The education minister says teachers should open windows “at a lower level” if their classrooms are cold.
Ventilation requirements for pandemic safety have seen some room temperatures dip below seven degrees Celsius this week.
Health and safety rules require teaching to be suspended at 16 degrees.
Teachers’ unions have criticised a lack of progress on acquiring air filtration systems for classrooms.
Minister Norma Foley says going straight to technology, like HEPA filters, is not the answer.
"Open them before class and after class [...] practicality in terms of how you would operate them during class, in other words they can be open at a lower level.
"I know myself from spending years within the classroom setting, teachers and staff know exactly how to operate the opening and closing of windows."