ISO/TS 16733-2:2026

Overview

ISO/TS 16733-2:2026 specifies best practices for defining design fires in fire safety engineering analyses of buildings and structures in the built environment. As part of the broader ISO fire safety engineering (FSE) framework, this Technical Specification provides essential guidance for specifying the quantitative fire characteristics needed for performance-based fire safety analysis.

A design fire is a conceptual fire model describing critical parameters (such as heat release rate, fire growth, and byproducts) for a selected scenario. These parameters serve as engineered representations-sometimes called “fire loads”-to determine consequences of fire in line with specific safety objectives such as life safety, property protection, and environmental conservation.

Key Topics

• Role of Design Fires in FSE: The design fire is central in analyzing how a building responds to fire, impacting occupant safety, structural integrity, and containment systems. Correctly specified design fires ensure that modeling and mitigation strategies are realistic and effective.
• Design Fire Characteristics: The document covers the main features of a design fire, including incipient, growth, flashover, fully developed, and decay stages, as well as factors that can modify fire development (ventilation, suppression, intervention, enclosure effects, and fuel properties).
• Heat Release Rate (HRR): The most important parameter for engineering analysis, HRR curves represent the time-varying energy output of a fire. ISO/TS 16733-2 details different methods to estimate HRR-for example, from first principles, composite item models, or empirical curves for common occupancies.
• Methods of Analysis: The standard accommodates diverse analytical approaches, from computational fluid dynamics (CFD) and zone fire models to parametric fires and hand calculations. It encourages practitioners to match model complexity, data input, and scenario details to project needs.
• Probabilistic Aspects: Recognizes the variability and uncertainty in fire development. Guidance is provided for integrating probabilistic methods (e.g., Monte Carlo simulation) into fire consequence analysis when required.

Applications

ISO/TS 16733-2:2026 is applicable for:

• Performance-Based Fire Safety Design: Essential for consulting engineers and architects employing risk-informed approaches to demonstrate code compliance or optimize fire safety beyond prescriptive measures.
• Fire Safety Assessments & Audits: Helps safety professionals conduct thorough evaluations, identifying risk and validating the adequacy of existing protections.
• New and Existing Building Analysis: Applied to the design of new projects or assessment and retrofit of legacy structures, ensuring that the defined design fire matches the expected use and occupancy.
• Evaluation of Fire Protection Systems: Supports the design and verification of fire suppression, smoke control, and fire-resistant structures-providing the input data necessary for system sizing and stress tests.
• Support for Regulatory Compliance: Enables local authorities, insurers, and facility managers to assess whether design fires used in computational analyses meet the required technical rigor and regulatory expectations.

Related Standards

For a comprehensive approach to fire safety engineering, ISO/TS 16733-2:2026 should be used in conjunction with:

• ISO 16733-1 – Selection of design fire scenarios
• ISO 23932-1 – General principles for performance-based fire safety design
• ISO 13943 – Fire safety vocabulary
• ISO/TS 29761 – Behavioral scenarios in fire safety engineering
• Additional supporting standards and technical reports on fire modeling, testing, and risk analysis as referenced within the specification

Practical Value

Utilizing ISO/TS 16733-2:2026 ensures that fire safety engineering in the built environment is robust, evidence-based, and tailored to the hazards present. By supporting consistent specification of design fires, it enables meaningful analysis, effective system design, and credible demonstration of fire safety objectives. This standard is a key resource for all stakeholders engaged in the development, review, and validation of fire safety strategies using performance-based methods.

Keywords: fire safety engineering, design fire, fire scenarios, performance-based design, heat release rate, fire modeling, built environment, ISO fire standard, risk analysis, fire suppression, fire system testing.