Fires in Underground Car Parks and the Need to Reinforce Passive Fire Protection

Madrid, September 3, 2025 – Fires in underground car parks represent a growing risk, especially with the increasing integration of electric and hybrid vehicles. This scenario poses technical safety challenges, both in emergency response and in the design of passive fire protection systems.

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Recent Fires in Underground Car Parks

The April 2, 2025 fire in a garage in Alcorcón, where two firefighters died following a collision involving lithium-battery vehicles, highlighted the complexity of car park fires (El País, 16/04/2025).

In February 2025, a fire in a car park in Moncloa (Madrid) affected two electric vehicles and required an extraordinary deployment of resources (El Confidencial Digital, 27/02/2025).

According to the Spanish Directorate General of Traffic, garage fires account for approximately 9% of fires in common areas of buildings (Revista DGT, 2023). Although less frequent, their consequences can be severe due to the enclosed configuration of these facilities and the number of vehicles parked in a single space.

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Technical Risks Associated with Lithium-Ion Batteries

Lithium-ion batteries pose specific risks: thermal runaway, extremely high combustion temperatures, toxic gas emissions, and re-ignition after apparent extinguishment (The Objective, 15/01/2024). These hazards require passive fire protection systems to be verified through certified laboratory testing prior to installation.

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Critical Passive Fire Protection Measures in Car Parks

To ensure safety in underground car parks, specialists recommend:

• Compartmentation with tested fire-rated walls and floors to preserve structural integrity and thermal insulation.

• Certified fire doors, with proven resistance against flames and hot gases.

• Fireproof coatings on load-bearing structures to delay loss of mechanical capacity.

• Intumescent sealants in service penetrations, preventing the spread of smoke and fire between sectors.

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Regulations in Spain and International Standards

The Spanish Technical Building Code (Código Técnico de la Edificación) and regional regulations establish fire resistance requirements for garages, although automatic sprinkler systems are not mandatory in most cases.

In contrast, the U.S. NFPA standards require sprinklers in all newly built parking structures (NFPA, 2022).

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Conclusion

Reinforcing passive fire protection in underground car parks, together with the integration of active smoke detection and control systems, is an immediate priority. Implementing solutions that are laboratory-tested and certified is essential to reduce vulnerability to fires involving electric and hybrid vehicles, ensuring both occupant safety and structural integrity.