Clockwise or Counterclockwise With Air Conditioning For Energy Savings?

This article discusses what direction a ceiling fan should spin when used with air conditioning.

If you are looking for a way to cool down your home without high air conditioning bills, then you might want to consider installing a ceiling fan. However, there is one thing you need to keep in mind when running the fan in conjunction with air conditioning. And that is the direction of rotation of the ceiling fan.

A ceiling fan should rotate in the counterclockwise direction when used with air conditioning. This increases the effectiveness of the air conditioning unit and reduces energy consumption.

But how does this happen? Why can’t a ceiling fan running in the clockwise direction achieve the same? Read further to learn more.

using a ceiling fan with air conditioning

Why should a ceiling fan spin counterclockwise when using with air conditioning

Most ceiling fans are reversible so they can be spin either clockwise or counterclockwise depending on preference. Spinning the fan in the counterclockwise direction will push the air down while spinning it clockwise will push the air towards the ceiling. A fan should rotate counterclockwise during summer and clockwise during winter. You can get more info about this in this article – Ceiling fan directions for summer and winter.

What is important for us here is the direction of airflow. Like I said before, the counterclockwise running of the fan pushes the air down. And this is how a ceiling fan is useful in reducing energy bills when used with air conditioning.

When the fan runs counterclockwise, it pushes the conditioned, cool air downwards towards the occupants in the room. This creates a chill effect that makes the occupants cooler than the actual temperature in the room. This chill effect can lower the effective temperature in the room by up to 4 degrees.

For example, if you are running a ceiling fan in a room with the thermostat set at 80 degrees Fahrenheit, the occupants will feel 76 degrees. So practically, you can set the thermostat at 84 degrees and feel as comfortable as in an 80 degree room by running a ceiling fan.

Typically, using a ceiling fan with air conditioning can reduce your cooling costs by 4 to 8%. For example, if you have installed a ceiling fan in a house where the thermostat is set at 60 degrees Fahrenheit, you would save around $40 per month on the electricity bill.

Does a fan with fewer blades improve cooling?

Other than the fan spin direction, another important factor that improves the cooling effect of air conditioning is the number of blades on the ceiling fan. Does a fan with more blades help air conditioning to save energy more?

Fans with fewer blades are more effective than those with a high number of blades when used with air conditioning. For example, a 3 blade fan does a better job at cooling a room with air conditioning than a 5 blade fan.

The reason behind this is the wind speed. For two fans with the same CFM rating, the one with fewer blades produces more wind speed. Therefore, a 3 blade fan will produce more wind chill effect than a 5 blade fan. Since wind chill effect is the reason behind lowering the effective temperature in the rooms, having fewer blades means higher efficiency.

So if you want to use a ceiling fan effectively with an air conditioner, choose a fan with few blades.

Recommended reading: 3 blades vs 5 blades: which is better?

High speed vs low speed

Should you run the ceiling fan at its low speed or high speed for better cooling with AC?

A ceiling fan should run at its highest speed when used with air conditioning for best results. A high-speed fan creates a stronger breeze of cool air in the room. This will make the occupants in the room feel much cooler than under a low speed ceiling fan.

Therefore, I recommend setting the ceiling fan’s speed to the maximum during summers. High speed fans help to lower air conditioning costs than low-speed ceiling fans.

Low CFM vs high CFM

When you buy a ceiling fan, the general recommendation is to buy the largest one with the highest CFM. The highest CFM part of this advice holds true when selecting a ceiling fan to run with your air conditioning. With the increase in airflow (CFM), the fan will be able to circulate more air through the room effectively increasing its wind speed. Therefore, I recommend using a high CFM fan with air conditioning.

However, the second part of the advice, about selecting the largest fan, may not be good when working with AC. While a large fan helps to evenly circulate air throughout the room, it effectively reduces the wind chill effect, thus reducing the fan’s effectiveness in lowering energy bills.

For example, the fan with the smallest size will produce more wind effect among two fans with the same CFM and different blade spans. This is because the smaller fan will have to run much faster to move as much air as the larger one.

Flush mount vs standard mount

Standard mount ceiling fans are recommended over flush mounted ones for use with air conditioning. This is because flush-mount fans have less space above their blades. This lack of space affects the wind speed of the fan. Therefore, if possible, use a standard mount ceiling fan over a flush-mounted one in conjunction with air conditioning.

Should I turn off the fan when leaving an air conditioned room?

Most houses use centralized air conditioning units. Therefore, turning off a room’s air conditioning is not practical when no one is in it.

However, you should turn off a ceiling fan when leaving an air-conditioned room to save energy. This is because ceiling fans do not lower the temperature in a room, they only make the occupants feel cooler. So running a ceiling fan in an empty room will not have any effect on air conditioning. Instead, it will only increase your energy costs.

Charles John

A novice DIYer who learns about home ventilation. I am a mechanical engineer and have a basic knowledge of HVAC systems but I learn continuously to make myself the best blogger in that space.

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