New research suggests that the environmental consequences of fires in timber buildings […]
New research suggests that the environmental consequences of fires in timber buildings extend far beyond smoke and flames. The findings highlight why fire safety and sustainability can no longer be treated as separate disciplines.
When a building catches fire, most people think about smoke, soot and greenhouse gas emissions from the flames themselves. According to new research involving DBI, however, the largest environmental impacts may often occur after the fire has been extinguished.
In a scenario-based study of fire incidents in a timber building, researchers found that post-fire reconstruction and replacement of damaged materials frequently contributed more to the total environmental impact than the fire emissions and emergency response activities.
For Mansoure Dormohamadi, whose PhD research focuses on the intersection between fire safety and environmental assessment, the findings underline why fire consequences need to be assessed beyond combustion emissions alone.
“Many people associate the environmental impact of fire mainly with smoke and combustion gases. Those emissions matter, especially for local air quality and toxicity. But in our scenarios, the largest environmental burden often came after the fire. If we only focus on combustion emissions, we miss what was often the dominant consequence pathway: replacement and reconstruction,” says Mansoure Dormohamadi.
The environmental cost of post-fire material replacement
The explanation lies in what happens once the fire is over. While flames may affect only part of a building, smoke, soot, heat and water from firefighting can damage furniture, floor coverings, finishes, linings and other building components well beyond the area directly exposed to fire. As a result, materials that might otherwise have remained in use throughout their intended service life are removed and replaced.
In the study’s more severe scenarios, the replacement scope expanded beyond furniture and finishes to include gypsum plasterboard and parts of the timber enclosure system. In these scenarios, post-fire material replacement accounted for more than 80 % of the total fire-related environmental impacts.
“The important point is that a fire can shorten the environmental service life of building components. Once those materials are removed and replaced, the production impacts of new materials are activated again,” says Mansoure Dormohamadi.
The researchers analysed four fire scenarios ranging from a minor object ignition to a fully developed enclosure fire. What surprised Mansoure Dormohamadi was how quickly the impacts escalated when detection and intervention were delayed, allowing the fire to develop further and activate more extensive damage mechanisms. Moving from a minor object ignition scenario to a localised object fire scenario with fire-service intervention increased impacts by 78 % across the assessed indicators, while the transition from that scenario to a fully developed non-sprinklered enclosure fire following delayed detection added a further 86 %.
“A slightly later intervention does not simply mean a slightly larger environmental impact. When a fire moves from an object fire to a fully developed enclosure fire, the damage regime changes. The problem is no longer only the amount of material burning. It becomes wider smoke damage, water damage, surface replacement, structural involvement and reconstruction,” says Mansoure Dormohamadi.
Why is fire largely absent from LCA?
The findings raise a broader question. If fire can have such significant environmental consequences, why is it rarely included in building LCAs?
According to Mansoure Dormohamadi, the answer is largely methodological. Conventional LCAs are designed around expected life-cycle stages such as material production, construction, operation, maintenance and end of life. Fire, by contrast, is a disruptive event.
“Fire has not been excluded because it is environmentally irrelevant. It has mostly been excluded because conventional building LCA is not structured to model disruptive events,” says Mansoure Dormohamadi.
Including fire requires information that is rarely available in conventional environmental assessments, including fire development, detection times, suppression, emergency response, smoke and water damage, repair strategies and replacement decisions. In other words, it requires bringing fire safety engineering and environmental assessment together.
A sprinkler system illustrates the dilemma
The study’s analysis of sprinkler systems illustrates why the relationship between fire safety and sustainability is more complex than it may first appear.
On one hand, sprinkler systems have their own own embodied environmental impact. On the other, they can significantly reduce the environmental consequences if a fire occurs and the system activates effectively.
In the timber-building scenarios analysed in the study, sprinkler protection reduced total fire-related environmental impacts by more than 85 % compared with the fully developed non-sprinklered enclosure fire scenario.
“The main environmental benefit was not only lower combustion emissions. It was avoided reconstruction,” says Mansoure Dormohamadi.
She stresses that the finding is scenario-based and does not account for the probability of a fire occurring. The study examines the environmental consequences if different fire scenarios happen, rather than assessing overall fire risk.
Nevertheless, the example illustrates a challenge for both fire engineers and LCA practitioners: Fire safety measures add environmental impacts, but they may also prevent much larger impacts later, depending on the fire scenario and how fire development is controlled.
Fire safety and sustainability are not separate decisions
That challenge was the starting point for Mansoure Dormohamadi’s research.
“My interest came from a practical tension in low-carbon construction. Timber buildings are increasingly promoted because timber can reduce embodied carbon, but timber is also combustible. That does not mean timber buildings are unsafe. It means their fire safety strategy must be part of their environmental assessment,” says Mansoure Dormohamadi.
According to her, the building sector still tends to treat fire safety and climate performance as separate design challenges, even though the two influence each other from the earliest design stages.
Fire safety decisions affect material selection, protection layers, technical installations, replacement cycles and, ultimately, the potential consequences of a fire. Yet those interactions are rarely assessed together.
“The main takeaway is early integration. Fire safety and climate performance should not be treated as separate design problems,” says Mansoure Dormohamadi.
Towards more complete building assessments
The latest paper forms part of a broader PhD project that explores how fire safety considerations can be integrated into environmental assessment.
The issue is becoming increasingly relevant as climate requirements expand and life-cycle environmental assessment becomes more important in both Danish and European regulation.
Yet significant challenges remain. One of the largest is the lack of reliable and comparable environmental data for fire protection systems. As environmental requirements evolve, the need for robust data and consistent assessment methods is likely to grow.
“We need better data, clearer methods and closer integration between fire safety engineering and sustainability assessment,” says Mansoure Dormohamadi.
Fire incidents and environmental impact
Research paper
‘Quantifying the environmental consequences of fire incidents in timber buildings: A Nordic case study’
What was studied?
Researchers analysed four fire scenarios in a Nordic timber residential compartment, ranging from minor object ignition to a fully developed enclosure fire, with and without sprinkler protection.
Key findings
Part of a broader PhD
The study forms part of Mansoure Dormohamadi’s broader PhD research into the integration of fire safety and environmental assessment, including the development of Fire Safety Life Cycle Assessment (FS-LCA).
Partners
DBI (The Danish Institute of Fire and Security Technology), Aalborg University and Lund University.
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