Various embodiments of wireless ambient sensor unit are presented. The sensor unit may include a wireless transceiver configured to transmit sensor data and to receive instructions. The sensor unit may include a sensor configured to measure an ambient condition. The sensor unit may include a controller in communication with the wireless transceiver and the sensor. The controller may be configured to compare data measured about the ambient condition to a stored threshold while the wireless ambient sensor unit is functioning in a low-power mode. The controller may be configured to exit the low-power mode in response to the comparison of the data with the stored threshold. The controller may be configured to cause the data measured about the ambient condition to be transmitted by the wireless transceiver as one or more messages in response to the comparison to the stored threshold.