My Department has published guidance for schools in line with public health advice in relation to the practical steps for the Deployment of good ventilation practices in schools. https://assets.gov.ie/85177/d9643a37-5254-483e-a72e-d2a08ae36d46.pdf.
The guidance sets out for schools good ventilation practices by considering if room ventilation especially in classrooms can be improved without causing discomfort. Where possible the opening of doors and windows should be encouraged to increase natural ventilation. The guidance also sets out that air flow and ventilation should be increased where climate allows.
The overall approach for schools should be to have windows open as fully as possible when classrooms are not in use (e.g. during break-times, lunch-times and at the end of each school day) and partially open when classrooms are in use. Windows do not need to be open as wide in colder weather in order to achieve the same level of airflow into the classroom. This will assist in managing comfort levels in classrooms during periods of colder weather.