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How can CO2 monitors aid school ventilation?

Hassan Sherbaz, Solutions Architect at Connexin, explains how high CO2 levels can lead to disruption within schools and how CO2 monitoring solutions can identify areas of concern —helping schools make informed decisions about ventilation across their buildings to protect students.


Following on from the recent announcement from the Department of Education, schools in the UK are now looking to deploy CO2 monitoring solutions that span roughly one device for every 2 classrooms within the next term. Whilst being an ambitious undertaking, it is a necessary one that ensures school premises with zones of poor ventilation are identified, and the appropriate improvement is applied. Whilst ventilation has been well managed in the summer months by keeping windows and doors always open, schools need to find a balance in the winter season by ensuring temperature and humidity conditions are also acceptable and comfortable for students. 

By monitoring CO2 levels throughout the day, schools can identify areas that require the windows and doors to be opened ahead of their unhealthy peaks, whilst still maintaining comfortable temperature and humidity. Once a particular schedule for opening windows is established for certain zones, the devices can be moved to other at-risk areas to collect data over several weeks. This allows schools to gain a full insight into their whole building without monitoring fixed devices across the buildings. 

Whilst COVID has accelerated the focus on ventilation, it’s not a new problem for schools. The preferred level of CO2 is currently 1000ppm (parts per million), with an acceptable baseline of up to 1500ppm. A significant number of research studies have shown that high CO2 levels can lead to: 


Health impacts – Extended exposure to levels of 2,000ppm can result in drowsiness and headaches. There is evidence that long-term health impacts can occur with exposure to 5000ppm. 

Reduced productivity – A study of 200 pupils showed a decrease in word recognition by 15% and picture memory by 8% if levels reach 5000ppm relative to the acceptable baseline. 

Higher rates of absence – For every 100ppm of CO2 above the recommended baseline, students on average had an extra half day as school year of absence 

Building damage due to damp – Condensation and mould growth is generally caused by poor ventilation which leads to damage to the building fabric and serious health problems, such as respiratory disorders.


Understanding long-term CO2 levels can also inform investment and upgrade of the building’s ventilation systems. For example, 2100 ppm of CO2 is a measurement indicator for requiring a ventilation rate of 3 L/s. Without having the baseline and identifying the areas at risk, it’s difficult for a facilities manager to know whether a regular schedule of opening and closing windows will be sufficient to meet the needed standards. If certain at-risk areas can’t be resolved, a business case can be built to a retrofit or upgrade of the ventilators. 

Such CO2 monitors should therefore be able to: 


Be easily installed and moved 

Be placed anywhere and aren’t limited by power 

Securely communicate the readings across the whole school 


From this, Connexin have launched a battery-powered CO2 monitoring solution that uses a low power network (LoRaWAN®), to connect many devices across schools. The data is then fed to a centralised platform that allows the readings to be mapped over the building schematic, providing short- and long-term trends for facilities managers. For some schools in the UK, Connexin already has network coverage meaning the devices are ready to be installed immediately. 

If you’d like to find out more about our CO2 monitoring solutions and check if our network has reached your area, please contact us using the form below and our team will be happy to help. 


Contact our team to discuss CO2 monitoring at your school 👇 (We’ll get back to you within 1 working day)