Heating and Ventilating

A new filter standard ratified on 23 March this year has big implications for building services companies, according to Colin Hitch
Although it has not been widely reported yet, 2012 will impose big changes to any H&V firm, building facilities manager, or facility management company which uses fine filters. Fine filters in this case are defined as filters graded F7, F8 and F9 to EN779.

These filter grades are instrumental in delivering good quality indoor air as defined under EN13779:2007, which is the nearest thing to an indoor air quality standard (IAQ) we have. EN13779:2007 is now a legally accepted standard in all member states of the European Union. The standard sets out to achieve comfortable and healthy IAQ in all seasons of the year at acceptable installation and operating costs, taking into consideration the outdoor air. It represents a major step forward, recognising the importance of external air in achieving better indoor air quality and/ or a healthier environment.

More than 98 per cent of all airborne dust is sized at less than 1 micron, which are the particles filters graded F7, F8 and F9 are designed to remove.

There are two main changes in EN779:2012 from the previous standard, EN779:2002, which are to do with grade designations.

F5 and F6 are reclassified as M5 and M6, acknowledging the fact that these filters are not 'fine' filters, but are 'medium' grade.

The major change, however, affects 'fine' filters grades F7-F9. From 2012, all fine filters must have any electrostatic charge removed from them as part of the test and a minimum efficiency established at a particle size of 0.4 micron.

F7 filters must exceed 35 per cent efficient at 0.4 micron, F8 filters 55 per cent and F9 filters 70 per cent - his for discharged filters.

Some 15 years ago we saw the introduction of new synthetic filter media which relied on an electrostatic charge to achieve their rating to EN779. These materials were cheap to produce and easy to handle and they quickly became the norm. It is estimated that more than 95 per cent of all filters F7-F9 in use in the UK right now are of this type.

However, under certain conditions the electrostatic charge in these filters can be removed in service. Diesel fumes, petrol fumes and aviation fuel vapours will all remove the electrostatic charge and, when that happens, these filters will typically perform at G3 or G4 at best.

The new standard guarantees minimum filter efficiency under all circumstances. To be clear, there is no law or statute that says your filters have to comply with EN779:2012. However if you specify a grade of filter to EN779 to your filter supplier they must legally provide a filter F7 to EN779:2012. The filter companies cannot offer F7 to 'the old standard'.

My own company can offer non-compliant filters. We are quite willing to do so providing the customer understands that they do not comply with the current standard. We go to some lengths to explain this, to ensure that it's absolutely clear that it is they who have decided that compliance is not appropriate for their application.

The filters that do comply with the new standard have massive dust holding advantages over non-compliant products and, as such, offer terrific energy ratings under Eurovent 4/11 and also much longer service life so, although they do cost more per unit the overall cost is actually reduced.

The most usual filters meeting the new standard are glassfibre bag filters, for example the Jayflow range from Jasun Envirocare, and compact filters, also known as rigid bag filters, again made using a glass paper media (beware of versions of these filters made using synthetics). Both these filter types far exceed in efficiency the minimum test efficiency required to meet EN779:2012.

Nano fibre products on the way
There is a lot of work being carried out by the synthetic media manufacturers to produce fully compliant bag filter media which can deliver acceptable pressure drops in service and we will soon see a new wave of 'nano' fibre products hit the market. Do not expect these to be priced as low as the old type non-compliant products.

I strongly advise that, during this period of transition, any filter user should request sight of an independent test certificate for any synthetic product claiming to meet EN779:2012. This is not because filter companies are deliberately trying to mislead customers, but because many filter vendors are unaware of the changes which have taken place to the standard. As I mentioned in my opening paragraph, these changes have not been very widely publicised.

These changes are far reaching, but will deliver improved IAQ and real energy savings to building owners and operators throughout Europe.

We have technical Bulletins covering EN779:2012 a guide to compliance, Eurovent 4-11 the Energy Rating Standard for Air Filters and for EN13779:2007 the IAQ standard.

The author is technical director of Jasun Envirocare