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On Saturday, December 20, from 5 a.m. to 6 p.m., the Lee Center complex, at 1108 Jefferson St., will be closed due to building system upgrades.

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City of Alexandria, VA City of Alexandria, VA
Green Building Resource Center
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Page updated Jul 27, 2012 9:39 AM
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Occupancy/Vacancy Sensors – Make the Switch Automatically

Occupancy Sensor imageHow often have you forgotten to turn off the light switch when leaving a room or opened the storage closet to see the light bulb still glowing?  Although this happens all the time, simply forgetting to switch the lights off contributes to a costly electricity bill.  The quick and easy solution lies with installing occupancy/vacancy sensors which offer huge energy savings with minimal effort. 

Many lighting occupancy sensors cost $20-100 each, depending on the features, and can provide average savings of up to 50% in offices and 80-90% in restrooms, hallways, and storage areas. Plus, lighting occupancy sensors feature a sleek low profile design which distinguishes them from the less aesthetically pleasing, old-fashioned paddle light switches.

Lighting occupancy sensors typically sense activity by detecting infrared radiation (body heat) or ultrasonic sound waves.  Once the sensor detects motion, the control signals the relay to turn the lights on or off, depending on the desired settings.  Make sure you do not place infrared sensors facing an open door or hallway, as the lights may turn on when people walk by but do not enter the space.  Ultrasonic sensors are ideal for areas requiring large coverage and in spaces where sensors must detect motion around corners or large objects.  Some newer models utilize both infrared and ultrasonic technologies to detect activity, which results in fewer false triggers.

Occupancy sensors generate maximum energy savings in frequently unoccupied spaces, like warehouses and storage rooms, but may not work best in large, open areas with high activity.  For these situations, vacancy sensors are an excellent way to conserve energy and save money on the power bill.  Occupancy sensors do, however, serve a key role in reducing your building’s plug load when connected to plug-in office equipment, like computers, phones, and workstation lighting.

Just as the name suggests, vacancy sensors switch the lights off when motion is no longer detected after a certain period of time but must be turned on manually.  Although occupancy sensors can be installed in a variety of settings from high-traffic areas to commonly unoccupied spaces, vacancy sensors are ideal for transitory areas, such as hallways, utility rooms, and bathrooms, as well as areas receiving generous amounts of natural lighting.  Once the area remains vacant for 5-30 minutes (depending on your settings), the sensor automatically switches the lights off and quickly begins racking up energy savings.

For other great lighting and daylighting tips and ideas to reduce your energy costs, visit http://www.energysavers.gov/your_home/lighting_daylighting/.

 

Green Building Resource Center
301 King St., Room 4100
Alexandria, Va 22314
703.746.4065
Fax: 703.519.3356
E-mail

Office Hours:
Monday-Friday
8:00 a.m. - 5:00 p.m.