This Technical Specification describes a methodology for the selection of design fire scenarios and design fires that are credible but conservative for use in deterministic fire safety engineering analyses of any built environment including buildings, structures or transportation vehicles. The selection of design fire scenarios is tailored to the fire-safety design objectives, and accounts for the likelihood and consequences of potential scenarios. The selection of design fires is also tailored to the fire-safety objectives and to ensuring credible but severe fire exposure conditions. While this Technical Specification provides more operational information on the selection of design fire scenarios and design fires than ISO/TR 13387-2[20], it is not intended to replace ISO/TR 13387-2 within the self-consistent set of parts making up ISO/TR 13387.