Ke-An Chiang joined the Portland studio as an historic preservation summer intern, participating in the firm’s robust internship program that includes conducting an in-depth research project. Currently pursuing a Master of Science in Historic Preservation at University of Pennsylvania, Ke-An also received a Bachelor of Science in Architecture from National Cheng Kung University in Taipei. Read more from our 2024 internship cohort and all our past intern research projects here.
Introduction to Resilience
Resilience and sustainability are two buzzwords in the field of environmental science, each addressing different aspects of how buildings interact with the environment. While sustainability focuses on minimizing a building’s impact on the environment, resilience emphasizes the environment’s impact on the building, its occupants, and the surrounding community. Understanding the difference between these concepts is crucial for developing effective strategies to mitigate environmental impacts, particularly those related to wildfires.
Environmental Impacts: Shocks and Stresses
Environmental hazards can be categorized into shocks, such as wildfires, and stresses, such as prolonged droughts. These hazards follow a timeline that includes pre-hazard exposure and sensitivity assessments, probability and magnitude evaluations, hazard impacts, and recovery processes. For example, buildings in the wildland-urban interface (WUI) are particularly vulnerable to wildfires because of their proximity to forests and other wildland areas, limited fire-resistant landscaping, and mixed developed and undeveloped terrain.
Wildfire, Ecosystems, and Climate Change
Wildfires, while dangerous to humans, play a crucial role in ecosystems by returning nutrients to the soil and thinning forest canopies. However, the 20th-century strategy of complete wildfire suppression led to the accumulation of vegetative fuels, resulting in larger, more intense fires. Climate change exacerbates this issue by creating drier conditions and increasing the frequency of lightning strikes, which can ignite wildfires.
Wildfire Occurrence and Conditions
The risk of wildfires in the U.S. is influenced by the distribution of forests and the intensity of drought. Areas with dense forests and severe drought, such as Northern California and Southern Oregon, are particularly susceptible. The 2020 Almeda Fire in Southern Oregon’s Rogue Valley, driven by strong winds, exemplifies the destructive potential of wildfires, having caused extensive damage to homes and businesses.
Factors Contributing to Building Vulnerability and Mitigation Strategies
Buildings are vulnerable to wildfires due to their proximity to vegetation, steep slopes, and dense neighborhoods. Wind-blown embers, direct flame contact, and radiant heat are the primary reasons homes burn during wildfires. To mitigate these risks, creating defensible space, replacing combustible materials, and covering openings with metal screens are essential strategies.
Roof and Siding Materials
Roofs and siding materials play a significant role in a building’s vulnerability to wildfires. Class A roof materials — such as composite asphalt fiberglass, clay, and some metals — offer the best fire resistance. Siding materials, such as glass fiber-reinforced, graphite-infused polystyrene ((GP)2) and engineered wood, provide varying levels of protection. The choice of materials should balance fire resistance, sustainability, and cost-effectiveness.
These charts explore roof materials and their relative performance.
Application in Historic Buildings
Protecting historic buildings from wildfires poses unique challenges, as it involves replacing existing materials with non-combustible ones while maintaining historic integrity. Historic significance is determined by the original materials, which contribute to the building’s visual character and authenticity. Use of substitute materials must adhere to guidelines like those outlined in the NPS Preservation Brief 16, which allows for historically accurate yet fire-resistant replacements.
This chart explores considerations for replacement materials used in historic buildings.
Conclusion
Existing and historic buildings in forested areas or the WUI are highly susceptible to wildfires. Implementing resilience strategies involves evaluating vulnerability, selecting appropriate materials, and adhering to regulatory guidelines. The ultimate goal is to achieve a balance between preserving historic integrity and ensuring life safety.
Integrating wildfire resilience strategies into projects is essential. This involves developing a timeline, identifying necessary permits and approvals, and implementing a detailed maintenance plan during the post-occupancy phase. Additionally, engaging stakeholders in the conversation and developing education and outreach initiatives can effectively raise awareness, emphasizing enhanced safety, reduced risk, and potential cost savings. By doing so, we can ensure that historic and existing buildings are better protected against the increasing threat of wildfires.
Historic Preservation Internship Experience
During my internship, I gained invaluable experience and insights into existing and historic buildings. I had the opportunity to work alongside a dedicated team of professionals, contributing to various stages of research, project planning, and implementation. I learned many useful skills and knowledge, including modeling and drafting in Revit, efficient field measurement techniques, and understanding the project process through attending meetings. I am profoundly grateful to Hennebery Eddy for providing me with this learning opportunity and for the firm’s unwavering support and guidance throughout my internship. The skills and knowledge I have acquired will undoubtedly shape my future career in both the historic preservation and architecture field.
Research References
- AIA Resilience and Adaptation online certificate program.
- AIA Resilient Project Process Guide, 2022.
- Oregon State University Technical Guide: Mapping Wildfire Hazard to Structures and Other Human Development.
- National Interagency Coordination Center Wildland Fire Summary and Statistics Annual Report 2023.
- Frontline Wildfire Defense: How Homes Catch on Fire.
- The New York Times: Inside the Deadly Maui Inferno, Hour by Hour.
- Wildfire Home Retrofit Guide (readyforwildfire.org) (2020), University of Nevada, Reno.
- National Park Service Preservation Brief 16.