The main focus of the "Office" variant is the concentration and performance capability, i.e. the mental fitness of the employees. Accordingly, the traffic light only switches to yellow at 1200 ppm CO2, from 2000 ppm CO2 to red and from 2500 ppm to red flashing with discreet acoustic support.The CO2 traffic light looks like a real fan. Only if the air is sufficiently fresh, where our human concentration and efficiency is fully available, and our immune system has the highest level of protection, the traffic light lights up green. In the case of bad air, i.e. the consumption of oxygen and the exhalation of carbon dioxide with the breathing air, the traffic light first lights up yellow, in the case of further increase from 2000 ppm red. At the latest, extensive ventilation should be urgently needed. As the CO2 concentration continues to rise above 2500 ppm, the traffic lights will flash red and sound an alarm. An internal light sensor switches the LEDs off in darkness and thus saves energ