The most common type of motion sensor used in home security is a passive infrared sensor, otherwise known as a PIR sensor. PIR sensors send out rays designed to detect heat. The sensor’s rays fan out, so they’re most concentrated right next to the sensor, and become less sensitive farther away from the sensor. The rays can’t detect heat through walls or furniture, so it’s important to place these sensors where the rays are clear of obstacles.

Occupancy sensors activate lighting once an occupant is identified. Once the occupant has left, the sensors automatically turn the light off. When leaving a room occupants can neglect to turn the lights off. This will end up costing you more and is hardly energy efficient. Occupancy sensors can resolve these issues. First developed for commercial applications, occupancy sensors have become increasingly prominent in domestic homes.

The principal advantages of employing occupancy sensors are :

Security

Energy Efficiency

Convenience

https://www.acelectricohio.com/benefits-of-having-motion-sensor-lights/