Patent ID: 7894942

Claim:
A method for a controller to control one or more devices associated with a monitored space, said method comprising: defining a plurality of states of the controller controlling a controlled device associated with the monitored space; at an initial state, receiving an event indicating a possible presence of a subject within the monitored space; changing from the initial state in which the controlled device is de-energized to a first state in which the controlled device is energized and in response to the received event, said first state indicating that the subject can provisionally be in the monitored space; while in the first state: initiating an event timer set to expire after a first delay; resetting the event timer in response to receiving a signal indicating a detection of one or more additional events before the expiration of the event timer; upon expiration of the event timer, issuing a query challenge and changing from the first state to a second state; and while in the second state: responsive to the issued query challenge, detecting a query response signal; responsive to the query response signal, changing from the second state to the first state and resetting the event timer when the query response signal represents an event that indicates the subject may still provisionally be in the monitored space; responsive to the query response signal, changing from the second state to a third state and disabling the event timer when the query response signal represents an event corresponding to an occupant action by the subject, said third state indicating that the subject is in the monitored space; and changing from the second state to the initial state in which the controlled device is de-energized when the subject fails to respond to the query challenge.