Daylight Groups Overview

This article explains the capabilities of grouping fixtures for daylight harvesting for lighting designers. Engineers and technicians may also use this note to configure the Manage to satisfy a lighting design.

Goal

Create daylight groups to provide a uniform dim level across a group of fixtures for improved aesthetics.

In most cases, daylight harvesting without grouping will provide light levels that do not impact lighting aesthetics. However, occasionally lights are directed at walls or ceilings, and noticeable differences in dim levels may create undesirable patterns of light and shade on walls and ceilings. In these cases, daylight groups may be used to ensure a uniform dim level. Daylight groups are not recommended to be set for optimizing occupant comfort or energy efficiency.

The following concepts are introduced in this article:

• Ambient Reading – The ambient light level that is measured by the sensor.
• Daylight Group – A set of sensors that respond collectively based on the reported Ambient Readings of sensors in the group.
• Light Level – The fixture's output light (frequently referred to as dim level by lighting professionals).
• Group Light Level – The light output is calculated based on the ambient readings of reporting sensors in the group.
• Target Ambient Light Level – The target ambient reading that the sensor attempts to achieve by adjusting its light level, previously referred to as ambient threshold value or daylight harvesting target.

Daylight Groups Scenarios

1. Open Office

Suppose an office with rows of pendant fixtures and large windows spaced along one wall. The pendants direct light both upward toward the ceiling and down toward occupants. The sensors point down toward the office workers to ensure ambient light levels fit for reading. Without a daylight group, the fixtures between windows may have higher dim levels than the fixtures in front of the windows. This pattern would create variations of shade and light on the ceiling if the daylight is directed toward the occupants but not at the ceiling. To provide a consistent shade on the ceiling, the light designer may want to create three rows of daylight groups with each subsequent group farther away from the window wall.

2. Office Atrium with Spotlights

Suppose an atrium with high ceilings and a few spotlights around the perimeter that are pointed at the ceiling to create indirect lighting for the office workers below. Without a daylight group, the dim levels of the spotlights would be based on the sensors controlling the spotlight. If one spotlight sensor were in the sun's direct path, the spotlight would dim, and a large area would be impacted. Similarly, the ceiling would have a hodgepodge of different shades depending on the ambient reading at each spotlight. To provide comfortable lighting for the entire group and a consistent shade on the ceiling, the light designer may want to create one large daylight group for the entire atrium.

3. Outdoor Parking Lot

Suppose an outdoor parking lot with hundreds of light poles. The parking lot is in a region where dark clouds occasionally block out the sun before sunset, creating the desire to use ambient light instead of an astronomical clock to govern lighting behavior. Without a daylight group, the fixtures would sporadically turn on as the sun starts to set, creating the false impression that the fixtures were not behaving correctly. To provide the impression that all the lights are functioning with more traditional lighting technology, a lighting designer may want to create a large daylight group. All the outdoor lights maintain a consistent dim level as the sun rises and sets.

Prerequisite Steps Before Creating a Daylight Group

1. Verify Firmware

TIP: Upgrade sensor firmware before creating a daylight group. Check that all sensor firmware is version 5.x or higher.

2. Verify Network Health

TIP: Verify Transaction Fail Rate is lower than 30%.

All sensors in a daylight group must have adequate communication with Manage. The group sensors send ambient readings to Manage, and then the system calculates the Group Light Level. Sensors that miss the command to achieve a particular Group Light Level may have different Light Levels and defeat the daylight group's purpose. Hence, ensure good network health between the sensors and the Manage.

To verify network health,

1. Select a Floor in the facility left panel and click the Floor Plan tab.
2. Select View > Network.
3. Select Diagnostics > Network Health, and Metric > Transaction Fail Rate.

For a daylight group of fewer than 100 sensors, a Transaction Fail Rate lower than 30% is unlikely to result in failed transactions that would be observable by occupants. However, if the Transaction Fail Rate is substantially higher than 30%, contact Enlighted Support to address the high rate.

3. Set Target Ambient Light Level

TIP: Automatically set the Target Ambient Light Level of sensors at night with light levels set to 100%.

The Target Ambient Light Level of the individual sensors in the group is used to calculate a group target ambient light level. This group target is compared to a group ambient reading to calculate the Group Light Level.

Generally, use the automatic calibration method to set the Target Ambient Light Level for all sensors in the group. At night, bring all the sensors to 100% dim level, and set the value automatically.

Refer to the Set Target Ambient Light Level for details.

4. Create appropriate Lighting Profiles

TIP: Set motion sensitivity to 0 to ensure uniform lighting in the daylight group.

For the Office Atrium with Spotlights and Outdoor Parking Lot scenarios, motion sensitivity is usually set to 0 during time periods that are typically occupied. Late at night, it may be desirable to set motion sensitivity to a higher value if it is acceptable to have lights at the minimum light level.

For the Open Office scenario, motion sensitivity greater than zero may be desired.

In the Advanced section of the profile, you may choose whether to allow the Group Light Level to dim lights below the minimum light level. Check the highlighted option shown below to accomplish this.

5. Assign Lighting Profiles

TIP: Assign all sensors within a daylight group to the same lighting profile.

Manage does not require all fixtures in a daylight group to have the same profile. However, Enlighted recommends that all fixtures in a daylight group share the same profile to ensure that all sensors within a group maintain a constant dim level.

A few cases exist where lighting designers may want different profiles within the daylight group. For example, suppose a fixture in the Open Office Scenario is close to a hallway or a strong air vent. The designer may want the entire group to respond to motion but may want to create a special profile for this individual sensor to reduce its motion sensitivity.

6. Create Motion, Switch, and Plugload Groups as Needed

TIP: If motion sensitivity is desired, create motion groups with the same sensors as the daylight groups.

Motion, switch, and plugload groups continue to function independently of the daylight group. If it is desirable to have uniform group levels that vary based only on occupancy, create motion groups that match the Daylight Groups. As Daylight Groups may span gateways and motion groups may not, it is not always possible to match them.

7. Steps to Create a Daylight Group

1. Select sensors: From the Floor Plan, select sensors, right-click, and select Create/Configure Groups > Create Daylight Group.

2. Choose a method for calculating the Group Light Level.

TIP: Generally, choose the Average Daylight method.

• Average Daylight: Some fixture light levels in the group will be brighter than the Target Ambient Light Level and some less bright. On average, the light levels will meet the required target light level. This is the recommended option.

• Maximum Daylight: Fixture light levels will optimize for reduced energy usage and maximize occupant flexibility. If all the sensors have the same target, then the sensor with the maximum daylight will be the sensor that dictates the Group Light Level. As daylight increases, the lights will be dimmed to the minimum required amount of light. The method is helpful in the Office Atrium scenario if lighting designers want to rely on task lighting outside of the group. With this setting, no occupants will have too much light, and occupants can always turn on their task lighting to increase comfort.

• Minimum Daylight: Light levels will ensure all targets are met or exceeded. All fixtures will be set to the maximum light level required to meet all the sensors’ targets. If all the sensors have the same target, then the sensor with the minimum daylight will be the sensor that dictates the Group Light Level. That is, all occupants will have sufficient light. Choose this method in an office environment where it’s important that all occupants have sufficient light, and it’s unlikely that too much light would cause discomfort.

• Daylight at Master Sensor: Light levels will ensure that the user-designated master sensor's light level is set to its target. In this case, the targets and ambient readings of all other sensors in the group are ignored. This method simulates more traditional lighting systems. It is a safe option only if one sensor accurately reflects the ambient readings for the group.

Average Daylight Group Light Level

Master Sensor Group Light Level 

3. Choose Group Ambient Sensitivity

TIP: Use a value of 5 for moderate utilization of daylight.
The group ambient sensitivity overrides the sensitivities set in the profile. With a value of 5, daylight will never dim a fixture to off. A value of 10 will aggressively optimize energy by utilizing daylight. A value of 0 defeats the purpose of a daylight group as daylight will have no impact on the group.

4. Choose the roles of each sensor.

TIP: Set all sensors in the Report and Act state for typical office environments.
Sensors in the group may be set to Report and Act, Report Only, or Act Only.

• Report and Act sensors report their ambient readings, and they respond to the Group Light Level.
• Report Only sensors only report ambient readings, but they act independently of the group and follow whatever behavior their profile dictates.
• Act Only sensors do not report ambient readings, but they respond to the Group Light Level.

An Office Atrium with Spotlights pointed at the ceiling would likely require that the sensors controlling the spotlights are Act Only sensors because they may be far removed from occupied areas. So, ambient readings are not relevant. Furthermore, the designer may want to place Report Only sensors throughout the workspace. In this case, the Report Only sensors, report ambient readings from occupied areas to Manage. The system calculates the Group Ambient Light Level for the Act Only sensors to control the spotlights.

5. Click Apply to create the daylight group

After creating a daylight group, it will take two to three minutes for the fixtures to adjust to a constant light level. As the amount of daylight changes, the daylight groups respond gradually over a 10 to 30-minute period. Occupants may likely not notice changes to the light levels.

8.  View Daylight Groups

From the Floor Plan tab, select View > Daylight Group. Each group is a different color. Double click the sensor to see the sensor’s Daylight Group Name.

9.  Delete or Edit Daylight Groups

From the Groups tab, select Daylight, and Delete or Edit the desired group.

Recommended Settings for Daylight Groups

If in doubt, use the settings in this table for daylight groups. Refer to the System Admin Guide for details about how to create profiles and motion groups.

Advanced Daylight Group Behavior

Lighting behavior will continue to influence light levels. For example:

• Switches and manual overrides will override daylight group behavior.
• Motion and vacancy settings (Min. Light Level, Max. Light Level, Ramp-up time, Active motion window Dim and Linger, etc.) will still influence light levels.
• Automated Demand Response, Demand Response, and Overrides will continue to function.

Daylight Group Overrides Daylight Harvesting Profile Settings

When a sensor belongs to a daylight group, the group behavior overrides most of the daylight harvesting settings in the sensors’ profile. The table below describes the parameters used for daylight group behavior instead of the parameters defined in the daylight harvesting profile.

Example Behavior

The examples below provide recommended settings for each type of scenario and illustrate how daylight groups affect light levels.

1.    Open Office:

Assume all fixtures in the daylight group have the following profile and are all in the same motion group.

The table below shows how the fixture light levels are controlled based on the profile settings, Group Light Level, daylight harvesting, and advanced settings.

2.    Office Atrium with Spotlights

3.    Outdoor Parking Lot

 Recommended articles:

• Create a daylight group
• Daylight Harvesting