The effective working area is the room size that the purifier can effectively clean and it is intrinsically related to the Airflow, filter efficiency and room size.
This is the single most important parameter you must look for when looking for an air purifier, as you should buy one that will work well for your room size.
To calculate the effective working area, you need to know the airflow and filter efficiency of the air purifier. If you don’t see these parameters on the specifications table of the product you are intending to buy, the manufacturer or vendor could have just created the effective working area from a random assumption instead of real data.
How we calculated the Effective Working Area of the AirCleaner Personal
From our tests, and ESRC Validation Report, we know the following parameters:
Filter Efficiency = 99.86%
Airflow = 285m3/h or 167.64 cfm
We can now calculate the Clean Air Delivery Rate (CADR) of the AirCleaner Personal:
CADR = Airflow(cfm)*Efficiency
CADR = 173.63cfm*0.9986 = 167.4
Now, according to the Association of Home Appliance Manufacturers, for a room with an 8ft (2.44m) ceiling, the CADR is multiplied by 1.55 to find out the effective working area:
EWA = 167.4*1.55 = 259.47 sqft = 24.1m2
Working backwards, if you know your room size, you can convert that value to sqft and then divide it by 1.55 to get the necessary CADR.
Room volume = 25m2 = 269sqft
CADR = 269sqft/1.55 = 173
You might have seen that manufacturers give the Effective Working Area in a range, for example, 25m2 to 30m2. That’s because rooms are not normally empty, there are beds, wardrobes and stuff around which effectively reduces the total volume of the room.
Knowing the CADR, can also tell us how long the air purifier will take to clean the room. For example, if we have a 25m2 room with a 2.5m ceiling:
Room volume = 25m2*2.5 = 62.5m3 = 2207.16 cft
Minutes to clean the room = room volume/CADR = 2207.16/167.4 = 13min
It is worth saying that these are purely theoretical calculations and in real conditions, there are factors such as leakage, non-ideal air purifier placement and filter ageing which will affect the final CADR of the air purifier.
