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Green Buildings: Sustainability Successes Challenge Fire Resiliency

By: Victoria Hutchison, Fire Protection Research Foundation

Over the last decade “going green” has become increasingly mainstream. In an effort to use less energy, save resources, and reduce pollution and waste, we now embrace alternative energy, support energy efficiency, and practice recycling. But It’s important to recognize that going green isn’t just about electric cars, solar panels or battery energy storage, it’s also about buildings, as structures are significant consumers of energy.

While the world’s cities occupy just 3 percent of the Earth’s land, they account for 60-80 percent of energy consumption, 70 percent of global carbon emissions and over 60 percent of resource use, per the UN Environmental Programme Emissions Gap Report. Rapid urbanization is exerting pressure on our supply of global resources, driving the need for buildings to be more sustainable, energy efficient, and resilient to fire and other disasters.

In response to societal objectives, there has been substantial global investment in clean energy and energy efficiency, which drives new innovations, including development of green and sustainable products and systems. As a result of this dramatic investment, these systems and materials are proliferating at an exponential pace.  ‘Green’ building materials, systems and features, collectively referred to as the “attributes” of a building, range from interior and exterior materials, systems and facades to alternative energy sources or electrification of infrastructure on-site. A recent study by the Fire Protection Research Foundation (FPRF) on the fire safety challenges of green buildings and attributes identified over 100 ‘green’ attributes that are being incorporated into modern building designs or sites.

‘Green’ building designs are fundamentally rooted in environmental, economic, and social sustainability, but aren’t necessarily focused on fire resiliency.   The FPRF study found that while fire hazards and risks of ‘green’ buildings and attributes have been addressed in many regards, fire safety is still considered relatively late in the design process. If it is considered, these efforts don’t always carry through to the operational phase of a building. And there are clear fire safety implications, as a result.

Over the last decade, there have been several major fire events, which involved ‘green’ building features or technologies, notably the Grenfell Tower fire in London (combustible insulation), the Dietz & Watson cold storage warehouse in Delanco, New Jersey (photovoltaic panels, combustible insulation), and a plethora of fires in buildings under construction using lightweight timber framing.  

These fire incidents indicate that the adoption of such systems can sometimes have unexpected consequences when safety considerations are not considered early in the development phase or where unexpected combinations of materials are used to create and install systems outside of the original specifications. Having fire safety take a back seat to other performance parameters in buildings is nothing new—fire safety often seems to be playing catch-up with developments occurring in the construction industry. Even when fire safety professionals are aware of a potential problem, a catastrophic incident often occurs before the issue starts to be addressed holistically. But this is no longer acceptable. Fire safety must move in lockstep with sustainability and be given due diligence up-front in the design process to avoid potential roadblocks in sustainable building.

Key fire safety challenges with emerging ‘green’ building trends are summarized below.

Structural Materials & Systems

In the 1980’s, the concept of lightweight construction materials was introduced as a green alternative to traditional building materials and a way to reduce consumption of raw materials. Since then, a vast array of materials and engineered solutions have been introduced, such as lightweight engineered lumber, fiber-reinforced polymer (RFP) elements, plastic lumber, bio-polymer lumber, bamboo, mass timber (e.g., cross laminated timber), among others. However, in comparison to traditional building materials, they present a heightened fire risk. They can contribute to the fuel load, burn readily once ignited, and increase the heat release rate. These lightweight structural materials and systems also introduce the potential for reduced time to failure, along with concerns of stability, flame spread, and adequate fire department access. Further, materials such as mass timber, e.g., CLT, can delaminate, further contributing to the fuel load and structural integrity issues. Additive manufacturing/3D printing technology has been applied to building applications where it is hoped that savings may be made in manufacturing costs or in building construction sustainability by reducing waste and material production emissions and life-safety at construction sites. However, it presents performance trade-offs when compared to traditional building materials, as it can fail more quickly, present stability issues and challenge egress and fire service response. For most of these materials and systems, utilizing approved or listed materials and incorporating fire resistive barriers where appropriate are significant steps in the direction of safety.

Exterior materials, systems, and façade features.

To facilitate energy conservation, green buildings often include interior or exterior insulation. Various types exist, such as fiber-reinforced polymer (FRP), rigid foam, spray-applied foam, structural integrated panels (SIP), or exterior insulation and finish systems (EIFS). These insulating materials are attractive from an energy conservation perspective as they are lightweight and composed of recycled plastics and have a high thermal resistance. However, if non-approved materials are used, adequate protection and barriers are not in place, or if the insulation materials are not properly constructed, some insulation materials can present a high fire risk if left unmitigated. This can result in fast fire spread, increased burn intensity and the generation of toxic products of combustion.

On February 9, 2009, a fire at China Central Television headquarters in Beijing demonstrated how nonapproved extruded plastic insulation panels behind curtain walls could fuel and quickly spread the blaze through the entire building. Data also shows that some metal class materials (MCM) used for exterior cladding has contributed to reduced fire safety in some cases, fueling the fire. The Grenfell tower fire in 2017 brought concern of combustible exterior walls and cladding systems to the forefront, as it prevented the egress of over 70 people.

It should also be noted that while the well-insulated nature of these structures is a clear attribute for energy efficiency, under fire conditions these structures also retain the heat from the fire, accelerating the time to reach flashover, further challenging fire service response. Standardized fire tests and adoption and enforcement of codes and standards can play an important role in helping ensure the use of appropriate materials and proper installation and arrangement of these systems.

Alternative Energy Systems

Photovoltaic (PV) systems are a commonly used green technology to generate electrical power, where the PV module can generate direct current from the sun’s energy and convert it into alternating current. However, PV systems can contribute to the fuel load, present an ignition and shock hazard. Research indicates some indication that for roof-mounted solar panels, the space between the roof and the installation can create flue-like conditions accelerating the spread of flame. In this case, the size of the space and angle of incline are important parameters to identify the fire risk.