CO2 Monitoring and Alerting with Aranet4 + an4mon

In my home office, I use an Aranet4 CO2 monitor to track carbon dioxide levels. CO2 levels can climb surprisingly quickly when the door is shut while I'm in meetings or calls.

I want to CO2 track levels in InfluxDB and integrate the monitor with Home Assistant via MQTT. And though the monitor is visible from my desk, I'd also like to get phone and/or desktop notifications when the CO2 level is high.

Enter an4mon:

GitHub - cdzombak/an4mon: CO2 level notifications + MQTT and InfluxDB logging for Aranet4 sensors

CO2 level notifications + MQTT and InfluxDB logging for Aranet4 sensors - cdzombak/an4mon

GitHubcdzombak

an4mon runs on the macOS desktop on my desk. It reads the Aranet4 sensor via Bluetooth every 2 minutes and writes the resulting CO2, temperature, and humidity measurements to InfluxDB and MQTT.

If the CO2 level is moderate (>1000ppm), it sends me a notification via Ntfy, and it repeats that notification every 30 minutes until the CO2 measurement declines; if the level is high (>1400ppm), I get a notification every 5 minutes. These notifications ensure I remember to open the door or a window.

If you use an Aranet4 CO2 monitor, try it today! an4mon is compatible with macOS and available under the MIT license. The README covers usage and Home Assistant integration.

In the future I plan to install a single-room energy recovery ventilator to help bring fresh air into the room even during summer & winter.