Q: We have ceiling fans in every room, and every year my husband and I argue about whether to reverse them for use during the winter. My husband has read articles explaining that reversing fans causes them to push warm air from the ceilings down toward the floor, giving us more warmth. To me, it makes more sense to run the fans blowing down, like we do in the summer, to pull the air down from the ceilings. Who’s right?
A: The short answer is that both of you are right, and neither of you is right. Fans cool you in the summer by moving air over your body, helping increase the evaporation of moisture from the skin. The technical term for this is “sweating,” the primary way our bodies cool themselves. When we sweat, excess heat gets carried away.
Air moving over our bodies also carries heat away, so we not only feel cooler, we actually are cooler. In the summer, if a breeze from the ocean or a ceiling fan is blowing on us, we’ll be cooler and can be more comfortable at a higher temperature. If our house is air conditioned, we can turn the thermostat up a couple of degrees, so the cooling system runs less, but we remain just as comfortable.
For this to save you money, you have to do two things: 1) run the fan only when there are people in the room, and 2) turn the thermostat up. The higher you set the thermostat, the more you’ll save, so experiment with what works in your house.
In the winter, air blowing on your body has the same effect as it does in the summer — it cools you. So, blowing air down on people is probably not a good idea, as it might cause you to crank up the thermostat to stay comfortable.
Some people recommend reversing the fans in the winter and running them on low speed to help “mix” the air in the room, which minimizes the drafty feeling. The theory is that warm air collects at the top of the room, and by gently circulating it, you can even out the temperatures and get more of the heat down where it does you some good.
There’s been minimal research on whether this actually works, and what has been done tends to show little, if any, winter energy savings from ceiling fans. And, don’t forget, the fans themselves use energy.
In some houses, if there is a big difference in temperature from floor to ceiling, it’s more likely that running the fan will help, but every house is different. The best advice I can give is to try an experiment. Set the thermostat wherever you need it to make you comfortable. Then turn the fans on (reversed) for a few days and check if you’re still comfortable with the thermostat setting a couple of degrees lower.
Go for a few days and see if the lower setting is fine even without the fans. Run through a few cycles of this, and see what happens. And don’t tell the rest of your family about the experiment. Just do it, and observe if they notice. If you can turn the thermostat down this winter and your loved ones don’t realize, everybody wins.
This article was originally featured in Carolina Country magazine.