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How to Implement CO2 Monitoring in Schools

How to Implement CO2 Monitoring in Schools

Carbon dioxide (CO2) monitoring in schools provides a way to assess indoor air quality and ensure a productive and safe learning environment. High levels of CO2 can lead to adverse health effects such as headaches, drowsiness, and poor concentration, which can affect both students and teachers. Studies have shown that high CO2 levels in classrooms can result in poor academic performance, decreased attention spans, and reduced learning outcomes. 

This issue is important enough that some states are taking the initiative to fund healthier ventilation in schools. For example, California’s Assembly Bill 841 (a.k.a. AB-841 and AB841) is designed to help educational institutions afford to buy and maintain CO2 monitoring equipment.

“The CalSHAPE Ventilation Program provides funding to local educational agencies for the reasonable costs of HVAC assessment, general maintenance and adjustment, filter replacement, and carbon dioxide monitor installation including certain repairs, replacements, and other improvements to HVAC systems.”

In this blog, we will explore how to implement CO2 monitoring in schools and the benefits it can provide.

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What Are Acceptable CO2 Levels in Schools?

The ASHRAE 62.1 standard recommended CO2 level for indoor schools is 1,000 parts per million (ppm) or below. The California-required alerting level for AB-841 consideration is 1,100 ppm. Concentrations above this range can have negative effects on human health and cognitive performance. When CO2 levels are too high, the body's oxygen supply decreases, which can cause an increase in heart rate and a decrease in cognitive function. 

Understanding the sources of CO2 and its impact on human health is important in maintaining safe CO2 levels in schools. The most common source of CO2 in schools is human respiration, which accumulates quickly in poorly ventilated areas. Other common sources are HVAC systems that have been improperly installed or maintained, cooking equipment, and building materials like carpeting, furniture, and adhesives. 

Selecting a CO2 Monitor for a School Environment

There are different types of CO2 monitors available, including handheld, desktop, and wall-mounted models, and those that are incorporated into thermostats. When selecting a CO2 monitor for a school environment, factors such as accuracy, reliability, and ease of use should be considered. Also, note that AB-841 requires a hardwired power connection to CO2 monitors. No batteries are allowed.

Furthermore, CO2 monitors that have onboard data logging, such as the NetX X7C Series, allow for the collection and analysis of long-term indoor air quality data. This helps identify trends and patterns in indoor air quality, which can help to inform decisions about building design, HVAC system maintenance, and other environmental controls. 

Implementing CO2 Monitoring in Schools

Identifying high-risk areas in the school is essential in determining where to implement CO2 monitors. Here are some of the biggest culprits of CO2 accumulation in schools:


Classrooms are where students and teachers spend most of their time during the day, and overcrowded or poorly ventilated classrooms can lead to high CO2 concentrations.


Gymnasiums are large spaces with high levels of physical activity and may also have poor ventilation systems or no windows, which can exacerbate the issue.


Like gymnasiums, cafeterias are often large spaces with high levels of activity. They may also have cooking equipment and other sources of contamination that can contribute to high CO2 levels.

CO2 levels should be monitored regularly in schools to ensure that indoor air quality is maintained at safe levels. The frequency of monitoring depends on a number of factors, including the size of the school, the number of occupants, and the ventilation system. 

It is also important to keep in mind that CO2 levels can vary throughout the day, depending on occupancy levels and ventilation patterns. Continuous, real-time CO2 monitoring is the best option to mitigate risk. 

Maintenance and Calibration for School CO2 Monitors

Regular maintenance and calibration are essential to ensure that CO2 monitors in schools are functioning properly and providing accurate readings. Here are some guidelines for maintaining and calibrating CO2 monitors in schools:

Regular maintenance

CO2 monitors should be checked routinely to ensure that they are functioning properly. This includes ensuring that the monitor is mounted correctly and checking for any physical damage.


Older electrochemical technology CO2 monitors are required to be calibrated regularly to ensure that they are providing accurate readings. Calibration involves comparing the monitor's readings to a reference standard of 400 ppm, which is outside fresh air, and adjusting the monitor as necessary to ensure that it provides accurate measurements. This process should be performed at least once a year, and more frequently if the monitor is exposed to extreme temperatures, humidity, or other environmental factors that can affect its accuracy.

Newer CO2 sensor technologies NDIR sensors and photoacoustic NDIR sensors for CO2 sensing with photoacoustic NDIR sensors being the perfect solution for school environments.  The Network Thermostat NT-MOD-CO2 plug-in CO2 sensor for the X7 series of thermostats (X7-WIFI and X7-IP) and the NetX X7C Series thermostats all include this latest technology.  The photoacoustic NDIR sensors have improved accuracy over many CO2 sensor technologies. These Network Thermostat products automatically self-calibrate and are guaranteed not to need to be recalibrated for a minimum of five (5) years and a life expectancy of more than 10 years.

CO2 Monitors in Schools: Products to Consider

NetX offers a range of Smart(er) Thermostats with CO2 monitors that are ideal for schools. These monitors are all connected to the internet and feature easy-to-use interfaces, data logging capabilities, configurable relays, and event scheduling to ensure a safe and comfortable learning environment. 

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