Hengelo must invest two hundred million euros in the coming decades in the renovation and new construction of dozens of school buildings in the municipality. In some schools, teachers are in the classroom with a traffic light system. If the CO2 level in the room rises too high, the windows must be opened. Buildings are outdated and need to be renovated, says director Herman Soepenberg of the Symbio school foundation. The need is great, several buildings are at risk of closure if something is not done quickly.