Modern cars increase the risk of dangerous fire in underground parking garages

Illustration: Beredskab Øst

Car parks and underground parking garages—especially those built after 2004—are so bad at withstanding fire caused by newer cars that they can pose danger to people sleeping in the same building or hotel.

This is the conclusion of a new new report (PDF) on fire safety in parking facilities, published by the Danish Housing and Planning Authority.

The problem is both the size of newer cars and the large amount of plastic, which means that a car fire can both develop faster and spread more than in older cars. In addition, the temperature can become dangerously high.

“We don’t drive around in the Fiat 500 anymore, but the sizes of parking spaces haven’t kept up. And if two SUVs are parked next to each other, they will be close together, and the fire will spread faster. So where we used to expect that a fire affects one, two, or at most three cars, we are now talking about the expectation of a fire affecting 5–6 cars, and maybe even more, as we have seen in several fires abroad,” says Ib Bertelsenn, director of the Danish Institute of Fire and Security Technology (DBI).

In more technical terms, it was previously assumed that a car could reach a heat release rate of 5 MW. But now, a heat release rate of 10 MW and higher was observed in several trials.

Structures may fail in a car fire

The problem is that higher temperatures can affect the load bearing structures of a building to such an extent that it can lead to a failure. In particular, parking facilities without fire sprinklers or ventilation systems are particularly problematic according to professionals.

A structural failure can—in combination with more smoke—be dangerous for people in the building. There may therefore be an increased risk of evacuation. Parking facilities built after 2004 are particularly problematic because the requirements for how large a parking facility must be before technology that can limit the spread of fire must be installed were reduced.

DBI and the Danish Technological Institute, which have prepared the report together on the basis of an extensive literature review, recommend that sprinkler systems be installed in parking facilities larger than 150 m2. For parking facilities of up to 150 m2, it is also recommended to install firefighting systems to counteract the spread of fire between cars and other combustible material.

Fire sprinklers must not only be installed but also triggered earlier than is the case today:

“A quick response is paramount to prevent the fire from spreading to more cars. But we can see that there are very few cases in which people activate the alarm when a fire occurs in a garage. They may think others have called 112, and then they just stand around and watch the fire. Therefore, the alarm needs to be activated automatically,” Ib Bertelsen says.

It is now up to the Danish Housing and Planning Authority to decide on the consequences of the report’s conclusions and recommendations.

This article is an excerpt from a longer specialised article on Ingeniøren’s FacilityTech media site on the new report on fire conditions in underground parking garages and car parks for modern cars.