Fire Dynamics & Building Materials: Designed to burn research
Fires today burn faster and create greater heat release than they did just a few decades ago, due in part to the evolution of building materials and construction techniques. This not only leads to greater property damage and more rapid structural collapse, but the time to escape a burning residential structure prior to flashover has also been drastically reduced. It’s not just the speed and intensity of the fire that has increased, though — the construction materials and interior contents in buildings today contain more plastics, synthetics, and chemical-based products which emit increasingly toxic products of combustion. Research has attributed some types of cancer to exposure to these products of combustion; that means first responders, building occupants, and bystanders have a higher risk of developing cancer when exposed to these toxins during and after a fire.
The National Institute for Occupational Health and Safety (NIOSH) has data that indicates firefighters are 14 percent more likely to die from cancer than the general population as a result of their chronic exposure to these toxic products of combustion. While nobody expects a building to burn, it happens every day; so, what can we, as an industry, do to design these buildings to be safer – even when they burn?
Henderson Engineers, in partnership with BNIM Architecture, Oklahoma State University’s Fire Protection & Safety Technology Department, Turner Construction, and Armstrong Forensic Laboratory, is taking a multidisciplinary approach to research that very question. This research will help identify how buildings can be designed and constructed to meet code requirements, and be more environmentally sustainable, energy-efficient, and cost-effective for the client by using safer methods and materials, but also that perform better during a fire – in other words, creating buildings that are designed to burn.
Solutions for Safer Buildings
The solution to making buildings safer is really two-fold. First, in order to slow or suppress fires, buildings utilize fire-rated barriers and/or are protected with automatic sprinkler systems. While this may seem obvious, fire protection systems greatly reduce the magnitude of the fire loss.
- Occupants have more time to egress the structure.
- In large scale fire tests conducted by UL and NFPA, sprinkler systems lowered the peak heat release rate from 13,200 kW to 300 kW.
- There was a 69 percent reduction in property damage.
- Since the fire size is greatly reduced, combustion emissions and toxic gases are reduced by more than 90 percent.
- First responders’ exposure to combustion products is greatly decreased.
- More importantly, there was an 81 percent decrease in the number of fire-related deaths.
However, while fireproofing a building provides us with a somewhat simple solution to part of this problem, the rest of the solution — being more intentional regarding the selection of building materials during the design process — is much less straightforward. Codes, standards, and product testing address the combustibility of construction materials related to height and area, as well as the flammability of interior finishes. Yet, there is no test or standard to evaluate how a construction assembly behaves when exposed to fire. Furthermore, LEED Certification and other green initiatives focus on sustainability and impact on the occupant and environment during every stage from material manufacture, to construction, to occupancy, but do not address the impacts during emergency conditions.
By better understanding the fire dynamics and products of combustion produced by different building materials and configurations, designers can make decisions to create construction assemblies that have both improved fire resistance and more favorable results in fire conditions.
Creating the Future through Research
As leaders in the industry, Henderson Research and its partners are aiming to better understand the fire dynamics and products of combustion for wall assemblies over the last 60 years. Through our Designed to Burn project, the research team designed and constructed wall assemblies typical of the 1950s, 2000s, and 2010s eras, as well as an ideal assembly for use in the upcoming 2020s and beyond.
The assemblies were recently burned under Oklahoma State University’s burn calorimeter. Data including heat release rates and mass loss was collected from a fire dynamics standpoint. Additionally, combustion products from each wall assembly were collected and will be analyzed for polynuclear aromatic hydrocarbons (PAHs), volatile organic compounds (VOCs), aldehydes, volatile acids, semi-volatile organic compounds (SVOCs), heavy metals, and total particulate. Once all the data is collected and analyzed, it’s anticipated that the heat release rates and the volume and toxicity of the products of combustion will be progressively more impactful from the 1950s to the 2010s. We’re hopeful that a decrease can be observed in the 2020s assembly as a result of the intentional selection of construction materials and techniques.
The right answer doesn’t exist yet. But through increased awareness and research, we as an industry can begin to design and construct buildings that are not only environmentally sustainable but are also designed to burn with less of an impact on the environment and occupants.