What is the Clean Air Delivery Rate (CADR)?

Clean Air Delivery Rate is a measurement that describes the effectiveness of an air purifier. You will often hear (or see) it referred to as CADR. The exact measurement tells you how much clean air is produced by a purifier. We will go over some of the information that you, as a consumer, want to know about CADR.

In order to develop a more standard way to determine how well an air purifier could handle a room, CADR was developed. You use the CADR to determine how much of a particle is removed. When you look at most CADR ratings will provide you with ratings for three different particles smoke (often tobacco smoke), dust, and pollen. Along with the rating for each particle, the recommended room size for the particle is listed.

Clean Air Delivery Rate

CADR Equation

CADR takes the amount of clean air that passes through the filter and the efficiency to determine a rating. If a 100 cubic feet of air per minute passes through a unit and has a 50% efficiency, the CADR rating would be 50. But how do you use that number?

Experts say that you should use the square footage of the area you are looking to purify as a way to start determining what CADR rating you need. Take the square footage of the area needing purification and divide it by 1.5.

An example of this if you have a room with a square footage of 250 you will want a CADR rating of 167. Here is the equation for that: 250/1.5=167.

Remember that this number might vary for different types of particles. Not all air filtration systems can handle particles the same way. CADR is not applicable to whole house air systems as they do not meet the testing standards needed to get a CADR rating. Another system has been put into place in order to measure whole house units or not portable units.

How Is A CADR Number Generated?

The process for determining the clean air delivery rate is standardized amongst the industry. A testing chamber of exactly 1008 cubic feet is used. The purifier is placed in the room but before it is activated, the room is measured for contaminants. For 20 minutes the purifier is run in order remove contaminants from the air.

Throughout the time that the purifier is running, air samples are being taken. This gives the technicians multiple points from which to calculate the CADR.

After the numbers have been collected the process isn’t over. Each particles decay rate is then compared to the natural decay rate of those particles in a room to ensure that the purifier is actually purifying the room. Once all of this is done, a CADR is finally assigned to the unit.

Who Created CADR?

CADR was designed by the Association of Home Appliance Manufacturers and has been in place since the 1980’s. The CADR rating system is generally recognized around the industry. An ANSI standard has been developed to spell out the specific testing and give the process some additional official backing.

In the United States the Environmental Protection Agency, recognizes CADR as an official rating system. Other organizations such as the Federal Trade Commission and the Consumers Union recognize CADR too.

More than CADR

While CADR will give you an idea of the amount of air that is purified, it won’t give you an idea of how it is purified. There are a number of purification methods and have different effects. Ionizers generate negative ions, as an example. Ozonators make the air smell like a thunderstorm. HEPA filters carry air through a filter where particles get stuck.

Make sure you investigate the different methods that you consider getting for air purification. A little bit of research into the different methods will give you an idea of what to expect.

Now that you have an idea of what clean air delivery rate is, you can make a more informed decision about the purification of air in your home or business. Before the CADR, Trying to figure out how much air a purifier could handle was complicated. It may still be somewhat complicated, but at least it is easier to understand.

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