Investigation of Fire Safety Strategies of Buildings with BIPV External Walls

With the increasing emphasis on sustainable architecture and the integration of renewable energy technologies, Building-Integrated Photovoltaic (BIPV) curtain wall systems have emerged as a dual-function solution—delivering both energy generation and contemporary façade design. However, the growing use of combustible photovoltaic components in external wall assemblies has brought serious fire safety concerns to the forefront, particularly in high-rise urban settings where vertical flame spread can pose substantial risks to life and property. Despite these concerns, existing fire testing protocols and simulation tools remain limited in their capacity to accurately assess the fire performance of BIPV façades under realistic, site-specific conditions. This research seeks to address this critical gap by developing a validated, simulation-based methodology for evaluating the fire dynamics of BIPV curtain walls, with a particular emphasis on vertical flame spread, wind-driven fire behaviour, and the role of mitigation strategies. The study adopts a multi-phase methodological framework. It begins with a comprehensive literature review and empirical data collection, drawing from certified fire testing laboratories and photovoltaic manufacturers. Particular focus was placed on Single Burning Item (SBI) tests, which provided empirical heat release rate (HRR)–time curves and temperature–time data for real-world BIPV products. These datasets were then used to calibrate and validate a suite of numerical models built using the Fire Dynamics Simulator (FDS). Validation was conducted by comparing simulated temperature–time curves with experimental results, employing the Root Mean Square Deviation (RMSD) method as a quantitative measure of agreement. Where RMSD values fell within literature-defined thresholds, the simulation framework was deemed reliable and suitable for subsequent application. Following validation, two core case studies were developed. The first focused on vertical flame spread along a 5.7-metre-high BIPV façade segment informed by ISO 13785-2 guidelines. A burning panel at the base of the façade served as the ignition source, with heat flux measured at upper levels to assess the potential for secondary ignition. No mitigation measures were applied in this baseline configuration. The second case study employed a Sole Occupant Unit (SOU) model simulating a five-storey residential building. Real meteorological data—including annual wind speeds and prevailing wind directions—from Melbourne, Sydney, and Brisbane were incorporated, enabling analysis of wind-driven flame behaviour and the determination of minimum fire safety separation distances for BIPV installations across different urban climates. Mitigation strategies were then systematically assessed through comparative simulations. Passive measures—including spandrels of varying thickness and projection lengths—and active systems, such as both internal and external sprinkler configurations, were individually integrated into the validated models. Simulation outputs, including peak heat flux, ignition delay times, and temperature field suppression, demonstrated that external sprinklers offered the most immediate and effective suppression—particularly under high wind conditions. Among passive measures, a spandrel with 600 mm thickness and 600 mm vertical projection was found to offer the strongest containment effect, significantly reducing high-temperature zones and limiting flame spread to the floor of origin. These findings underscore the importance of adopting a hybrid mitigation strategy—combining passive and active systems—to achieve comprehensive façade fire risk reduction. This research contributes meaningfully to both theoretical and practical domains. The validated simulation framework presents a scalable, cost-efficient alternative to full-scale fire testing, offering a flexible platform for scenario-based analysis using intermediate-scale experimental data. From a design perspective, the study provides evidence-based recommendations for safely integrating BIPV panels into modern façade systems, particularly in wind-prone, high-density urban environments. It also highlights the pressing need for context-sensitive, performance-driven fire safety strategies that reflect the unique combustion behaviours of photovoltaic materials and the geometric complexity of contemporary building envelopes. Nonetheless, the study acknowledges several limitations. The current simulation tools lack native material definitions tailored to BIPV products, necessitating manual input and calibration. Wind and sprinkler behaviours were simulated under idealised conditions, which may not fully capture real-world variability. Furthermore, spandrel configurations were assessed using fixed geometries without accounting for architectural constraints or potential impacts on daylighting and aesthetics. While necessary for model control, these simplifications highlight the need for ongoing refinement and empirical validation. Future research is recommended in three key areas: (1) expanding the range of BIPV materials and system configurations examined; (2) integrating post-incident data from actual façade fires to enhance model realism; and (3) exploring the combined effects of spandrel material, sprinkler characteristics, and façade geometry under diverse ignition scenarios. Advancing research in these areas will support the development of more adaptable, regulation-compliant, and climate-responsive fire safety solutions for the next generation of photovoltaic-integrated buildings. In conclusion, this study establishes a robust foundation for applying numerical modelling to the fire safety evaluation of BIPV façades. It delivers a practical, scientifically grounded framework to assist architects, fire engineers, and regulatory bodies in balancing energy performance goals with the imperative of occupant safety in an increasingly complex and sustainability-driven built environment.