Cold facts about reducing AC bills

Myth: It's cheaper and more efficient to cool your home with an evaporative cooler than with a central air-conditioner.

Reality: An evaporative cooler consumes only about a quarter of the electricity required to run an air-conditioner, but it uses enough water over the summer to fill a swimming pool. That's all lost water because it quickly evaporates. In our desert climate, that's not an efficient choice.

Today's Super-efficient Air Conditioners generally trump evaporative coolers in the efficiency department. If you're running an evaporative cooler along with your air-conditioner, they're competing with each other, as the air-conditioner removes humidity from the air and the evaporative cooler adds it back. That's just a waste of money.

Rosie's tip: Reserve your evaporative cooler for spot cooling, like in the garage or on your back patio.

Myth: Running ceiling fans all day in every room will help cool your home.

Reality: Ceiling fans don't cool the air. They make you feel cooler because they move the air, so it feels as if a breeze is cooling your skin.

A ceiling fan that's running in an unoccupied room is using electricity without doing any good. Turn off your ceiling fans when you leave a room, and flip them on when you come back in.

Rosie's tip: Install ceiling fans, especially in rooms where your family tends to congregate. A ceiling fan will allow you to raise the thermostat setting about 4 degrees with no reduction in comfort.

Myth: Cranking your thermostat way up whenever you leave the house will reduce your air-conditioning bills.

Reality: The U.S. Department of Energy says you can save 10 percent a year on heating and cooling bills by setting your thermostat up 10 degrees or so in summer or back in winter - for eight hours. You can do this automatically without sacrificing comfort by installing a programmable thermostat.

Here's what doesn't work:

1. Changing the thermostat setting for short periods several times a day. If you'll be gone for less than six hours, leave your thermostat where it is.

2. Lowering the thermostat to 60 degrees when you get home to kick the air-conditioner into high gear to cool the home more quickly. That doesn't cool your home off any faster, but it will use more energy than if you set the thermostat to a reasonable temperature.

Rosie's tip: Set it and forget it. You can set various schedules for work and sleep on weekdays and weekends - and let the programmable thermostat "remember" when to change for the most efficient - and comfortable - result. A caution: Don't use a regular programmable thermostat with a heat pump.

Myth: Closing air-conditioner registers in unused rooms will save energy and money.

Reality: If you seal off a room's registers, you can create more pressure on your air-conditioning system, and that could result in air leakage throughout the system. A study by the Lawrence Berkeley National Laboratory proved that closing registers in unused rooms increases energy use throughout the home.

Rosie's tip: Leave your registers open. To save energy in unused rooms, close the drapes on sunny days.

Myth: Your air-conditioner ducts need regular cleaning.

Reality: For most people, duct cleaning has no benefit. It doesn't make your air-conditioner work better, or reduce dust in your house.

Even the U.S. Environmental Protection Agency says there's no need to clean ducts unless your air-conditioning professional finds visible mold growth inside the ducts, your ducts are infested with bugs or mice or are so clogged that dust is blowing through the supply registers into your home.

Rosie's tip: Keep your ducts clean by preventing dust and dirt from getting into them. Invest in a $5 pleated filter, and change it every month.

Romero has been in the Arizona home-building and remodeling industry for 35 years. He has a radio program from 8 to 11 a.m. Saturdays on KTAR-FM (92.3) in the Valley, from 10 a.m. to noon Saturdays on KNST-AM (790) in Tucson, and from 8 to 11 a.m. Saturdays on KAZM-AM (780) in northern Arizona. For more do-it-yourself tips, go to rosieonthehouse.com.