Indoor simple illuminance chart card

Who it’s for

Facility managers, building automation engineers, and workplace managers ask “how has illuminance in this space trended over the last few hours or days?” They want a compact trend chart that fits into a multi-zone lighting dashboard without the overhead of a full chart card.

What it does

A sensor reporting illuminance = 350 lx renders a time-series chart of those readings, color-coded by band: dark gray for Dim (0–100 lx), orange for Low (100–300 lx), dark orange for Moderate (300–500 lx), and red for Bright (above 500 lx). The chart fills the card without a large numerical readout, maximizing the visible time window.

• Trend chart of illuminance over the selected dashboard time window
• Color-coded by band at each point in time across four levels
• Shows one sensor’s data per widget; add multiple widgets to compare trends across zones

How to set up

Data keys

Key	Role	Type	Description
illuminance	Chart series	Timeseries	Illuminance in lx; change the key name to match your device’s telemetry key
Latest	Latest value	Timeseries	The headline figure above the chart. Its own color ranges are where the band colors are edited

The widget ships with a simulated function datasource key labeled Illuminance, so it draws random values until you point the datasource at a device and rename the key.

To point it at your own device: open the dashboard in edit mode, open the widget’s Datasources, pick the entity or entity alias, and replace the function key with the key your device reports.

Value ranges

Range (lx)	Level	Color
0–100	Dim	Dark Gray
100–300	Low	Orange
300–500	Moderate	Dark Orange
500+	Bright	Red

How to customize

• To change the time window — adjust the dashboard time filter to show the last hour, day, or week of illuminance readings.
• To change the band thresholds — open the widget settings and adjust the boundaries to match your space’s lighting standard.
• To change the chart colors — edit the color of each range on the Latest data key.

Tips

• Use this chart in a grid alongside simple charts for temperature, CO2, and humidity to give facilities staff a side-by-side multi-parameter indoor environment overview.
• The illuminance trend over a sunny day shows a characteristic shape — flat artificial baseline before sunrise, a step up when occupants arrive, a midday peak from direct sunlight through south-facing windows, and a decline as the sun moves west — any departure from this shape warrants investigation.
• An illuminance chart that shows the same flat line for days in a row likely means the sensor has lost connectivity or the telemetry pipeline has stalled; verify by checking the last-seen timestamp.