Clean-air Delivery Rate - Applicability

Applicability

The CADR ratings were developed by Association of Home Appliance Manufacturers (AHAM) and are measured according to a procedure specified by ANSI/AHAM AC-1. The ratings are recognized by retailers, manufacturers, standards organizations, and government bodies such as the EPA and the Federal Trade Commission. Whole house air cleaners are not covered by the CADR specification because the measurement is performed in a standard 1008 cubic foot room, the size of a typical house room, which has different airflow patterns than whole-house filters. Measurements are made with the filter running and not running, so particles that naturally fall out of the air are not being counted as part of filter's operation. The measurement only applies to particulate matter, not to gases.

Any device or technology that removes particulate matter from the air can be tested for CADR numbers. Anyone with the necessary equipment can perform the ANSI/AHAM AC-1 measurements. The AHAM performs the tests for manufacturers who choose to use their service which allows the manufacturer to display a seal that certifies AHAM performed the test.

The rating is only valid for a given filter used in a specific equipment design, and only at the beginning of its service life. Choosing a higher or lower efficiency filter than the unit was designed for may decrease its ability to filter air. An exception is when a high efficiency filter does not decrease the fan's airflow rate. This is usually achievable only with physically larger or thicker filters, which usually can't be used in a unit designed for smaller filters. Filters with efficiencies higher than the original may slow the fan's air flow rate down which may result in a lower CADR rating.

Due to the measurement process, the CADR rating is intended for use only with equipment designed for residential spaces. Clean rooms, hospitals, and airplanes use high-efficiency HEPA filters and do not use a CADR rating, but instead may use MERV ratings.