Does Leaving a Fan on Waste Electricity?


Most homes have their fan on during the summer to cool the room and circulate air. They’re a simple solution and are known to be inexpensive.

But does leaving a fan on waste electricity? Fans are powered by motors, so leaving fans running will obviously waste electricity. For example, if you leave a fan running for 10 hours during the day while at work, it will add approximately $2 to $5 per month to your electricity bill per each fan.

Let’s take a closer look at the math and share some other tips you may find useful.


Estimating Your Electricity Costs of Running a Fan

For the fan blades to turn and cause convective cooling, they must have a motor running them. It comprises mainly of a motor and blades. The electromechanical device (motor) converts electrical energy to mechanical energy. 

The type of motor and its wattage rating will determine the amount of energy it consumes. The higher-rated the fan and its motor is, the more power it will consume. You will need some mathematics to calculate the energy consumed.

To calculate the amount of electrical energy consumed by the motor, simply read its wattage rating and multiply it by the number of hours used.

For example, a fan rated at 50 watts will use 500 watt hours (Wh) if it runs for 10 hours.

To get kilowatt-hours (KWh), simply divide the watt-hours (Wh) by 1000. In this case, it’s 0.5 KWh.

Electricity consumers pay electricity bills per KWh (kilowatt-hours) consumed. For most people, using the example above, the cost of running a fan for 10 hours would barely cost 7 to 10 cents per day, or  $2.10 to $3.00 a month. This cost would be slightly higher with more powerful fans or if you keep a fan running on its highest setting.

Indeed, ceiling fans don’t generally cost a lot to run compared to your overall electricity bill. However, this also doesn’t mean that you should just mindlessly leave the fan on, either.


Still, Leaving Fans On Wastes Electricity!

So technically, to the original question at hand, does leaving your fan on waste electricity –

The answer is YES. If you leave your fan on, even when no one is in the house, you increase the running hours. As a result, the total watt-hours consumed increase. And most homes have several fans, so leaving 5 or 6 fans on in your house at all times can add up in energy costs little by little.

You also need to consider another cost – unnecessary wear and tear.


The Downside of Using a Ceiling Fan Too Often

Fans are a must-have in the summer. However, leaving your fan on at all times can cause the motor to overheat up due to electrical losses, friction, and vibration. The fan radiates the heat to the air around it circulates in the house.

Rather than having a cool breeze rushing through your skin, you will now have a warm breeze emanating from the overheated motor. To try and correct the situation, you then raise the motor’s speed even further, which translates to more electrical power consumption.

The point of the story is to only use the fan as needed. This will prevent it from overheating and increase its lifespan. Not only will you save a few dollars a month in your electricity bill, but your fan will actually not break down sooner and you won’t have to rush out to buy a replacement sooner than you really should.


How You Can Minimize Electricity Usage by Fans

Electricity might be a readily available commodity, but it is not always the cheapest. So, you might want to lower your consumption to save up some money over the summer. Here is how you can save energy during the summer:

  • Switch off your fan when you are not using it

One vital tip to help you lower your electricity bill is to ensure you switch off the fan when you leave the room.

A fan is instantaneous. It will start cooling your skin when you turn it on. You do not need to precondition the room for the fan to work. So, you can switch it off when you leave and turn it on when you come back to the room. 

  • Use your AC during the day when it is too hot

Also, there are times when using your fan will do more harm than good. For instance, it might not be cool air if the fan draws air from vents and ducts. Remember, these ducts are in the attic or along the walls, absorbing all the heat from the sun. 

Then, an AC will need to cool the room first before you can start using a ceiling fan to circulate the air.

However, keep in mind that a central air conditioning system will use far more electricity than a ceiling fan ever will. In fact, it isn’t unusual for air conditioners to contribute $150 or more to the cost of a monthly electricity bill in many homes. So it’s wise to be mindful of the times when you’ll use both your air conditioning system and ceiling fans.

  • Invest in occupancy sensors

If you find yourself forgetting to switch off your fan when you leave your house, you can buy an occupancy sensor. This sensor detects movements in the room and switches on the fan. When there is no one in the room, the sensor disconnects the fan from the supply.

Temperature sensors are another excellent option to use when you want to control the temperature of your room at night. 


Related Questions

Can you run your fan all night safely?

Leaving your fan on all night will be safe. However, due to the heat it generates, it reduces its lifespan considerably. Heat is not a friend to the wires used in making the motor or its switching circuit.


How much energy does a fan consume when left on all night?

Even if you have a small fan, it consumes a lot of power if you keep it running overnight. So, if you have a 75-watt fan and leave it on for 12 hours, it consumes 900Wh (0.9KWh). If you leave it on every day, then in a month, you add 27KWhs to your bill. That’s generally just a few dollars a month.