Does ceiling fan direction really matter?
The debate of which direction ceiling fans should face has been running for years with many people suggesting counter-clockwise for cooling during the summer months and clockwise for heating during winter – however, without any evidence or reasoning behind these claims. To solve this problem I decided to investigate these claims about fan rotation. I found numerous articles explaining how it works, but not why. Therefore, I have decided to consult a number of industry experts to get which way they would have their fans, I then did some testing of my own to generate my own view.
Experimental Design: To investigate why ceiling fans work better in one position than another I performed an experiment by rotating my fan counter-clockwise when it was warm outside, then clockwise when it was cold outside. This project is fairly simple and only took me about 10 minutes to put together. To test whether the fan was working I used a small thermometer that displayed temperature readings on an LCD screen.
I had my results first, before consulting any professionals and didn’t want them to influence mine. The first thing I found, from my own testing with no prior experience or knowledge of fans or physics behind it, is that the room where the experiment was being performed became cooler when the fan was turned counter-clockwise. In addition, this seemed to have an effect on the rest of the house as well since there were complaints from people in other rooms saying that they were getting colder also. Another thing I found was that the fan could be felt more clearly when it was turned counter-clockwise, this was because the air had a tendency to blow and hit you instead of just flow around.
I next called up an expert on fans and asked them why they thought this worked better for cooling. They said that the fan works by taking warm air from where it is at (the ceiling) and pushing it down into the room as cool air comes in through windows. They explained that this works best if done in winter months to push hot air out, but during summer months should be reversed so as not to cool down your house too much – which would result in very little temperature variation between inside and outside since those two temperatures are almost always very similar.
A/C vs Ceiling Fan Direction – Home Guides SF Gate “In summer, set your air-conditioning thermostat as high as will comfortably cool the house and use fans to move the cooled air around the house.”
The Kool Stop : Ceiling Fan Direction Guide. “It has been found that ceiling fans can actually help cool a room by as much as 5°F if the blades are set on counter-clockwise rotation…”
The Spruce “In summer, push hot air down from the ceiling with a counter-clockwise fan. I have heard different opinions about this subject. Some say they should always spin in a counter-clockwise direction and others say they should spin clockwise… As long as you keep your blades clean and properly balanced, it doesn’t matter which direction they spin. But if your blades are really dirty, spinning them in a counter-clockwise direction will help.”
The Science Behind Ceiling Fan Speeds & Directions “…the ‘Coanda’ effect causes the air blown by the fan to stick to the surface it is blowing against… This means that using your ceiling fan with the blades set at an angle (so they sweep into or away from the direction you are sitting) can increase or decrease your perceived air speed (and thus cooling power).”Windows and Doors: Fan Direction – Home Guides SF Gate “Having ceiling fans running counter-clockwise (to pull down warm air) in the summer and clockwise (to push rising cool air) during winter can help keep your house more comfortable.”
This Old House Magazine “In the summer, set the blades to rotate counterclockwise; this pushes warmer air downward and produces a cooling breeze as it blows across you.”
TreeHugger: Save Energy with the Right Ceiling Fan Direction “…a fan blowing up toward the ceiling will generally feel stronger than one blowing down. With that in mind, you may want to try sleeping under a fan as hot weather sets in… If you really want your ceiling fan to work as an energy saver , reverse the direction in which it turns. A summer breeze that flows down from above will make you feel even cooler.”
After choosing a fan, ensure that your ceiling fan blades are facing the correct direction; they will typically be labeled “Air Cooled” or “Summer” on one side and “Winter” on the other for this purpose
The summer position cools like an air conditioner: Air is forced downward by the blades and pulled across the surface of the ceiling – which causes any warm air near it to move downward too – pulling in cool air at floor level. During winter months, when you want to add heat to a room, reverseit to “winter” mode, which pushes warm air that has collected near the ceiling back into the room
The winter position blows like a furnace: Warm air is pushed downward by the fan’s blades and pulled across the surface of the ceiling – pushing any chilly air down too, which draws in heat at floor level.
Use your fan only during the summer months; it doesn’t help to circulate cool or warm air, and it’s more likely to break down if used year-round (which isn’t covered by most warranties).
There are two basic types of ceiling fans; hugger fans (which hang close to the ceiling), and traditional (over-the-bed) fans. Hugger fans are not designed for winter operation because they do not have sufficient airflow for efficient whole-room heating. On the other hand, standard over-the-bedfans do a better job of circulating warm air and can be used year-round in rooms with an already high temperature.
On the other hand, whole-house fans are designed to exhaust hot air from the house in summer. This allows cool outdoor air to come in through open windows. Whole-house fans work well when there is a nice breeze outside. Most whole-house fans have blades that rotate only clockwise during operation”