Homey Community Forum

Air Quality / CO2: what is it exactly and which sensor to buy

I am a bit confused about air quality and CO2 sensors.

First off all: what is is and where is it measured in?
My Withings Scale and Netatmo Weatherstation measure CO2 in PPM. Which is quite straightforward.
I have also a Dyson. Which reports the outside quality (AQI) in a scale from 1 to 11. And measures the inside quality (particles and VOS (= Dutch; Vluchtige Organische Stoffen) in a scale without any numbers (it uses good, average, bad, very bad).
What is Dyson really measuring?

Second: I want 2 sensors to measure quality
I really like 2 CO2 sensors, to measure the home office and bedroom for CO2. While working from home, I noticed that the living room CO2 is peaking. I want to monitor those rooms too.
Are there any good sensors? Or is an extra inside module for Netatmo the better option?

Also, are there sensors that also measure what my Dyson measures? Or is that not good information to know (other for Dyson to sell their air cleaners)?

Can anybody help or explain? :slight_smile:

CO2 is an indication for air quality / level of ventilation

I use the Netatmo sensors as you mention and have those connected to Homey. Every morning if CO2 levels went over 1000 it sends me a warning.
In optimal situation it would trigger a process which would open a window or increase ventilation.

You could buy the Netatmo healthy home coach if you want more plug and play CO2-sensors.

PM2.5/PM10-sensors reacts to particles in the air, like dust, smoke, pollen and so on.

VOC-sensors also reacts to human breathe but also to general “bad smell”, paint and so on. And sometimes it’s a bit to hard why the value is increased. Often the value is calculated to some index instead of ppm where low value is the best air quality the sensor has measured and a high value is the worst. The sensors often self calibrate so it’s not possible to compare those values between different homes but they are good to measure the change in air quality in a specific location.


Insights from one of my arduino air quality sensors, measuring CO2, VOC and PM2.5.

MCO Home CO2. Works perfectly and accurately.

Thanks!
@Toon_Vos you have an excellent last name for this topic! :slight_smile:
@Martijn_C for that price I think I add just a Netatmo module to my system. @rindler, the Home Coach is, unfortunately, a different Netatmo product (and does roughly the same as the Weather Station). I think Arduino projects are not really for me.
I had hoped there was a bit of an affordable sensor.

Sure, but in my opinion the quality is better and you’re not relying on WiFi/API’s. Direct integration.

Just thought it’s not possible to add another netatmo indoor module? That was why I suggested the home coach.

That is stating the obvious indeed. But to be honest I am not looking for that level of quality I guess. I do agree that locking in into a third party service is always the second best option, but putting everything in the balance: for ⅓ of that price I am happy with it. But thanks! :slight_smile:

@rindler I believe you can add up to 2 extra modules to the weather station, adding it up to a total of three (plus one outside module).

Ah, seems right. Then I think it’s the best choice except that you don’t get any values when the netatmo cloud is down, hehe. Happened me once for a couple of days, but other than that I think the values are about right for that price.

I have build one this weekend based on a Wemos mini and the SGP30 shield for around €18. It measures TVOC and eCO2.

It uses my MQTT server to connect with Homey using the Tasmota MQTT app.
Installing Tasmota on the Wemos is pretty easy and well documented on the wiki pages.

I don’t know how accurate the measurements are because of the use of eCO2.
But for my purpose I think it will work.

i’m using the Awair sensors, which have more than only co2. really like those and have direct integration.

I’m using a Norwegian designed air quality monitor that works perfectly with Homey, called AirThings.
Here’s a screenshot from within the Homey app, as you can see it covers most of the data you need.