Laboratory test
Photo: Frazer Waller.

How we tested

Go back to 'Major differences between air purifiers in Testfakta’s test'

Testfakta Research has conducted a comparative laboratory test of air purifiers on behalf of the manufacturer Blueair. The purpose of the test is to compare performance for a selection of competing air purifier manufacturers in the Nordic, British, German, Dutch and Polish markets.

The laboratory test was performed by Intertek Testing & Certification and SGS-IBR Laboratories in the UK. Testfakta has drawn up the test report together with the laboratories.

The following air purifiers were tested:

– Beurer LR 300
– Blueair Classic 405
– Coway AP-1008DH
– DēLonghi AC150
– Dyson Pure Cool Link TP04
– Electrolux EAP300
– Fellowes AeraMax DX95
– Meaco CA-HEPA 47×5
– Philips AC3259/10
– Rowenta Intense Pure Air XL PU6020
– Soehnle Airfresh Clean Connect 500
– Stadler Form Roger
– Venta LP60
– Wilfa AP-5W
– Wood’s ELFI 300

Some of the air purifiers were tested in 2017, while others were tested in the second half of 2018. All the models are currently available in their respective markets.

 

The laboratory test comprised the following elements:

A. Measurements at 37 dB, or the nearest level below 37 dB:
·     Room cleaning capacity for pollen and dust
·     Sound level (instrumental measurement)
·     Noise level on lowest power setting (subjective assessment)
·     Energy consumption

B. Measurements at max power:
·     Room cleaning capacity for pollen and dust
·     Sound level (instrumental measurement)
·     Noise level (subjective assessment)
·     Energy consumption

C. User friendliness
·     Filter replacement and cleaning
·     Display and menus
·     Controls
·     Programming and settings

D. Ozone emissions

The air purifier’s capacity to purify air was tested according to test standard ANSI/AHAM AC-1-2015. The test measures the air purifier’s capacity to eliminate various types of particles (dust and pollen) from the air in a room. The cleaning capacity is stated as the Clean Air Delivery Rate (CADR), which shows the air purifier’s capacity expressed in cubic metres of clean air per hour.

Many of the manufacturers state cubic metres of air per hour or the room size in square metres that the air purifier is able to clean. However, the figure of cubic metres of air per hour says nothing about the air purifier’s capacity to clean the air. It is more about the capacity of the fan. If the particles that are sucked in are not filtered out, they will simply be returned to the room.

How many square metres the air purifier is able to clean depends in part on the cleaning capacity (CADR), but also on how many times an hour the room’s air should be purified. According to the Swedish Asthma and Allergy Association, an air purifier in a bedroom should clean the air twice an hour. A bedroom measuring 25 square metres and with a ceiling height of 2.4 metres has a volume of 60 cubic metres. In order to purify the air, the air cleaning capacity (CADR) should in this case be at least 120 cubic metres per hour. If you want the air in the room to be cleaned three, four or five times an hour (as some manufacturers and retailers recommend), the air purifier needs to have a greater capacity.

The sound level is an important factor, since the air purifier is often used to clean the air in a bedroom. According to the Swedish Asthma and Allergy Association’s guidelines, the air purifier’s cleaning capacity should be considered in relation to its sound level. If an air purifier has different fan speeds, the capacity should be measured at a power setting that creates a sound level of 37 dB or the nearest level just below that.

In the test, the air purifiers’ performance was measured at a low sound level (37 dB or the nearest level just below that) and on max power. Before the measurements were taken, the sound level was measured at different power settings to find the power level that produced 37 dB or the nearest level just below that. The sound level was measured in a controlled laboratory environment that mimics the real-life conditions in the home. The measurements were carried out 1 metre from the air purifier and from all angles (the air purifier’s sound level is stated as an average value).

In addition to the instrumental measurements of sound level, the laboratory also had a group of trained engineers judging how disturbing the noise was on different power settings. The assessment was conducted on the lowest and the highest power setting.

Most of the air purifiers require relatively little power (W), but since they are intended to run more or less continuously, their energy consumption remains important. The energy consumption was measured at 37 dB and on maximum power.

The assessment of user friendliness was carried out by experts at the laboratory.

Some air purifiers clean the air using ordinary filters and ionising. Ionising involves the particles in the air being given a negative charge and then sticking to a positively charged metal plate inside the air purifier. If an ionising air purifier charges not only the particles but also the air itself, this forms ozone. Ozone is a health hazard over a certain threshold. The current threshold value for ozone (EU guidelines) is 0.055 ppm (parts per million). The laboratory measured the difference in ozone levels between the input and exhaust air from the various air purifiers.
None of the air purifiers tested emitted ozone above the current EU recommendation (0.055 ppm).

The measurement results from the test have been interpreted and graded in consultation with the laboratory. The grading is done on a scale from 1 to 10, where 10 is the best. A grade of less than 6 is only given if the performance is poor or worse than one might reasonably expect for this type of product.

The grades from the different elements of the test have been combined to give an overall grade, using the following weighting:

Measurements at 37 dB, or the nearest level below 37 dB: 45%
Room cleaning capacity for pollen and dust 67% (33+33%)
Sound level (instrumental measurement) 22%
Energy consumption 11%

Measurements at max power: 45%
Room cleaning capacity for pollen and dust 67% (33+33%)
Sound level (instrumental measurement) 22%
Energy consumption 11%

User friendliness: 10%
Filter replacement and cleaning 50%
Display and menus 17%
Controls 17%
Programming and settings 17%

Check the operating costs before purchase

All air purifiers have some form of filter that cleans the air. Particles in the air are trapped in the filter and after a certain amount of use the filter will need to be replaced.

– Some models have a pre-filter, for coarser particles, that can be cleaned.

– With particle filters and carbon filters, you will generally need to buy a new replacement.

– The cost of a new filter or pack of filters varies depending on the make and model, but assume from around 35 to over 90 British Pounds for a complete filter replacement.

– How often you need to replace the filter depends on how much the air purifier is used, the size of the filter (surface area) and the amount of particles in the air.

The manufacturers recommend a range of time spans for filter replacement, from every six months to once a year or every other year. Some models have an indicator that tells you when it is time to replace the filter.

 

No elevated ozone levels

Air purifiers’ possible ozone production has been much debated in recent years. Ozone can be formed by air purifiers that use a technique where the air is cleaned by charging (ionising) the particles. The EU has clear guidelines for ozone, since ozone that exceeds certain thresholds can be harmful to health.
None of the air purifiers tested showed elevated levels of ozone.

Check the operating costs before purchase

All air purifiers have some form of filter that cleans the air. Particles in the air are trapped in the filter and after a certain amount of use the filter will need to be replaced.

– Some models have a pre-filter, for coarser particles, that can be cleaned.

– With particle filters and carbon filters, you will generally need to buy a new replacement.

– The cost of a new filter or pack of filters varies depending on the make and model, but assume from around 35 to over 90 British Pounds for a complete filter replacement.

– How often you need to replace the filter depends on how much the air purifier is used, the size of the filter (surface area) and the amount of particles in the air.

The manufacturers recommend a range of time spans for filter replacement, from every six months to once a year or every other year. Some models have an indicator that tells you when it is time to replace the filter.

 

No elevated ozone levels

Air purifiers’ possible ozone production has been much debated in recent years. Ozone can be formed by air purifiers that use a technique where the air is cleaned by charging (ionising) the particles. The EU has clear guidelines for ozone, since ozone that exceeds certain thresholds can be harmful to health.
None of the air purifiers tested showed elevated levels of ozone.