For decades, sustainability has been a topic of discussion for innovators and designers looking to conserve resources in the built environment. As green technologies and materials are becoming more affordable and available, the market demand for sustainable infrastructure and alternative energy has increased.
How will these new technologies and systems affect the fire protection industry? Decades of building experience with traditional building materials have led to well-established building and life safety codes and standards. When new materials and systems are added to the built environment, the solution to the fire safety equation changes. Societal expectations for how our buildings respond to other hazards, including fire, also change with time. This report outlines some of the potential fire hazards associated with sustainable materials and technologies and summarizes some of the mitigation strategies which might include operational criteria, code requirements or both. It also includes a discussion on how fire safety can be considered a sustainable practice.
Hazards
This list describes a few of the emerging fire hazards associated with sustainable materials and systems.
Building Materials
- Lightweight construction: Lightweight construction has become more popular in residential construction during the last decade. It is a popular choice since it can offer lower costs, reduced use of natural materials, allow for large open floor plans in both low rise commercial and residential buildings and improved structural stability. Lightweight construction can come in many forms, but the one of the most popular is composite wood assemblies. Composite wood joists often have considerably thinner web sections than traditional sawn lumber members and have reduced inherent fire resistance.
- Engineered wood trusses: The metal gusset plates used to connect the truss can deform when exposed to high temperatures and can contribute to early failure of the truss.
- Insulation: New insulation methods help reduce energy costs by regulating building temperatures and reduce the amount of “leaks” in a building. While materials like rigid foam insulation, spray-applied foam insulation, structural integrated panels (SIP), exterior insulation and finish systems (EIFS) and foil insulation systems are beneficial for sustainability goals, they can contribute to fire spread and increased smoke production. Airtight construction can create abnormal conditions during a fire event including backdrafts. Insulated concrete forms are another example of new insulation methods. “Stay in place” concrete forms are made of expanded polystyrene. If left untreated or uncovered during or after construction, these forms can contribute to a fire.
- Glazing: Increased glazing areas including skylights and light wells can contribute to hazards for fire fighters trying to access and navigate a building. Increased amounts of glazing can present more opportunities for breakage or fire spread.
- Furnishings and Contents: Some modern furnishings and contents can contribute to more fire spread and smoke production when compared to traditional furnishings and contents.
Building Systems
- Water supply: Local jurisdictions or weather conditions may put limits on water availability and discharge into public water sources. During fire conditions, the water demand for the building may exceed the available supply. Designers should be sure to include water storage in their system designs if the required supply cannot be met. Consideration should be given to water runoff during sprinkler testing and contaminates in water runoff during a fire event.
- Natural ventilation: Natural ventilation is used to circulate building air without the use of mechanical equipment. While this reduces energy costs, it also can create an obstacle for firefighters when trying to control smoke movement.
- Standoff/Double skin facades: A standoff or double skin façade creates a vertical flue space for air to travel along the outside of a building. This feature helps regulate building temperature and conserve energy. While beneficial for ventilation and energy conservation, standoff facades can create vertical flue spaces for flame and smoke to travel if not protected properly.
- Vegetative Roof Systems: Also known as a “green roof”, a vegetative roof system is a roof of a building that is covered in plant material. The roof is covered with layers of barrier materials, soil, irrigation systems, and plants. These roofs help insulate a building, collect rainwater, and reduce heat island effects. It is important to ensure the plant material is maintained and watered properly because dry plant material can contribute to fire spread. The impact on the roof fire rating should also be determined.
- Photovoltaic Panels (PV): PV systems are used to generate electricity and can be found mounted on roofs, walls, or as standalone systems. These systems each have a number of components that work together to generate usable electricity. The PV cells are grouped together into panels and when grouped together, they form a PV array. PV systems also include batteries to store the current and inverters that change the current into usable electricity. While any electrical current is dangerous, one of the most hazardous components of a PV system is the actual panel. The panels continuously produce electrical current when exposed to the sun, even when they are disconnected from the rest of the system. The panels are also covered in glass and can easily be damaged. It is important to understand the electrical shock hazards associated with these panels and to design arrays with proper spacing to allow for firefighter access to the roof. It is also important to evaluate the impact the arrays will have on the roof fire rating.
Fire Service Concerns/Mitigation Strategies
Today’s fire service has many responsibilities ranging from fire suppression to technical rescue and hazardous material response. As their responsibilities have expanded so has the knowledge base needed to continue performing the job safely and effectively. New technologies and building materials are being introduced into the consumer environment faster than ever before and firefighters trying to adapt to this new built environment are getting caught off guard.
Many of the firefighting tactics used today are based on the past hundred years of firefighting experience. When new materials and systems are introduced into the built environment, firefighters have to adapt their tactics to both help control the fire and to protect themselves. Photovoltaics have already been a factor in several large loss fire incidents where firefighters were unable to access roof areas due to photovoltaic arrays. Typically, firefighters access roof areas during a fire to ventilate the structure by cutting a hole in the roof. This helps firefighters in rescue and suppression efforts by removing heat and smoke from the building while also helping to keep the fire contained. When photovoltaics are present firefighters risk electric shock by working on the roof and are often times kept off the roof as a precaution. This often changes firefighting tactics from aggressively attempting to save a building from the inside to defensively fighting it from the outside of the structure.
New building materials and structural systems like lightweight construction and engineered wood trusses can fail sooner than traditional wood members. Members of the fire service should be aware of these new construction types and have plans on how to attack fires in these structures. This will ensure that the materials have been properly tested and reviewed. Authorities Having Jurisdiction (AHJs) may also require buildings to be labeled when they are constructed of lightweight materials and trusses. These labels can provide responding firefighters with a heightened suspicion for early collapse under fire conditions.
These emerging technologies reinforce the importance of fire sprinkler systems as a mitigating measure. An effective sprinkler system can prevent a fire from ever damaging lightweight building materials and causing a collapse. Sprinklers can also contain a fire so that firefighters do not need to access roof top areas to conduct ventilation. Sprinkler systems are invaluable in a fire by helping occupants evacuate structures safely and giving them time to get out of harm’s way. These systems also save the lives of responding firefighters by mitigating the fire before it gets out of control and threatens vulnerable building systems.
The fire service is on the front lines of environmental protection in the United States. Often serving as the first response agency, the fire service makes critical decisions and takes critical actions to mitigate not only typical building fires, but explosions, hazardous material fires, chemical spills, and wildfires. Fire prevention inspections are not limited to regulating fire hazards. The inspections could also include managing hazardous materials to ensure they are properly contained and protected. The fire service’s training, planning and response help protect the environment from toxic runoff and hazardous pollutants.
Regulatory Context
As new materials and construction practices emerge, codes and standards addressing safety will need to stay at the forefront of the industry and address these materials and practices while maintaining safe and reliable buildings.
The International Code Council publishes the International Green Construction Code (IGCC). This code serves as an overlay to building codes by including requirements for measuring sustainability. The code addresses building energy efficiency, water usage, and occupant health and safety. The IGCC does not specifically address fire hazards. A similar green code was developed by the state of California. The California Green Building Standards Code or CALGreen also serves as an overlay to the state building codes. It is important to note the differences between green codes and green rating systems like the US Green Building Council’s LEED. The codes establish minimum requirements and the rating systems set goals to achieve certification.
Building codes such as NFPA 5000, Building Construction and Safety Code, address the minimum construction requirements for buildings. Some building materials, like EIFS, are addressed specifically. Materials like lightweight construction are not specifically addressed by construction requirements, but are addressed by sprinkler requirements. NFPA 5000 and NFPA 101®, Life Safety Code® have required all one and two family dwellings, where lightweight construction is typical, to be protected by sprinklers since the 2009 edition.
NFPA 70®, National Electric Code® addresses PV systems in Article 690 and small wind (turbine) electric systems in Article 694. NFPA 70 addresses requirements on wiring methods, disconnection, arrangement and signage. NFPA 1, Fire Code also has requirements in Chapter 11 on photovoltaic systems. These requirements include disconnection requirements, marking locations, and maximum array sizes. The arrangement requirements in NFPA 1 include provisions for ventilation operations and access pathway dimensions.
In response to local regulations and reduced water supplies, some NFPA committees are developing new requirements to help regulate and reduce water use. In the 2011 edition, NFPA 25, Standard for the Inspection, Testing, and Maintenance of Water-Based Fire Protection Systems, established minimum run times for annual pump tests to help reduce water and save energy. The 2013 edition of NFPA 13, Standard for the Installation of Sprinkler Systems, allows recycled or reclaimed water (after being analyzed) to be used for water supplies.
Fire Safety is a Sustainable Practice
It can be argued that fire safety is a sustainable practice. Reducing the amount or severity of fires can reduce wasted materials, pollution, and save money. During a fire event, building materials are damaged, property is lost, water is wasted, and pollutants are released into the environment through the air and water. After a fire event, materials that were damaged are transferred to landfills and new materials are brought in to replace them. The environmental impact of the fire depends on the size and severity of the event. It is important to consider the lifecycle of a building when reviewing sustainability concepts.
In a report published by FM Global, the environmental impact of automatic sprinklers was studied. The results compared the fire test data from two large-scale fire tests, one in a room with automatic sprinklers, and one without. The report stated that the use of sprinklers reduced greenhouse gas emissions by 97.8% and limited the area of damage to the room of origin. The non-sprinklered room flashed over in 5 minutes, meaning that the damage would have spread outside the room of origin before the fire service arrived, resulting in additional damage. The amount of water used to extinguish the fire in the sprinklered building was 50% less than the water used to fight the non-sprinklered fire. This study proved that fire sprinklers could help reduce the environmental impact of a fire event and contribute to sustainability goals.
Risk Balance
As the fire protection industry adapts to recognize new materials and products, the solutions can often times create new unforeseen problems. Each year new products, systems, and materials are developed to try and reduce the size, severity, and number of fire events. While these new solutions might protect against one risk, they could be creating a new risk of their own. One example is the current debate regarding flame retardants.
By reducing fires in materials that would otherwise easily ignite, flame retardants are acknowledged to have played an important role in reducing fire-related injury and property damage. However, they have also begun to be scrutinized in recent years as environmental contaminants which may adversely impact human and environmental health. Although there is limited data available from human studies, some flame retardants are considered possible carcinogens, while other health effects may include damage to endocrine, immune, reproductive, and nervous systems. The ability of some flame retardants to bio-accumulate raises concern about the potential for harm to firefighters and the general public from even low levels of exposure.
Sustainability efforts have the potential to comprehensively address safer and healthier conditions by eliminating hazards through all phases of the life cycle. Any new solutions to a problem should not introduce an unacceptable new set of risks to a different population or through a new medium. Sustainable design will be better able to evaluate the full spectrum of risks and hazards if it includes health and safety concerns as an essential design criteria. Such integration will minimize the potential for the introduction of new risks or, at least, facilitate informed decisions regarding risk tradeoffs.
Future
Additional focus on the issue of sustainability and fire safety is needed. Building designers, architects, engineers and members of the fire service need to be aware of the hazards associated with certain sustainable features. An action plan should be developed to determine how our industry should address these hazards.
Resources
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