Dual mode system for detecting occupancy of a room

A method for detecting occupancy in a room, comprising:

• operating an infrared sensor to detect a presence of a person in the room, wherein the operation of the infrared sensor draws a first power level from a battery;
• receiving, by a processor, a signal from the infrared sensor detecting movement in the room;
• determining, by the processor, whether a first threshold duration has passed since a most recent signal from the infrared sensor detecting movement in the room has been received;
• triggering, by the processor, operation of a RADAR based sensor based on the first threshold duration having passed since the most recent signal from the infrared sensor detecting movement in the room was received, wherein operation of the RADAR based sensor draws a second power level from the battery that is substantially higher than the first power level;
• determining, by the processor, whether the RADAR based sensor detects a presence of one or more persons in the room or an absence of persons in the room;
• in response to the RADAR based sensor detecting the presence of one or more persons in the room or the absence of persons in the room, changing operation of the RADAR based sensor into a sleep mode, wherein the sleep mode draws less power than the first power level and substantially less power than the second power level;
• and
• operating the infrared sensor again to detect movement in the room, drawing the first power level from the battery.