As summer temperatures — and utility bills — rise, there are some easy ways to keep cool that are cheaper and greener than air conditioning.

A little savvy about when to open windows and when to keep them closed with curtains drawn goes a long way toward cooling a home, as does putting thought into what cooling appliances to use and when, experts say.

[naviga:h3]Cooling curtains[/naviga:h3]

Pull down the shades or draw the curtains on windows facing south, east and west during the day, says Con Edison, which provides power to New York City. It says 40 percent of unwanted heat comes in through the windows. Even if air conditioning is needed later in the day, drawing the curtains earlier means you can use less of it.

“And it’s better to shade the outside of the window than the inside,” said Abigail Daken, cooling products manager for Washington, D.C.-based Energy Star. “Shutters and awnings are very effective,” Daken said.

[naviga:h3]Get in the flow[/naviga:h3]

When outdoor temperatures fall below 70 degrees, the Natural Resources Defense Council recommends turning off the air conditioner and opening the windows instead.

In climates with low to moderate humidity, where it’s cold in the evening, a “whole-house” fan to help draw cool air in through windows and force hot air out through upstairs vents is extremely helpful, Daken said. “A cheaper version is to open the windows and use the bathroom fan for exhaust, especially if there’s no cross breeze,” she said. “This helps create some flow.”

[naviga:h3]Be a fan of fans[/naviga:h3]

Ceiling fans are a great substitute for air conditioning when it’s not overly hot or humid, and they make you feel cooler by moving air across your skin, says Meg Waltner, of the Natural Resources Defense Council.

If you need to buy fans, look for Energy Star ratings and rebate offers, she said.

[naviga:h3]Plant a tree[/naviga:h3]

A tree is as sophisticated as any electronic device around, conservationists say. It lets sun through in winter and grows sun-blocking leaves in summer.

Large deciduous trees planted on the east, west and northwest sides of your home create shade from the hot summer sun and can reduce summer air conditioning costs by up to 35 percent, according to the Arbor Day Foundation.

[naviga:h3]Avoid some appliances[/naviga:h3]

Con Edison recommends minimizing the use of household appliances when temperatures climb. Summer is a great time to opt for outdoor grilling and foods that don’t require cooking.

Washers, dryers and dishwashers should be used at night, when temperatures are cooler, the utility says.

[naviga:h3]Using air conditioning[/naviga:h3]

Be sure they’re Energy Star-certified, have programmable thermostats and are set no lower than 78 degrees when you’re around, 80 when you’re away for part of the day, and “off” when you’re on vacation, Waltner says. Programmable thermostats can cut power use by 20 percent to 30 percent, she says. Many power companies offer free programmable thermostats to clients, and it’s worth checking their websites for offers and rebates.

“Raising the temperature by 7 degrees when no one is home, 4 degrees at bedtime, along with proper programming during the winter, can save you more than $180 every year,” according to Daken.

Make sure windows are well-sealed to keep cool air from leaking out.

And don’t cool an empty room: Block vents in unused rooms and turn the system off entirely while you’re away.

Keeping central air conditioner filters clean adds to their efficiency. Air conditioners and cooling systems should be inspected and cleaned annually, and kept clear of leaves and dirt, experts say. “We recommend that filters be checked every three months, or more often for homes with pets,” Daken said.