Schools ventilation

It is important you consider how you ventilate your teaching and other occupied indoor spaces.

Along with testing, vaccination, good hygiene and physical distancing, good ventilation is important in minimising the risk of airborne transmission of the virus that causes COVID-19.

Most New Zealand schools are naturally ventilated, with windows, doors and vents which can be opened and closed. Some school buildings have ducted ventilations systems, which provide air flow to occupied spaces.

If you have concerns about ventilation or require advice, please contact your Ministry property advisor.

What is ‘good’ ventilation?

There are three factors which influence ventilation in indoor spaces: 

  • How a space is occupied and used
  • How the space is designed to manage temperature, humidity, and air flow
  • Ambient outdoor conditions

Good ventilation in schools is achieved when these three factors work together to supply fresh, clean air to the room’s occupants, while maintaining comfortable and healthy temperature and humidity levels during the school day.

Your teaching space may require more fresh air flow if it is feeling stuffy, if you can’t feel any breeze, if smells linger for a long time and/or learners are finding it more difficult to concentrate.

We encourage you to open windows and doors or run your mechanical ventilation systems prior to the start of the school day, and then during the day, especially during break times.

How to ventilate classrooms and other occupied school spaces

Getting as much fresh air as you can into occupied indoor spaces will minimise the risk of airborne transmission of COVID-19. This approach is consistent with the advice of the World Health Organisation and the US Center for Disease Control, and in New Zealand has been endorsed by the Ministry of Health, the Indoor Air Quality Research Centre and NIWA.

Consider how each learning space is used

Regardless of the design of your teaching spaces, you can improve the air quality in your space by: 

  • Limiting vigorous indoor activities such as singing, kapa haka and physical exercise,
  • Limiting the number of people in smaller, confined spaces,
  • Having regular breaks and stand-down times between classes where everyone exits the room while leaving windows and doors open to flush the air in the room.

Natural ventilation (opening windows)

Most New Zealand schools are naturally ventilated using windows that can be opened. The fastest, easiest, and most effective way to get fresh air into classrooms or indoor spaces is by opening the windows, doors, and any vents. 

  • It’s good practice to keep your windows open all day, not just during breaks, to readily replace indoor air with fresh air from outside.
  • If it’s not practical to fully open windows and doors during class times, try opening them just a little and then fully open them in break times or when the room begins to feel stuffy.
  • Where it is an option, opening windows and doors on the opposite sides of a room may increase the flow of air through the space. Opening high windows can also be very effective.
  • Ensure that security is not compromised by leaving windows and doors fully open after hours.

Some schools may have had their windows painted or fixed shut, are missing window winders or have other maintenance issues. If your windows don’t open as much as they were originally designed to do, please ask your caretaker or another appropriate person to repair them. 

Mechanical ventilation

Some school buildings have ducted mechanical ventilation systems, which provide air flow to occupied spaces. Examples are Heating, Ventilation and Air Conditioning (HVAC) systems, heat recovery and heat transfer systems.

For spaces with any form of mechanical ventilation system, ensure that the system:

  • is well-maintained and is being regularly serviced, including the changing of filters
  • has been configured to use as much fresh air as possible, with limited recirculation
  • begins operating prior to, during, and after the school day or until after a space no longer in use for the day.

Mechanical ventilation systems are installed and maintained by qualified professionals, who should be consulted in reconfiguring the system to maximise fresh airflow and improve how the air is being filtered.

Heat pumps

Heat pumps do not provide fresh air – they only heat, cool and recirculate the air in the room. The thin mesh filters fitted to heat pumps should be regularly cleaned but are not designed to filter fine contaminants from the air.

You can continue to use a heat pump to heat or cool a space and can use them with windows and doors open to help move fresh air through a space. 

Portable HEPA air cleaners/purifiers

We are aware that schools are being approached by suppliers offering to sell air monitoring and air treatment technologies.

Advice from leading international authorities including World Health Organisation and the US Center for Disease Control is that portable air cleaners are not a substitute for good ventilation in any circumstance.

HEPA refers to a high-efficiency particulate absorbing filter used in mechanical ventilation systems and portable air cleaners.

When used properly, portable HEPA air cleaners can remove exhaled particles from the air, reducing airborne transmission of viruses by aerosols, including the virus that causes COVID-19.

We are investigating how active technologies like air monitoring and air treatment may supplement the management and ventilation measures already in place in schools. We are working closely with a panel of experts including the Ministry of Health and NIWA on this.

If you have been approached by a supplier, it’s important to understand that products on the market vary greatly in how they function, their suitability in a teaching space, quality and accuracy and where they’re ideally located. Some systems promoted as air cleaners can produce ozone or other products that can be harmful in a classroom setting.

We will continue to keep you updated on the work we are doing and will provide further advice. In the meantime, please contact your property advisor before purchasing air cleaners to discuss any concerns about ventilation.

Ventilation self-assessment

We have prepared an assessment tool to help you ensure your classrooms or indoor spaces are well ventilated and help identify steps that you can take to improve ventilation.

Please check this page regularly for updates to the guidance and further self-assessment tools being made available by the Ministry.

We’re here to help. If you need support, have any questions, or have a learning space you are concerned about, please contact your Ministry Property Advisor.

Self-assessment tool for classroom ventilation [PDF, 145 KB]

Frequently asked questions about ventilation

We have prepared some frequently asked questions to help you determine where your best ventilated spaces are, and how you can increase fresh air flow as some students return to school.

While we have prepared this information specifically for learning spaces, it also applies to other spaces like staff rooms, offices and break out rooms.

Can my classroom be well ventilated if it only has opening windows on one side?

Yes – this is called single sided ventilation and can provide good air flow. If you have a door you can open on the other side of the room this will also enable ‘cross-flow’ ventilation which can be more effective, even if you only open the door periodically (for example during breaks or before or after school).

My classroom has high windows – are they effective at ventilating a space?

High windows can be very effective in supporting good ventilation as they draw in replacement air at the lower levels regardless of whether they are on the same or another side of the classroom.

What if I can’t ventilate a classroom?

All classrooms have either natural or mechanical ventilation. If you have a classroom, learning or other indoor space that you can’t ventilate, use our ventilation self-assessment tool to identify the right course of action.

If your class involves physical activity, heavy breathing, or expulsion of air (for example singing, kapa haka and physical exercise), consider moving your activity outdoors or to a better ventilated space, or a bigger space such as the gym or hall.

How can I adjust my room temperature and keep it ventilated?

While we are encouraging schools to keep their windows open, we understand it won’t always be possible, especially in winter or in hot weather.

If you need to heat/cool the air in your classroom, you can turn your heater, heat pump or air conditioner on, and partially close the windows or open them periodically during the day to let fresh air in. Please note that heat pumps only recirculate air which is why it’s important to still have some air flowing into and out of the space.

If you have an air conditioner or heat pump you can use to cool the air in your room, please make sure you also keep your windows open partially or periodically during the day so there is still fresh air flow.

If it’s too hot, cold, windy or rainy and you need to close your windows and doors, open them during breaks or for short intervals (i.e. 10-15 minutes every hour).

What about bathrooms?

We recommend that bathrooms have very good ventilation at all times. This may mean operating extractor fans for the full school day, and/or keeping windows open where possible.

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