How Ceiling Fans Can Cut Your Winter Heating Bill

Running a ceiling fan and furnace together is more efficient than running a furnace alone. 

Key takeaways

  • In the absence of disruptive airflow, warm air from your furnace will naturally rise and pool at the ceiling. 
  • When you set your ceiling fan to reverse, or "winter," mode, the clockwise blade rotation creates an updraft that redistributes the pooled warm air throughout the room.
  • Research has shown that a ceiling fan and furnace working together can maintain a comfortable room temperature far more efficiently than a furnace working alone.
  • Running your ceiling fan and furnace simultaneously might seem counterintuitive, but the science is sound. Your furnace will run less often - and you'll save on your heating bill.

Most people associate ceiling fans with cooling downdrafts that keep their homes feeling comfortable on hot summer days. But a ceiling fan can help make your home more comfortable in winter, too! Even more, it can cut your winter heating bill.

The key is reversing the direction of your fan blades

Remember, warm air rises and cool air sinks. So in a room with limited airflow, the air warmed up by a furnace or other heating appliance will tend to pool at the ceiling.

And the higher your ceiling — think of rooms with vaulted ceilings — the larger the pool of warm air.

Needless to say, this is a very inefficient way to heat a room. Warm air up above your head doesn't do you much good. Except for the odd occasion when you need to climb a ladder, you're going to spend your time at lower levels, whether standing, sitting or lying down.

In short, if you allow warm air to pool at the ceiling, you're throwing money away. That's because you need to run your furnace longer to heat the air to your desired temperature at the level of your thermostat — that is, at the level where humans occupy the room.

Winter mode disrupts and redistributes the pooled warm air

When a ceiling fan is set to "summer" mode, the blades rotate counterclockwise, pushing air downward to create a cool breeze.
If you reverse the direction to "winter" mode, the blades rotate clockwise. This generates an updraft, drawing the cooler air from lower in the room up toward the ceiling.

This upwards airflow disrupts the warm air collected at the ceiling, causing it to travel toward the walls, down to the floor and throughout the room. The result of the warm air being redistributed and mixing with the cooler air down below is the air temperature rises at the lower room levels where you are sitting or standing, and you enjoy greater physical comfort.

It gets even better: You save money!

Now that the warm air is being distributed evenly in the room, your furnace won't have to run as often to heat the air to your desired temperature at the level of your thermostat, which is typically about 1.5 metres (5 feet) off the floor. 

And, of course, the less often your furnace runs, the better your bank account looks.

What about the cost of running the fan?

You may wonder if the money you save by using your furnace less often gets eaten up by the cost of operating the ceiling fan. The answer is an emphatic NO.

Modern ceiling fans are incredibly energy efficient. In particular, fans with DC motors are energy efficiently superheroes.

The power consumption of your ceiling fan depends on various factors, such as the blade size and the speed it’s run at. But on average, a DC ceiling fan will use 70% less energy than an AC ceiling fan.

Fanimation, for example, estimates that its 52-inch Triaire Custom with DC Motor can run continuously at average speed (energy use = 12 Watts) for an entire year at a cost of just $3. That's right - less than a penny a day.

Truthfully, the cost to operate a ceiling fan is negligible, whereas running your furnace is expensive. In Canada, the average pro-rated monthly gas heating bill is $125 - $150.

So any energy-saving steps you take that result in your furnace running less often could save you a substantial sum.

Thermal heatmap demonstration

To demonstrate the benefits of running a ceiling fan and heater simultaneously, CHOICE, an Australian consumer advocacy group, enlisted ARS labs to conduct a test using thermal heatmap imaging.

In a room, a convection heater consuming 1.67kW of power was used to maintain a temperature of 18.5°C.

As the heatmap below illustrates, most of the heated air pooled at the ceiling, too high up to be helpful to someone sitting or lying on a sofa. Even someone standing might feel uncomfortably cool in the lower parts of their body.

After the ceiling fan was turned on in reverse, or "winter," mode, the power required by the heater to maintain a temperature of 18.5°C dropped to 0.70kW. Moreover, the fan itself used just 0.009kW.

Doing the savings math

When the ceiling fan and heater were running simultaneously, the total power consumption was less than half of that used by the heater alone.

That difference could have a huge impact on your energy bill.

Here's a heatmap showing the heated air distributed far more evenly in the room with the ceiling fan turned on in reverse, or "winter," mode.

Bottom line

By running your ceiling fans and furnace simultaneously, you can significantly reduce the amount of energy required to maintain your home's temperature at a comfortable level, thereby meaningfully lowering your heating bill.

Important note about fan speed

A good rule of thumb to help you choose your fan speed is higher in the summer and lower in the winter.

Summer: On warm days and nights, you want to feel the air moving and experience the wind-chill effect, so a medium or high speed works best.

Winter: In cool weather, it's best to avoid creating too much air movement as that would cool you down when your goal is to keep warm. In this case, choose a low speed to circulate the air slowly without creating a wind-chill effect.

So, how do you tell if your ceiling fan direction is set correctly for winter?

It's easy. Turn on the fan, stand directly under it and observe the rotation of the blades. If the fan is set for winter, the blades will spin clockwise, from the top left downwards to the right and then back up to the top.

Additionally, you should not feel air blowing down onto you. If you do, then the fan is spinning counterclockwise, and it's set for summer.

How to change the fan direction

  1. 1
    Turn off your ceiling fan.
  2. 2
    If you have a hand-held remote to control the fan direction, use it to make the change. Otherwise, look for a switch at the base of the fan motor. There should be only two settings. Move it to the other setting.
  3. 3
    Finally, verify the fan blades are rotating in the direction you want

Just remember, clockwise in winter, counterclockwise in summer.

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