A new study from Johns Hopkins University researchers in the Whiting School of Engineering’s Department of Civil and Systems Engineering found that performance-based fire designs (PBFD) significantly outperform the one-size-fits-all approaches currently required by U.S. building codes, delivering enhanced safety, resilience, and lifetime cost savings.
The three-year study was funded by the National Institute of Standards and Technology (NIST).
Published in Engineering Structures by Thomas Gernay, an associate professor of civil and systems engineering, and Chenzhi Ma, a doctoral candidate, the study compares lifetime costs of prescriptive fire designs with PBFD, a goal-oriented approach to fire safety design. Unlike current codes that apply the same prescriptive rules to broad classes of buildings, PBFD creates customized fire-safety solutions by analyzing each structure’s characteristics, from layout, materials, and occupancy, to how fire would weaken and damage the building.
“Focusing on buildings with steel-concrete composite floor systems, which are commonly used in buildings with wide, open spaces, like offices, hospitals, and multi-family residential buildings, we developed a rigorous model to evaluate life-cycle costs of PFBDs and prescriptive designs,” said Ma.
The researchers’ cost-assessment model examined three major components: initial construction and labor costs; expected lifetime losses from fire damage—both direct, such as physical destruction, and indirect, like business interruptions; and environmental impacts associated with construction and post-fire recovery.
Current prescriptive methods, while straightforward and enforceable, are based on generalizations that treat each structural member in isolation and don’t account for how buildings behave as a system under fire, Gernay said.
One of the new study’s most striking findings is just how vulnerable prescriptive design is.
“We found that when applying current building codes to steel-concrete composite flooring, those buildings were unable to withstand a two-hour standard fire before reaching structural failure, which is the benchmark for fire safety, also stipulated by U.S. building codes,” said Ma.
By contrast, performance-based designs were shown to be significantly more robust. While these building designs showed visible deformations during a fire, like bending, the overall building maintained structural integrity under extreme fire conditions, reducing the risk of catastrophic failure.
The researchers validated their model using data from full-scale fire tests conducted by NIST between 2019 and 2022.
“Using real data from NIST’s live fire experiments in combination with numerical simulations, we could see that prescriptive designs frequently underperform in extreme fire conditions,” said Gernay. “Performance-based designs may initially seem more complex, but our analysis showed that they consistently result in fewer catastrophes and lower lifecycle costs.”
In addition to safety improvements, PBFD offers significant economic advantages: reduced material and total maintenance costs on protection methods that slow or impede the spread of fire, shorter construction timelines, and the potential to dramatically reduce fire-related damage over the life of a structure.
“Prescriptive design may have lower initial construction costs than PBFD, but PBFD had lower overall construction associated costs when factoring in fewer maintenance costs and a shortened construction schedule. Interestingly, we found that designs based on the current prescriptive approach have higher lifetime losses compared to PBFD,” said Gernay.
For policymakers, the findings present a compelling case to revisit current codes, especially given the highlighted vulnerabilities of prescriptive design and the growing need for sustainable design.
The implications go beyond individual projects, however. With total U.S. fire-related costs reaching nearly $328 billion in 2014—including $57 billion for preventative fire measures—even minor improvements to fire safety design could yield substantial savings and improve disaster recovery.
The researchers plan to expand their model to other structural systems, including timber construction and single-family homes in fire-prone areas, while refining their economic analysis with real-world insurance and regulatory data.
“Our goal is to provide the data and tools so that engineers, developers, and policymakers can make informed choices,” Gernay said. “When you consider the big picture with these steel-concrete floors—human safety, construction costs, and environmental impacts—PBFD clearly comes out ahead.”