The current heat wave is sure to produce higher energy bills for residents operating air conditioners and other cooling appliances.
But you can keep cool and minimize costs at the same time, energy experts say, if you practice simple conservation habits and use appliances properly.
Here are the answers to five common questions about air conditioning, based on information from energy specialists, including Eric Oganesoff, manager of the energy services department at Potomac Electric Power Co.
Q: Is it better to turn off the central air conditioning in my house when I am gone, turn it to a higher setting or leave it at the regular setting? Also, what is the recommended setting for air conditioning when I am home and how much difference do variations make in my electric bill?
A: If you will be gone from your home for more than four hours and there is relatively low humidity of 89 percent or less, turn off the air conditioning. But if the humidity is 90 percent or more, leave the air conditioning on and turn up the thermostat to 80 or 85 degrees.
The best setting for the thermostat when you are at home will depend on your own comfort level. If you can feel good with the normal setting of 78 degrees, fine. But if you are too warm at that level, turn it to where you are comfortable.
The higher the setting, the more you save. The estimated savings is about 5 percent per degree per 24 hours. That means that having the thermostat at 80 degrees, rather than 78 degrees, would enable you to save 10 percent on your energy bill for that day. So if you are using about $4 worth of electricity a day, your savings would work out to 40 cents.
Q: What is the best way to use window units? And how do I find out if mine are the right size for the area I am trying to cool?
A: The general rule for window units is to run them only when you need them and only in the part of the house where you need them. Close off any unused rooms, so you don't waste the cool air. Turn the units off if you will be away for more than four hours when there is low humidity. When there is high humidity, leave on the units that you need but adjust them to put out a minimum amount of cool air.
To find out if your unit sizes fit the area you want to cool, check with department stores and dealers who sell air conditioners. Or call Pepco at 872-2465 and ask for energy assistance.
Q: Fans--overhead and portable--are supposed to be less expensive than air conditioning, but how much do they really save? Do I save money by combining fans and air conditioning? And if so, how much?
A: You spend about one-sixth as much energy operating a fan as an air conditioner, so anytime you can use a fan instead of an air conditioner, you cut your electric bill. You also can save money, although not as much, by using the fan in conjunction with the air conditioning. The trick is to set the thermostat higher than normal and turn on the fan to move the air so that you feel cooler. By raising the thermostat 2 degrees and using a fan at the same time, you generally could expect to save about 7 percent on your summer cooling bills.
Q: Does sunscreen tape sold for windows really reduce energy use? How much?
A: Sunscreen tape does reduce energy use by cutting the amount of sunlight coming into the house, but it doesn't necessarily save you all that much on your electric bill. One calculation by Pepco showed the sunscreen tape cost $96 to $144 to install in a test house saved only $8 a year on the house's $310 seasonal cooling bill.
A less expensive way to reduce energy would be to pull down the shades and close the draperies because many people already have them anyway.
Q: What are the peak hours for electrical consumption and how much does it help for me to use my oven, dishwasher, clothes washer and other appliances during the off-peak hours?
A: The peak time generally is noon to 8 p.m., although the greatest demand on the system comes between 4 and 5 p.m. Anytime you postpone energy use to nonpeak hours, you help hold down the electric company's energy costs and ultimately your own electric bill.