New study shows significant effect of good indoor climate: “It results in a full extra school year over 10 years”

If there is light, sound and air in the classroom, students’ motivation and efficiency increase significantly, shows a new study from the Technical University of Denmark (DTU). The City School in Valby has put the premises, students and staff into a large study from DTU, the result of which is that student’s results improve significantly when light, sound and air are controlled in the classroom. School principal, Morten May, can also clearly notice the changes in the premises. Heavy air, noise and poor lighting are three ingredients that ruin the indoor climate in classrooms in schools across the country.

It creates difficult working conditions for teachers and reduces students’ ability to concentrate, and most importantly, learning.

The results of the new study from DTU show the impact of students sitting in a room where they get plenty of oxygen, where the acoustics are good and with the right bulbs in the lights.

The researchers from DTU followed 92 students in the 4th and 5th grades [age 9-10] in connection with their refurbished classroom, which allowed researchers to do research into the different relationships.

For several weeks, the conditions were adjusted while the students were given different tasks to test their cognitive and professional abilities. The results of the study are that there is a great benefit to student’s learning when there is a good indoor climate.


When comparing the results of the tasks that the students solved in the classroom, the number of correct answers in students’ tests increased by up to 12% when indoor climate was controlled.

“The effect could easily be 20% better if the starting point is really bad. In our case, we found about a 10% overall improvement in student performance. So, it results in a full extra school year over 10 years,” says Christian Anker Hviid, an Associate Professor at DTU and the research lead. He emphasizes that the acoustics, for example, were already good in the classrooms examined.


Morten May, School Principal:

“It’s remarkable what it’s like to be in there now. We have an employee who said it’s like stepping into a completely different climate zone.”

The study has also been organized in such a way that the researchers have neutralised other effects, such as the individual teacher’s teaching methodology or students’ financial background.

“If you take a good class with a good teacher and give them a good indoor climate, they will, on average improve by 10%. But the data actually shows that the poorest of students will gain more than 10%,” he states.


At the same time, the study from DTU shows that there is some positive effect if you fix either light, sound or air in class, but the effect is enhanced if all three elements are controlled at the same time.

In response to the new information, The City School in Valby in Copenhagen has refurbished other classrooms. Staff, pupils and the principal, Morten May, say they can clearly see the difference it has made in refurbishing the classrooms for the school pupils in 4th, 5th and 6th grade.

Before, there was more unrest in the common areas and there were more teachers complaining about recurring headaches, but since the refurbishment things are completely different. It is quiet in the classrooms, and no one complains of headaches anymore.


“From an ethical perspective, it is difficult not to use this knowledge when you know children cognitive readiness is enhanced by better indoor climate. But then there’s the financial perspective,” says principal of City School Morten May.

“It’s remarkable what it’s like to be there now. We have an employee who said that it’s like stepping into a whole different climate zone. It’s hard to put your finger on, exactly what it does. There is just an incredibly comfortable atmosphere,” says Morten May.


The obvious question, of course, is why he and the school will not get the rest of the school’s classrooms to the same standard as those who have participated in DTU’s study. But there are two barriers, tells the school inspector: physical constraints and finances.

The school is located in an old sausage factory. It creates some limitations and therefore it is not possible to completely remodel, such as in the older pupils’ classrooms. In the younger pupils’ classrooms, the school has planned to renovate. But like the school principal emphasizes, the finances must also be in place.

On the whole, he believes that the knowledge gained from the study should provide the politicians something to think about.


“From an ethical perspective, it is difficult not to use this knowledge when you know that children cognitive readiness is enhanced by better-improved climate. But then there is the economic perspective. Can we afford to act on it? This is a political issue,” the school principal emphasizes.

Previous studies have shown that many pupils across the country receive instruction in classrooms with bad indoor climate. This was reflected in the Labour Inspectorate’s remarks in 2018: according to DR [Danish equivalent of the BBC], every third school had problems with the indoor climate. Furthermore, 2016 DTU study showed that in 60 out of 277 schools there was insufficient ventilation in nine out of ten classrooms.

Berlingske would like to have asked the local council what is being thought about the results of the study in many schools that have problems with poor indoor climate, but it has not been possible to get answers.


This article has been translated from Danish, and was originally published at the following link:

The referenced study from DTU, “A field study of the individual and combined effect of ventilation rate and lighting conditions on pupils’ performance” can be found at the following link:

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