Sensors are Z-Wave devices, which transmit certain environmental values or certain behaviour to a wireless control centre. They also control other Z-Wave devices directly, using the association function of Z-Wave.   An example of such an association is the switching of a light with a motion detector.
Sensors are typically battery-powered devices. Depending on the radio transceiver utilization the units have a battery lifetime between one and three years. Particularly of interest are multi-sensors, where multiple sensor values such as temperature or humidity are made available from one device via Z-Wave.