Underground EV Garages Face Fire Safety Crisis as Adoption Surges
As electric vehicle (EV) ownership accelerates across China’s urban centers, a hidden danger is emerging beneath the streets: underground parking facilities are increasingly ill-equipped to handle the unique fire risks posed by lithium-ion batteries. With over 7.8 million EVs on Chinese roads by the end of 2021—and charging infrastructure expanding rapidly—architects, fire safety experts, and policymakers are sounding the alarm over outdated building codes and fragmented regulatory oversight. The result? A growing mismatch between the pace of EV adoption and the readiness of subterranean infrastructure to manage its thermal, chemical, and operational hazards.
Unlike conventional internal combustion engine vehicles, EVs store immense energy in high-voltage battery packs that, when compromised, can ignite with terrifying speed and intensity. Lithium-ion battery fires burn at temperatures exceeding 900°C—nearly double that of gasoline fires—and release toxic gases such as hydrogen fluoride (HF), carbon monoxide (CO), and methane (CH₄). Worse still, these fires are prone to reignition, sometimes hours or even days after initial suppression, due to ongoing electrochemical reactions within damaged cells. In the confined, poorly ventilated environment of an underground garage, such characteristics transform a single vehicle fire into a potential catastrophe for entire buildings.
Despite these known risks, national building codes in China have yet to be comprehensively updated to address EV-specific fire dynamics. While the 2019 Technical Standard for Decentralized Charging Facilities for Electric Vehicles offers some guidance, it stops short of mandating full architectural redesigns for existing structures. Consequently, thousands of underground garages—particularly those attached to residential complexes built before 2019—lack basic safeguards like fire-rated compartmentalization, dedicated ventilation for toxic fumes, or sufficient water-based cooling systems needed to prevent thermal runaway propagation.
Field investigations reveal a troubling patchwork of retrofitting practices. In residential developments, individual owners often install third-party charging units without oversight, leading to inconsistent equipment quality, haphazard wiring, and zero integration with fire alarm or suppression systems. Public buildings fare slightly better, with property managers typically coordinating charger installations, but even these efforts rarely undergo rigorous fire safety reviews. Mechanical parking systems—common in dense Chinese cities—almost never include charging capabilities, not only due to weight limitations but also because the technology for safely integrating power delivery into moving platforms remains immature.
“The core issue isn’t just the presence of EVs underground—it’s the absence of a systemic safety framework,” says Zhang Yi, Executive Chief Architect at Nanjing Urban Construction Architectural Design Consulting Co., Ltd. “We’re retrofitting a fuel-based infrastructure paradigm with an energy storage technology that behaves like a chemical reactor under stress. That mismatch is where the danger lies.”
Zhang’s recent research, published in Architecture Journal, proposes a four-pillar architectural strategy to mitigate these risks: optimized spatial layout, enhanced fire compartmentalization, robust building construction details, and reengineered evacuation protocols. Central to this approach is the concept of the “fire unit”—a sub-compartment within a standard fire zone, limited to 1,000 square meters, specifically designated for EV charging. Each unit must be enclosed by firewalls with a minimum two-hour fire-resistance rating, separated by Class-B fire doors, and isolated from pedestrian egress routes.
Critically, Zhang recommends that all new underground garages—whether for residential or commercial use—be designed from the outset with full EV readiness. This includes pre-installed conduit pathways, reinforced electrical infrastructure, and sprinkler systems calibrated for lithium-ion thermal events. For residential projects, where individual ownership complicates centralized management, he advocates designing the entire garage to EV fire standards, even if only 10% of spaces initially feature chargers. This “future-proofing” ensures that as adoption grows, expansion can occur without compromising safety.
Location matters too. Fast-charging stations, which generate significant heat during operation, should be restricted to the first basement level (B1), where ventilation is superior and emergency response is faster. Deeper levels—B2, B3, and beyond—are discouraged for charging due to reduced visibility during smoke events and longer evacuation times. Moreover, charging zones must be kept away from vibration sources such as diesel generator rooms or adjacent rail lines, as mechanical stress can degrade battery integrity and loosen electrical connections.
The paper also emphasizes human factors. In many existing garages, charging equipment is installed directly behind or beside parking spaces without regard for operational clearance. Zhang specifies a minimum 0.4-meter buffer between chargers and vehicle edges to allow safe access, prevent door interference, and provide space for maintenance or emergency intervention. Anti-collision measures—such as reflective corner guards on columns, tactile floor markings, and convex mirrors at blind turns—are deemed essential to reduce impact-related battery damage, a known ignition trigger.
Evacuation planning receives special attention. Unlike traditional garages, where fire spread is relatively predictable, EV fires can project flaming debris up to six meters, blocking escape routes instantaneously. Therefore, evacuation corridors must remain entirely free of charging hardware, cabling, or storage. Safety exits should be distributed across multiple fire units within a single fire compartment to avoid funneling evacuees through a single choke point. Shared stairwells between adjacent units are encouraged—but only if protected by Class-A fire doors to prevent smoke migration.
Perhaps most urgently, the research calls for stricter oversight of retrofits in existing structures. Currently, building owners can add chargers with minimal regulatory scrutiny. Zhang proposes that any modification to introduce EV charging—especially in pre-2019 garages—must undergo mandatory review by certified fire safety engineers, assessing structural load, electrical capacity, compartmentalization, and egress compliance. Without such gatekeeping, the risk of “DIY electrification” turning underground spaces into tinderboxes remains high.
Industry observers note that China’s push toward carbon neutrality—pledging peak emissions by 2030 and net-zero by 2060—has turbocharged EV deployment, but lagging infrastructure standards threaten to undermine public confidence. A 2022 report indicated over 640 EV fires in the first quarter alone, outpacing overall vehicle fire trends. While absolute risk per vehicle remains low, the consequences of a single underground incident could be severe, potentially triggering building evacuations, structural damage, or even loss of life.
Global parallels exist. In Europe and North America, fire departments have begun revising response protocols for EV garage fires, emphasizing prolonged water application—often thousands of gallons—to cool battery packs and prevent re-ignition. Some cities now require new parking structures to include dedicated “EV fire containment rooms” with enhanced drainage and exhaust. China, with its unparalleled scale of underground urban development, may need even more aggressive measures.
Zhang’s work arrives at a pivotal moment. As municipal governments draft next-generation building codes, his architectural fire prevention framework offers a technically grounded, implementable blueprint. It bridges engineering rigor with practical design constraints, acknowledging that safety cannot be an afterthought in the EV era.
For investors and developers, the message is clear: underground parking is no longer just a real estate amenity—it’s a critical node in the EV ecosystem that demands upfront investment in resilience. For policymakers, the challenge is to accelerate code modernization while enforcing retrofits without stifling adoption. And for architects, the task is to reimagine subterranean spaces not as passive storage, but as active, intelligent environments engineered for the energy transition.
The road to sustainable mobility runs underground—and it must be built to burn less, not more.
By Zhang Yi, Executive Chief Architect, Nanjing Urban Construction Architectural Design Consulting Co., Ltd., Architecture Journal, DOI: 10.19875/j.cnki.jzywh.2024.08.013