"About 50 percent of heat gain in homes is because of the sun hitting the windows," Hines said. "Anything you can do to create shade on the outside is seven times more effective than shading from the inside."
http://www.azcentral.com/news/articles/0425hotdays0425.html
Cool down home, save money
William Hermann The Arizona Republic Apr. 25, 2006 12:00 AM
The pleasant spring we've been enjoying must inevitably become a typically searing summer, but experts say we can stay cool in our houses, and save money, if we follow a few guidelines.
But we'd better follow them soon. The National Weather Service says we could be in the 100s within two or three weeks.
According to Tom Hines, manager of energy-efficiency programs at Arizona Public Service Co., that means homeowners should be doing their most important "cool house" chore: getting the cooling unit checked out. Ignoring a service check could be costly.
LJ Refrigeration Co. of Scottsdale has been in business since 1963, and manager Kelly Engbarth says, "Our guys have seen it all" when it comes to air-conditioning-unit neglect.
The two most common mistakes homeowners make, Engbarth said, is letting the Freon in their unit get low and not changing the filter.
"If you're low on Freon, the unit has to work harder and run longer and of course that raises the electric bill," Engbarth said. "And when people don't change the filter, their unit can't breath. When the filter is clogged it's like putting a fan in front of a wall; the air can't go anywhere. And when it runs that way any length of time it will take out your compressor, and it's about $1,400 for a compressor."
LJ service representative Paul Coen said he sees filters that haven't been changed in years.
"I'll take out someone's filter and it's all dirty, like it has fur, and I'll say, 'There's your missing cat,' "' Coen said.
But it's not all Freon and filters.
APS experts say homeowners can take a major step to cool their house more efficiently by installing a programmable thermostat, which allows you to set the time when the air-conditioner will turn on and off and at what degrees.
A programmable thermostat can be purchased for between $80 and $200.
"A lot of people forget to adjust the thermostat when they go to work; a programmable thermostat will give the air-conditioning unit a programmed time to change the cooling level," APS spokesman Alan Bunnell said.
A more obvious way to lower one's power bill is to raise the thermostat level.
"For every degree you turn your thermostat up you will save 2 to 3 percent on the air-conditioning portion of your bill. And in the summer, the cooling portion is more than half your bill," Bunnell said.
APS energy expert Tom Hines said the effect of raising your thermostat a degree or two can be considerably mitigated by installing ceiling fans or using portable fans.
"Fans make it feel like you are 3 to 4 degrees cooler by virtue of the air on skin, which produces a cooler effect," Hines said.
Experts also say it's vital that all doors stay tightly closed, because if a door isn't shut properly the air-conditioner will push the door open, and cool air will flood out.
Hines said one of the most effective ways to keep heat from coming into the house in the first place is shading windows on the outside.
"About 50 percent of heat gain in homes is because of the sun hitting the windows," Hines said. "Anything you can do to create shade on the outside is seven times more effective than shading from the inside."
Another source of heat gain in a home is through walls, doors and the ceiling. Homeowners should look for visible gaps and seal them with weather stripping or caulk.
Phoenix homeowner Dallas Dudley, whose refrigeration unit was serviced on Monday, has made his house more energy efficient through window screening and other measures.
"Your cooling unit is a big investment, and spending a few dollars to keep from having to replace something like the compressor is money well-spent," Dudley said.