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Hollingsworth & Vose at the FILTECH 2019:
Interview with Matthias Frei, Managing Director of the UNIFIL AG

Bad Vilbel, Germany 
3 April 2020

At the FILTECH 2019, Matthias Frei, Managing Director of the UNIFIL AG, a manufacturer of Air Filters based in Switzerland,
agreed to answer a series of questions related to the importance of Air Filtration.

Matthias Frei, UNIFIL AG 


See the complete Interview on the ThinkNanoWave YouTube Channel: Interview with Matthias Frei, Managing Director of the UNIFIL AG




1. Today everyone is talking about climate change, air pollution, CO2 emissions. When talking about Air Pollution, people mostly refer to Outdoor Air Pollution. However, especially in developed countries, people should be more concerned over indoor than outdoor.
What would you say, why does Indoor Air Quality matter?

I think that indoor air quality matters because it is important for our health, our mind and finally our performance.

However, we have to distinguish between outdoor air pollution and indoor air pollution. I think talking about outdoor air pollution, and particularly fine dust particle concentration, it has been increasing over the last years.
Whereas indoor air pollution, or the problem with indoor air pollution, has become more and more important and challenging.

Poor indoor air quality can cause a certain amount of discomfort. I think most people, after taking away the source of pollution, feel much better.

However, there are still pollutants that are dangerous in the long run and that can cause diseases like respiratory diseases or even cancer. I think that is why indoor air quality matters so much.

2. We can agree that there is a lot of scientific information pulled together by many scientists on the topic of IAQ. That means that a decision maker – let’s say an HVAC planner, or a facility manager – needs to look at a lot of information. 

What would you recommend as useful to make a decision about how to protect human health from indoor air pollutants?

Well, by getting rid of those air pollutants or by using adequate filtration and ventilation.

I think with an ePM1 90% filter you have an excellent protection against outdoor particles.

Regarding indoor particles, I think it is important to make sure that the building is well ventilated and that the mechanical ventilation system is designed and operated in a way to provide enough amounts of outdoor air.

Furthermore, I think good office concepts and well-planned exhaust air requirements can help reduce indoor air pollution.

And last but not least, I think doing more exercises can help become more resistant. I think it is a fact that a variety of illnesses has increased over the last years and that people tend to be more sensitive and less resistant. Or, shall we work in our offices in the future in protective clothing because of that?



Unifil Synawave® Filter Unifil Synawave® Filter



3. Decision makers are often facing increased cost pressure, making them decide to install a low-cost solution.
Can you explain why what seems to be cost-efficient in purchase causes much higher overall lifecycle costs?

I think a higher price of a premium quality filter with a high energy efficiency class can always be compensated by its lower energy costs.

Energy costs represent about 70% of the total cost of the bag (pocket) filter and the price of the filter itself only makes about 10%.

Low-cost solutions often have much higher pressure drops and therefore end up with a short lifetime and higher energy costs.

For instance, a difference of 30 Pa per filter is equivalent of about 60 Swiss Francs in energy costs. That shows how significant low pressure drop and therefore a premium quality solution like NanoWave® XT is.

The pressure of a filter is a big part of the total pressure of the whole system. That is why NanoWave® XT can help plan and run a whole installation in the most efficient way.

4. Globally there are numerous standards recommending the right filter performance or filter class. Although being considered common knowledge among air filter manufacturers, end-users are mostly overwhelmed by the amount of information available to them.

Is there a simple way to select the right filter? Is there a simple way to select the right filtration solution?


There are in fact a lot of information from standards, but also from manufacturers and Sales people, which makes it difficult for end-users to understand. In addition, there were many changes over the last 10 years in the filter and energy classification, which contributed as well to a certain confusion on the market.

Nevertheless, I think that the new standard ISO 16890 and Eurovent offer a clear simple way to select the filter in both ways: Regarding the filtration efficiency and the energy efficiency.

In Switzerland, we have domestic standards that require the use of filters that have at least energy class “A” for all new installations.

In general, I think when you plan a building it is essential to understand the scope of filtration, to know the outdoor air quality as well as how the requirements are in regards to the indoor air quality.

As a rule, I would recommend using NanoWave® XT filters with efficiencies ePM1 70% or ePM1 90%, at least energy class “A” and a pocket length of 450mm. Then in my opinion, you have in every sense a very good solution or even the best solution.




 5. The main task of a filter in an Air Handling Unit is to protect people by creating a clean and healthy environment.
What makes a filter “good”? What are the most important factors and contributors to the performance of air filters?


Well, I think it is what I have said before. The most important factors are the efficiency, the filtration efficiency, combined with low pressure drop throughout the whole lifetime.

Of course, to achieve that you need a really good filter media, but also a good manufacturing process. It is not all just about the media, it is also how you manufacture the product (filter) in the production. How the airflow can enter into a product, into the pockets and come out again without losing a lot of energy.

If you also look from a hygienic point of view, I think it is important that filters are not the source of particle shedding and that they do not touch the units’ floor. That is why it is important that the pockets are firm and not too long.

In addition, I think a good filter needs to have a sturdy, environmentally friendly frame.

And last but not least, I also believe that a good manufacturer can also make a filter good. When introducing a new filter to the market it is important to have field test to know exactly what the real behavior of the filter is under real conditions.



6. What do you see as trends and important future developments in the Air Filtration Segment?


I think it is like everywhere, the future in the air filtration segment will ask for more efficiency. That means higher performance but less energy consumption.

I think on the other hand, also quite important from the economic perspective, is that longer lifetime intervals for filters will be more and more important to reduce lifecycle costs.


Download the Press Release and find out more at


Learn more about UNIFIL AG, the Swiss manufacturer of Air Filters on their Website unifil.ch.


#CleanAir           #IAQ      #NanoWave®   #InnovationForACleanerWorld™               #thinknanowave    #indoorairquality   #energyefficiency    #unifil

“The future in the air filtration segment will ask for more efficiency.

That means higher performance but less energy consumption.” 

Matthias Frei, Managing Director of UNIFIL 


Suzana Vidakovic

Business Development Manager


+49 6101 981 6729 (Germany)