Regulation on Mandatory Ventilation in Schools: What Awaits Their Founders?

In 2023, the Ministry of the Environment submitted a proposal for a regulation on hygiene requirements for the spaces and operation of facilities for the upbringing and education of children and adolescents and children’s groups. What will this mean for schools and other facilities in terms of ventilating indoor spaces?

Classrooms – Many People in a Small Space

Monitoring concentration of carbon dioxide (CO₂) in the indoor environment is crucial for the health and well-being of the people who stay there. The concentration of CO₂ is a very good indicator of stale (polluted) air because when air is exhaled, not only does CO₂ increase, but similarly, other pollutants in the air, released by breathing and sweating – due to the metabolic activity of the human body, also rise. These are so-called volatile organic compounds – VOC (from English Volatile Organic Compounds). CO₂ is much easier and more accurately measured compared to thousands of types of VOC.

Appropriate ventilation will greatly contribute to the comfort of both students and teachers and will prevent undesirable effects of stale air such as reduced concentration ability, fatigue, drowsiness, headaches, nausea, or even dizziness.

Ventilation through Windows is Generally Insufficient and Often Inappropriate

Natural ventilation through windows is usually not sufficiently effective, and often due to noise or low quality of outdoor air, it is neither suitable nor energetically advantageous. Unfortunately, during the renovation of school buildings, walls were often insulated with thermal insulation material, and old windows were replaced with new ones, leading to significant sealing of the building envelope. This considerably worsened the quality of the indoor environment, which is evident from our measurements, where the concentration of CO₂ at night or over the weekend decreases much more slowly than before the renovation, meaning that natural infiltration of outdoor air is significantly limited.

Natural ventilation through windows is effective only in rooms with a small number of people or in rooms with occasional use (e.g., art school classrooms, offices, etc.). Ventilating through windows in traditional classrooms cannot meet the requirements for a quality indoor environment and for reducing the energy demand of the building. See the table below.

Table of the Amount of Supplied Outdoor Air in Classrooms and Gyms and the Amount of Exhaust Air in Changing Rooms and Sanitary Facilities

Requirements for Classrooms

Regulation No. 410/2005 Coll. as amended requires the amount of supplied outdoor air to classrooms to be 20 to 30 m³/h per student. Furthermore, in accordance with Regulation No. 268/2009 Coll. on technical requirements for buildings, the concentration of CO₂ in occupied spaces must not exceed the value of 1,500 ppm (= Parts Per Million). See CO₂ Concentration Scale.

What About Other Spaces in the School?

Cabinets, staff rooms, or gyms can still be ventilated through windows. Spaces such as toilets or washrooms are better ventilated using ventilation units controlled by air quality sensors.

Unfavorable Findings from Measurements in Classrooms

We have conducted and are conducting monitoring of CO₂ concentration in many classrooms, whether in primary or secondary schools across the Czech Republic. Our measurements led to a relatively simple conclusion: the concentration of CO₂ in classrooms rises to unacceptable levels in the vast majority of cases during the first lesson (sometimes even after the first half hour of teaching) right on Monday morning. And this can reach values of 4,000 to 5,000 ppm, which is already very stale air with unpleasant odors and smells, negatively impacting the people present.

Monitoring and Regulation According to CO₂ Concentration

In order to achieve the greatest possible savings on energy needed for ventilation and heating, it is necessary to effectively control the ventilation system based on the concentration of CO₂ in the ventilated space.

The air quality in classrooms should be monitored according to the value of carbon dioxide concentration. For these purposes, we have prepared a special school sensor.

SCHOOL SENSOR

School Sensor NLII-CO2-R-5-A will visually and acoustically alert to high concentrations of carbon dioxide (CO₂) in the air, indicating the need for ventilation without significantly disrupting the teaching. The sensor is equipped with an advanced optical CO₂ monitoring system and also has outputs for automatic, efficient control of ventilation systems.

Thus, in the first phase, the sensor serves for monitoring the quality of indoor air in classrooms and in the future also for effective ventilation control. For some cases or as a hybrid solution, there is also a function for controlling the opening of windows or skylights where appropriate.