The aim of this project is to build a framework to enhance the resilience of built environments at the WUI by establishing a cohesive approach congruent with extreme hazardous wildfires in the United States leading to a new standard for protecting the habitats at the WUI. In response to destructive wildfires threatening the WUI, protective action for residents is generally limited to two options of evacuation or an alternative which is shelter-in-place. Evacuations are essentially deemed as a standard protective solution by officials in the U.S., Canada, and Australia. However, the operational standards have limitations in comprehensively pinpointing the evacuation plan of action during post fire events. Hence, we propose to build our strategy for advanced shelter design and tenability by implementing modeling to meet the operational requirements set forth by national USFA/NIST led evacuation messaging and standardization campaign, which is missing in the current standards for future wildfires in the US and specifically in California. This strategy should incorporate new standards that cover the full spectrum of operational needs associated with the severest consequences of wildfires throughout the United States, with a focused emphasis on the particularly intense wildfire scenarios in California.
Figure. Project Concept and Scope
Our team will take an integrated methodology by incorporating an ensemble of: (1) current standards, and national requirements, which are set forth by fire officials and first responders, and (2) available experimental data WUI fire scenarios in the literature for modeling and validation of fire scenarios across varying levels of exposure and parameters that employs both HMM and FPE principles to balance between the fire exposure and hardening of structures and parcels. We propose to incorporate WUI Fire model over built environments using Wildland Urban Interface Fire Dynamics Simulator (WFDS), and to validate its capacity to correctly simulate the real scenarios by comparing with the available experimental databases.
This endeavor aims to culminate in the establishment of a unified standard for shelter design for which we propose to take three steps towards this goal. These stages were described as (1) data integration and classification, (2) design, and (3) modeling and validation. A fourth step is also introduced for the future of this research leading to developing a cohesive standard which is demonstrated as stage four in Figure 3.
Stage 1: Data Integration and Classification
Information about different WUI fire scenarios is a necessity to build the framework of design and modeling process. The fire data to build the exposure scenarios for WUI fires is accessible through the research data available in the literature together with sparse but accurate measures from wildfires and WUI fire databases. Investigating the availability of these two sources of data needs to be integrated to account for different exposure scenarios required to mitigate the risk of WUI fires. The data is classified into two aspects of quantitative and qualitative based on fire, building, and environmental conditions out such as exposure duration, fire intensity (Heat Release Rate (HRR), Fire Line Intensity (FLI), heat flux), fire regime, exposure mechanism (flame contact, radiation, firebrands), temperature, environmental conditions, topography, material properties at the parcel level and wildland, and emission factors (CO2, CO, PM2.5). The primary objective of this phase involves the development of a database capable of accommodating updates derived from new wildfire data, essential for formulating the definitive fire exposure scenario requisite for establishing a standard. This stage is essential for the progress of the project for future validation cases as described in Figure below.
Stage 2: Design
The goal of this stage of the proposal is to develop an optimal and cohesive shelter design to be implemented as the case study for standard development. The integrated database in stage one would contribute an essential role developing realistic exposure scenarios to be utilized by our proposed tierd-based system. This system constitutes a formulation structured around three tiers, delineated according to the exposure scenario chosen from the database, aimed at facilitating the development and standardization of fire shelters:
Tier 1 Fire Shelters (Short Duration): Designed for immediate and short-term (6-9 hours) protection from fire and firebrands. These shelters will be hardened structures within parcels following the methodologies set forth by HMM and FPE in regards to the tenability criteria, potentially requiring collaboration with neighboring property owners for mitigation of external exposures. Ventilation is not a requirement, but smoke ingress prevention measures are necessary. Power needs are limited to battery-powered lighting. Sanitation may be addressed through mobile systems.
Tier 2 Fire Shelters (Intermediate Duration): Designated for critical infrastructure facilities such as the emergency response centers. These shelters will provide clean air ventilation (not hospital grade) and supporting power for up to 48 hours, with infrastructure capable of extending occupancy to 7 days. Sanitation can be handled through mobile systems. Hardening of communication systems, including secure lines and broadcasting equipment, is crucial. Smoke-proof door systems are essential.
Tier 3 Fire Shelters (Long Duration): Developed for critical infrastructure requiring extended operation during wildfires, such as hospitals and nursing homes. These shelters will offer long-term occupancy (3 days, expandable to 30 days with resupply) with built-in ventilation for very clean air (hospital grade), power, water, and sanitation systems. Smoke-proof door systems are mandatory.
Figure. Technical stages of the project
Each tier demonstrates realistic scenarios which uses a range of exposure scenarios required to establish the framework of the optimal shelter design. The final design is then being utilized in the next stage of the research for modeling, however, it serves as a robust draft to be interactively modified depending on the modeling results in cases of improvements to match final goal of the standard. The design stage is capable of being modified for any future reported fire hazard at the WUI to be compatible with the latest databases available in the United States.
Stage 3: Modeling and Validation
In this stage of the project, we aim to test our tier-based shelter design using the exposure scenarios corresponding to each tier by adjusting the fire hazard for desired outcome leading to the standard development. We propose to use NIST’s Wildland-Urban Interface Fire Dynamics Simulator (WFDS) for the modeling of the WUI scenarios which demonstrated a useful tool for WUI fires. WFDS will be used with the prescribed environmental conditions (wind speed, direction, humidity, and temperature) in the vicinity of fire. Further, accurate emission yields (CO, CO2 and soot) for different wildland fuels will be adapted from the literature to simulate the emissions from fire.. This enhances our understanding of how the fire is being developed and spread through the shelter with the conditions described for each tier at the time of the incident. The fire scenario and the exposure parameters will be varied to infleuence the desired results from the model. The simulation boundary conditions are dependent upon the choice of fire scenario to be changed based on the tier type in which all the environmental, as well as fire exposure conditions were considered.
These simulations will be performed using WPI’s state-of-the-art computational resources consisting of a High-Performance Computing (HPC) capability comprised of 1,736 CPU cores and 64 GPUs spread across 56 compute nodes. The peak performance rating of the system is well over 100 teraflops. The cluster is managed using the Bright Cluster Manager software in conjunction with the Slurm batch manager. In addition to the hardware listed, and the standard HPC software stack (MPI, OpenMP, CUDA, PETSc, Lapack, etc.), the HPC user community also has access to software development training and support, including parallelization and porting of scientific code to new platforms, and information on current and new approaches to parallel code development.
The simulations will be accompanied by a comrehensive validation process in which the database in the first is being used for validation of the model depending on the availability of the data in the literature. In cases where the data is unavailable to validate the scenario, future experiments will be conducted to address the requirements of validation process. These experiments can be conducted at the large-scake testing facility of Fire Protection Engineering Department at WPI that has a 190-square-meter floor space and a 9.2-meter-high ceiling. It features a 6-meter by 6-meter exhaust hood positioned 6 meters above the floor, ideal for testing different types of fires like open burning and compartment fires.
Future stage: Standard Development
The roadmap demonstrated in Figure 3, leads to the final goal of this work which will be the standard development. Following the completion of data integration, classification, design, and modeling/validation phases. This stage represents the culmination of the research efforts, aiming to establish a unified standard for shelter design in Wildland-Urban Interface (WUI) areas. The tier-based system will be the framework for a standard to capable of being implemented in any specific WUI fire hazard scenario for sheltering within the range of thirty days post fire event. The standard will address the performance expectations for ventilation, power, water, and sanitation systems within each shelter type.
The standard aims to address the full spectrum of operational needs associated with severe wildfire events. This includes ventilation, power, water, and sanitation systems within each shelter type, ensuring long-term habitability and functionality. The proposed standard will undergo validation processes to ensure its efficacy and applicability in real-world scenarios. External experts, fire managers, and decision-makers will assess the credibility, feasibility, and versatility of the standard with respect to the requirements in California and other States facing the WUI fire hazard. A recursive loop of improvement is applied at the final stage of standard development ensuring the proper revisions for accurate definition of the framework for the shelter design. It will improve the safety and well-being of residents and critical infrastructure personnel in WUI zones.