By Laura Jean Whitcomb

The fall breeze blowing through your windows feels wonderful right now, but how will it feel this winter? If you’ve closed the window, pulled the shades and still feel a draft, it’s time to check the energy efficiency of your windows.

Why Replace?

According to Handymanonline.com, the number one reason people replace their windows is to realize substantial savings on utility bills. Single pane windows and aluminum sliders aren’t enough to keep out the Northeast winters. “People upgrade their windows to make the glass and sash opening more energy efficient,” says Frank O’Donnell, co-owner of Blodgett’s Sash and Door, Inc., in Lebanon, N.H. “At the same time, they also are able to better insulate around the window frame.”

In the average home, 38 percent of heat loss is through the windows and doors. The U.S. Department of Energy says that household energy costs in most U.S. homes could be reduced up to 15 percent by installing more energy-efficient windows.


“ENERGY STAR windows can be twice as efficient as the average window produced just 10 years ago. Proper selection of windows, doors and skylights can significantly effect how much money is spent or saved on energy costs.”
— Terry Rex

The second reason is maintenance savings. Homeowners tire of wrestling with old windows that are hard to open or won’t stay open. When the seals are gone in a window — making the glass look foggy — there goes your view. And cleaning some of the older-style windows is an effort in futility.

“Most people replace their windows because they are old and rotten from years of neglect,” says Bob Seavey, a millwork buyer at LaValley’s Building Supply in Newport, N.H. He’s worked with builders, contractors and homeowners for 24 years. “Older windows did not have the vinyl or aluminum cladding that today’s windows have, and had to be painted to protect them.”

In addition, new windows can dramatically change the look of a house, from both the inside and the outside. “New windows have lots of features that can enhance the appearance of the home, such as concealed jamb liners and architecturally correct divided lights,” says Seavey.

Kathy Krafka Harkema, corporate public relations specialist for Pella Corporation, agrees. “Windows (and doors) are one of the only elements of a home that can be seen from both the interior and the exterior of the home — so it is very important from both a design and function perspective. When we replace windows for people, they are often amazed at the change in the appearance and feel of a room.”

Look for ENERGY STAR®

When shopping for replacement windows, there are two rating systems you should look for. ENERGY STAR is a government-backed program helping businesses and individuals protect the environment through superior energy efficiency. The program started in 1992, when the U.S. Environmental Protection Agency (EPA) introduced ENERGY STAR as a voluntary labeling program designed to identify and promote energy-efficient products to reduce greenhouse gas emissions. Computers and monitors were the first labeled products. In 1996, EPA partnered with the U.S. Department of Energy and the ENERGY STAR label is now on major appliances, office equipment, lighting and home electronics, to name a few.

“The ENERGY STAR labels make it possible for consumers to identify efficient windows, doors and skylights,” says Terry Rex, president of the Northeast Windows & Door Association (NWDA), an organization that provides education and information regarding codes, markets and other business influencers shaping the window and door marketplace. “ENERGY STAR windows can be twice as efficient as the average window produced just 10 years ago. Proper selection of windows, doors and skylights can significantly effect how much money is spent or saved on energy costs.”

Look for NFRC Certification

The National Fenestration Rating Council (NFRC) — a non-profit organization that provides accurate information to measure and compare the energy performance of window, door or skylight products — also has a ratings label. “A NFRC label is the only way to be sure that the energy performance claimed by the manufacturer has been tested and certified by an independent third party,” says Leonard Greenberger, spokesperson for NFRC. “Without a NFRC label, you have no way of knowing if a window is going to perform as promised.”

There are four components of a NFRC label:

U-factor
If you want to compare the energy efficiency of several different types of windows, look at U-factor first. U-factor measures how quickly heat will pass or conduct through a window.

When it comes to U-factor, the lower the better — and the less you’ll spend heating and cooling. In the Northeast, look for a U-factor of .35 or less. To give you an idea of how U-factors range, here’s how a few different types of windows are rated:

▪ Old metal casement window: 1.3
▪ Good quality single pane window: 1.0
▪ Good quality single pane with storm window .6
▪ Double pane with low-E glass: .4
▪ Triple pane with low-E glass .25

Solar Heat Gain Coefficient
The Solar Heat Gain Coefficient (SHGC) is a measure of how much heat your house gains from the sun. If a window has a rating of .5, it means that the unit admits 50 percent of the heat that strikes it. The lower the number, the better the window’s ability to block warming caused by sunlight.

If you want to compare the energy efficiency of several different types of windows, look at U-factor first.
U-factor measures how quickly heat will pass or conduct through a window. When it comes to U-factor, the lower the better — and the less you’ll spend heating and cooling.

If you live in the Northeast, the ENERGY STAR program suggests looking for a low U-value and any solar heat gain coefficient. (Heat loss, not heat gain, is more of an issue.) To qualify for the ENERGY STAR label in a northern climate, window products must meet the following criteria: U-factor of .35 or less for windows and .45 or less for skylights.

Visible Transmittance
The visible light transmittance (VT) rating indicates how much light gets through a product. VT is a number between 0 and 1; the higher the VT, the more light is transmitted. Efficient Windows Collaborative — a coalition of window, door, skylight and component manufacturers; research organizations; and federal, state and local government agencies interested in expanding the market for high-efficiency products — recommends that New Hampshire and Vermont homeowners and builders select windows with a higher VT to maximize daylight and view.

Air Leakage
Air Leakage (AL) is indicated by an air leakage rating expressed as the equivalent cubic feet of air passing through a square foot of window area. The lower the AL, the less air will pass through cracks in the window assembly. In New Hampshire, windows should have an AL of .3 or less.

What Else?

You may have heard about low-E glass. Low-E, which stands for low emissivity, has a special coating (thin layers of metallic oxide bonded to the surface) that blocks certain kinds of light, including harmful ultra-violet (UV) rays. It looks like normal glass but does a better job keeping heat in during the winter and out during the summer. Windows manufactured with low-e coatings typically cost about 10 to 15 percent more than regular windows, but they reduce energy loss by as much as 30 to 50 percent. O’Donnell notes that “other coatings could be determined by climate. Glazings such as bronze, gray or obscured glass are available.”

It’s important to do your research, then shop around. Look in your price range, look at ratings labels and ask questions. It’s not always true that energy-efficient products are more expensive.

“Manufacturers have made great strides in developing and marketing energy efficiency technologies, to the point where just about every homeowner should be able to find affordable and energy-efficient products,” says Greenberger. “Plus, when looking at cost you have to consider the savings on your heating and cooling costs that will result from replacing old, inefficient windows with new, better-performing ones. They could be substantial. Homeowners can visit
www.efficientwindows.org to see how much they’ll save depending on the efficiency of the windows they buy.”
Are more people opting for energy-efficient windows? “They definitely are,” says O’Donnell. “Builders, contractors and consumers are more knowledgeable today, especially when trying to cut heating costs.”

To get the word out, organizations like the NWDA sponsor seminars on energy-efficient products, Pella Corporation has developed a tip sheet for consumers about when to replace their windows and the NFRC is working with Home Depot to provide awareness of window energy performance. Scan the real estate ads and you’ll even find that a few national brands of windows are even called out as key selling points.

“New energy-efficient, eye appealing, easy-to-operate-and-maintain windows add value to the home, especially at resale time,” says Pella Corporation’s Harkema. “And more importantly, new windows add to the quality of your life with easier cleaning, better aesthetics and improved home comfort.”