Effect of Motion Sensitivity, Active Motion Window, Motion Threshold on the Light Level due to Motion

This article describes the effects of the three settings that affect the changing of the light level due to occupants' motion. 

  1. Motion Sensitivity: The sensor's sensitivity to detect occupancy due to motion. 
  2. Active Motion Window: The length of time to hold a light on after motion has not been detected.
  3. Motion Threshold (Advanced): The threshold between 1 (min) and 10 (max) for detecting motion.

Refer to Understanding Profile Basic Attributes for a description of these fields.

To view Active Motion Window or Motion sensitivity for a sensor, double-click a sensor on the floor plan, and select the Profile tab from the Fixture Details window.   


Scroll down and select Advanced to view Motion Threshold.


There are several possible reasons to modify the values:

  • The lights turn off even when there are occupants present. 
    This is reduced by setting the value of motion sensitivity to 1 and increasing the active motion window value. These changes cause the fixtures to be more reactive to motion. Note that in extreme cases, the value of motion sensitivity can be set to 0, which will behave as if an occupant is always present.
  • The lights turn on when passersby (transient) motion is detected. 
    This is reduced by increasing the value of motion sensitivity. Also, the value of ramp-up time can be increased so that when lights are turned on, the light level increases over a longer time and reduces the distraction.
  • The lights turn on due to false triggers of motion.  
    This can be due to heat from a printer located beneath the fixture or air from a vent. A value should be selected between 1 and 10. The value 1 is the lowest threshold, and higher values raise the threshold. Thus, if false triggers are occurring, then the value should be raised.
  • The lights delay too long before turning on. 
    This is due to a high value for motion sensitivity. Reducing the value will shorten the time but may result in lights turning on due to transient motion detection. Note that there is an additional attribute to tune sensitivity to motion.
  • Lights stay on for a long time after the last occupant has left the area. 
    This is the result of having a large value for the active motion window. Reducing the value will shorten the time the lights are on when there are no occupants present but may result in the lights turning off when very still occupants are present.
  • Title 24 Enabled. 
    • Min light level when on (0-50)(%) - The minimum light level set should be greater than 0 percent and less 50 percent.
    • Max light level when on (30-100)(%) - The maximum light level set should be greater than 30 percent and less than 100 percent.
    • Active Motion - Must be set to less than 20 minutes.

As you can see, there are potentially conflicting trade-offs. Another approach is to physically relocate the sensor slightly to change the occupancy sensor's motion detection.

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