During the Corona pandemic, schools in Germany must ventilate their classrooms regularly in order to reduce the risk of infection. Schools which are equipped with a heat recovery ventilation system,including Passive House schools,offer significant benefits for their users.© Pixabay
Passive House Institute about schools: ventilation systems offer major advantages
Darmstadt, Germany. With the start of the cold season, attention is increasingly shifting to schools and the question of how the risk of infection with theSars-CoV-2 virus in classrooms maybe reduced. The German Environment Agency recommends frequent air replacement;in schools that do not have ventilation systems,this air exchange should be achieved by opening the windows. The German Environment Agency expressly advises against mobile air purification units as a substitute for ventilation with fresh air. These mobile appliances should only be used in addition to active ventilation. The Passive House Institute endorses this recommendation and draws attention to the advantages of a ventilation system with heat recovery.
Fresh air mandatory
According to a recent publication from the German Environment Agency, the likelihood of high concentrations of infectious particles existing in classrooms is very high due to the rooms’ low air volume in relation to the high number of individuals. “Because most schools in Germany are not equipped with a central ventilation system, air exchange via the windows is the best and often the only way to let fresh air into the classroom,” explains the German Environment Agency (UBA).
Removing infectious particles
According to the recommendations of the UBA, in the cold season,the rooms should be aired every 20 minutes for3 to 5 minutes, in the summer for10 to 20 minutes. With this ventilation,not only infectious particles but also moisture, particulate matter and carbon dioxide (CO₂)will be removed.
Air purifier no substitute for ventilation
In contrast, mobile air purification units usually are not able to quickly and reliably eliminate viral particles in the indoor air, especially in densely occupied classrooms, according to the German Environment Agency. In addition, they cannot remove CO₂ or moisture.Therefore mobile air purification units are only helpful in addition to active ventilation. The UBA goes even further and claims that if a room cannot be properly ventilated,it is unsuitable for school lessons.
The Passive House Institutes hares the view of the German Environment Agency and, at the same time,draws attention to the advantages of a ventilation system with heat recovery. According to the Institute, in buildings which do not have a ventilation system with adequate supply air, the only other possible alternative is ventilation via the windows. Professor Wolfgang Feist also emphasises that mobile air recirculation units are no substitute for ventilation with fresh air. Although using these recirculating air purifiers may certainly reduce the risk of infection when used as an additional measure,since they reduce the number of suspended matter which can transport viruses. For this, however, they must be equipped with HEPA filters that only trained personnel with personal protection equipment can replace and dispose.