In solving problems of fire safety, it is often necessary to perform a series of calculations with different initial conditions: space-planning decisions, the parameters of operation of fire protection systems, and others. In such cases using FDS becomes difficult because each calculation requires significant time and computing resources. To solve this problem we have developed a program - FIM (Fire Integral (one-zone) Model). FIM implements calculation of the dynamics of fire hazards by using a one-zone integral model, using the input file format of FDS. If the building topology corresponds to the definition of the integral model, the FIM significantly speeds estimation, before launching into a lengthy calculation FDS. There is no need to create a new model of the building in any other format: the program reads the source FDS file, calculates the dynamics of the fire hazards and generates output files similar to FDS, which can be analyzed in programs like Smokeview, FireRisk and others. Limitations of FIM 1.0: • sealed room (no openings) are ignored in the calculation; • the material of walls is the concrete; • in ventilation ignored the task of certain types of gas (MASSFRACTION - mass fraction of the incoming gases); • ignored job control facilities (open/closed, on/off); • ignored the ventilation systems HVAC; • ignored complex parameters of combustion (the ignition of surfaces from high temperature, the effect of fire extinguishing systems, etc.). Output data are only the sensors and slices, measuring the following parameters: temperature, visibility, concentration of oxygen, carbon dioxide, carbon monoxide, hydrogen chloride. Other output data set in the file FDS is ignored.