Where there are many people in a room, "stale" air quickly collects. The CO₂ concentration in the room is increasing, and the risk of corona infection is also increasing. To ensure adequate air quality in classrooms, the rule of thumb is 20-5-20: 20 minutes of lessons, 5 minutes of shock ventilation, 20 minutes of lessons.
This rule is particularly important in the current situation, because the risk of corona infection in closed rooms can be reduced by regular and consistent ventilation, in addition to protective measures such as maintaining minimum distances and wearing a mouth-nose covering, according to the Federal Environment Agency.
Small suspended particles, so-called aerosols, which are produced when breathing, coughing, talking and sneezing, are released into the air and remain in the room for hours to days. They are considered the main transmission route for the coronavirus. Especially in classrooms where students and teachers are close together, a high supply of fresh air must therefore be ensured. In cold temperatures, however, constant ventilation also means heat loss and thus results in an increased health risk.
The energy service provider enercity is therefore supporting schools in the Hanover area with a pilot project: classrooms in three schools in Laatzen and the Humboldt School in Hanover have been equipped with so-called CO₂ traffic lights – intelligent measurement sensors that enable teachers and students to ventilate according to their needs.
How are CO₂ traffic lights used?
CO₂ traffic lights measure the concentration of carbon dioxide (CO₂) in the indoor air and give a color signal as soon as the air quality in the room deteriorates. This signal gives students and teachers an indication when it is time to open the windows again. According to the Federal Environment Agency, a CO₂ concentration of no more than 1000 ppm – parts per million – indicates sufficient air exchange under normal conditions.
Although such CO₂ measurement does not allow a statement to be made about virus-containing aerosols, it can still be a tool to reduce the risk of corona infection. This is because an increased concentration of carbon dioxide in the indoor air is an indicator that there is a lot of "used" air in the room – and thus also an increased concentration of aerosols.
enercity takes care of both the selection and procurement of the measurement technology and supports the installation. The data measured by the CO₂ traffic lights is also made available to schools in real time via a website and can be used for climate and health topics in the classroom, for example.
enercity considers the pilot project a success. In the future, more schools are to be equipped with the intelligent metering technology. The Lower Saxony Ministry of Education and Cultural Affairs is promoting the corona protection measures in schools and is making 45 million euros available for this purpose. 20 million euros of this will go into material protective equipment such as CO₂ traffic lights.
source : Corona-Schutzmaßnahmen: CO₂-Ampel für Schulen - enercity Magazin