Indoor simple CO2 chart card

Who it’s for

Facility managers, HVAC engineers, and building managers ask “how has CO2 concentration in this space trended over the last few hours or days?” They want a compact trend chart that fits into a multi-room overview without the overhead of a full chart card.

What it does

A sensor reporting co2 = 720 ppm renders a time-series chart of those readings, color-coded by severity: green for Good (0–600 ppm), orange for Moderate (600–800 ppm), and red for High (above 800 ppm). The chart fills the card without a large numerical readout, maximizing the visible time window.

• Trend chart of CO2 concentration over the selected dashboard time window
• Color-coded by severity at each point in time across three bands
• Shows one sensor’s data per widget; add multiple widgets to compare trends across rooms

How to set up

Data keys

Key	Role	Type	Description
co2	Chart series	Timeseries	CO2 concentration in ppm; 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 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.

Value ranges

Range (ppm)	Level	Color
0–600	Good	Green
600–800	Moderate	Orange
800+	High	Red

How to customize

• To change the time window — adjust the dashboard time filter to show the last hour, day, or week of CO2 readings.
• To change the severity thresholds — edit the color ranges on the Latest data key.
• 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 chart cards for temperature and humidity to give facility staff a side-by-side multi-parameter trend view without cluttering the dashboard with large value cards.
• A 24-hour time window captures the full occupancy cycle — CO2 rising from 400 ppm at 7 a.m. to 900 ppm by 11 a.m. and recovering to 500 ppm at midnight — making abnormal days (no recovery overnight, unexpected weekend peaks) immediately obvious.
• Rooms whose CO2 never fully recovers to ambient between occupancy periods have insufficient air change rates; the trend line slope during empty periods reveals how fast the HVAC purges the space.