Lighting Occupancy Sensors
Lighting occupancy sensors are a comvient way to eliminate the forgetfulness that many people tend to over-look when it comes to turning the lights off. Lighing occupancy sensors are devices that can detect movement with-in a defined space, such as a bedroom. Only when movement is detected will these sensors light the area to which they coorespond. Depending on both the settings of the sensor and the particular room where the sensor is installed, there could actually be a reduction in energy consumption costs for that particular room. These sensors are used most effectively in spaces that are rarely occupied, which may include: offices, warehouses, storerooms, restrooms, loading docks, corridors, stairwells, office lounges, and conference rooms. Conversly, there are spaces where lighting occupancy sensors would be nearly useless, for example; high traffic areas containing steady activity. There are two types of lighting occupancy sensors that are much more commonly used today; they are the passive infrared and the ultrasonic sensors.
Infrared sensors are triggered when a warm object moves either in or out of the line of sight defined for the sensor, such as a person’s body. These sensors are best used within a fifteen foot range of human activity due to potential dead spots in the room where the sensor can not be activated and because the detection becomes more difficult as the object moves further away. Ultrasonic sensors emit a very high sound frequency which is well above both human and animal hearing capabilites. Ultrasonic sensors are triggered when they detect changes occuring in the reflected sound surrounding the room in question. Ultrasonic sensors can cover a much larger area are more sensitive then the infrared sensors. For example, ultrasonic sensors are sometimes prone to being set off by movement in the air or by a HVAC system turning on or off. A diagram of how lighting occupancy sensors operate is shown below:
Light Occupancy Sensor Diagram(above)
Lighting occupancy sensors have been around for years now and are an inexpensive and easy way to save money on energy costs. Below is a list of some typical energy cost savings that have been studied and determined for various types of rooms:
Type of Room |
Energy Savings (%) |
Private office |
13 to 50 |
Open-plan office |
20 to 28 |
Classroom |
40 to 46 |
Conference room |
22 to 65 |
Restroom |
30 to 90 |
Corridors |
30 to 80 |
Storage area/closet |
45 to 80 |