Most air purifiers mention their Clean Air Delivery Rate (CADR), which is a measure of the unit’s airflow times the filtration efficiency in air purifiers. As two variables are used to calculate the CADR, an increase in one can offset a decrease in the other—but still result in an higher CADR rate. The CADR is meant to be impartial and is advertised as the the best way to compare air purifiers. However, it can be misleading.

Why is CADR a misleading comparison for air purifiers?

The CADR is biased towards air purifiers that circulate a higher rate of semi-clean air, rather than air purifiers that can clean the air well, but circulate air at a lower rate. Greater filtration efficiency can slow a units airflow, allowing for air purifiers with lower efficiency, but faster air circulation to have a higher CADR.

While airflow rate is important to consider when researching air purifiers, higher filtration efficiency will give you the greatest benefit with more purified air.

The Problem with CADR Testing

This may be caused by the test used to calculate CADR. In this test, a unit is placed in an enclosed room that is then filled with airborne contaminants. After running the unit for 20 minutes, the air quality is then tested and the CADR is calculated.

This is a relatively small amount of time for most air purifiers, as many higher-end air purifiers require at least an hour to circulate air and improve air quality, especially if the filtration efficiency is high. Therefore, the air purifiers that circulate more air tend to have higher CADR, despite the fact they removed a smaller amount of contaminants.

In order to score well on this test, many manufactures have designed their air purifiers to circulate a lot of air quickly, filtering only the larger contaminants. This can mean companies who compete based on their CADR usually do not have other filter offerings other than standard HEPA filtration. Adding filter options with carbon, odor removal or silver-ion technology will reduce their air purifiers’ CADR score, making them less competitive with other lower-end units.

Alen Air Purifiers and CADR

CADR also fails to indicate a product's ability to capture and remove bad odors, bacteria, or volatile organic compounds (VOCs). Alen Air Purifiers successfully removes these contaminants from your indoor air with versatile filter options, which the CADR does not take into account.

For this reason, Alen Air Purifiers are not rated by the CADR system. We believe a higher filtration efficiency is more important than a higher airflow rate, giving you the greatest benefit from our air purifiers. Our purpose is to help our customers Live Better by removing an effective amount of airborne particles and contaminants from your indoor air, not to receive a higher CADR.

Are you interested in learning more about Alen Air Purifiers or CADR? Visit our Product Advisor or call an Alen Air Quality Specialist 800-630-2396 to learn more.