Why CADR Can be Misleading

May 08, 2017

Why CADR Can be Misleading

Clean Air Delivery Rate, or CADR, is a measurement of an air purifier’s rate of airflow multiplied by the unit’s filtration efficiency. The official CADR is meant to be fair and unbiased, and many companies proudly boast a high CADR as a selling point in their advertising. However, since two independent variables are used to calculate the rating, one that is unusually high can outweigh a weakness in the other. Because of this, the CADR can often be misleading.

Why CADR Can be Misleading.

An air purifier that circulates the air in a room at a higher rate, yet does so without efficiently removing contaminants, may earn a higher CADR than another air purifier that cleans air well but circulates the air at a more gradual rate. A higher level of filtration may require a slower rate of airflow. This allows for air purifiers with a low filtration efficiency but more rapid circulation to score a higher CADR.

Airflow rate is certainly an important consideration when researching air purifiers. However, a higher rate of filtration is ultimately what gives you clean air.

How CADR is Determined.

When an air purifier is tested to determine its CADR, the unit is situated in an enclosed room that is full of airborne contaminants. The air quality of the room is tested before the unit is turned on and again after the air purifier has run for a full twenty minutes. The measurement of the remaining contaminants is used to calculate the unit’s CADR.

However, twenty minutes is often too short an amount of time for many higher end air purifiers to be effective. Because of the higher level of filtration, at least an hour is necessary for most units to completely circulate the air to effectively improve the quality of air in a room.

The test is biased toward air purifiers that circulate air at a faster rate, even though they may have removed fewer contaminants.

Because a high CADR is often used as a marketing tool, many manufacturers design their units to circulate air at the fastest rate possible, even though this allows for only the largest size particles to be removed from the air. Companies who tout their CADR may not have other filtration offerings, such as activated carbon, odor removal, or silver-ion technology. These features help air purifiers remove more contaminants from the air, but often slow the rate of air circulation. This slower air circulation can reduce a unit’s CADR score making them less competitive with more inexpensive air purifiers.

CADR and Austin Air Purifiers

CADR ratings only indicate rate of air circulation and the contaminants removed in an abbreviated period. It does not consider the product’s capability to remove odor, bacteria, or volatile organic compounds (VOCs). Austin Air Purifiers use many varied filtration options to remove these contaminants and improve air quality. These options are not considered when the CADR is calculated.

Austin Air Purifiers do not have a CADR rating for these reasons. We believe that the greatest benefit to the consumer is a higher filtration efficiency, not a faster rate of air flow. Our purpose is not to score a high CADR, but to improve the quality of our customer’s lives by removing the most amount of airborne particles and contaminants possible.

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