Measuring bad atmosphereRed, amber, green: a CO2 traffic light

When heads start spining in a lecture, lack of oxygen becomes a problem. As THGA's campus lies next to a noisy freight railtrack and it gets quite cold here in winter, permanent airing of rooms is not really an option. Therefore, airing has to be optimised: when is the best time to open the windows and for how long? These are the questions Frank Schleking explored in his Master thesis of Electrical Engineering and Information Technology: he developed a microcontroller-based CO₂ detector which uses the global IoT network Sigfox to transmit data wireless and at low energy consumption: that was the beginning of the CO₂ traffic light.

Red means action

This traffic light shows very precisely when the breathing air exceeds a certain CO₂ limit value and windows should be opened. To make this work, a sensor records the air parameters; a microcontroller is installed on this sensor which converts these parameters into data which can be displayed as numbers: not only the CO₂ content, but also temperature and humidity. If people do not want to read the numbers in detail, they can follow the traffic light code: if the light is green, everything is fine; if it turns to red, action needs to be taken and windows and doors opened. The department's own lecture theatre is the testing ground of the system. Due to the Sigfox connection users all over the world can access the data online and check the local air quality.

How important such a system is for everyday life has become crystal clear during the Covid-19 pandemic because the spread of the virus depends on the air quality in a room. The more people get together, the higher the CO₂ level in air and the easier the virus can travel. This is another reason why THGA intends to install more of these detectors in its lecture theatres. Moreover, a flower-shaped variant has been designed for offices and school classrooms in collaboration with the business engineers at THGA.