A building automation server characterized by comprising: a memory for storing a database comprising a plurality of user accounts, wherein each user account includes an associated building location of a building, an associated geofence defined relative to the building location, and one or more group member ID's, wherein each of the one or more group member ID's is associated with a corresponding mobile device with location services, and each user account identifies a geofence status for each of the one or more group member ID's, where the geofence status indicates whether the corresponding mobile device for each of the one or more group member ID is within the geofence associated with the user account or outside of the geofence; a communication interface; a controller coupled to the memory and the communication interface, the controller configured to receive via the communication interface geofence crossing notifications issued by the mobile devices that correspond to the one or more group member ID's as those mobile devices cross the geofence that is associated with the user account; the controller is further configured to update the geofence status for each of one or more group member ID's in the memory using the geofence crossing notifications; the controller is further configured to recognize when the geofence status of all of the one or more group member ID's of a user account are outside of the geofence that is associated with the user account, and interprets the building that is associated with the user account as being unoccupied, and recognize when the geofence status of at least one of the one or more group member ID's of the user account is inside of the geofence that is associated with the user account, and interprets the building that is associated with the user account as occupied or soon be occupied; the controller is further configured to notify a building controller of the building associated with the user account via the communication interface that the building has become unoccupied when the controller interprets the building that is associated with the user account as being unoccupied; and the controller is further configured to notify the building controller of the building associated with the user account via the communication interface that the building has become occupied or will soon be occupied when the controller interprets the building that is associated with the user account as being occupied or soon to be occupied. a memory for storing a database comprising a plurality of user accounts, wherein each user account includes an associated building location of a building, an associated geofence defined relative to the building location, and one or more group member ID's, wherein each of the one or more group member ID's is associated with a corresponding mobile device with location services, and each user account identifies a geofence status for each of the one or more group member ID's, where the geofence status indicates whether the corresponding mobile device for each of the one or more group member ID is within the geofence associated with the user account or outside of the geofence; a communication interface; a controller coupled to the memory and the communication interface, the controller configured to receive via the communication interface geofence crossing notifications issued by the mobile devices that correspond to the one or more group member ID's as those mobile devices cross the geofence that is associated with the user account; the controller is further configured to update the geofence status for each of one or more group member ID's in the memory using the geofence crossing notifications; the controller is further configured to recognize when the geofence status of all of the one or more group member ID's of a user account are outside of the geofence that is associated with the user account, and interprets the building that is associated with the user account as being unoccupied, and recognize when the geofence status of at least one of the one or more group member ID's of the user account is inside of the geofence that is associated with the user account, and interprets the building that is associated with the user account as occupied or soon be occupied; the controller is further configured to notify a building controller of the building associated with the user account via the communication interface that the building has become unoccupied when the controller interprets the building that is associated with the user account as being unoccupied; and the controller is further configured to notify the building controller of the building associated with the user account via the communication interface that the building has become occupied or will soon be occupied when the controller interprets the building that is associated with the user account as being occupied or soon to be occupied.