More Information about Lighting Controls
Occupancy and daylight sensors are capable of saving significant energy and operating costs for building owners. These sensors continuously monitor a space for activity or daylight and automatically adjust the lighting accordingly. Occupancy and daylight sensors can be installed in a variety of fashions, as shown below, making them a great energy-saving option for almost any facility or situation.
- Wall-switch mounted sensors replace a traditional wall switch and fit directly into the existing electrical wall switch box. All fixtures wired to the previous wall switch will be controlled by the sensor. Wall-switch sensors are inexpensive and are good options for small enclosed spaces.
- Fixture-mounted sensors are integrated with or attach directly onto a light fixture. These sensors can control one fixture or, if desired, a handful of fixtures. Fixture-mounted sensors are excellent options for high-ceiling spaces such as warehouses or gymnasiums.
- Remote-mounted wall or ceiling sensors consist of a remotely mounted sensor wired to a control mechanism, called a power pack. One or more remote sensors monitor a space for occupancy or daylight and, when appropriate, communicate back to the power pack to shut off or dim the lighting. Remote-mounted sensors are recommended for large, open areas.
- Wireless sensors are remote-mounted sensors that communicate without wires with a companion wall switch. Since no new wiring is needed, wireless sensors are an ideal option when upgrading existing lighting installations.
Occupancy sensors can utilize a number of different sensing technologies, described below, to detect the presence or absence of people within a space. The configuration of a space or the type of activity within a space will determine which sensing technology is appropriate.
- Passive Infrared (PIR) – Passive infrared occupancy sensors use a thermal image to detect activity. PIR sensors are inexpensive and work well when a direct line-of-sight exists between the sensor and the occupant(s). PIR sensors should not be installed in rooms with partitions or dividers. Also, PIR sensors may inadvertently turn off the lighting in occupied areas where the activity is subtle, such as typing.
- Ultrasonic – Much like sonar, ultrasonic occupancy sensors emit a low frequency sound wave and monitor the returning signal for changes indicating movement and occupancy. Ultrasonic sensors are more sensitive to subtle movements and can be used in spaces where direct line-of-sight is not possible.
- Acoustic – Acoustic sensors respond to audio signals in order to detect occupancy. As with ultrasonic, acoustic sensors can be used in spaces without a direct line-of-sight between the sensor and occupant(s).
- Dual Technology – Dual technology sensors utilize two of the technologies above, most often PIR and ultrasonic, on the same sensor, to provide the most robust and accurate response to occupancy. Inadvertent turn off issues are virtually eliminated when using dual technology sensors.
Some occupancy sensors can be purchased as or configured as a “vacancy” sensor. With a vacancy sensor, the lighting will only be turned on if manually done so by a switch. The sensor will then automatically turn off the lights when the space becomes vacant. This type of sensor saves even more energy since the lighting is only turned on when an occupant truly needs or desires light.