Sensor

Types of occupancy sensors include:

• Passive infrared sensor, which works on heat movement detection. Inside of device is a pyroelectric sensor calibrated to detect infrared radiation radiated by human body movement. Based on the detection, the sensor operates and starts lighting load connected to it.
• Ultrasonic sensor, similar to radar. It works on the doppler shift principle. An ultrasonic sensor will send high frequency sound waves in area and will check for their reflected patterns. If the reflected pattern is changing continuously then it assumes that there is occupancy and the lighting load connected is turned on. If the reflected pattern is the same for a preset time then the sensor assumes there is no occupancy and the load is switched off.
• Microwave sensor similar to the ultrasonic sensor , a microwave sensor also works on the doppler shift principle. A microwave sensor will send high frequency microwaves in an area and will check for their reflected patterns. If the reflected pattern is changing continuously then it assumes that there is occupancy and the lighting load connected is turned on. If the reflected pattern is the same for a preset time then the sensor assumes there is no occupancy and the load is switched off. A microwave sensor has high sensitivity as well as detection range compared to other types of sensors.
• Key-card, a hotel energy management system used to detect when a hotel room is occupied, by requiring the guest to place their key in a slot to turn on the lights and HVAC.
• Door operated switch.
• Audio detection.