A method for exchange of data between a mobile communications unit carried by a user and at least one of a first communications unit, a second communications unit and a computer unit positioned at different locations in an environment such as a building. When the first communications unit and the mobile communications unit are spaced at a predetermined distance, a near-field radio connection is generated within this distance. After data exchange between the mobile communications unit and the first communications unit, the data are communicated by the first communications unit to the computer unit. When the second communications unit and the mobile communications unit are spaced from one another at the predetermined distance, a near-field radio connection is generated within this distance. A data exchange takes place between the mobile communications unit and the second communications unit by the near-field radio connection.