Mounting means with a sensor for determining the humidity and incipient fogging in a compartment

Sensor device for determining the humidity or dew point of an interior space defined by a wall, especially a passenger compartment (3) of a motor vehicle, and the fogging tendency of an inner surface of the wall, especially a window pane (5) of a passenger compartment, comprises a dew point sensor (10) with a humidity sensor element (1) and a temperature sensor (2), and a surface temperature sensor (4). The dew point sensor measures the humidity and room temperature of the interior space and the surface temperature sensor measures the temperature of the inner surface. An independent claim is also included for a fixing device with the above sensor device in the form of a base (13) of a rearview mirror (14).