VIEWS & OPINION
Why CO2 monitoring in schools is not enough to
protect against COVID-19 Comment by Cat Goldsmith, Jaga UK's Marketing Manager and Climate Designer
The Department for Education recently announced the provision of 300,000 carbon dioxide (CO2) monitors to all state-funded education settings from September, to enable staff to identify where ventilation needs to be improved. Although CO2 levels are not a direct
measure of possible exposure to COVID- 19, checking levels using a monitor can help identify poorly ventilated areas. The government also mentioned the
launch of an air purifier trial in 30 schools in Bradford, designed to assess the technology in education settings and whether they could reduce the risk of transmission. But is CO2 monitoring and providing air purifiers enough?
Why use CO2 monitors? In educational spaces, CO2 is the key indicator of ventilation performance for the control of indoor air quality, so monitoring levels in classrooms is a sensible first step for UK schools. But the UK’s Health and Safety Executive (HSE) says that CO2 measurements should be used as a broad guide to ventilation within a space rather than treating them as ‘safe thresholds’ [1], so care must be taken when staff are using these monitors in isolation. It’s well known that the World Health Organisation and Center for
Disease Control advise letting fresh air into indoor spaces to help remove air that contains virus particles, preventing the spread of Covid-19. If the CO2 monitor tells staff that the room is filling up with potentially
infectious exhalations and there is not enough ventilation, then action must be taken to do as these health agencies advise and bring fresh air in from outside. This should always be the first option.
Why air purifiers aren’t the solution Air purifiers remove particles from the air, usually using a filter made of tightly woven fibres. They can capture particles containing bacteria and viruses and can help
reduce disease transmission. Removing the virus from the air inside the building using an air purifier
should only be done if fresh air cannot be brought in through effective ventilation strategies. In the US, the EPA guidance for schools in relation to Covid-19 states
that “portable air cleaners can be used to supplement increased HVAC system ventilation and filtration, especially in areas where adequate ventilation is difficult to achieve”, but that “air cleaning is not a substitute for source control and ventilation.” [2]
Effective ventilation strategies There are three methods of ventilation:
• natural ventilation – fresh air that comes in through open windows, doors, or air vents, • mechanical ventilation – fans and ducts that bring in fresh air from outside. • hybrid ventilation – part natural and part mechanical
The government’s BB101 document which provides guidance for
ventilation, thermal comfort and indoor air quality in schools, recommends a number of strategies depending on school building design constraints, from completely natural to completely mechanical [3]. In any room, the more people inside, the faster the air should be
replaced, which is not always possible with natural methods. Although opening a window for natural ventilation is a quick and easy method, it can lead to cold draughts, and if the school is in a city location, can also lead to increased noise and air pollution. Many older schools have their windows painted shut so this is simply is not an option for them. Natural ventilation is unpredictable, being reliant on external air movement and pressure to drive the stack effect. Mechanical ventilation, on the other hand, is controllable and exact.
Fully programmable supply and demand systems monitor air quality and room occupants and deliver clean, filtered, fresh air on demand, ensuring optimum indoor air quality (IAQ) all year round. In general, it is recommended that a balance of both natural and mechanical is best, as a school building ventilated only by a mechanical system misses out on ‘free’ natural ventilation on the days when conditions are right.
A more reliable solution BB101 specifies that “Where mechanical ventilation is used, or when hybrid systems are operating in mechanical mode in general teaching and learning spaces, sufficient outdoor air should be provided to achieve a daily average concentration of CO2 of less than 1000 parts per million (ppm), during the occupied period, when the number of room occupants is equal to, or less than the design occupancy. “The maximum concentration should also not exceed 1500 ppm for
more than 20 consecutive minutes each day when the number of room occupants is equal to, or less than the design occupancy.” It is crucial that a ventilation system can achieve this and that it can
adapt depending on the number of occupants in each room. This can be achieved with a demand-controlled ventilation (DCV) strategy and system such as Jaga’s Oxygen which can be built in to Jaga’s standard, energy- efficient Low-H2O radiators. Jaga’s Oxygen ventilation system is built into school radiators. It
monitors CO2 levels, occupancy, and activity, bringing in the right amount of fresh, filtered air from the outside for a healthy indoor school environment. A DCV system uses a variety of sensors to constantly monitor the
concentration and rate of change of CO2 in each school room. It considers the number of occupants and their activity levels, automatically adjusting the volume of fresh, filtered air that is brought into the room, balancing the airflow to provide the best comfort level and CO2 control. As well as ensuring a healthy, comfortable indoor climate for the school
throughout the year, Oxygen is an energy-efficient, low power consumption system, so it’s a great solution for schools looking to reduce their carbon footprint, energy bills and lifecycle costs. Oxygen is a proven system already being used by many schools across
the UK. A handful of these are listed as case studies on the Jaga UK website so please view our case studies page for more information.
Here to help If your school is not one of the 300,000 being provided with a CO2 monitor under the government scheme, or if the results of your monitor are showing high CO2 levels, Jaga UK may be able to help. We are inviting schools and local authorities to email us with ‘CO2 Monitor’ as the subject line and we will contact you to discuss your requirements. Alternatively, visit
www.jaga.co.uk for more information.
References: 1. Health and Safety Executive (HSE) (2021) Ventilation and air conditioning during the coronavirus (COVID-19) pandemic. Available at:
https://www.hse.gov.uk/coronavirus/equipment-and-machinery/air-conditioning-and- ventilation/
identifying-poorly-ventilated-areas.htm 2. United States Environmental Protection Agency (EPA) (2021) Air Cleaners, HVAC Filters, and Coronavirus (COVID-19). Available at:
https://www.epa.gov/coronavirus/air-cleaners-hvac-filters-and-coronavirus-covid-19 3. Education and Skills Funding Agency (2018), ‘Building Bulletin 101 (BB101); Guidelines on ventilation, thermal comfort and indoor air quality in schools. Available at:
https://www.gov.uk/government/publications/building-bulletin-101-ventilation-for- school-buildings
24
www.education-today.co.uk
September 2021
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52
