This Green Life
A monthly journal of sorts by Sheryl Eisenberg

JULY 2013: Americans use more energy on air conditioning than the rest of the world combined—just one sign that we've come to depend on it a bit too much.

Breaking the A/C Habit
Using fans to keep your cool

Air conditioning can be a godsend in a heat wave when the usual ways of coping with summer's heat are inadequate. But what happens when air conditioning becomes our usual way...when we use it to dispel normal and seasonally appropriate heat?

For starters, we lose our natural tolerance for the heat, in effect becoming de-acclimated to our own climate.

As a result, we stay inside too much, denying ourselves the pleasures and physical and spiritual benefits of spending time outdoors.

We may expose ourselves, in the process, to unhealthy levels of indoor air pollution, a risk of hanging around too long in air conditioned spaces.

And, of course, our electric bills go up, along with our contribution to global warming.

Summertime, itself, becomes a thing of the past. We forget its heady fragrance and delights—from ending the workday with a refreshing dip in the lake or pool to sharing iced drinks with neighbors on the porch. Inside our climate controlled fortresses, the once lazy amble of the season fades to memory. We keep up the pace, not just 24/7, but 365.

It's the principle of unintended consequences in action. The promise of air conditioning didn't include the side effects, but there they are.

I'm not saying air conditioning is the devil. (Quite the reverse: when temperatures get dangerously hot, it can be a lifeline.) But I do say most people could get by with a lot less of it and still be reasonably comfortable. The strategy, in a nutshell, is this:

1) Keep heat from entering the home by reflecting or blocking it with shades, shutters, louvers, awnings, trellises, window and roof coatings, insulation and/or trees.

2) Remove heat by using natural ventilation during the cooler time of day. Then close the home back up during the hot time per #1.

3) Reduce heat-producing activities, such as using the oven, dryer and dishwasher's heat cycle, and limit them to the cool times of day.

4) When the above three passive methods of cooling are insufficient, use circulating fans to get comfortable or, on extremely hot days, circulating fans combined with air conditioning. (Another alternative, if there is a significant differential between daytime and nighttime temperatures where you live, is to use window or whole house fans at night to pull in the cool air and expel the hot.)

I've addressed #1-3 in a previous piece on natural cooling so I'll focus on #4 here—a topic I've recently learned more about in the course of renovating the apartment that will soon be my new home.

By circulating fans, I mean ceiling, table and standing fans. Unlike air conditioners (or window or whole house fans), they do not bring room temperature down. Rather, they cool people directly through the wind chill effect.

Of the different kinds of circulating fans available, ceiling fans provide the most desirable set of features. The best ones reach every corner of the room with their breeze, run quietly, are operable from wall switches and remote controls and can do double duty as ceiling lamps. They come in a variety of styles and can be integrated into the room decor much better than freestanding fans.

It is essential to get the right sized fan for the room and to choose fans with sufficient airflow, which is measured in cubic feet of air moved per minute (CFM) at high speed. The minimum airflow for an Energy Star fan is 5,000 CFM, but 6-7,000 CFM provides more effective cooling and does not, by itself, cost more. Manufacturers are required to make CFM data available, so check the manufacturer's website if you can't find the information elsewhere.

Another important figure is the CFM per Watt, which measures the energy efficiency of the fan. Energy Star's minimum requirement for a fan running at high speed is 75 CFM per Watt, but many fans do much better than that. For instance, one of the fans I just bought for my apartment has a CFM/W of 336 (more than 4 times the minimum).

Don't wipe out your energy savings by getting a fan with halogen lighting. Those halogen bulbs will use more energy than the fan itself. Instead, choose a model that takes compact fluorescent or LED bulbs.

When you do turn on the A/C, use the ceiling fan, too. The fan will enable you to turn the thermostat up by at least 4 degrees and feel just as cool. For every degree you raise it, you will use 3% to 5% less energy, according to the American Council for an Energy Efficient Economy. So, turning the thermostat up by 4 degrees—e.g., from 76 to 80—should bring your energy cost down by as much as 20%. Meanwhile, you will continue to feel as if it's 76 degrees or lower.

Take note that if you use the fan with the A/C and don't turn the thermostat up, you will end up using more electricity, not less.

Note #2: for the full energy savings, turn off the fan when you leave the room. The fan cools you, not the air, so running it when no one is there is a waste.

In winter, ceiling fans can be run in the opposite direction to send warm air that collects at the ceiling down to the people below. This can reduce electricity used on heating as long as you remember to turn the thermostat down a few degrees. (If you don't adjust the thermostat, it will increase your energy usage instead.)

The one major downside to ceiling fans is the installation they require, which adds trouble and expense and means they can't be moved. Standing and table fans, by comparison, are ready to use as soon as they're plugged in and can go with you from room to room.

But standing and table fans take up space on the floor and furniture. Also, table fans are relatively weak because they're small. Moreover, to reach all parts of a room, both standing and table fans have to oscillate. Relief from the heat is intermittent when fans oscillate and some people find the sweep of air on and off to be annoying. Still, if you're the only one in a room and can train the breeze on you, a standing or table fan could be all you need.

Do check out these natural cooling techniques, too. I can assure you, from personal experience, that closing windows before the heat rises in the day, shielding windows from the sun and refraining from heat-producing activities except at cool times will make a world of difference on their own. Remember, adapting your behavior to the seasons is part of living a natural life.

—Sheryl Eisenberg

Join me on Facebook

Ice fortress


Join me on Facebook

Related TGLs

Naturally Cool Naturally Cool
Keeping comfortable without the A/C
Summertime and Green Living is Easy Summertime & Green Living is Easy
Solutions get simpler in July
Light and Bright Light and Bright
Energy-saving lighting solutions

On This Topic

Drinking lots of fluids
ADJUST YOUR PERSONAL HABITS to the weather. When it's hot, slow down; wear loose, light-colored clothes; drink lots of decaffeinated, unalcoholic fluids; and if you sweat heavily, replace salt and minerals with salt pills or a sports drink (assuming you are not on a low-salt diet, in which case, consult your doctor first).

When you get too hot, drink iced beverages, take a cold shower, go swimming, put a cold washcloth on your forehead or run the fan to cool down.

If you travel to a place with a hotter climate than your own, pace yourself the first few days. Your body needs time to acclimate.

Be careful in a heat wave. Heat stress and stroke can develop very quickly and can become life-threatening if left unaddressed. If you experience a headache, dizziness, nausea, vomiting, confusion, rapid breathing or muscle spasms, get out of the heat right away and drink plenty of water.

People over 65 years old, children and people with chronic medical conditions are at special risk in extreme heat. If you have air conditioning, do not hesitate to turn it on. Otherwise, seek it out at a public place.

Ceiling fan
CEILING FANS can be used year-round to cool or warm you as the season demands.

In summer, when you want the fan's wind chill effect, run it in the forward—or counter-clockwise—direction to send the air straight down. You can tell the fan is spinning in the right direction if you feel the breeze on you when you stand directly underneath.

In winter, use the ceiling fan in the reverse—or clockwise—direction at low speed to chase the warm air at the ceiling up and out toward the walls. This delivers the warm air to the people below without blowing directly on them, which would have an unwanted cooling effect.

Window fan
WINDOW FANS can be used to enhance natural ventilation in regions where the temperature drops significantly at night. By drawing the cool night air through the home, the fans lower the indoor temperature and create a wind chill effect at the same time. Get instructions for setting up window fans.


Air-Conditioning Will Be the End of Us

Yale Environment 360
Cooling a Warming Planet: A Global Air Conditioning Surge

Cooling Your Home with Fans and Ventilation

Low-Cost Cooling

Installing a Ceiling Fan

How Ceiling Fans Work
Definition of a Heat Wave Varies

Centers for Disease Control and Prevention
Extreme Heat: A Prevention Guide

More to Do

This Green Blog Switchboard Save Biogems
Sheryl Eisenberg is a writer, web developer and long-time advisor to NRDC. With her firm, Mixit Productions (, she brought NRDC online in 1996, designed NRDC's first websites, and continues to develop special web features for NRDC. She created and, for several years, wrote the Union of Concerned Scientists' green living column, Greentips, and has designed and contributed content to many nonprofit sites. Sheryl makes her home in Tribeca (NYC), where—along with her children, Sophie and Gabe, and husband, Peter—she tries to put her environmental principles into practice. No fooling.
Share | |
Find NRDC on