Indoor temperature chart card

Who it’s for

Facility managers, building managers, and smart home owners ask “what is the temperature in this space right now, and has it been drifting outside the comfort range?” They need both the current reading and the trend to distinguish a brief temperature excursion from a sustained HVAC problem.

What it does

A sensor reporting temperature = 21°C shows the current value color-coded by comfort level alongside a time-series chart of recent readings: blue for Cold (below 18°C), light green for Comfortable (18–24°C), and red for Hot (above 24°C). The chart lets facility staff see whether a temperature deviation is a momentary fluctuation or a sustained issue.

• Live temperature reading in °C with color coding across three comfort bands
• Historical trend chart shows how temperature has evolved over the selected time window
• Shows one sensor’s data per widget; add multiple widgets to monitor different rooms or zones

How to set up

Data keys

Key	Role	Type	Description
temperature	Chart series	Timeseries	Indoor temperature in °C; 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
Delta percent	Percentage change	Timeseries	Change against the previous period, as a percentage
Delta absolute	Absolute change	Timeseries	Change against the previous period, in the key’s own unit

The widget ships with a simulated function datasource key labeled Temperature, 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 (°C)	Level	Color
0–18	Cold	Blue
18–24	Comfortable	Green
24+	Hot	Red

How to customize

• To change the time window — adjust the dashboard time filter to show the last hour, day, or week of temperature readings.
• To change the comfort 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

• A temperature that drops gradually through the night and fails to recover in the morning suggests a boiler or heat pump fault; a sudden spike in the afternoon followed by a slow recovery suggests a cooling failure or excessive solar gain through an unshaded window.
• Comparing temperature and CO2 trends side by side is a useful diagnostic: if CO2 is rising alongside temperature, the space is both under-ventilated and overheating — often caused by an AHU that has switched to recirculation mode.
• For energy audits, a temperature chart covering a full week reveals setback periods (nights and weekends) and shows whether the building achieves its scheduled cool-down, which is a good indicator of envelope and HVAC efficiency.