Ceiling Fan Airflow & Wind Speed
Understanding airflow and wind speed is crucial to choosing a fan that meets your needs. This guide will walk you through how they're measured, what CFMs and RPMs are, how much air a ceiling fan should move, and which type of fan delivers the best airflow.
What Is CFM?
Airflow is measured in CFMs (Cubic Feet Per Minute). This is the actual volume of air that the fan is capable of moving at high speeds. This is one of the most important pieces of information for comparing ceiling fans, even more crucial than efficiency levels.
The most powerful fans on the market will move around 10,000 CFM while the average run-of-the-mill fan only has around 4,000-5,000 CFM airflow. You will find a dramatic difference in your level of comfort when sitting beneath the two different fans.
How Is CFM Measured & How Many CFM Do I Need Per Room?
First, you'll need to measure the volume. For a room that's a rectangle or box, multiply height × width × length. For example, take a kitchen that is 8 feet tall, 6 feet wide, and 5 feet long. The volume will be 8 × 6 × 5, which equals 240. For more complicated shapes, you'll need to separate the room into multiple simple shapes and then combine the measurements to determine the total.
Next, figure out how frequently you need to exchange air. This will depend on the room and what it's used for. A kitchen, for example, needs air circulation that's moderate to high (roughly every 3 minutes).
Finally, take the total volume of air (in cubic feet), and then divide by the exchange rate (how fast the air circulation needs to be). The number you come up with is the CFM your fan needs.
What Are RPMs & How Do They Affect Airflow?
RPM stands for Rotations Per Minute, and it measures the number of times a ceiling fan rotates per minute. The higher the RPM, the faster the blades will spin, moving more air.
The amount of air that a ceiling fan produces is affected by how fast it spins. However, RPMs alone don't produce airflow. The aerodynamics of the blades is every bit as important as the RPMs. If a fan has blades that are straight and flat, it doesn't matter how fast it spins; it's not going to generate much airflow. Take the same blades and give them a 15-degree pitch, and the fan will move air, but the RPMs will be slower, as the angled blades have to perform some work, which puts drag on the motor.
Consider the difference in airflow between two fans that operate at the same RPM, yet one has flat blades, and the other has angled blades. The latter needs a more powerful motor to maintain the same RPM as the former. Judging the airflow performance of a fan strictly by comparing RPMs is misguided. What you really need to know is how much airflow a fan will produce when operating at a particular RPM.
If you want a fan with the ideal airflow options, get a model with six speed settings; this will allow you to adjust the airflow from low to high.
What Are the Maximum RPMs Allowed for Ceiling Fans?
Ceiling fans only go so fast, as there are UL® standards that place limitations on manufacturers. These limitations are for safety purposes and are meant to minimize the risk of injury should a person raise their hands (or any other object) into the path of the ceiling fan blades while the fixture is in operation. While this is protective, it also presents challenges to engineers who design ceiling fans for maximum airflow and efficiency.
The first basic limitation is that no residential ceiling fans are allowed to be installed with the blades less than 7 feet from the floor. The second one has to do with the RPMs at which a fan can spin relative to the thickness of the blades. Thinner ones can cause more damage from laceration, so they aren't allowed to spin as fast as those with thicker blades.
The RPMs allowed for any residential ceiling fan that can be installed on a ceiling that's less than 10 feet high are restricted based on the blade span and thickness of the blades. Any blade less than 3/16" thick cannot exceed the RPMs for 1/8" thick blades. Any blades 3/16" thick or greater can't exceed the RPMs for 3/16" thick blades. The fan blades must always be more than 1/8" thick.
What Kind of Ceiling Fan Moves the Most Air?
First, look for a ceiling fan that has high RPMs but meets the highest safety standards. Avoid low RPM fans. Next, make sure the model has high CFMs, which show the volume of air a fan can move when it's on the highest speed. The strongest ceiling fans offer 10,000 CFM, but an average room only needs 5,000 to 6,500. Smaller spaces will need even less than that.
Because the blade span and pitch impact how cool a room feels, you should also consider the wind speed factor, which measures how fast the air is moving. This is, perhaps, the most important aspect to keep in mind. Higher wind speeds will make you feel cooler.
Our Wind Speed Factor online tool allows you to compare the potential cooling effect of fans with different sizes and CFMs. This is particularly useful if you are choosing whether to use a single large fan or two or more smaller fans in a particular area. For large rooms, two or more smaller ceiling fans are better than a single large one.
What should you look for when it comes to wind speed? The average wind speed factor of a ceiling fan is about 2.5 MPH, which won't cool you off adequately. Instead, find a model with a wind speed factor of 4 MPH or higher.
The Ceiling Fans That Move the Most Air
If you don't have the time to search through different models, here are a couple of ideal options:
i6 From Big Ass Fans®
This fan has an overall quality rating of 5.5 (the average is 3), which means it's durable and operates quietly. Additionally, it has a ceiling fan Wind Speed Factor of 4.36 MPH, giving it a Breeze Rating of 5.5 out of 5. This model provides about the strongest breeze you can get from a ceiling fan.
On top of that, this model moves 9,676 CFM of air. This will allow you to raise your thermostat by up to 10 degrees, saving you as much as 40% on your cooling bills. Fans like this often pay for themselves after just one or two seasons.
Above: i6 From Big Ass Fans
Maverick From Monte Carlo®
The overall quality rating of the Maverick is 5, as it runs smoothly and won't wobble or make noise. Plus, you can let it run 24/7 for years without the motor burning out. The ceiling fan Wind Speed Factor rating is 4.01 MPH, giving it a Breeze Rating of 5.5 out of 5. In addition to the wind chill this model will provide, it offers 6,928 CFM, which is above average airflow.
Above: Maverick From Monte Carlo
When looking at fans on our website, click on the “Performance” section to get information on a model's quality rating, Wind Speed Factor, and CFMs. The “Features” tab will provide data on Blade Pitch and RPMs.
If you're looking to buy a ceiling fan with optimal airflow and wind speed, Hansen Wholesale has you covered. Call (800) 201-1193 to get in touch with one of our experts.
For a chance to be featured on our Facebook page, share your best photo of a Hansen product in your home! Make sure to include the hashtag #HansenHome and tag us.