Fire Risks
Fire engineering has evolved into a formal profession in New Zealand over the past two decades. The methods employed in fire engineering are increasingly standardized. Initially, fire engineering was characterized by the application of international best practices, a risk-based approach, and research to develop fire design solutions. However, in recent times, fire engineering has become more standardized and less dependent on research. While this trend may facilitate approval processes, it has resulted in a growing disconnection from the original intent of the profession.
There is now a tendancy to ‘shoehorn’ designs into standardised methods to avoid an Alternative Solution. We have a generation of fire enginners who may have never constructed an Alternative Solution from first principles. By using a ‘cookbook’ approach we begin to lose grasp of fundamental fire engineering principles.
The ‘cookbook’ approach can be an issue when confronted by new risks created by emerging technology. These include mass timber buildings, electric vehicles and modular construction. Acceptable Solutions/DTS does not address the impact of these risks as its based on traditional construction methods. The building code permits the use of the Acceptable Solutions without taking into account the emerging risks.
We may not be equipped to respond to these new risks if we are too familiar with standardised methods. Instead of a risk-based approach, the design becomes a ‘best guess’ approach. If we don’t comprehend and fully understand the risk of emerging hazards, then how can we continue to design buildings that are taller and more complex? This places unknown risks to occupants, property and Fire Services.
The following is some examples of where the Acceptable Solutions fall short of an acceptable level of risk and further consideration is required:
Multi-Level Residential Buildings
Modern timber construction is light weight and easier to build, which can be as little as one layer of plaserboard between floors of a multi-level buidling. This construction is easily compromised with service penetrations where there is no requirement for automatic warning system. These buildings could also contain battery powered devices, such as EV vehicles and bikes. We have to start asking ourselves is a manual fire alarm really sufficient in any residential building? The fire at Loafers Lodge in Wellington, NZ has taught us the tragic outcome of a building without an operational automatic fire alarm system.
Foam Plastic in Housing
The Acceptable Solutions have strict requirements for internal surface finishes. However, there is no restriction on material up to 5m2 or on the extent of foam plastic within walls or attic spaces. Ignition of foam plastic in a home or stairwell could have significant consequences in a fire. More and more, we are seeing houses constructed of foam plastics and roof cavities filled with thick plastic insulation. What is the outcome of a fire in these dwellings which are have battery powered devices and electric vehicles? In multi-unit dwellings the fire rating can be as little as 30 minutes to the neighbouring unit!
Mass Timber Buildings
In New Zealand, mass timber buildings are being built up to 10 storeys in height. Timber burns at a faster rate than traditional construction. Cross laminated timber will cause delamination after a certain time period, placing an increased risk to occupants and the Fire Service. What is the risk of enhanced burning on crtical structural elements, cladding systems and stairwells? The Acceptable Solution permits a fire rating of 30 minute FRR for up to 20 storeys without any encapsulation. International guideance would require minimum of 60 minutes FRR and protection of critical structure. Without this protection, Fire Services would be reluctant to enter these buildings with exposed timber construction.
Electric Vehicles
The growth of electric vechiles (EV) are grown to more than 20 million vehicles on the road where an average car parking building currenlty have at least 20% car as EV. An EV is essentially a mobile battery and when a battery becomes damaged or over heats it goes into thermal runaway ie cannot be extinguished. A battery in thermal runaway produces a highly toxic vapour cloud and rocket like flames projecting from the vechile. This is a huge risk to occupants and Fire Services and needs to be addressed in car park designs particulary underground & in homes.
Conclusion
In my perspective as a chartered fire engineer, it is inadequate to solely design the Acceptable Solutions. It is essential to apply sound judgment and integrate the risks associated with emerging technologies to ensure that buildings are safe and suitable for their intended purposes. We bear a responsibility to the public, broader society, and our profession to acknowledge and address the risks that may affect these structures.
This is a call to all interested parties (MBIE, FENZ, SFPE) to have additional checks for any building with an emerging technology. The responsibility currently lies within Building Control, across different local authorities, to ensure that buildings are safe and who are often under resourced to carry out checks.
I believe that as an absolute minimum, we need to notify clients of the fire risks so they can make an informed choice around the fire safety of the buildings and protect the people that occupy them so we can all sleep at night.
