A Systems Thinking and Graph-Theoretic approach to balancing fire safety and sustainability in building design

Fire Safety Engineering is challenged by the need to reconcile life-safety objectives with sustainability goals in building design. Sustainability-oriented measures that reduce embodied carbon and operational energy demand may also modify fire engineering characteristics, such as fire load, material combustibility, and operational complexity. Conventional fire safety methods do not readily diagnose the feedback architecture through which these interactions propagate. This study develops and applies an integrated framework combining Systems Thinking and Graph-Theoretic analysis to examine fire safety–sustainability interactions at the building design level. A Causal Loop Diagram is first developed based on fire safety literature to represent feedbacks linking design variables, fire protection measures, material choices, operational practices, governance responses, cost considerations, and sustainability indicators. The CLD is then formalized as a directed network, enabling multi-metric centrality analysis and composite structural role identification to evaluate the importance of the respective variables within the larger fire safety – sustainability network. The resulting network contains 63 nodes and 101 directed edges and forms a strongly connected but sparse causal architecture. Within the analyzed network, Fire Risk emerges as the dominant central variable, Required Fire Protection Level as the most stable robust Driver, Perceived Fire Safety Gap as the clearest robust Mediator, and Material Use as a robust Outcome where multiple pathways converge. An assessment of the robustness of the analysis supports the conclusions from the role-identification procedure, while showing that Driver and Outcome archetypes are recovered more reliably than Mediator archetypes. Overall, the framework can support earlier identification of structurally important pathways for project-specific fire safety, sustainability, and feasibility assessment.