Let It Flow
Air conditioning is a staple in America: 87% of U.S. homes have it (compare to 1973, when only 47% did). That’s a lot of power being used just to keep us all at that perfect temperature zone, whatever “perfect” might happen to be.
Of course, no one likes being hot and sweaty. But, with proper planning, you can stay in comfort and be energy wise -- saving hundreds of dollars and thousands of pounds of carbon. Let’s look at the numbers.
The cost of cooling a home
On average, your window air conditioner uses roughly 1.2 KW (kilowatts))/hr and costs $0.14/hr to run. Have central air? Power costs are likely in the 3KW/hr range, or $0.36/hr. Compare either of those figures to a good ceiling fan: 30 watts/hr (note no kilo involved) and $0.03/hr.
So, where does any of that power come from? The U.S. generates some 30% of its electrical power from coal, with one KWH of energy requiring about a pound of the black stuff. With a ceiling fan, each of those one-pound coal rocks you’re using for power will last you ten times as long. Put another way, you’ll use 1/10th as much.
Different types of fans and how to use them
Fans and air conditioning cool you down in completely different ways. Air conditioning cools air and removes moisture. Fans simply move air over your skin faster; because sweat evaporates, you feel cooler. Fans cool people, not air.
So, it’s important only to run fans in rooms that are occupied. Fans actually raise room temperature very slightly, because of the heat generated by the motor. But it’s offset by the movement of the air. There are, however, some “smart” fans on the market which operate only when people are in a room, but they’re often expensive.
Then, there are ceiling fans, of which there are two options (but they’re not equal in value). One type runs off an alternating current (AC) while the other off a direct current (DC). DC ceiling fans can spin in both directions and consume almost 70% less energy than AC fans. (Make sure the fan blades are turning counterclockwise -- pushing the air down and not up.)
Window fans are a different beast. The idea is to push warm, stuffy air out and bring cooler, fresher air in. This means you’ll need two, in different windows. But they’ll give you the airflow you need to be comfortable on a warm day without kicking the AC unit into gear.
How to use a fan with AC
Not an either/or person? Even without making a complete switch from central air to fans, combining the two creates savings. A ceiling fan, for instance, in conjunction with air conditioning increases efficiency by pushing cool air directly down to people and keeps the air circulating better -- requiring less from the more costly AC.
According to the U.S. Department of Energy, the combined technique will let you raise your thermostat by 4⁰ F and feel no change in comfort. You’ll save something like $100 and severely cut down on power usage during the hottest months.
Health hazards
Fans aren’t suitable for all home environments. Because they do not actually cool down air temperature (but just circulate it), they don’t protect against hazards such as heatstroke on extremely hot days.
For small children, the elderly or anyone with a chronic illness or heat sensitivity, air conditioning should be used to reduce temperature and high humidity on days above 90⁰ F and 35% humidity.
Additionally, if you live in a highly polluted area or have sensitivities to air-borne particulate matter, it might be wise to avoid window fans -- because you don’t want to be pulling bad air into your home.
The LADWP also offers a air conditioning optimization program in which a professional will come to your home to ensure your system is up to its high standards.
Also, don’t forget about maintaining both your system’s and your air ducts’ health for optimal performance.
Learn more ways to save on power with LADWP.
Learn more about the assumptions behind Magenta House water and power savings calculations.
DETAILS
Upgrade: Fans
Goal: Stay cool but decrease energy use.
Potential Savings*: 833-4,500 KWH (Kilowatt-Hours)/yr, $100-$515/yr.
Skill level: ★★☆
Bonus: If you have an old window AC unit, recycle it here through LADWP for some free gift cards.
SAVINGS*
The average home savings calculation is based on the usage needs of a family of four and includes the following assumptions:
for higher savings, switch your home entirely from AC to fans (assume the average family will need five);
to save significantly but not as much, raise your AC by 4⁰ F in conjunction with the fans.
Based on these assumptions, fan costs are $150-$750 (assuming $30-$150/fan) in the first year.
Yearly energy savings amount to 833-4,300 KWH per home, or $100-$515/yr.
