Aranet

Aranet4 Home CO2 Monitor

Native integrationLocal control

Bluetooth

Verified July 2026

The reference-grade NDIR CO2 monitor — years on two AA batteries, always-on e-ink display, and a core Home Assistant integration that reads it passively over Bluetooth (enable 'Smart Home integrations' in the Aranet app first). Expensive, but it is the one CO2 number you can actually trust to calibrate cheaper sensors against.

Specs

power: 2x AA, circa 2 years
display: E-ink, always on
requires: HA Bluetooth adapter or ESPHome Bluetooth proxy
sensor type: CO2 (NDIR), temperature, humidity, pressure

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