I bought a Nedis SmartLife Air Quality Monitor 8 month ago, and it was a huge mistake, let me show you why.

I spend an enormous amount of time looking for cheap CO2 sensors that I could integrate in Home Assistant. During that period I bought this device in the hope that it could provide me with cheap VOC and CO2 readings beside the more standard temperature and humidity readings. At the time I purchased this unit I couldn’t find much information online about it, so I took a chance.

Since you´re not going to make the same mistake as me, I won´t document the entire process of connecting it to Home Assistant, but it requires an app, a cloud account, a developer account at Tuya, and an integration in Home Assistant. After the initial setup is done, it works reliable and updates with low latency when there are changes to the readings.

To test it, I placed it next to my Airthings View Plus in my office, since I was working from home in that period. That gave me a great opportunity to test it, since my office is relative small, so the air quality drops quickly when no ventilation is running.
I soon had problems comparing the 2 though, because the Airthings measure VOC in ppb, and the Nedis measure VOC ppm (billion vs million). Well, it´s just a factor 1000, so it´s easy to convert, but it shows something about accuracy, or lack of it.
In CO2 they both measure in ppm, so that should be easily compared.

And now to the problems. The Nedis SmartLife Air Quality Monitor uses a cheap VOC sensor that only detects major changes in air quality, and the CO2 sensor is not a real CO2 sensor with a NDIR sensor. Instead it´s a calculated number from the VOC sensor, this is also known as a eCO2 sensor. So when the VOC reading don´t change, the CO2 reading don´t change.

They say a picture says more than a 1000 words, and in this review, I agree.
Here are some graphs where you can see the readings from the 2 devices.
First one is CO2, where the blue line is the Airthings wave plus, and the purple line is the Nedis SmartLife Air Quality Monitor.

Next up is the VOC readings, where the top graph is the Airthings wave plus and the bottom graph is the Nedis SmartLife Air Quality Monitor.

My first thought was “Oh no, it´s defect”, so I reached out to the store, and they referred me to Nedis support. I sent these graphs to Nedis support, and their response was that it looked completely normal. They wrote “Unless there is a clear change, the VOC values will be fairly constant”, I replied that a change from 50 to 1800 ppb on the VOC reading was a clear change in my opinion, and they just told me to buy a device with a NDIR sensor if I wanted better readings.

As you can see on the graphs, this device is completely useless as a VOC or CO2 sensor.
And it´s too big and expensive for a temperature and humidity sensor, so I wanted to return it, but after 6 months on my table I installed it in my garage instead, so I can track temperature and humidity there.

Conclusion:
Don´t buy it! It´s not working as a VOC and CO2 sensor, and that defeat it´s purpose.
It requires a USB cable for power, and it´s connected to wifi, and that makes it a poor humidity and temperature sensor.
I did find a cheap CO2 sensor that work after searching enough, so stay tuned for a review of that.