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Analysis: Aranet4 HOME wi-fi indoor air high quality monitor

We are always interested in air quality sensors and the latest that appears in the automated home is the Aranet4.

It is the first household air quality sensor of the sub-brand of the Latvian company SAF Tehnika. It measures carbon dioxide (CO₂), temperature, relative humidity and air pressure.


The outstanding feature of this device is its ability to display all of its measurements on the screen. The display uses technology similar to that of the Eve Room and uses an e-ink screen that provides an informative, if somewhat small, display.

The advantage of this type of display is the low power consumption and the high contrast, which is easy to read with good ambient lighting. The device can stand on a table or shelf or be mounted on the wall if you prefer.


There are no VOC or PM2.5 detectors here, but the on-board electronics use a special NDIR sensor for CO₂ measurements.

Aranet4 uses a non-dispersive infrared sensor (NDIR) to measure the CO₂ level. The device has a small gas chamber with an infrared light source in which CO₂ absorbs the light. An optical filter in front of a detector then filters all the light except for the wavelength that the CO₂ molecules can absorb, so that an exact measurement of the CO₂ level can be carried out.

In addition to the integer display, the screen also shows a 3-color traffic light system. The maximum indoor CO₂ value that is considered acceptable is 1,000 ppm, and the colors mean the following:

  • Green – good (below 1,000 ppm). Optimal indoor air quality
  • Yellow – average (1,000 ppm). Brain cognitive function drops 15%
  • Red – unhealthy (1,400 ppm). The cognitive function of the brain drops by 50%

There is an audible warning buzzer that can be activated or deactivated as an alarm for dangerous levels. It is recommended to calibrate the device once a year. This can be done automatically or manually.

You can select the measurement to be recorded every 1, 2, 5 or 10 minutes. Aranet states that this is the difference between your batteries that lasts 4 months to 2 years.

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It should be noted that the device warns that incorrectly inserting the batteries will damage the device to such an extent that it must be returned to the manufacturer for repair. The FAQ also warns that a drop could permanently damage the sensor. So be careful.


There is an Android and iOS app, which is a little basic at the moment. We want this app to evolve and improve over time.

Some functions can be controlled via the app, while others are only accessible via a DIP switch, which is located under the cells in the battery compartment.

1) The standard measuring interval is set to 5 minutes.
2) The automatic calibration of the CO2 sensor is deactivated.
3) The standard temperature measuring units are set to Celsius.
4) Bluetooth connection is activated;
5) The transmission range of the Bluetooth connection is set to normal.
6) The buzzer for audio alarm messages is deactivated.
7) The CO2 display is set to human mode.
8) Access to the Homey Smart Home Assistant is activated.

The 2nd, 3rd and 4th settings can be changed using the switches in the battery compartment on the back of the device. However, the remaining five settings can only be changed through the Aranet4 phone application.

The app works in portrait mode, but if you rotate it in landscape mode, you get a wider view where you can enlarge your data.

Aranet4 app


There is an unofficial web API as well as a python client and a python library if you want to try out a DIY integration and the sensor also works with Homey.


Rating: 4 out of 5.

The Aranet4 is a nice little air quality monitor with a high-quality CO₂ sensor.

Its unique selling point is the ability to show you real-time measurements at a glance without having to pull your phone out of your pocket to start an app.

Now available.

Available from Amazon

Last update on June 9th, 2020 / Affiliate Links / Images from the Amazon Product Advertising API

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