Many times you would have heard to use a ceiling fan with an air conditioner.
Others may say it is not a good idea to run a fan with AC.
Which one is right?
Well to answer this question I have written this post.
There are many benefits of running fan with AC
- Increased Comfort Level
- Decreased Power Consumption
- Lower Electricity Bill
And there’s a reason for all these benefits.
Let’s know why.
Actual Temperature vs Perceived temperature
There’s a difference between the actual surrounding temperature and the temperature perceived by your body.
What this means is, if on a hot sunny day the outdoor temperature is 35 °C (95 °F) then you may feel 32°C(90°F) or 38 °C(100°F) depending on other factors like wind speed and humidity.
This is perceived temperature by the body.
Our perceived temperature depends on actual temperature, humidity, and wind speed.
Let’s take two examples
Example 1: Hot Weather, High Humidity, Low Wind Speed
Assumption:
- Outdoor Temperature = 35 °C (95 °F)
Your perceived temperature will be greater than that of 35 °C (95 °F).
In this case, you may feel hotter as if the outdoor temperature is 38-40 °C.
Example 2: Hot Weather, Low Humidity, and Moderate Wind Speed
Assumption:
- Outdoor Temperature = 35 °C (95 °F)
Your perceived temperature will be lower than that of 35 °C (95 °F).
You may feel as if the outdoor temperature is 30-32 °C.
Why does this happen?
This is due to the temperature maintaining mechanism of our body.
In hot weather, our body releases sweat in the form of water. If there is high humidity then this sweat will not easily evaporate making you feel uneasy and you will feel as if the temperature is too hot.
But if humidity is low and the wind is flowing then the sweat from your body will easily evaporate making you feel cooler as if the temperature is nice and low.
Also at moderate-high wind speed, we will feel colder than the actual temperature due to the wind chill effect.
Running Fan with AC
If you run the ceiling fan with your air conditioner then you will feel a high level of comfort even if you increase the thermostat temperature by 2-4 °C.
This happens because of the actual vs perceived temperature of your body as discussed in the previous section.
The ceiling fan has no role in cooling the room, it only circulates the room air.
AC cools the room air and the fan circulates it.
Without a fan you will have to run AC on 20-22 °C for maintaining the comfort level but with a fan you can easily maintain your comfort level even at 25 °C.
This will also lower the AC power consumption.
Electricity saving with ceiling fan
I have taken the example of my Voltas 1 Ton window AC and have used this calculator for calculating its power consumption.
Running on 22 °C without a ceiling fan
Units consumed in 1 hour = 1.06
Running on 25 °C with a ceiling fan
Units consumed in 1 hour = 0.8
You can see the difference of 0.2 unit (approx) in both cases. It is clear that I will save 0.2 unit each hour if I use my AC with a ceiling fan.
Also both the cases provide me with same level of comfort.
When not to use a ceiling fan
1. In case of taller rooms or halls
If the room or hall is very tall and the ceiling is at 15-20 feet from the ground.
Then what happens when an air conditioner is running, the lower portion of the room gets cooler but the higher portion of the room remains hotter.
Why?
Because physics tells us hot air rises above and cooler air settles down.
In this case, if you run a ceiling fan with AC, the fan will push the hot air down increasing the load of AC.
This will increase power consumption.
So it is not a good idea to run a ceiling fan in tall rooms or halls.
2. In case your room is on the top floor
In this case, sunlight falls directly on your room making the ceiling hotter and if you run the ceiling fan along with AC.
The fan will push the hot air from the ceiling downwards increasing the load on AC increasing the power consumption.
Will other types of fan work
The ceiling fan is better at circulating room air.
Other fan types like table fan, pedestal fan, etc may not be that good as a ceiling fan for circulating room air.
In case your room is on the top floor, then a table fan or pedestal fan will be better than a ceiling fan.
Wrapping up
This was all about using a ceiling fan with AC. I always run my ceiling fan with the AC.
What’s your take on this topic.
Do you run your fan with AC?
Let me know in the comment box.
