Air changes per hour, abbreviated ACPH or ACH is a measure used in ventilation calculations to measure the amount of ‘new’ air added or removed from a room.
Equivalent air changes per hour, or e-ACH, on the other hand is a measurement of the ‘equivalent’ amount of air a purifier changes per hour. Air purifiers do not actually bring in new air into a room, or change the air in a room. Instead, they clean the air already existing in the room.
Learn more about: How to calculate an air purifiers equivalent air changes per hour (e-ACH) »
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