Spaichingen secondary school uses CO2 traffic lights

Spaichingen secondary school uses CO2 traffic lights

WERMA traffic light set promotes correct ventilation in classrooms


The smart CO2 traffic light set made by WERMA Signaltechnik, based in Rietheim-Weilheim, Germany, continuously measures the current concentration of carbon dioxide (CO2) in the ambient air. Three traffic light colours accurately indicate whether or when it is time to air the room. This regular ventilation is intended to protect all persons compelled to remain in closed rooms for longer periods of time from a COVID-19 infection and other infectious diseases.


Clever, safe and easy to understand

The secondary school in Spaichingen uses these innovative traffic lights to provide maximum safety for teachers and pupils alike. Headmaster Jürgen Pach is delighted that all classrooms are now equipped with CO2 traffic lights. He says: "I think this is a step in the right direction: it will protect all those present in the long term and give us the best possible air quality." He adds: "We also have CO2 traffic lights in our staff room and meeting room, so everyone feel nice and safe."


Manuel Vogel teaches mathematics, chemistry, natural sciences and technology at Spaichingen secondary school and is also enthusiastic about the new traffic light system: "The official advice is to air rooms every 20 minutes. But when we teach 20 or more pupils in a classroom, the CO2 traffic light shows us that we urgently need to air the room after 10 minutes at the most." He is also pleased that the children approve of the traffic lights: "The traffic light is clear, easy to understand and needs no explanation. Our pupils usually notice that the traffic light signal has changed to yellow before the teachers. They even squabble about who gets to open the windows.”


He is sure that the CO2 traffic lights are not a short-term investment, but will be of lasting advantage in the classrooms: "Because low CO2 content in the room not only protects against infection, but also improves the concentration and performance of all those present."


The WERMA CO2 traffic light

WERMA's solution for CO2 measurement in indoor air consists of a three-tier signal tower, which is immediately ready to use and very easy to install thanks to Plug & Play: simply plug in the supplied power supply unit, wait until self-calibration has been completed and the traffic light is ready for use. The system instantly measures the current CO2 concentration in the ambient air and displays the result using three traffic light colours:

  • If the CO2 concentration is below 1000 ppm, the traffic light is green, indicating that the air quality is OK.
  • If the CO2 concentration exceeds 1000 ppm, the traffic light turns yellow and indicates that ventilation is recommended.
  • The red signal indicates that significant ventilation is necessary as the CO2 concentration is above 2000 ppm.
  • If the limit of 3000 ppm is exceeded, a red flashing light indicates an acute need for ventilation.


The signals are clearly visible from all sides thanks to the 360-degree illumination and the extremely bright LEDs guarantee that they are clearly visible even in direct sunlight and bright surroundings.


Ideally, the CO2 traffic light is placed in the middle of the room, i.e. not too close to the window and not higher than 2 metres from the floor. Since carbon dioxide is distributed fairly evenly throughout the room, a traffic light is sufficient for most rooms. Two traffic lights are recommended in larger conference rooms or sports halls.


For more information regarding the CO2 traffic light click here.

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