Clean Air Delivery Rate Made Simple for Air Purifier Buyers

So you're in the market for a new air purifier, but you're not sure what to look for in terms of clean air delivery rate. The clean air delivery rate (CADR) is a crucial metric to consider, as it measures the amount of clean air an air purifier can deliver to a room.

A CADR of 100 means the air purifier can remove 100 cubic meters of polluted air per hour. This is a useful benchmark for comparing different air purifiers.

For a small room, a CADR of 100 may be sufficient, but for a larger room, you'll need an air purifier with a higher CADR, such as 200 or 300. This ensures you get clean air throughout the room.

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CADR, or Clean Air Delivery Rate, is a measure of how well an air cleaner can remove pollutants from the air. It's a bit like a report card for air cleaners, showing how well they can filter out different types of particles.

CADR is based on the volume of filtered air an air cleaner delivers, with separate scores for tobacco smoke, pollen, and dust. The higher the CADR number for each pollutant, the faster the unit filters the air.

Here are some examples of CADR ratings for the Honeywell HPA060 air cleaner:

The reason CADR ratings improve as particles get larger is that larger particles are easier to catch, making it easier for the air cleaner to filter them out.

The CADR rating is a crucial factor in determining the effectiveness of an air purifier. It measures the rate at which the air purifier can clean the air, but it's essential to understand how it's tested.

The CADR is measured with the air purifier running on the highest fan speed, so if you plan to use a lower fan speed, the CADR will be lower. A new, clean filter is used in the test, which doesn't reflect the performance of the air purifier over time.

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A small, thin filter may test well in the CADR test, but its performance will drop significantly soon after. To better understand this, look for information on the amount of filter media in the filters and the size of the air filters.

The CADR rating doesn't factor in noise level, so you'll need to consider this separately. It's also not a safety test, so it doesn't measure ozone production, motor reliability, or energy usage.

Here's a simple way to understand the CADR rating: if the air purifier has a CADR of 400 m³/hr, it can clean 400 cubic meters of air per hour. To calculate the number of air changes per hour, divide the CADR by the volume of the room in cubic meters.

For example, if your room is 30 sqm with 2.5-meter-high walls, the total volume is 75 cubic meters. Dividing the CADR by this volume gives you 5.33 air changes per hour. Aim for at least three air changes per hour to filter PM2.5 sufficiently, and six to twelve air changes per hour to filter the Coronavirus.

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To choose the right air purifier, you'll want to consider the room size and the type of filter it uses. For smaller spaces (below 150 sq. ft.), look for an air purifier with a CFM of around 250, which is a good balance between effectiveness and cost.

CADR, or clean air delivery rate, can be deceiving, especially for ionization-based air purifiers that have high CADR ratings but may not be as effective as HEPA-filtered units. Instead, focus on the CFM, which shows how much air is processed, not how well it's processed.

A good rule of thumb is to use the CFM to determine the right air purifier for your space. Here are some general guidelines to keep in mind:

Remember, CFM is a more transparent and reliable metric than CADR, so look for air purifiers that specify their CFM output.

CADR is a crucial factor to consider when choosing a purifier. It's measured in cubic meters per hour (m³/hr) or square feet per minute (sqft/min).

Many brands label their machines with square meter specifications, but this is not reliable.

The CADR rating gives you the most accurate information on how effective an air purifier is.

CADR is a more accurate measure than square meter specifications because it takes into account the air purifier's actual cleaning capacity.

The CADR rating is found in the spec sheet, so be sure to check it out.

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To determine the right air purifier for your space, consider the room size. A good rule of thumb is to use an air purifier with approximately 250 CFM of output. This is because anything more than 250 CFM can be a poor value for the price, while anything less may not be effective enough.

In smaller spaces (below 150 sq. ft.), use an air purifier on lower settings. For larger spaces (up to 300 sq. ft.), use it on higher settings. In extra-large spaces (well over 300 sq. ft.), you may need to use multiple units.

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Here's a rough guide to help you choose the right air purifier for your space:

CADR can be deceiving, so it's essential to look at the CFM rating instead. CFM measures the volume of air an air purifier can clean in a minute, making it a more transparent and reliable metric.

The CADR, or clean air delivery rate, is a measure of an air purifier's effectiveness in removing pollutants from the air. It's a reflection of the air flow (CFM) times the efficiency of the air filter. If an air filter has 200 cfm and 100% efficiency, the CADR would be 200.

The CADR is a useful way to compare air purifiers that consider both air flow and filter efficiency. It helps to balance the two, so you're not misled by marketing messages that highlight one aspect over the other. For example, if a filter has a high filter efficiency but low air flow, the CADR helps to give you a more accurate picture of its performance.

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The CADR is a fraction, with the top part representing the CFM of air in an approx. 1,000 cubic ft. from which all particles have been removed, and the bottom part representing the rate at which those same particles would naturally fall out of the air under the same conditions.

The CADR rating is a game-changer for consumers, giving us a way to compare air purifiers that consider both air flow and filter efficiency.

It's a reflection of air flow (CFM) times the efficiency of the air filter, providing a consistent way to compare performance across products.

If an air filter has 200 cfm and 100% efficiency, its CADR would be 200, while a filter with 200 cfm and 75% efficiency would have a CADR of 150.

This helps us avoid being misled by marketing messages that focus on high filter efficiency but low air flow.

Particle counters can show impressive results, but they don't factor in other important data points like air flow and noise level, giving us an incomplete picture of how well an air purifier will work in our environment.

So, you want to understand CADR, right? CADR stands for Clean Air Delivery Rate, and it's a way to measure how well an air purifier can clean the air in a room.

The CADR rating gives you a way to compare air purifiers that consider both air flow and filter efficiency. It's like comparing two different air purifiers to see which one can clean the air better.

The CADR is calculated by multiplying the air flow (CFM) by the efficiency of the air filter. For example, if an air filter has 200 CFM and 100% efficiency, the CADR would be 200.

A more technical definition of CADR is a fraction, where the numerator is the CFM of air in a 1,000 cubic ft. space with all particles removed, and the denominator is the rate at which those particles would naturally fall out of the air.

The EPA EnergyStar program uses CADR as the basis for performance, and they also factor in energy usage to get an energy efficiency ratio, which is the CADR per watt.

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To put it simply, a higher CADR means a cleaner and more efficient air purifier. But, it's not the only thing to consider when choosing an air purifier. You also need to think about the energy usage and the size of the room.

Here's a table to help you understand the minimum smoke CADR to watt ratio standard:

For example, if you have a CADR rating of 250, the power on high needs to be 86 watts or less. This means that a 250 smoke CADR can clean 387.5 sq ft.

So, remember, CADR is not just about air flow, but also about how well an air purifier can clean the air. It's like comparing two different bartenders - one might work faster, but the other might make a better drink!

The Clean Air Delivery Rate (CADR) standard isn't limited to certified air cleaners. You can calculate your own CADR for non-certified air cleaners, such as those using MERV-rated filtration devices.

To do this, you need the filtration efficiency for the MERV rating of your filters and the air flow rate going through the filter. For example, if you have a MERV 13 filter in your heating and air conditioning system operating at 600 cfm, you can calculate your CADR by multiplying the air flow rate by the decimal form of the efficiency.

Here's a breakdown of the efficiency for different MERV ratings:

For a MERV 13 filter, this would result in CADRs of 300 cfm, 510 cfm, and 540 cfm for different particle sizes.

You can calculate your own CADR for non-certified air cleaners, like those using MERV-rated filters. This can be a helpful way to compare their performance.

To do this, you'll need to know the filtration efficiency for the MERV rating of your filters and the air flow rate going through the filter. You can find this information in the table below.

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Here's an example of how to calculate your own CADR:

For instance, if you have a MERV 13 filter in your heating and air conditioning system that operates at an air flow rate of 600 cfm, you can calculate your CADR by multiplying the air flow rate by the decimal form of the efficiency.

This method can be a useful alternative to certified ratings, and it's actually how some DIY air cleaners, like the Corsi-Rosenthal box, were tested.

In the world of air purifiers, there are two notable CADR standards: the American AHAM (Association of Home Appliance Manufacturers) and the Chinese GB 18801-2015.

The American AHAM standard is a widely recognized benchmark for air purifier performance in the US.

The Chinese GB 18801-2015 standard is a key regulatory requirement for air purifiers in China.

These two standards have gained significant traction in the industry and are often referenced in discussions about air purifier quality.

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