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Disclaimer and credits: this repository is a fork fromhttps://github.com/kmetz/coro2sens.

Several changes have been made in this fork. Please also consult the README file of the original version.

The following sections have been updated for this repository:

Build a simple device that warns if CO₂ concentration in a room becomes a risk for COVID-19 aerosol infections.

• Measures CO₂ concentration in room air.
• Controls two LEDs (green + orange/red) for indication of warning/critical CO2 level.
• Controls a NeoPixel ring for indication of CO2 level and its criticality (optional).
• A buzzer can be connected that alarms if levels are critical (optional).
• Also opens a WiFi portal which shows current readings and a graph (not connected to the internet; optional).
• Can be built for ~ $60 / 50€ (parts cost).

This project was heavily inspired byideas from Umwelt-Campus Birkenfeld.

You can also find a good overview of the topic by Rainer Winkler here:Recommendations for use of CO2 sensors to control room air quality during the COVID-19 pandemic.

The sensor used here is the Sensirion SCD30 (around 70 USD / 60 €).

The pressure compensation by an additional sensor BME280 is currently no longer supported in this forked repo.

Based on aRecommendation from the REHVA(Federation of European Heating, Ventilation and Air Conditioning associations,rehva.eu)for preventing COVID-19 aerosol spread, especially in schools.

You can read current levels and a simple graph for the last hour by connecting to the WiFicoro2sens_<serialno> that is created.Most devices will open a captive portal, immediately showing the data. You can also openhttp://10.0.0.1/ in a browser.You can also control most of the settings via the web interface. Visithttp://10.0.0.1/config in a browser.

• A NodeMCU board (any other ESP8266 based board might also work).
• Sensirion SCD30 I²C carbon dioxide sensor module (mouser,digikey).
• (optional) NeoPixel ring
• (optional) 2 LEDs (green + yellow/red); the green one indicates "all good" (< 800 ppm) the other one that this limit has been exceeded
• (optional) A 3V piezo buzzer or a small speaker.
• (optional) You may want to work with Guido Burger's IoT Octopus PCB. This helps fixing the sensor and the NodeMCU, as well as the LEDs.
• (optional) A nice case :) Make sure the sensor has enough air flow.
• An Arduino IDE (select the board "NodeMCU 1.0 (ESP-12E Module)", v2.7.1 and v2.7.4 have been tested and should work; you may need to install the board support for the "esp8266")
• Arduino libraries:
  • FastLED (via the library manager)
  • zip file libraries(download .zip file, then import it viaSketch –> Include Library –> Add .ZIP Library...)
    • paulvha/scd30 (.zip)
    • me-no-dev/ESPAsyncTCP (.zip)
    • me-no-dev/ESPAsyncWebServer (.zip)