How International Organization for Standardization Intends to Address Low Carbon Energy Specificities for Reliability Modeling and Safety System Calculation

Abstract Safety systems are essential for preventing hazardous events in industrial installations. To evaluate their performance, ISO/TR 12489:2013 provides comprehensive guidance on probabilistic calculations and reliability modeling for safety-related systems, complementing IEC functional safety standards. This technical report consolidates decades of research and international expertise, offering a decision-oriented framework for selecting appropriate modeling techniques, from analytical formulas to advanced dynamic methods such as Markov models and Petri nets, while considering operational and maintenance constraints. This paper presents the ISO/TR 12489 framework and demonstrates its application to hydrogen safety systems, a key component of low-carbon energy strategies. A case study illustrates how robust reliability data, standardized failure classifications, and probabilistic methods enable to calculate accurate performance indicators, avoiding overly conservative estimates from simplified formulas. By bridging theory and practice through certified software tools, this work supports reliability, safety, instrumentation, and automation engineers in ensuring the integrity of critical safety barriers across both traditional and emerging energy domains.