Why is Clean Air Delivery Rate Important?

When you first start looking into air purifiers and ventilation there’s a lot of technical jargon to get your head around.  CADR (Clean Air Delivery Rate) is one term you will come across, but it’s definitely one to understand.

The Clean Air Delivery Rate of an air purifier/Hepa filter tells you how efficient the purifier is at removing pollutants from indoor air.  Typically this means the effectiveness of the purifier or filter has been tested on how quickly it can remove pollen, smoke and dust from the air

Normally CADR is measured in M3 per hour, but it can also be in cubic feet per minute. 

The CADR that is shown on technical specifications and air purifier packaging is normally at the maximum fan setting and shows you how much air in M3 can be cleaned of those pollutants in the space of 1 hour. 

The recommendations for air changes per hour varies according to the environment – but typically in a non-healthcare setting – the target should be 5 air changes per hour in a space.

This means that when you choose an air purifier for a space, you must ensure that the CADR of the device (or devices) is ample enough to purify the air 5 times per hour in that given space. 

One word of advice.  Don’t be conned by the many advertised devices that say they are suitable for rooms up to 40m2, but only have a maximum CADR rating of 180m3 per hour.  If you assume a typical ceiling height of 2.4m – the total volume in a 40m2 room is 96M3.  Times that by 5 and the target clean air delivery rate you need is 480m3!  A device with a CADR of only 180m3 will only clean the air every 33 minutes.  Granted – that’s better than nothing at all, but is not going to be as effective as a device that is cleaning the air every 12 minutes!

As a guide – we have listed below some typical CADR ratings for devices with the max size of room they are suitable for:

CADR RATING OF AIR PURIFIER	MAX SIZE ROOM (assuming normal ceiling heights)
100	8M2
250	20M2
500	40m2
600	50M2

Decided that you need an air purifier?

At Zonitise we distribute world class medical grade HEPA air purifiers for every type of space.  From a large corporate office to your kitchen!   You can check them out here!

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