098:2012, for 3 cars, modifying it to take into account a very rapid fire, which gives a shift in the first phase of the fire according to the graphic below.
Is this the only right approach – probably not, but in our opinion, as the MERCOR design department, we are somewhere between these pieces of information. At the moment, this is a method that reflects the impact of such a fire on evacuation, which we are obliged to verify under national regulations, while allowing for the analysis of conditions for rescue teams, in the context of the designed fire ventilation system. The fire curve is selected by the simulation author in consultation with the fire protection expert who agrees on the report, but it should be remembered that we should be guided by the principle that the simulation should reflect real conditions as much as possible and show possible design errors, and not help achieve the expected positive results, depending on the needs for a given garage.
Is there a chance that, given the scale of electric car introduction, clear guidelines and regulations reflecting real needs will be created in the near future?
JM: Personally, I am waiting for the issues related to fires in cars with EV engines in underground garages to be sorted out, in the form of a standard curve or an amendment to the regulations, but I am afraid that as designers we will still be facing the dilemma of how to approach these issues for a long time.
Thank you very much for the interview!
Interviewer: Izabela Adamska, Marketing Project Coordinator at MERCOR.
