Balancing classroom ventilation and heating in winter

A class at Papanui Primary School in Ōtautahi enjoy the fresh air from an open outdoor entrance.

Fresh air flow is always an important part of a classroom environment, but especially as we head into winter when fully opening windows and doors isn’t so practical.

Making sure indoor spaces are well-ventilated and have lots of fresh air is recommended for schools at all levels of the Covid-19 Protection Framework. To keep this top-of-mind, teachers at Papanui Primary School have made ventilation part of their daily routine and daily set-up.

Striking a balance

A class at Papanui Primary School in Ōtautahi enjoy the fresh air from an open outdoor entrance.

“In our Covid-19 response planning, we’ve layered different tools together including good ventilation, good hygiene and hand washing, and the use of face masks. Our teaching team are active leaders of teaching and learning in their classrooms, but also of the public health response for our school,” says Papanui School principal Paul Kingston.

Paul adds that as it’s getting colder, they’re making sure ventilation and heating are working hand-in-hand.

“We’ve found that we don’t have to compromise on having one or the other, we just do our best to balance them throughout the day. It’s one of the key things our teachers think about now when using a space – ventilation is part of our role in managing a classroom environment.”

Air flow behaves differently at different temperatures and cooler weather can actually improve air flow compared to when it’s warm outside. The bigger the temperature difference between outside and inside, the more efficiently fresh outside air is drawn in through open windows. This means windows that are just partially open by five centimetres can create good air flow in cooler weather.

There are different ways to promote air flow in cooler weather, which can be combined depending on what works for a particular room or space. As a rule of thumb, schools can partially open windows (5cm) to allow air flow. They can also take short refresh breaks every hour to flush the air in a room by opening all the windows and doors, pre-heat rooms before the start of the school day to improve the draw of outside air in through smaller window openings, and continue to heat rooms while the windows are partially open.

Having partially open windows supports good air flow alongside heating.

Monitoring ventilation

To keep track of how well-ventilated a space is, schools can continue using portable CO2 monitors. Sustained high CO2 levels can indicate a need to improve ventilation, but there are other ways to tell if a room needs some air.

“In addition to using our CO2 monitors to assess ventilation, our teachers have developed a good sense for when a room is well-ventilated – basically if a room feels or smells stuffy, it’s time to open the windows or take a refresh break to flush the air in the room. Once you have that awareness of what it feels like to be in a poorly ventilated space versus a well-ventilated one with lots of fresh air, you can usually tell by your gut instinct,” explains Paul.

“We manage any stuffiness or elevated CO2 levels by taking a balanced, pragmatic approach and keeping the rooms warm with our heating going while having windows partially open and then using break times to totally flush out the room with fresh air.”

Ventilation advice and information

Making ventilation part of their daily routine is key at Papanui Primary School, including getting ākonga involved.

Te Tāhuhu o te Mātauranga | The Ministry of Education has published advice about promoting air flow in winter on Te Mahau website, which has been informed by local research and endorsed by its expert ventilation advisory group.

For further ventilation assistance and support schools should contact their Ministry property advisor or ventilation.mailbox@education.govt.nz.

For ventilation advice, including information about CO2 monitors, air cleaners and guidance for cooler weather, visit temahau.govt.nz/covid-19(external link)