Ventilation System Made from Hardware-Store Parts

Ulrich Pöschl and colleagues, Max Planck Institute for Chemistry (MPIC), Mainz, Germany, have developed a ventilation system made from hardware-store parts to make classrooms safer during the coronavirus pandemic. The ventilation system was developed to be suitable for DIY building and easy replication, and the blueprint was published free-to-view on the internet along with studies. The MPIC window ventilation system was designed, built, and tested in collaboration with several pilot schools. Data proving the high effectiveness of the ventilation system was scientifically collected and evaluated.

The system collects stale air directly above people before it can disperse into the room, transports it to the outside through a window, and replaces it with fresh air that flows in through another window. The natural convective, i.e., upward, flow of warm air is used for this purpose. This is created by the people themselves, as their body temperature is higher than the room temperature. Together with the exhaled air, CO₂ as well as aerosols that could contain bacteria or viruses are also carried upwards. Once it reaches the ventilation system, the stale air is extracted in a targeted manner, as in the case of an extractor hood in the kitchen, and is led outside via a pipe system.

The team was able to show that the window ventilation with a simple exhaust fan is similarly effective to various air filtration and disinfection devices. In addition, the system increases the overall air quality in the room, as opposed to filtering devices that recirculate air.

In the city of Mainz, window ventilation systems based on the MPIC model have already been installed and successfully commissioned in over 600 elementary and secondary school classrooms. Similar initiatives have taken place in Kaiserslautern, Pirmasens, and elsewhere in Germany, as well as in other countries.

The advantages of the MPIC window ventilation system include low cost and low weight, high airflow and the efficient direct extraction of respiratory aerosols, quiet operation, hardly any pressure differences with adjacent rooms, and low energy consumption. By using transparent materials, a darkening of the rooms is also avoided, and in winter there is no massive cooling of the classrooms.