If wintry drafts have you sidling farther and farther away from your windows and glass doors, it may be time to consider switching your window treatments to improve energy efficiency.
"About 10 percent of the heat energy lost from a building goes straight through the windows," said Denise Willard, owner and principal of Decor by Denise in Vienna.
"About 40 percent of unwanted heat comes through those windows. Simply closing your shades during the day and opening them at night in the summer will help homeowners capture and keep the cool night air, and reversing the process in the winter will help contain the solar gain," she said.
While the right window treatments definitely can help lower your utility bill, there is no doubt new windows and some extra caulk also work.
"If you can afford to replace your windows, this will do the most to improve your energy efficiency," said Arif Durrani, a window and door consultant with fred, the home repair division of Case Design/Remodeling in Bethesda. "You should look for the highest-performing window for your budget by comparing U-values. The second step is to make sure your windows are properly installed, which is half the battle right there."
One option for homeowners who can replace their windows is to purchase double-paned windows with blinds or shades installed between the glass, which adds to the energy efficiency of the windows.
Mr. Durrani said homeowners who are not able to replace their windows can improve energy efficiency by making sure to lock their windows, which makes a tighter seal to keep out drafts. He also recommends caulking every year or two on the outside of the window to eliminate air flow and then experimenting with different window treatments.
"Honeycomb cellular shades have been designed for both privacy and better thermal performance, which would reduce your utility bills," Mr. Durrani said. "Wood blinds are not quite as good as the honeycomb blinds, but they do offer some energy efficiency."
Iantha Carley, owner of Iantha Carley Interiors in the District, said the Hunter Douglas Duette Architella honeycomb shade, which features a honeycomb inside a honeycomb, qualified for an energy-efficiency tax credit because of the level of energy efficiency it offers.
"Customers who place energy concerns as the most important factor usually choose honeycomb shades, but these are essentially functional items, not a wow factor," Ms. Carley said. "The honeycomb shades compress pretty tightly to less than two inches, so you can raise them on a sunny day to let in radiant heat and sunlight. They definitely work. One client of mine saved 25 percent on his utility bill after he installed them all over his house."
Honeycomb shades can work as a base layer inside the window, suggested Liz Levin, owner of Liz Levin Interiors/Design in the District, with drapery panels on the outside of the window to add style as well as extra protection against drafts.
"White wood blinds and plantation shutters with draperies outside and above the window can make a big difference in energy efficiency," Ms. Levin said. "If your primary concern is energy efficiency, you should get a lined drapery rather than a sheer panel."
Ms. Willard said insulating wood plantation shutters work year-round by blocking excess heat from the sun in the summer and keeping cold air out in the winter. Ms. Carley said plantation shutters made of composite materials can be as energy-efficient as a honeycomb shade because of the materials used in the frame and the shutters.
"A lot of products like blinds and shades are mostly just energy-efficient in the summer, but drapery panels that are lined add insulation in winter to keep the cold air out and the heat in," Ms. Carley said. "The most energy-efficient drapes have a 'bump' inside, a layer of heavier material between the outside fabric and the liner that adds insulation."
Ms. Willard said you also can add a black-out lining for greater energy efficiency, noise reduction and room darkening. Insulating shades and Roman shades, which are horizontal fabric panels hung over a cellular liner, especially when combined with insulated drapery panels, provide a double layer of energy efficiency.
Mr. Durrani said the closer a blind or shade is installed to the window, the greater the energy efficiency it provides. Ideally, blinds should be mounted inside the window frame.
"In a smaller home, if you want to make the window look bigger, you can mount blinds on the outside of the window," Ms. Levin said. "If you add a valance or Roman shade at the top of the window, it looks like the window goes all the way to the top of the ceiling."
Sliding glass doors provide a particular challenge because they are drafty and offer fewer decorative options.
"One look that works with a sliding glass door is a big panel of draperies that you keep closed when you want to keep the cold air out but push to one side for an asymmetrical look," Ms. Levin said. "For French doors, you can do drapery panels on either side of the windows."
Ms. Carley said sliding glass doors are the least energy-efficient windows and suggests replacing them with French doors if homeowners have that option in their budget.
"One option for any window is to install a window film, which will reduce your cooling costs by 30 percent, reduce fading on furniture, hardwood flooring and carpet and rejects up to 60 percent of the heat in your home," Ms. Willard said. "The window film is designed not to change the appearance of your home, and you can choose a film that is clear to lightly tinted that allows up to 70 percent of the visible light to come through your windows."