Room capacity air purifiers

Room capacity air purifiers

An exact statement of the capacity of an air purifier in terms of surface (m²) or volume (m³) is hardly possible. There are too many other factors at play, such as:
• Degree of air pollution in the room.
• The type of pollution (dust, smoke, viruses, allergens, pollen, odors, volatile substances, etc.
• The amount of people in the room.
• The degree of ventilation in the room.
• The required air quality.
• Is the level of pollution constant or is there peak pollution that must be cleaned up quickly?
If an air purifier has a certain maximum specified room capacity, you should also take into account that in order to purify the air in such a room, it must operate at the highest operating mode, which produces more noise and is at the expense of the life of the filters, and in the long run of the device itself.

US and Japanese Certifications

However, there are some measuring methods to measure the surface capacity, devices from renowned manufacturers will therefore be provided with a certification, 2 certifications are known worldwide; the JEM 1467 guideline. (Japanese Electronics Manufacturing association), and the CADR (Clean Air Delivery Rate) standard of the American AHAM (Association of American Home Appliance Manufacturers).

The Sharp air purifiers are tested according to the JEM 1467 guideline, the Winix and Coway devices are certified according to the AHAM/CADR guidelines.

In both measuring methods, the effectiveness against dust particles is measured on the basis of the amount of purified air and the quality of the purified air. In addition to dust, the CADR standard also measures the effectiveness against smoke and pollen.

Subsequently, a surface effectiveness is linked to these values. In the case of the JEM 1467 guideline, the area of ​​the room is shown in which 88% of the dust particles can be removed within 30 minutes.
In the case of the CADR/AHAM method, the area of ​​the room is shown in which 80% of all smoke particles can be removed within 20 minutes.

In the case of the JEM 1467 method, therefore, a greater degree of air purification is displayed (88% against 80%), but measurements are taken for 10 minutes longer (30 minutes against 20 minutes).

However, the CADR measurement method of surface effectiveness measures the effectiveness against smoke particles because these of the measured contaminants are the most difficult to filter and remain in the air the longest.

It can therefore be concluded that the CADR/AHAM measurement method is the strictest. The JEM 1467 method requires a somewhat higher degree of air purification, but gives 50% more time for this and measures a pollution that is easier to filter.

Certified space capacity versus deployment in practice

Given that an air purifier is normally switched on all day long, it is generally not necessary that it has to purify all contaminants within 20 minutes. The CADR/AHAM indicates what an air purifier is capable of under extreme conditions, but normally an air purifier will rarely need to purify such levels of contaminants.

Therefore, it can be taken as a rule of thumb that an air purifier that is used for general use is suitable for rooms 2 to 3 times as large as the CADR/AHAM purification capacity within 20 minutes.
If the appliance is used against allergies, strong pollution, there are higher requirements for air quality or if the appliance has to be effective within a few minutes, the CADR/AHAM guideline is a very good indication of the space capacity of the appliance.

Differences in space capacity specifications by the different manufacturers and suppliers

In general it can be said that the various suppliers/manufacturers of air purifiers make very different statements regarding the space capacity. The statements of brands such as Coway and Winix are very conservative due to the application of international standards such as AHAM/CADR.

In many other cases this is grossly exaggerated. Examples are known of air purifiers with a filter capacity of 180 m³ per hour, but the device is stated as suitable for use in rooms up to 70 m². However, in practice this is far from sufficient for a room of this size
That is why when it comes to HEPA air purifiers it makes sense to look at the filter capacity in m³ (cubic meters) per hour, on the basis of this air purifiers can be compared most objectively.

Rule of thumb for calculating room capacity of HEPA air purifiers

The filter capacity in m³ can be used to compare HEPA air purifiers (provided that the air moved through the unit is filtered equally well), but there is also a formula that gives an indication of the size of the room where an air purifier is used. is appropriate; with mild pollution it is advisable to use an air purifier with a filter capacity that is twice as large as the volume of the room, with average pollution 3.5 times as large as the room and with heavy air pollution (such as cigarette smoke) or if very high demands are made on air quality, such as with asthma or allergy patients five times the size of the room.

For example, if an air purifier has a capacity of 300 m³, it is suitable for a room of 150 m³ with mild pollution, with an average air pollution for a room of 85.7 m³ and with strong pollution or if the air needs to be very clean. space of 60 m³.

Please note; we’re talking cubic feet here, not square feet.

Comparison with plasma/electrostatic air purifiers

These measurement methods can only be applied to air purifiers with HEPA filter and fan. Ionizers, plasma and electrostatic air purifiers cannot be measured in this way. In terms of effectiveness against dust and other contaminants, nothing beats a HEPA air purifier, it has a greater airflow and more effective filtering of the contaminants in the air than plasma air purifiers. In particular, the most difficult to filter (fine) dust particles are filtered out of the air up to 2x more effectively by a HEPA air purifier.

In combination with HEPA air purification, a plasma ionization system can achieve added effectiveness, but certain volatile substances and micro-organisms that cannot be caught by filters or are not sucked in by the device can be effectively combated as a result. Plasma ionization also has an antistatic effect, which allows the particles suspended in the air to remain suspended instead of adhering to surfaces, which means that they end up faster in the air purifier to be permanently filtered out of the air. That is why Winix and Sharp make air purifiers from a combination of air purification with filters and a plasma system.

Certified effectiveness against allergens

Various organizations devoted entirely to allergy control also have certifications that test and confirm the effectiveness of air purifiers against allergic reactions, ECARF (European Center for Allerge Research Foundation) grants the ECARF Seal of Quality for air purifiers that have the following properties:
• Achieves significant reductions in the amount of pollen, bacteria and mould/spores in the air:
• Filtration of more than 90% of fine dust particles smaller than 7 m.
• Filtration of more than 95% of bacteria in house dust.
• Less than 1 ng/m³ airborne allergens in the room.
• Filtration of more than 85% of moulds/spores.
• No production of ozone, ozone value should be in accordance with DIN EN ISO 16000-9:<15 μg/m³.
• No change in room temperature.
• The exhaled air is odorless.

Another well-known organization that certifies the effectiveness of air purifiers is the BAF (British Allergy Foundation), which has various products, including air purifiers, scientifically tested for effectiveness against allergens, bacteria, pollen, mold and other contaminants.

A demonstration of the effectiveness of a HEPA air purifier against fine dust particles (in this case smoke):

Fine dust test

Personal advice for your individual situation

As can be read above, there are many factors that influence the suitability of an air purifier for a particular room or application. If you are therefore wondering which device is best suited for your situation, you are welcome to contact us for personal advice, we can be reached by e-mail and telephone:


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