EN 779 : 2012

EN779 (High Efficiency)

EN779: 2012

The new standard forces our competitors to be better
– but not as good!

At Camfil, we have always put every effort into improving your machinery's performance. Thus, no one is more pleased than us that, since early 2012, a new air filter standard imposes tougher requirements. Unfortunately, the requirements are not as tough as we would have liked. For example, our Hi-Flo XLT7 (a class F7 filter) has a minimum filtration efficiency of 56 percent. For an F7 filter, the new standard requires no more than 35 percent. That does not meet the quality levels we have set for ourselves. Indeed, our development of the market’s most efficient, energy optimised filters will continue.

What does EN 779:2012 do?

The new European standard for air filters (EN779:2012) purpose is to classify air filters based on their lowest filtration efficiency, also referred to as minimum efficiency (ME). The standard is an initiative that we welcome and a step towards better machine performance.

The new standard will help to eradicate a number of problems such as electrostatic charged synthetic filters. Most electrostatic filters can demonstrate good initial filtration efficiency but they discharge extremely rapidly. This entails a considerable deterioration in their filtration efficiency. Unfortunately, this results in many turbine operators using F7 class filters that have ME values of between 5 and 10 percent. This means that as much as 90 to 95 percent of the contaminants in the outdoor air find their way into the clean side of the inlet. 

By basing classification on ME value, the new standard will force these filters out of the market. At the same time, it will contribute to the development of synthetic filter materials offering considerably higher particle separation.  The downside will inevitabely be higher pressure drop.

Not all filters are the same
– even when they are in the same class!

The problem with the new classification is that, although the worst filters will vanish from the market, there is room for good filters to be made worse. Although energy savings can be achieved by having the lowest possible pressure drop, such development could be retrograded. For example, with 0.4 μm particles, our Hi-Flo XLT7 (class F7) filter has an ME value of a full 56 percent. However, for classification as an F7 filter, the standard requires no more than 35 percent. As we have already made clear, we will not be lowering the efficiency of our Hi-Flo filters. That would result in an approximately 40 percent worsening of air quality. However, there is a risk that other manufacturers will not think the same way. Instead, they may see the standard as an opportunity to reduce pressure drop, but with poorer air quality.

Classification of air filters1)
Group Class Final pressure
drop (test)

arrestance (Am)
of synthetic dust

efficiency (Em)
for 0.4 μm
for 0.4 μm particles
Coarse G1 250 50≤Am<65 - -
G2 250 65≤Am<80 - -
G3 250 80≤Am<90 - -
G4 250 90≤Am - -
Medium M5 450 - 40≤Em<60 -
M6 450 - 60≤Em<80 -
Fine F7 450 - 80≤Em<90 35
F8 450 - 90≤Em<95 55
F9 450 - 95≤Em 70
1) The characteristics of atmospheric dust vary widely in comparison with those of the synthetic loading dust used in the tests. Because of this, the test results do not provide a basis for predicting either operational performance or service life. Loss of media charge or shedding of particles or fibres can also adversely affect efficiency. 2) Minimum efficiency is the lowest of any of the following three values: initial efficiency, discharged efficiency or efficiency throughout the test’s loading procedure.


To understand the differences between the EN:779, EN:1822 and ASHREA 52.1 and 52.2, see our comparison chart below.

EN vs ASHRAE comparison (pdf)


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