A method of synchronizing includes providing a sensor network including sensor nodes having object recognition sensors (ORS's) and building automation network nodes. The ORS's have partially overlapping fields of view in a sensed overlap area in the building. Movement of an individual through the sensed overlap area triggers dynamic synchronizing with the first sensor node waking up and sending a first RF request to join a subnet and for a schedule of wakeup times, the first sensor node receiving a response from any sensor node that receives the first request including synchronization information having times the first sensor node should wake up. The second sensor node is activated by the individual's movement and sends a second RF message to join the subnet and for a schedule of wakeup times. The first sensor node receives the second RF message and in response sends the synchronization information to the second sensor node.