Simple CO2 chart card

Who it’s for

Building managers and HVAC engineers ask “how has CO2 trended over time, without the clutter of delta comparisons?” They want to see the current reading and a trend line in one card, nothing more.

What it does

A sensor currently reading 680 ppm shows a color-coded value above a chart that reveals whether CO2 has been rising or falling over the selected period.

• Large current CO2 value in the center, color-coded across four concentration levels from Good to Hazardous
• Time-series chart of CO2 readings over the selected time window, averaged per interval
• Shows one sensor’s data; it does not compare multiple rooms or show period-over-period deltas

How to set up

Data keys

Key	Role	Type	Description
co2	Chart series	Timeseries	CO2 concentration in ppm; drives the chart. The Latest value overlay is automatically derived from this same 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 CO2 level, 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.

If the key has never reported for the selected time window, the chart is empty and the value overlay shows no data.

Value ranges

Range (ppm)	Level	Color
0–600	Good	Green
600–1000	Moderate	Light Green
1000–1500	Elevated	Orange
1500+	Hazardous	Red

How to customize

• To use your own CO2 thresholds — edit the color ranges on the Latest data key; adjust the four default levels to match your facility’s targets.
• To hide or show the chart — toggle Show chart in the widget settings.
• To change the chart line color — set Chart color.
• To show min, max, or total in the legend instead of avg — edit the Legend settings.
• To hide the entity name subtitle or the timestamp — turn off Show subtitle or Show date.
• To match your dashboard’s fonts — set the font options under each data key’s appearance settings.

Tips

• Use this card when the trend shape matters more than the exact period-over-period change. Add the full CO2 chart card if you need a delta percentage alongside the chart.
• For CO2, a rising trend means ventilation is getting worse. A falling trend means it is improving.
• The aggregation interval controls chart granularity. For a daily view, an hourly interval makes trends visible without too many data points.