Q: We have ceiling fans in every room in the house, and every year my husband and I argue about whether to reverse the fans and use them during the winter. My husband has gone on the web and read articles explaining that reversing the fans will cause them to push warm air from the ceilings down toward the floor, giving us more warmth. To me, it would make 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: First, let me offer my congratulations on having such a wonderful marriage if this is all you have to argue about. A lot of couples generate more heat arguing about all kinds of things than will ever be saved by a ceiling fan.
The short answer is that both of you are right, and neither of you is right. Let me explain. Fans cool you in the summer by moving air over your body, helping increase evaporation of moisture from the skin. The technical term for this is “sweating,” which is 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 the house is air conditioned, we can turn the thermostat up a couple of degrees, so the air conditioner will run less, and we will be just as comfortable.
For this to save you money, you have to do two things: 1) only run the fan 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 in the summer—it will cool you. So, blowing air down on the people is probably not a good idea. It will often cause you to crank up the thermostat on the heater in order to be comfortable.
So, some people recommend reversing the fans in the winter and running them on low speed to help “mix” the air in the room. This minimizes the drafty feeling. The theory is that warm air collects at the top of the room and by gently circulating that warm air, you can even out the temperatures and get more of the heat you paid for down where it does you some good.
There’s been very little research on whether this actually works, and the research that 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 in your house. Set the thermostat wherever you need it to make you comfortable. Then turn the fans on (reversed) for a few days and see if you can still be comfortable with the thermostat setting a couple of degrees lower.
Next, go for a few days and see if the lower setting is okay even without the fans. Go through a few cycles of this, and see what happens. And, of course, don’t tell the rest of the family this experiment is going on. Just do it, and observe if they notice. If you can turn the thermostat down this winter and your loved ones don’t notice, then everybody wins.
This article was originally featured in Carolina Country Magazine. Carolina Country is a monthly consumer magazine reaching more than 700,000 families, farms and businesses in North Carolina. Published continuously since 1946, Carolina Country is distributed by subscription to members of North Carolina’s electric cooperatives. For more information visit www.carolinacountry.com.