Occupancy Sensors and Lighting

Add convenience and security for tenants while brightening your bottom line

By William and Patti Feldman

Whilefacility owners and managers have, for many years, had to grapple with the needless wasteof keeping lighting in buildings turned on, even when areas and rooms are unoccupied, fewhave made the leap to install occupancy sensors in their facilities. Instead, they havewoefully had to contend with the high utility bills that result from having lights workingall day and night, or play policeman and remove tape, wedges or other jury-rigs thatrenters commonly use to override mechanical timers that are installed to control lighting.

Recognizing that occupant-responsive lighting controls resonate advantageously on thebottom line, Ron Urban, owner and manager of Electrical Concepts and Construction Inc., aNew Jersey-based electrical-contracting firm that specializes in design/build work for theself-storage industry, suggested these devices to several clients as part of theelectrical installation he performs for new construction projects. These devices automateon/off light switching to correspond to actual occupancy patterns throughout a building.Urban cites two benefits: First, facility owners/managers save money year round on energycosts; second, they simultaneously provide tenants with automated, safe, secure lightingthroughout all parts of the facility.

In the sixoccupancy-sensor installations covering more than 600,000 square feet of self-storagespace that Urban has performed to date, he installed state-of-the-art occupancy sensorsfrom Leviton Manufacturing Co. of Little Neck, N.Y. These were typically installed inplace of manual timers. "No one likes being left in the dark," notes Urban."Occupancy sensors that reliably jump-start lighting in the nick of time are a greatway to avoid the potential hazard of someone entering a darkened area and having to gropefor a light switch.

"The renter doesn't have to juggle bundles or put down bulky items to turn on aswitch," Urban points out. "And without any action on the part of the renter,the device saves energy by turning lighting off after a specified period, once movement isno longer detected in the area."

Two Technologies

The intent ofoccupancy sensors is to monitor an area or room for human presence and turn lights onautomatically when the area is occupied and off once the person has left. There are twotypes of sensor technologies: passive infrared (PIR), which requires an unobstructed viewof the occupant, and ultrasonic (US), which relies on frequency changes. Both areeffective control solutions in locations with infrequent occupancy such as offices,storage areas, utility closets or restrooms. Technical preference of one sensor overanother depends upon room layout and environmental factors, such as what type ofequipment, obstructions, or heating and cooling devices are present.

PIR sensors react to the movement of a human body as a heat-emitting source in a directline of sight or "field of view" and would be a good match for an entryway,hallway, office or open space; however, they may not work well in a space such as arestroom, where the sensor's field of view could be obstructed by a stall or partition. Inthis instance, an ultasonic sensor might be the better choice, since it does not depend ona direct line of sight.

Ultrasonic sensors continually generate high-frequency sound waves beyond the capacityof human hearing, in the 25kHz to 40 kHz range, which means they that bounce offeverything in their range. These sensors monitor changes in the return time of thereflected sound waves, and turn lights on when they sense a change in frequency. Becausethey can detect motion behind fixed objects in a room, they are suited to enclosed areasand are a versatile choice for installation throughout a storage facility.

Significant Energy-Savings

In storage facilities, where space is occupied by people only sporadically, annualelectrical savings for lighting usage can quickly supercede the cost of the sensors. (EPAfigures indicate that first cost makes up only about 8 percent to 9 percent of the wholecycle cost of a lighting system, with maintenance responsible for about 1 percent to 2percent and energy consumption responsible for the remaining 90 percent.) Furthermore,occupancy sensors have been shown to extend usable lamp life and the time between lampreplacement, minimizing maintenance costs. In addition, air-conditioning costs are alsolowered because less heat is generated from lamps and ballasts that are turned off whenthey don't need to be on.

Benefits of Using Sensors

Urban says he typically installs the sensors in indoor, multi-floor facilities, usingas many as 30 to 50 devices throughout a facility. "Automated lighting controlenables users of the self-storage facilities to have their hands free while unloading orloading their equipment, cartons, files and furniture," he says. "We havedetermined that occupancy sensors are a valuable asset to the owners because the lightsare on only when they need to be.

"A secondary benefit of occupancy sensors is that renters were taping up timerswitches to keep them on so that they didn't run the risk of having the lights in thehallway go out while they were inside the building. The occupancy sensors, which go onimmediately, eliminate the potential hazard of someone getting hurt in a darkened areawhile looking for a light switch."

Today, the useof sensors is becoming increasingly popular in self-storage facilities. "From myexperience, I see that all the big players are installing them. We are incorporating theoccupancy sensors into our design and having tremendous results with our customers, whoare very happy," Urban says.

Occupancy sensors also work well in both new construction and in retrofit projects. Infact, savings may be biggest for owners of self-storage facilities that were converted forthat purpose. Typically, owners of converted facilities will leave the lighting fixturesin place or move them around, but they leave the lights on all of the time. If theceilings in the hallways are higher than those typically found in a building constructedfor self-storage, and the fixtures and lamps are not energy efficient, that much morelighting will necessarily be used. All that lighting remaining on for intermittent visitstranslates into a lot of wasted energy consumption. A retrofit with occupancy sensors cansave owners a bundle on energy expenditures, while helping to avoid the possibility of apersonal-injury judgment resulting from the hazards of poor lighting.

William and Patti Feldman write for magazines, newspapers and corporations onindustry-related trends and products. They can be reached at [email protected], or call (914)238-6272.

Leviton Manufacting Co. is a privately-held manufacturer of wiring devices switchesand receptacles, lighting controls, surge- protective devices, personnel-protectionproducts, voice/data products and a wide range of connection products.