This preliminary standard deals with the determination of the analytically required fire resistance time of the structural components of a fire compartment. It depends on the equivalent fire duration, a safety coefficient ? and an adjustment coefficient ?nb. This fire duration is determined from the evaluated fire load density, taking into account the ventilation conditions and the heat penetration behaviour of the surrounding structural components. The coeffcient ? likewise accounts for the location and size of the fire compartment and the function of the structural component. The coefficient ?nb allows sprinkler systems or factory fire brigade.