This European standard describes a thermophysiological model (thermal human simulator) that uses the output data of the first part to obtain physiological heat load criteria that predicts the (maximal) duration of work in the protective clothing in fire fighters’ relevant conditions. NOTE The human simulator method using the Sweating Torso (i.e. coupling of the instrumented manikin with a thermo-physiological feedback model) is validated for different scenarios by comparison to human subject trials(1, 2). The scenarios also included warm and hot environments as can be expected for firefighter applications. Core temperature, being one of the most important physiological variables, and mean skin temperature, which is a useful indicator of thermal comfort sensation and of the overall condition of the body, are chosen as relevant physiological parameters for the thermophysiological human simulator.