A building system comprises a camera system and an image processing device, which generates a real-time face template for facial features of the user from a camera capture of a user when the user is in a building zone. A control and processing device searches a storage device for a reference face template that matches the real-time face template to a specified degree, wherein the user is a registered user if there is a match. A bidirectional communication channel for private communication between the building system and a mobile phone of the user is determined from the user profile of the user.