Open Source Indoor Air Quality Sensor by CRT Labs (
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Open Source Indoor Air Quality Sensor

An open hardware and software indoor air quality sensor provided by the National Association of REALTORS and CRT Labs in collaboration with the Built Environment Research Group at Illinois Institute of Technology.



  • Can measure upto 8 indoor environmental quality parameters (listed below)
  • Atmel ATmega328P 16MHz 8-bit processor (based on Arduino platform)
  • Genuine FTDI chip for serial communication with host computer
  • Mini RGB LED for status and notification
  • Programmable button for custom actions such as reset, configuration, etc.
  • Long range wireless data transfer using FSK radio (no dependence on WiFi, cellular, etc.)
  • Small footprint PCB board (less than 2x2 inches or 50x50mm)
  • Low power requirements (35mA idle with all sensors running, 190mA peak during wireless data transfer)

Measurement Points:

  • Temperature (Si7021)
  • Relative Humidity (Si7021)
  • VOC (Volatile Organic Compounds) (CCS811/IAQ-Core)
  • CO2 (MH-z19)
  • Particulate Matter, PM2.5 (PMS7003)
  • Barometric Pressure (BMP280)
  • Light Intensity (TSL2591)
  • Sound Intensity (Electret Microphone)


  • FSK radio (RFM69HW 915MHz)
  • MicroUSB (FTDI FX231XQ)

License: Apache License Version 2.0

For the Raspberry Pi HAT, please visit the PiAQ Website and repository