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Occupancy Sensors

Occupancy sensors will automatically turn lights on when they sense that someone is coming into an area and then turn them off when they sense that the space is empty. They are most effective when they are used in rooms that are not in constant use, such as attics, basements, garages, closets, bathrooms and storage areas. These sensors can substantially reduce energy costs because they make sure that lights are not left on unnecessarily for long periods. Occupancy sensors can usually pay for themselves within two to three years. They are installed on either the wall or ceiling of the room.

There are three basic types of sensors: ultrasonic motion detectors, infrared heat sensors, and audio sensors. If you are thinking of buying an occupancy sensor, consider the following:

  • Ultrasonic sensors use quartz crystals that radiate high frequency sound waves, which cannot be heard by the human ear. The waves are emitted into the monitored area, where they bounce off the objects and people in the space. The sensor measures the frequency of the waves, and small changes in frequency caused by motion activate the sensor.
  • Infrared heat sensing sensors detect changes in the infrared heat radiated in the monitored area. The sensor is controlled by low voltage wiring. They work best in small areas where no obstructions block the sensing field. Sudden changes in temperature (such as the entrance of a warm body into the sensing field) triggers the sensor, so look for models with a daylight filter to prevent sun rays from triggering the sensor.
  • Audio sensors work by monitoring the sound levels in the area with a microphone. A noise activates the sensor

No matter which type sensor you buy, you will get the best results if you look for models that can be adjusted for both time delay and occupancy sensitivity.

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