Window coverings are like the finishing touch on a room, adding style, grace and identity. And while it's exciting to shop for the prettiest or most interesting, it's also important to consider the treatment's energy efficiency.

Window coverings are like the finishing touch on a room, adding style, grace and identity. And while it's exciting to shop for the prettiest or most interesting, it's also important to consider the treatment's energy efficiency.

As the whole nation moves toward practices that conserve energy, new technology is being developed all over the place and some of it has definitely hit the world of window treatments, creating a plethora of choices for homeowners who choose to conserve.

However, before you start shopping, it's vital to make sure the window itself is supporting your mission (see sidebar). It needs to be double-paned and have an Energy Star "R" value of at least 2.

"The R value measures resistance to heat flow; it's what you use in the winter to measure how well you're keeping heat in your house," explains says Lee Rickords, co-owner with his wife, Maria, of Blinds Are Us in Jacksonville. "And with the right treatment on the right window, the energy efficiency can get up to about a 7.5."

One such treatment is a honeycomb shade—outer layers of fabric with synthetic webbing between; as a comparison, wood or metal blinds can increase efficiency to just under 4.

"To get the highest R rating, you're looking at a mylar coat inside the shade and a triple layer of honeycomb," says Rickords.

A shade's efficiency is further boosted by having a white or light-covered fabric exterior. These can be found in several styles.

Honeycomb shades also block solar heat gain—heat that seeps into the house from outside. To measure heat gain, the industry uses the number "1" to indicate products that are the most "heat-entering." Rickords says a high-end, triple-layer, honeycomb shade can have a rating near 0.15.

For best solar heat gain blockage, look for shades with a rating around 0.3 or lower.

To maximize energy savings from window coverings, it's also imperative to consider the window's exposure and the season. West sun heats up things the fastest, so keep coverings open in the winter to allow solar heat gain; in the summer, cover the windows in the afternoon to prevent solar heat gain. The same, in reverse, applies to east-facing windows.

"The summer morning sun can heat the house all day, so keep those windows covered in the a.m.," Rickords counsels.

South-facing windows are fairly safe to keep uncovered or lightly covered in most seasons, as they will allow for passive solar heat gain in the winter and for optimal light year-round. Many "green" builders prefer to keep north windows small and few, as that is the coldest side of the house and windows should be kept covered for optimal energy efficiency.

Aesthetics and protection should also be addressed. When well-chosen, window treatments allow homeowners to create the desired ambiance by controlling the light and mood of any room. Certain coverings can also provide complete UV protection, stopping the sun's rays from fading furniture, art and wood.

"Sheer fabrics can cut up to 50 percent of UV rays, but you can still see out and have the light come in," says Rickord.

Finally, don't ignore the home's basic design when choosing window treatments.

"What most people may not understand is that a standard, 2-foot roof overhang on a standard pitched roof will cover three-quarters of the windows in the summer sun, blocking that heat, and will allow for solar gain in the winter," says Darrell Boldt, president of D.A. Boldt Construction in Ashland. "So the roof design in itself can be energy efficient."

In all cases, enlist the services of a professional to measure for windows and window coverings. Ending up with the wrong size can tear a hole in the budget—and waste more of the precious energy you're trying to conserve.