The push for a greener planet has transformed the construction industry. Innovative materials like mass timber, recycled plastic bricks, green "living" walls, and energy-efficient claddings are being used to build the spaces we live and work in today. But as we embrace sustainability, a critical question emerges: Are these new materials fire-safe?
This was one of the questions posed in the GCI Resilience & Sustainability Working Group’s 2023 white paper. As such, the SFPE Foundation decided to fund research that might answer it.
The outcome of this research funding is a new report titled Fire Testing of Resilient and Sustainable Building Materials, by Richard Walls, Miss Hasimawaty Mat Kiah, and Natalia Flores-Quiroz of Stellenbosch University, Yohannes Shewalul of the University of Waterloo, and Carlo Kuhn of Ignis Fire Testing. Their report dives deep into this question, providing essential guidance for engineers, regulators, and builders. The report’s central finding is also a warning: the fire tests we have relied on for decades were not designed for these novel materials, and they may not be catching critical safety risks.
The Challenge: Old Tests, New Materials
For over a century, fire testing has provided a standardized way to compare how building products stand up to flames. These tests, however, were developed primarily for traditional, non-combustible materials like concrete and steel. The new generation of sustainable materials, often biomass-based or synthetic, can behave very differently in a fire.
The report highlights several overarching needs to address this gap:
- Existing tests are often unsuitable. They can fail to measure a material's own contribution to the fire, overlook hazards like toxic smoke and smoldering, and misrepresent the performance of modern composite materials.
- Material databases must be expanded. As new products enter the market, we need reliable test data to assess their fire risk properly.
- Engineering expertise is more critical than ever. With increasing material complexity, skilled engineering and Performance-Based Design (PBD) are crucial for mitigating fire risks in innovative structures.
A Look at the Materials
The report provides a state-of-the-art analysis of key material categories, evaluating their fire performance.
- Biomass-Based Products: Materials like mass timber, bamboo, hempcrete, and cork are inherently combustible. While thin, fibrous products can burn readily, thicker systems like mass timber or biomass mixed into a cementitious matrix (like hempcrete) can achieve good fire resistance. However, they can increase a fire's fuel load and may smolder for hours after flames are extinguished.
- Low/Non-Combustible Materials: This category includes "green" steel and aluminum (produced with renewable energy), adobe, and various types of concrete made with recycled content. While generally performing well in a fire, the report notes that their specific composition and geometry matter. For example, 3D-printed concrete may be susceptible to cracking when heated.
- Synthetic-Based Products: This group, which includes recycled plastic bricks, crumb rubber aggregates, and aluminum composite panels (ACPs), presents the greatest potential fire hazard. These materials often have high calorific values and can produce large quantities of toxic smoke when they burn. The tragic 2017 Grenfell Tower fire, which was significantly affected by combustible ACP cladding, serves as a stark reminder of the risks involved.
Where Do We Go from Here?
The transition to sustainable construction presents a fire safety challenge because current testing standards are not fully equipped to evaluate the novel materials being introduced. The report concludes with several key recommendations:
- Quantify the Hazard: Fire resistance tests should be updated to measure the energy a combustible material adds to a fire, not just how long it survives. Furthermore, the production of smoke and its toxicity must be more explicitly assessed.
- Address Smoldering: For biomass materials like timber, the risk of smoldering—a slow, flameless burning that can persist for days and lead to structural collapse—is not adequately addressed by current tests and requires further research.
- Test Systems, Not Just Components: The fire performance of a material can change drastically based on how it is installed. This is especially true for façades and photovoltaic (PV) systems, where there is an urgent need for more large-scale data on how entire systems perform, including the impact of aging.
- Invest in Competency: Safe buildings ultimately depend on the technical competency of fire safety professionals, engineers, and installers, combined with strong regulatory enforcement. As materials become more complex, we cannot rely on a simple pass/fail test; we need experts who understand the limitations of test data and can apply it correctly.
Ultimately, the goal is to create a "Sustainable and Fire Resilient Built Environment". This report provides a foundational guide for the industry, pushing for a proactive approach to fire safety—updating our standards and knowledge before a disaster forces our hand. By doing so, we can ensure that the sustainable buildings of the future are also safe.
Read the full report at the SFPE Open Library. And join us for a webinar with lead author Richard Walls on November 20, 2025.