The task of fire safety is to prevent loss of life and health of persons and loss of property. It is mainly about creating conditions for safe evacuation from a burning or fire-endangered building, and preventing the spread of fire inside and outside the building and creating conditions for effective intervention of fire brigades. The construction part of the building must be dimensioned for the expected effects of fire. The focus of the development of PBS is the specification of expected effects of fires and determination of optimal fire prevention measures, which includes: fire prevention, fire risk of fully developed fire, dimensioning of building components and construction systems for expected thermal stress, optimization of fire protection measures, spread of combustion products in object, movement of persons during evacuation, conditions of fire spread outside the building object, intervention routes and conditions of effective fire intervention.