measuring air quality (CO2 / VOC) with ESP8266
Posted: Wed Jul 13, 2016 2:49 pmAfter toying around with the ESP8266 for a few months, measuring various things, like temperature, humidity and barometric pressure (with a lot of help from this great forum) I now want to add another measure to my dashboard, namely "indoor air quality".
After googling around, I found there are 2 things that could say something about the indoor air quality: CO2 and VOC (Volatile organic compounds).
Now the challenge is finding a suitable/affordable sensor.
For CO2, there are some cheap sensors around, like the MQ serie of sensors (especially the MQ135), problem is that they are analog and will provide a voltage between 0 and 3.3v, while the ADC of the ESP8266 requires a value between 0 and 1v. To use them, some kind of scaling would be required.
There seem to be some more sophisticated CO2 sensors around, but they come at a much higher price, for instance these http://sandboxelectronics.com/?product_tag=gas or these: http://www.co2meter.com/collections/co2-sensors
There's also a CO2 sensor on indiegogo that even uses a ESP8266 already. It's using a "dual beam NDIR" sensor, which apparently is very good, because it requires no calibration: https://www.indiegogo.com/projects/vthi ... -wifi--2#/ but again a quite expensive sensor...
I've also found 2 sensors that actually combine co2 and VOC measurements:
https://sgx.cdistore.com/ProductDetail/ ... 4aXOLiLSUk
http://ams.com/eng/Products/Environment ... iAQ-core-C
Both of the communicate via i2c and should therefore be usable with the ESP8266. For the second one there's even code available already that someone used with a arduino: https://forum.arduino.cc/index.php?topic=350712.0 but even without that, it should be easy enough to figure it out with the datasheet.
The only problem is that even these sensors are still quite expensive ($ 37.70 for 1 piece + $ 29.90 shipping costs).
My question is: are these the best sensors I could go for, or is there anything better around for a better price?
(Since all commercial products around are also quite expensive, I'm kind of guessing that measuring co2/voc is just a lot more complicated than temperature or humidity. have a look at this list for instance:
http://www.energycircle.com/guide/guide ... althy-home)
After googling around, I found there are 2 things that could say something about the indoor air quality: CO2 and VOC (Volatile organic compounds).
Now the challenge is finding a suitable/affordable sensor.
For CO2, there are some cheap sensors around, like the MQ serie of sensors (especially the MQ135), problem is that they are analog and will provide a voltage between 0 and 3.3v, while the ADC of the ESP8266 requires a value between 0 and 1v. To use them, some kind of scaling would be required.
There seem to be some more sophisticated CO2 sensors around, but they come at a much higher price, for instance these http://sandboxelectronics.com/?product_tag=gas or these: http://www.co2meter.com/collections/co2-sensors
There's also a CO2 sensor on indiegogo that even uses a ESP8266 already. It's using a "dual beam NDIR" sensor, which apparently is very good, because it requires no calibration: https://www.indiegogo.com/projects/vthi ... -wifi--2#/ but again a quite expensive sensor...
I've also found 2 sensors that actually combine co2 and VOC measurements:
https://sgx.cdistore.com/ProductDetail/ ... 4aXOLiLSUk
http://ams.com/eng/Products/Environment ... iAQ-core-C
Both of the communicate via i2c and should therefore be usable with the ESP8266. For the second one there's even code available already that someone used with a arduino: https://forum.arduino.cc/index.php?topic=350712.0 but even without that, it should be easy enough to figure it out with the datasheet.
The only problem is that even these sensors are still quite expensive ($ 37.70 for 1 piece + $ 29.90 shipping costs).
My question is: are these the best sensors I could go for, or is there anything better around for a better price?
(Since all commercial products around are also quite expensive, I'm kind of guessing that measuring co2/voc is just a lot more complicated than temperature or humidity. have a look at this list for instance:
http://www.energycircle.com/guide/guide ... althy-home)