Showtime for Occupancy Sensors

Contractoors who set their sights on adding sensors and detectors to their installation base will find it a wise move, one that will serve them well in the future.

Occupancy sensors are a perfect example of a product whose time has come. The sensors could include passive infrared (PIR), ultrasonic or, sometimes, combination configurations. The units resemble those devices used to detect intruders at the protected premises; that’s where they got their start. In occupancy sensor applications, they are generally wired to control the heating, ventilation and air-conditioning or, more commonly, a building’s lighting. After all, lighting continues to consume the bulk of a facility’s energy demands, and codes and standards may now mandate their use.

According to Green Seal, a nonprofit that provides science-based environmental certification standards, lighting accounts for 30 to 50 percent of a building’s energy use and about 17 percent of the total annual energy use in the United States. Turning lights off when not needed, according to Green Seal, can result in reducing direct energy consumption by as much as 45 per-cent. Those stats alone point to the importance of integrating these types of devices in a building’s energy-saving scheme.

The sensing technology of passive infrared detectors is based on the heat emitted within their field of view. Some PIR occu-pancy sensors are mounted like light switches and replace this electrical component altogether. In an eating establishment rest-room, for example, the sensor can switch on the lights when someone enters and turn them off after a specified amount of time or when that heat is no longer in the field of view, meaning the occupants have left. Ultrasonic sensors send out sound wave pat-terns to read the reflection of a person within the space of a room. The sensors detect minor motion and may be even more ap-propriate for spaces where you don’t want lights turned off prematurely.

Many faces of occupancy sensors

Dual-technology occupancy sensors use both passive infrared and ultrasonic to minimize the risk of false triggering (lights com-ing on when the space is unoccupied).

Some sensors can be used in conjunction with dimming controls. This keeps the lights from turning completely off; instead, these lessen the amount of illumination. It helps reduce both the lighting load and energy consumption. In these situations, the lights can be dimmed to a predetermined level when the space is unoccupied. Occupancy sensors also can be used with ballast-based lighting systems, but the type of switching it uses, such as instant-start or preheated, must be considered, as this has a direct effect on the longevity of the lighting.

“Occupancy sensors have become an integral component of a comprehensive lighting control system,” said Tom Leonard, di-rector of marketing and product management for Leviton Lighting Management Systems in Tualatin, Ore. “Occupancy sensors have moved from being ‘forward-thinking’ devices to a core part of a building construction project.” Leonard added that today’s modern occupancy sensors use the latest in digital circuitry and provide “install-and-forget” performance.

“The devices have auto-adapting features to match the requirements of the facility,” he said.

There are many unusual niche and other applications for occupancy sensors. In two Wal-Mart stores near Bentonville, Ark., light-emitting diode (LED) lighting and occupancy sensors were used in the refrigerated cases in fall 2006. The test resulted in energy savings so significant that the retailer decided to expand the trial to hundreds of stores in 2007. According to an article in Chain Store Age, October 2007, motion sensors from Watt Stopper/Legrand, Santa Clara, Calif., were used to sense motion in store aisles and activate the case lights when a shopper approached. When the customer would leave, the lights would turn off. LEDs, according to the article, can be switched on and off without any loss of life expectancy.

The New York Power Authority (NYPA) recently installed a digital dimming advanced lighting control to save energy in several areas of its main administrative office building in White Plains, N.Y. NYPA wanted to reduce energy consumption in specific con-ference rooms and offices, and the results were impressive.

The demonstration began in May 2005 and ran through November 2006. It included conference rooms with different configura-tions and several offices on two floors of the NYPA building. Along with dimming ballasts and controls, occupancy sensors were used in all areas to ensure lights would automatically switch off when a room was not in use.

NYPA estimates energy savings from its systems with dimming alone to reduce power consumption by 20 percent, and the occupancy sensors are expected to reduce electrical use by an additional 20 percent.

What facility doesn’t want to save money? Every vertical market, from warehouses to hospitality to healthcare, can put occu-pancy sensors to use, and electrical contractors can help the user obtain their energy-saving goals when they learn to apply these detection devices.     EC

O’MARA is the president of DLO Communications in Park Ridge, Ill., specializing in low-voltage. She can be reached at 847.384.1916 or





About the Author

Deborah L. O'Mara

Freelance Writer
Deborah L. O’Mara is a journalist with more than two decades experience writing about security, life safety and systems integration, and she is the managing director of DLO Communications in Chicago. She can be reached at

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