This article is quite old. Read the new article, with the updated tutorial to build the home CO2 meter here:
CO2 (Carbon Dioxide)
CO2 (Carbon Dioxide) is a gas dangerous to humans. In high concentrations it can produce dizziness, headache, high blood pressure, rapid heart rate, choking and loss of consciousness.
Caution should be exercised with it, especially in the places where there are many people and little ventilation, as we expel it in the breathing process.
Plants produce the reverse effect. Through the process of photosynthesis, they absorb CO2 and release oxygen..
I have been thinking for years about having Wifi CO2 sensors in the house, which would allow me to trigger alarms when levels are too high or perform other actions.
About a year ago, I installed a Netatmo weather station (which I didn't need, as I have a Davis Vantage PRO2) and one of the nice things about it is that it has an indoor CO2 sensor.
The interior module of the Netatmo station is installed in the living room (providing data on temperature, humidity, brightness, sound pressure and CO2) but I would like to be able to measuring CO2 in more places and, in particular, to take spot measurements to know if we are "at risk", e.g. measuring CO2 levels. in different bedrooms while we sleep.
- Real-time monitoring of your indoor and outdoor environment: temperature, humidity, indoor and outdoor air quality, indoor noise level, barometric pressure, etc.
- Receive real-time alerts: with our weather station, set up indoor and outdoor alerts and receive notifications on your smartphone; know when to ventilate with the ventilation alert.
- Access your data remotely and with your voice: easily access your weather measurements at any time from your smartphone, tablet or computer, or use your voice to interact with alexa on amazon echo or siri thanks to apple homekit compatibility.
- Analyse the past: access your historical data to see what happens when you are away or analyse graphs to understand weather trends.
- Anticipate the future: check 7-day weather forecasts to adapt your clothing and outdoor activities.
Until relatively recently, CO2 sensors were very expensive and needed a calibration which was not normally available to amateurs. This has changed considerably in recent months with the emergence of some economic sensors easy to use and pre-calibrated at the factory.
I recently started looking for information about the "state of the art"I was looking for a way to see if it was finally time to tackle the issue of sensors, and I came across a number of rather interesting sensors. Among the ones I came across was one that stood out from the rest, the MH-Z19.
CO2 detector features and design
I had already decided that I was going to build a CO2 meter, now I had to decide what functionalities it would have and make the design.
As features, the most important thing was that it had a wifi connection and that I could connect it to my home automation system, the rest didn't matter much to me.
However, I wanted it to be a cheap design, as I was planning to put several detectors in the house and I didn't want the budget to go through the roof.
Construction of the Wifi CO2 detector
The detector consists of an ESP8266 microcontroller module with integrated Wifi and a CO2 sensor.
Find the NEW tutorial to build the new version of the CO2 meter here: