Outdoor Fan Air Flow

What is Air Flow for an Outdoor Fan?

Air flow measures a fan’s ability to convert electricity to moving air. It measures the fan as a unit, not just the motor or the blades. Manufacturers that have measured their outdoor fans for CFM/CMM will gladly display this information.

If a manufacturer or retailer only gives you CFM or CMM, you may want to convert it to measurements you’re more comfortable with:

1 cubic foot x 35.315 = 1 cubic meter
1 cubic meter x .0283 = 1 cubic foot

How Much Air Flow Do You Need?

We can pick up a general rule from the field of indoor cooling:

The amount of CFM or CMM needed to cool an area is about 3 to 4 times the area.

Example:
If you’re holding an outdoor event for 10 people in a tent that’s 10′ x10′ x10′ (1,000 cubic feet), you’ll need an outdoor fan with about 3,000 to 4,000 CFM.

In international measurements:

If you’re holding an event for 10 people in a tent that’s 3m x 3m x 3m (~28 cubic meters) you’ll need an outdoor fan with about 85 to 113 CMM.

You can use a conversion calculator to easily switch between measurements.

The fan’s blades can maximize the fan’s air flow, helping it to cool an area more effectively.

The Setup Can Maximize an Outdoor Fan’s Air Flow

An example

Beyond general rules, fine tuning the air flow you’ll need can be done by experimenting. A fan with variable speeds can be extremely helpful for this. In a small area like a booth-sized 10-foot by 10-foot (3-meter by 3-meter) area filled with ten people, you’ll want one or more fans that can move a total of 3,000 – 4,000 CFM (85 – 113 CMM).

consider what kind of fan(s) you would use and where you would put them:

• If the people will be standing, a floor fan in a corner or against one side could work well as long as it is not a tripping hazard – a real risk if those 10 people would be walking around that space. But that many people walking around that sized space could interrupt the air flow.
• If the people will be seated you could consider a standing / pedestal fan or a table fan. If there is room, two smaller fans set up in different corners can be set on lower speeds and would likely be less nuisance to anyone sitting right next to them than one stronger fan.
• What about a ceiling fan? Its air flow is largely unobstructed and it would be out of the way. Even small ceiling fans need a strong overhead structure to mount onto, so these would not be suited to a popup tent. Also, ceiling fans must to clear the ground by at least 7 feet / 2.14 meters so no one bumps into them. Any support it’s mount to needs to be at least 8 feet / 2.44 meters to allow.
• You could also consider outdoor fans that attach to the tent’s support posts. Look for smaller fans lightweight enough to attach to the posts. Again, smaller fans create softer breezes and can reach more areas than a single fan. Smaller fans will move less air, so you may need more than one – maybe on on each post. For four fans, each would need a CFM of 700- 1000 or 21.4 – 28.32 CMM.
  Here’s the link to that conversion calculator to easily switch between CFM and CMM.
• Remember to consider power supply. Electric cords can be a tripping hazard, so battery powered fans could solve that issue.

What would you choose?