A method and a system evaluate a security situation in a building. The building has accommodation areas with access authorization for authorized persons. A count of the persons present in the accommodation areas is determined in that, in a radio network which contains a plurality of radio stations arranged spatially distributed in the ceiling, wall or floor, the influencing of the radio field of the radio stations between one another by persons physically present there is evaluated, by a radio tomographic location and detection method. A current count of identifiers which are read by RFID reading devices of RFID transponders is determined, the identifiers being carried by authorized persons. The RFID reading devices are arranged there spatially distributed in the ceiling, wall or floor. Based on the respective counts of personal identifiers and the determined person count, an indicator for evaluating the current security situation in the building is determined.