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Fresh air in the classroom: CO2 traffic lights should give teachers an overview

2020-11-16T14:17:23.183Z


The Bad Tölz-Wolfratshausen district is purchasing 400 CO2 measuring devices for its schools. Teachers can use them to assess the room air and improve ventilation behavior.


The Bad Tölz-Wolfratshausen district is purchasing 400 CO2 measuring devices for its schools.

Teachers can use them to assess the room air and improve ventilation behavior.

  • Parents are concerned about the risk of infection in closed classrooms

  • The district purchases CO2 measuring devices in order to be able to assess the indoor air

  • Air purification devices are out of the question

Bad Tölz-Wolfratshausen

- Schoolchildren for hours in a classroom: In the corona pandemic, this worries teachers and parents in particular about aerosols and the risk of infection.

The district is now gradually equipping its schools with CO2 traffic lights to improve ventilation behavior.

Since September teachers have been carrying out CO2 measurements at many schools in order to be able to assess the quality of the indoor air.

In addition, ventilation systems, if they exist, can be checked for their effectiveness.

"With the help of the measurement data, pupils and teachers can be made aware of adequate ventilation," explains René Beysel from the district administration.

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René Beysel, head of the district office

© Sabine Hermsdorf-Hiss

Teachers collect data in schools

Data were also collected at the grammar school in Geretsried.

There are rooms with and without ventilation technology (RLT), renovated areas, newly constructed parts of the building, an interim building and specialist rooms.

It was shown, for example, that poor CO2 values ​​were measured, especially in a classroom in an interim building.

The previous ventilation was not sufficient there, according to a physics teacher.

Beysel: "After using the CO2 measuring device, the users adjusted their ventilation behavior so that the limit value is not exceeded."

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According to the teacher, regular ventilation is also crucial in the upper school room and in the music and physics rooms.

The new teachers' room in the grammar school and the measured room in the new learning landscapes would show relatively low CO2 values.

Where there are many people in a room, there is a lot of exhalation.

The exhaled air contains CO2 and aerosols.

In classrooms, the CO2 concentration should not exceed 1000 ppm.

Ppm is the abbreviation for the unit of measurement “parts per million”, which means parts per million parts in German.

For comparison: In the fresh air outside, the CO2 concentration is 400 ppm.

Aerosols and ventilation 

Aerosols are tiny droplets of liquid and one possible way of transmitting the coronavirus.

According to the Federal Environment Ministry, they are distributed quickly and throughout the room, especially in closed indoor spaces.

Regular ventilation through intermittent and cross ventilation or ventilation technology in the rooms can significantly reduce the risk of infection with SARS-CoV 2.

For schools, it is recommended to ventilate intensively with the windows wide open during every break in lessons, and during longer lessons of more than 45 minutes.

But: "Due to the permanent ventilation in winter, the air in the rooms will become increasingly drier," fears René Beysel, chief office manager at the district office.

However, this may balance out: with the moisture that the students exhale and carry into the classroom with their clothes.

The air quality in the classrooms is now to be checked with so-called CO2 traffic lights.

“The users can keep an eye on this 'box' and, if necessary, also air it,” Beysel said in an interview with our newspaper.

The threshold for schools is 1000 ppm.

"I have received feedback from all schools that it is possible to maintain this value," assures the head of the office.

“Even in rooms that are not automatically ventilated.” The CO2 traffic light is green up to 1000 ppm.

The meter's display jumps to orange when 1001 to 1999 ppm are displayed.

It glows red from 2000 ppm.

"Then at the latest it is indicated that ventilation has to be carried out."

Also read:

This is how young people from Bad Tölz-Wolfratshausen experience the time of restrictions

District creates 400 CO2 traffic lights

But proper ventilation, especially in rooms without air conditioning, “will still be a challenge,” says Beysel.

Perhaps it is enough to just open a window, but perhaps the door and window should also be open.

But: With the CO2 traffic light you can see relatively exactly what is happening.

And: in winter it is probably enough to ventilate two minutes, in contrast to summer, where you had to wait 20 minutes for the air to change.

According to Beysel, the reason for this is the high temperature differences from outside to inside.

The district will purchase a total of 400 CO2 traffic lights for its schools - 200 are to be delivered before the Christmas holidays, the rest is expected for the end of January.

There is funding for this from the state.

“That's 57,000 euros,” says Beysel.

But this amount does not cover the costs incurred by the district.

Air purification devices in classrooms

The district office keeps receiving inquiries from concerned parents who request air purification devices for the classrooms.

“These are boxes the size of a refrigerator,” explains René Beysel.

"They suck in air and blow it out again, with a filter in between that has to be replaced regularly."

Beysel is of the opinion that such devices are not a solution.

"They pull fine dust and aerosols out of the air." But there is no way to measure the cleaning success, says the employee of the district office.

"Used air, enriched with CO2, indoor air toxins, odors and other pollutants can only get out of the classroom with correct window ventilation or an air conditioning system and thus create the necessary indoor air hygiene."

In addition, the devices are 40 decibels loud, reports Beysel.

The maximum value for a ventilation system in the classroom is 35 decibels.

Which district school has ventilation technology?

René Beysel says that ventilation and indoor air hygiene have not only been the focus of the planning of new buildings and renovations since the corona pandemic.

In general, one tries to equip all classrooms with ventilation systems - teachers' rooms, individual offices and administrative areas not.

"Here you can ventilate through the window," says Beysel.

In all construction measures in the past ten years, powerful air conditioning systems have been installed and these are equipped with CO2 sensors in the classrooms.

“This ensures that adequate room hygiene can be achieved,” explains the expert.

Of course there are still a lot of classrooms that only have classic window ventilation - but here they are below the national average.

An overview of the schools in the jurisdiction of the district:

• Gymnasium Icking: comprehensive ventilation technology (RLT)

• Realschule Wolfratshausen: no RLT

• Wolfratshausen vocational school: k.

RLT

• Geretsried grammar school and secondary school: around 30 percent RLT

• Geretsried special school: no RLT

• FOS / BOS: around 20 percent RLT

• Vocational school Gudrunstraße Bad Tölz: around 10 percent RLT

• Vocational school Bairawieser Straße Bad Tölz: no RLT

• Bad Tölz grammar school: around 30 percent RLT

• Bad Tölz secondary school and special needs school: RLT across the board

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Source: merkur

All news articles on 2020-11-16

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