Green Technology Minimizes Energy Waste

BY NICOLE DIGIOSE   

An occupancy sensor does exactly what it sounds like it does. It senses whether or not an indoor space is occupied. Advanced occupancy sensors can even count the number of people in a given area.

Image via wattstopper.com

What's the Purpose?     

This green technology was created to minimize energy waste and enable serious savings. It's accomplished through HVAC (Heating, Ventilation, and Air Conditioning) control. Occupancy sensors are suitable when an indoor area is being occupied, and where lights and HVAC systems are usually left on when the space is no longer being used. This commonly happens in places like offices, classrooms, restrooms, warehouses, and hallways.

How Do They Work?   

There are three technologies that are used to detect occupancy: passive infrared, ultrasonic, and microsonic. Many systems use only one, and some use dual technology, combining two of them, which provides better performance.

The most common occupancy sensing technology is passive infrared, which is used in basic security sensors. A passive infrared sensor sends out invisible infrared beams that respond to differences in temperature. If no one is in range, the sensor doesn't respond. When something warm, like a person, crosses at least two beams, the sensor activates and responds to the temperature difference.

Microphonics is also used to detect occupancy. This type of sensor detects sounds typically made by human activity, such as talking, typing on a keyboard, even a squeaky computer chair. Microphonics sensors work best in large areas because they're able to cover lots of space.

High frequency ultrasound also recognizes occupants in a room. It works by sending out a high frequency sound wave that bounces around the space and returns to the sensor, much like a submarine's sonar.

Major subsystems include sensor devices, processing, and connectivity. For additional information, or to view Mouser's list of occupancy sensor products, including ambient light sensors, motion sensors, and processors, click here.