Method for operating a system for controlling access to a restricted access zone in a building or on a site, wherein the system comprises a transmitting and receiving device for radio communication with mobile electronic devices carried by users, a storage device (26, 28), and an image processing device (16, 22, 24) which has a camera located at the entrance to the restricted access zone, wherein the method comprises: receiving, by the transmitting and receiving device, a device-specific identifier of a mobile electronic device of a user and an electronic reference template, transmitted by the mobile electronic device, for facial parameters of the user as soon as the mobile electronic device is within radio range of the transmitting and receiving device in a public zone from which the user can request access to the restricted access zone; storing the received identifier of the mobile electronic device and of the electronic reference template in the storage device (26, 28) as a data set belonging to a user present, wherein a plurality of data sets relating to users present can be stored in the storage device (26, 28) in order to store, for each user present, in the data set belonging to the user present, the identifier of the mobile electronic device assigned to the user present and the reference template of the user present, wherein the data set belonging to a user present is deleted and the storage device (26, 28) is updated as soon as this user present leaves the public zone and their mobile electronic device is outside the radio range of the transmitting and receiving device; generating a real-time template for facial features of the user as soon as the user requests access to the restricted access zone and comes into a detection range of the camera located at the entrance to the restricted access zone, wherein the real-time template is generated from an image of the user by the image processing device (16, 22, 24); determining whether the real-time template matches a reference template stored in the storage device (26, 28) to a specified degree, wherein, if there is a match, the user is recognized as the user requesting access; and generating a result signal which, if there is a match, prompts a building action to be carried out, wherein a control signal is generated depending on the result signal in order to prompt reading of a user profile, stored in the storage device (26, 28), of the user requesting access in order to determine a user-specific building action. receiving, by the transmitting and receiving device, a device-specific identifier of a mobile electronic device of a user and an electronic reference template, transmitted by the mobile electronic device, for facial parameters of the user as soon as the mobile electronic device is within radio range of the transmitting and receiving device in a public zone from which the user can request access to the restricted access zone; storing the received identifier of the mobile electronic device and of the electronic reference template in the storage device (26, 28) as a data set belonging to a user present, wherein a plurality of data sets relating to users present can be stored in the storage device (26, 28) in order to store, for each user present, in the data set belonging to the user present, the identifier of the mobile electronic device assigned to the user present and the reference template of the user present, wherein the data set belonging to a user present is deleted and the storage device (26, 28) is updated as soon as this user present leaves the public zone and their mobile electronic device is outside the radio range of the transmitting and receiving device; generating a real-time template for facial features of the user as soon as the user requests access to the restricted access zone and comes into a detection range of the camera located at the entrance to the restricted access zone, wherein the real-time template is generated from an image of the user by the image processing device (16, 22, 24); determining whether the real-time template matches a reference template stored in the storage device (26, 28) to a specified degree, wherein, if there is a match, the user is recognized as the user requesting access; and generating a result signal which, if there is a match, prompts a building action to be carried out, wherein a control signal is generated depending on the result signal in order to prompt reading of a user profile, stored in the storage device (26, 28), of the user requesting access in order to determine a user-specific building action.