‘In addition to ventilation, schools should also work on air purification’

With the increase in corona infections, many schools face a significant challenge. According to Prof. Bert Blocken, professor of building physics at Eindhoven University of Technology and KU Leuven, this challenge can be tackled with air purification.

Blocken hopes that, in addition to ventilation, air purification will also be an important topic in the fight against particles and corona. That is why he is working on a study in which more than a thousand classrooms in the Netherlands and Belgium participate, and where the schools are supplied with air purifiers and measuring equipment. Johan Cruijff Arena has also been involved in such a project in the past year and a half. “Because the omikron variant has created chaos in 2021, it is now the schools’ turn. We hope so bottoms Up to realize.”


When you think of schools and corona, you probably think of ventilation. Blocken regrets that. “Air cleaning is really a missed opportunity, especially when you see what’s happening overseas,” he says. “In America, $122 billion is being released for this, and Finland, Germany and England are also working on it. Belgium and the Netherlands are lagging behind because the governments are procrastinating.” Because many schools are already in a financial dilemma, the subject does not start there.

That is why the professor is very worried about the autumn of 2022. “Let’s hope that the situation around the virus goes well,” he says, “but there is a chance that the government will say: ‘Open the windows and doors to avoid much damage in order to ventilate more strongly. It becomes dramatic in connection with energy costs. Last winter it was already difficult for some schools to keep heating costs under control. We try to teach our children that you have to be energy efficient, but on the other hand, we burn with windows and doors wide open.”

Furthermore, air purification is not only a remedy against corona. “We’re also looking at schools near heavy industry or busy roads,” says Blocken. “Eleven of the schools that have come along are located near a steel manufacturer’s facility. They’re just as concerned about particles there as they are about viruses.”

'In addition to ventilation, schools should also work on air purification'

An air purifier in the De Kiezel school in Best (photos Bert Blocken, Eindhoven University of Technology & KU Leuven).

Full investigation

The results of the study are currently being compared to see if air purification has an effect on sickness absence. “We are now going through a corona wave, so we hope to see a difference soon,” says Blocken. These are not easy comparisons, because corona infections do not just happen in a classroom. “So we hope to suppress that noise by measuring a large number of classes and thus detect a trend.”

The study also performs a financial analysis to show that an air purifier can quickly pay for itself. “And it happens very quickly, I can tell you,” says Blocken. “Furthermore, the alternative is heating with open windows and doors.”

Reduce by a factor of 20

Blocken will elaborate on this matter during the Sustainable & Healthy Schools Congress 2022 on November 9 in Zwolle. He then shows the preliminary results of the study. With attention to the capacity required to reduce the particle concentration by a factor of 20 and to reduce the risk of pollution via aerosols by a factor of 12. “It is not at all impossible to achieve sufficient capacity,” says the professor. “It even fits perfectly into the ventilation budget that the government has made available [voor scholen, red.].”

According to Blocken, these are air purifiers that can be delivered very quickly and which simply need to be plugged into a socket. “That technology has existed for decades, but it is hidden in airplanes and operating rooms. That’s why most people don’t know this.”

During his session, Blocken will also take a look at the future: what will installations in buildings look like in the future? “I think we need to move towards an integration of ventilation and cleaning,” he says. “In this way, you remove particles from traffic and industry and also respiratory viruses from the air, and you are therefore immediately prepared for future pandemics. We can now work on that.” It will cost a bit more, Blocken admits, “but adding air purification is not too big a chunk of a construction or renovation budget”.


With the research and his session at the Sustainable & Healthy Schools Congress 2022, Blocken hopes to highlight the need for air purification in the Netherlands. “Air purification is the most underrated weapon against the coronavirus,” he says. “The awareness of this has increased during the pandemic, but the awareness is still not there in many layers of society. Unknown makes unloved.”

Nevertheless, there are rightly many complaints about the danger of particles, so the attention is there. Blocken: “People often think: there will be a solution later. But tackling the source – the industry – doesn’t work, so we go for the next best option: fix it before you breathe it in. And that in premises such as classrooms.”

'In addition to ventilation, schools should also work on air purification'On 9 November, the block will show the first results of the research into air purification in educational buildings. His session is particularly interesting and useful for school boards because new research can be used to justify the investment in a fresh indoor climate.

Don’t miss this session and register now for Sustainable & Healthy Schools Congress 2022.
Good news for education: if you work in a school, you get a discount of € 125!

Source: Urbanism & Architecture

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