By Michael Young, sales engineer, Trox

Effective and highly efficient filter systems filter dust, bacteria and pollen out of the ambient air, ensuring that we can breathe clean air in enclosed indoor spaces.

The standard for testing large and fine dust particles has changed where filter performance is no longer accessed on laboratory test methods but with real application conditions.
The new ISO 16890 standard is based on a range of particle fractions, and tests are conducted using Di-Ethyl-Hexyl-Sebacat (DEHS) and potassium sensitivity testing (KCI) test aerosols where filters are now divided into four different groups:

  • ISO course filters which has a rated containment capacity against ISO A2 dust.
  • ISO PM10 which filter fine dust particles that are less than 10µm
  • ISO PM2.5 which filter fine dust particles that are less than 2.5µm
  • ISO PM1 which filter fine dust particles that are less than 1µm


Filters are more than just an investment in room air quality, they are an investment in efficiency too.

Alongside the filter performance, another important aspect to consider is the energy performance of the filter in day-to-day use.

Filters are more than just an investment in room air quality, they are an investment in efficiency too. High quality filters with patented NanoWave technology features a wavy profile that creates a larger filter area which reduces differential pressures. This is all accomplished without reducing the dust and containment performance.

NanoWave filters are more complex to produce than standard synthetic filters which is clearly indicated by the higher price premium. However, when the overall costs for industrial applications are compared to those of for a standard filter, it is clear that the product is more than worth the additional investment.

Air conditioning contractor, Trox, constructed two identical air handling units (AHU) to perform filter differential pressure testing in parallel. One of the systems (AHU 1) was fitted with a synthetic filter and the other with NanoWave filter technology (AHU 2). The differential pressures were measured over the course of one year to take into account all seasons and weather conditions.

The energy consumption of both systems was calculated on the fan volume flow rate, its efficiency (50%), the number of operating hours (8 760 hours) and the average differential pressure which ranged between 61.8Pa to 146.9Pa.

To compare the two systems, the energy consumption in kWh/a was calculated for the specific operating volume flow and applied as a specific value in cents per m3 of processed air per year.
The AHU containing the synthetic filter had an associated cost of R182.24 to deliver 1m3/hr of air while the AHU containing the NanoWave had an associated cost of R76.67 to deliver the same 1m3/hr of air. Use of the NanoWave filter reduced the operation costs by 51%.

Performing the return on investment calculation and noting that NanoWave filter come with a 50% premium compared to a synthetic filter. One can expect to recover the capital investment cost of the filter in less than one month.

Trox understands that different filters perform differently, so a life cycle cost (LCC) tool helps you determine the economic efficiency of fine dust filters. With the tool, customers are able enter the volume flowrate of the system and the programme will indicate the approximate annual energy consumption of a specific filter.

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