Daylight Harvesting

As daylight levels increase, light levels can automatically decrease to save energy. In a facility with skylights, windows, sidelights, you have available daylight, which varies according to the day's time. By enabling Daylight Harvesting, you can take full advantage of ambient sensitivity to manage light levels. The Target Ambient Light Level, also called Ambient Threshold, determines the light target levels.

Target Ambient Light Level

The Target Ambient Reading that the sensor attempts to achieve by adjusting its light level.

The Target Ambient Light Level is determined and set up during the initial set up of the system. This command should only be used under the direction of Enlighted field support engineers. The procedure for obtaining the best value is to perform this command when there is no ambient light (such as at night) with all the lights set to full-on. You can also set the Target Ambient Light Level for selected sensors. The value can be set manually, or the sensor’s current ambient value can be set to be the target ambient value. Contact Enlighted Customer Support to determine or set this value or refer to the Determine and Set Target Ambient Light Level article.

Ambient Reading

The ambient light level measured by the sensor.

Ambient Sensitivity

Determines a sensor’s sensitivity to light, and it ranges between 0-10.  For Daylight Harvesting to have maximum effect, it is recommended to set the ambient sensitivity to a higher value in the corresponding lighting profile. Ambient sensitivity value, which determines a sensor’s sensitivity to light, ranges between 0-10. The value 0 means that the light will not be dimmed, and value 10 means that the light is most sensitive to ambient light. Daylight Harvesting will be most effective when the value is 10.

Daylight Harvesting

Lighting Profiles can be different over different periods of the day. The Enlighted system allows for four profile periods: Morning, Day, Evening, and Night. Each profile period has individual minimum and maximum light settings and Ambient Sensitivity settings (among other settings).

Values in the lighting profile specify the minimum lighting level [Min. light level when on (0-100%)] that is applied to a fixture. Normally, the light is never lowered below the profile minimum. For example, if the minimum light level is set to 15% in the profile, the lights will never turn off but will be dimmed to 15% of lighting. However, when there is sufficient daylight, the lights can be turned off and not merely dimmed to the minimum value.

To enable daylight harvesting, check the option Enable Daylight Harvesting Override mode in the Profiles Advanced menu. By default, Enable Daylight Harvesting Override mode will be unchecked.

For the lights to turn off, select the Allow Daylight Harvesting to dim lights below the minimum light level. Daylight harvesting override mode is thus enabled, turning the lights off rather than merely dimming them to 15% of the min. light level specified in the lighting profile. 

Daylight Groups: You may also choose to have these options set for Daylight groups to allow the Group Light Level to dim lights below the minimum light level.


Profile Minimum Override

As the system transitions between profiles, the profile setting for minimum light is not automatically applied to maximize energy savings. The lighting profile setting and occupancy state determine whether the light is turned on or dimmed.

For example, if the lights are off because there is no occupancy detected, then the lights will continue to be off as the system moves from the day to evening profile. This is not desirable for outdoor lights or in company lobbies because the lights should turn on irrespective of occupancy, for safety or business reasons at certain times. For example, in a parking garage or company lobby, the lights should turn on to profile minimum value even if no one is there -- for safety reasons.

In the above example, the light needs to be turned on to profile minimum value at the beginning of the profile period. For this option to be effective, enable the option At a time period change when there is no motion, allow a change in minimum light level to raise light levels as shown below.

You must also enable this option (At a time period...light levels) when the evening period is set based on the astronomical clock. See  Setting Advanced Attributes when Astronomical Clock is Set.


Profile Maximum Override

By default, when daylight harvesting is active, the light level ramps to the Max light level, and decreases to the Ambient Light Level within the ramp-up time set in the profile when motion is detected.

If you would like lights to go to the Ambient Light Level instead of the Max light level when motion is detected, check the option as shown below in the Advanced Settings.


When this option is selected, the light level goes to the Target Ambient Light Level over three seconds when motion is detected. The ramp-up time in the profile is overridden and set to three seconds. If there is sufficient daylight, the lights may not turn on when motion is detected, thus increasing energy savings.  

To enable Daylight Harvesting for your organization, refer to the article Enabling Daylight Harvesting.


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