What is a CO₂ Traffic Light?

CO₂ Guard 10

A CO2 traffic light measures the CO2 concentration in indoor spaces. It is a tool for correct ventilation behaviour in public buildings, schools and offices. The measuring device, equipped with indicators in traffic light colours, shows how good the air quality in the room is and signals when a threshold value is exceeded. Ideally, the measurement scale of a CO2 traffic light is based on the EN 13779 standard, which regulates the ventilation of non-residential buildings. 

Better Indoor Air – Fewer Aerosols

Germany's Federal Environment Agency (UBA, Umweltbundesamt) has been recommending CO2 meters for assessing indoor air quality in schools since 2008¹. The CO2 traffic light is currently attracting attention due to the good measurability of the odourless gas compared to aerosols. After all, a higher CO2 content is accompanied by an increased aerosol count in the air. These microscopic particles are emitted with the air we breathe and can be carriers of viruses or bacteria. The CO2 content can therefore be a good indicator of the aerosol concentration indoors and shows when a room should be ventilated

¹ https://www.umweltbundesamt.de/sites/default/files/medien/publikation/long/3689.pdf

How a CO₂ Traffic Light Works

The CO2 traffic light contains a sensor that continuously measures the CO2 content of the indoor air. The traffic light colours indicate the gas's concentration range. The carbon dioxide content of the air is usually stated in ppm (parts per million). The preset threshold values can vary depending on the manufacturer. The following typically applies: a green light is shown for a value of less than 1,000 ppm CO2, yellow up to 2,000 ppm and a red light if the CO2 concentration is more than 2,000 ppm.

The CO₂ Traffic Light by Sensor Manufacturer E+E Elektronik

E+E Elektronik is one of the leading manufacturers of CO2 sensors and measuring instruments in Austria. Designed for measuring CO2 in schools and public buildings, the CO₂ Guard 10 features a high-quality CO2 sensing module for accurate measurements, and an easy-to-understand LED traffic light system with an audible threshold indicator. 

Highlights of the CO2 Traffic Light by E+E Elektronik

  • Immediately ready for use, battery operated
  • Easily wall mounted, or can be used as a desktop device 
  • 6-part measured value scale, for all common indoor situations
  • High-quality CO2 sensing module with pressure and temperature compensation
  • Maintenance-free thanks to smart auto-calibration (NDIR dual-wavelength measurement principle)


More details on the CO₂ traffic light »

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