Commercial HVAC, Residential HVAC
Do Ceiling Fans Save Energy?
Ceiling fans use much less energy to run than air conditioners, so it would seem like a simple conclusion that ceiling fans save energy. But in most parts of the country, fans don’t provide enough cooling to replace air conditioners. So the question is really: do ceiling fans save energy when used with air conditioning? And that’s more complicated.
Read on to find out if you can use ceiling fans to help improve your energy efficiency and keep you cooler.
How do ceiling fans keep you cool?
To get an idea of how ceiling fans save energy, it’s important to understand how ceiling fans work. You may have heard that fans don’t cool rooms, they cool people. Fans work for the same reason why wind feels cold; it’s called the windchill effect. If you’ve stood beneath a ceiling fan on a hot day, you know that while the temperature might not actually be lower, the cooling help it provides is very real.
Moving air makes you feel cooler because it assists your body’s natural cooling process through evaporation. The more air is moving, the more moisture can evaporate from your skin, making you feel cooler. This means that a ceiling fan does not actually lower the temperature in a room. This is why you should not leave a fan on in an unoccupied room – it has no effect and would be wasting energy.
You may have heard that ceiling fans add heat to a room. This is where most of the debate about whether ceiling fans save energy or not comes from. That’s technically true: fans work by powering a motor, which creates friction that is given off as heat. If you were to take the temperature of the fan motor while it was running, you’d see that it is a bit warmer than the surrounding air. But a ceiling fan uses a small motor, and the amount of heat that it adds to a room is negligible. And the cooling windchill effect more than compensates for that small amount of heat.
Since a ceiling fan’s job is to cool people, it accomplishes that just fine. It’s just not a replacement for air conditioning, especially in hotter climates. But you can use them together to create better cooling conditions and possibly save energy.
Ceiling fans used to help AC systems perform better…
The idea that ceiling fans save energy comes from a variety of assumptions. For one thing, ceiling fans used to be more important to the performance of AC units than they are today.
Early air conditioner models were very inefficient. Duct layouts were often poorly designed, or they had none at all (as is the case with window AC units). This meant the room was cooled unevenly: there were stuffy corners the cool air failed to reach, and icy cold spots right in front of the window unit or supply vent. In addition, homes at the time were often poorly insulated, meaning much of the cooled air was lost.
In these circumstances, a ceiling fan helped tremendously. It circulated the air, making the temperature more even across the room. It also added the windchill effect, helping to make up for some of the cooling power that was lost. This has led some people to believe their ceiling fans save energy, because if fans used to help ACs work better, why not now?
The reason is that modern air conditioners are so much more efficient, they don’t suffer the same problems as early models. Unless your AC unit was installed before 2000, you don’t need to correct temperature variance issues with a fan. Modern ACs are designed to have proper air circulation for the space they’re in.
How to use ceiling fans to save energy in summer & winter
Ceiling fans don’t save energy if you run them without changing your AC usage. Ceiling fans save energy when they allow you to reduce your use of air conditioning (especially old systems that can be inefficient energy hogs).
The windchill effect makes you feel a few degrees colder, so if you have the fan on, you can turn your thermostat up by four degrees, and feel just as cool.
Obviously you won’t save as much energy as simply turning the thermostat up and forgoing the fan, but you can get a slight energy savings and comparable comfort level by combining these methods.
AC units cost an average of 36 cents an hour to run, compared to a ceiling fan’s 1 cent per hour. So combining these cooling methods is the best way to save a bit of money on your energy bill.
You can use this same strategy in winter to get the most out of your heating as well. You just need to switch the direction of the fan, from counterclockwise in the summer to clockwise in the winter. Most fans have a switch on the base that changes the direction of the motor. Heat rises, so switching the fan direction will create a downdraft in winter, allowing warm air near the ceiling to circulate throughout the room. That can allow you to turn the thermostat down a few degrees and still be comfortable.
Tips for choosing a ceiling fan
If you are looking to install ceiling fans, choosing the right one and having it installed properly will help make the most of these savings. When you’re shopping for a new fan, look for models with the highest energy efficiency rating.
Fans with bigger blades move more air around, and can increase the cooling effect. Make sure to get a fan properly sized for the room you have.
Fan blades should be a foot from the ceiling and not less than 7 feet from the floor.
So, do ceiling fans save money on energy bills?
So when you look at all the facts, do ceiling fans save energy? Besides an environmental interest, usually what we’re really asking when we look at that question is: do ceiling fans save money?
In a question with so many variables, unfortunately it’s never going to be straightforward yes or no. It depends on how you use your HVAC systems, and what your priorities are.
Here’s what we do know: there are ways to use ceiling fans and AC systems together to improve cooling conditions. And when you use ceiling fans along with a decreased use of air conditioning and/or heating, it can help improve your energy efficiency and reduce your energy bills.
Another proven way to save on energy bills
If you’re looking to reduce your energy consumption, consider having your air conditioning system regularly maintained by professionals. Doing that once or twice a year keeps your system operating as efficiently as possible. That means it runs less to achieve the same set temperature, so it uses less energy.
Chances are, you’ll see a bigger difference in your energy bills with regular maintenance than you will from using ceiling fans in your space.
If you’re in the NYC metro area, we’re happy to explain how that works and get you started.