Fire shelters serve as a crucial safety measure for those trapped in wildfire zones, yet the existing strategies in Wildland-Urban Interface (WUI) zones are plagued by significant deficiencies. These limitations compromise the effectiveness of fire shelters in safeguarding residents and vital infrastructure during wildfires. A critical issue is the absence of a standardized approach that integrates a cohesive plan for evacuation messaging, or shelter-in-place strategies tailored to the specific needs determined by decision-makers during WUI fire incidents. This gap increases the vulnerability to wildfire hazards, emphasizing the urgent need for a more unified and effective response framework. A significant flaw in current fire shelter strategies is the inconsistency in designs and capabilities across different models. This lack of standardization complicates the evaluation of fire shelter effectiveness, as the substantial variations in design and functionality make it challenging to accurately compare and assess their protective qualities. This inconsistency necessitates the development of a standardized approach to ensure that all fire shelters meet uniform safety and performance criteria.  

Additionally, the complexity of protecting buildings in the Wildland-Urban Interface (WUI) is exacerbated by the high density of structures in populated areas and the presence of uncontrollable external fuels [18, 34]. Fire shelters that are built with insufficient fireproofing materials or that lack adequate ventilation systems may fail to offer adequate protection during wildfire. This inconsistency in shelter quality and capability fosters uncertainty and diminishes public trust in the effectiveness of fire shelters as a reliable measure for wildfire protection. 

The prevailing approach to fire shelter design predominantly concentrates on providing immediate, short-term protection against flames and embers, neglecting the crucial aspect of long-term habitability in critical infrastructure settings. Most shelters are designed to offer basic protection for a limited time, often lacking essential features for prolonged stays such as adequate ventilation or sanitation systems. This oversight presents a significant challenge in critical facilities like hospitals and nursing homes, where occupants may need to shelter for several days during a wildfire. The absence of features that support long-term habitability in fire shelters reveals a critical gap in WUI fire preparedness for essential services, potentially compromising the health and safety of vulnerable groups. 

Moreover, the vulnerability of critical infrastructure to wildfires continues to be a pressing concern. Many of these facilities lack robust fire-hardening measures, such as fire-resistant building materials and protection for communication systems, which are essential for maintaining operational capabilities during wildfire events. Additionally, the absence of a standardized classification for materials used in WUI structures, coupled with a lack of a comprehensive inventory database detailing their fire vulnerability parameters, further diminishes the resilience of these facilities against wildfires. 

Given these challenges, the existing standards and approaches to fire shelters in WUI zones fall short in several key areas, including the lack of standardization in design and capabilities. As a result, there is an urgent need for a standardized, tiered system for fire shelters that categorizes them based on their duration of use and addresses these deficiencies. Such a system is vital for enhancing comprehensive WUI fire protection and bolstering community resilience against wildfires.