By David Starr

Big, uncovered windows do not necessarily mean a loss of insulation. Photo courtesy of Marvin Windows.

Do you picture all your household heat whooshing out through your old windows every winter? Or in summer, do you imagine the hot sun streaming in competing with your air conditioning? If the thought of replacing your windows seems overpowering and too expensive, it's no wonder. With all this vinyl-clad and gas-filled jargon, how can you choose? Well, you can have beautiful new windows, save money on energy and often you can do it yourself!

Types of Windows
First, a primer on windowspeak. Materials vary - they have good and not-so-good points. And you should consider aesthetics, energy savings, ease of installation and cost.

Don't freak. This short list of materials and their strengths and weaknesses should clear the fog.

• Wood: generally considered best because of its strength, insulating characteristics and its ability to be custom stained or painted. However, it expands and contracts and you may get that dreaded sticking. Plus it needs seasonal painting for upkeep.
• Vinyl-clad wood: More expensive than plain wood, it has a vinyl exterior coating which is resistant to weathering. The interior is exposed wood that allows you to paint or stain to match your d�cor. But in extreme cold, the vinyl has been known to become brittle.

Windows as doors: all wood interior trim adds to the designer look and is an excellent insulator. Photo courtesy of Marvin Windows.

• Aluminum-clad wood: Like vinyl-clad, the outside is coated in aluminum for weather protection and the interior wood is exposed. Aluminum has been known to corrode eventually and these windows have no thermal insulation.
• All-Aluminum: Very inexpensive! The exterior lasts longer if anodized to prevent corrosion, but will corrode eventually anyway. Again, it has no thermal capabilities.
• All-Vinyl: Usually white, they can discolor to brown in heat and become brittle in cold. But they have better thermal qualities than aluminum. The easy retrofit installation is a DIYer's dream. Many are inexpensive and they don't need painting. Thermal characteristics depend on the manufacturer. Because quality can vary greatly, look for the AAMA certification sticker.

Energy Performance
What makes one window more energy efficient than another? Without delving too far into advanced engineering, just manage to remember these three attributes:

• Gas Fills: Still air is an excellent insulator but better still are windows filled with gas which has a thermal conductivity lower that that of air. Argon and Krypton are two such gases. Argon is cheaper and requires the full inch spacing. Krypton is more expensive but works optimally in narrower windows.
• Conductance Spacers: The aluminum spacers that the glazing sits on. Recently stainless steel, fiberglass and fluted shapes have taken precedence over aluminum for maximal insulation control.
• Low E: Low Emittance. These are virtually invisible metallic oxide layers which coat a glazing surface to increase insulation.

Two seasons (summer and winter) of astronomical energy bills forced Megan Douglas, a 30-year-old homeowner from Dallas, Texas, to invest in new windows. "Energy performance is the only reason I wanted new windows."

Can you tell in advance how a window is going to perform? Thank goodness for labels. The National Fenestration Rating Council Certified sticker rates the following in large easy-to-read numbers:

• U Factor: how well the window keeps the heat inside your home. The lower the U value, the greater the window's resistance to heat flow and the better the insulation.
• Solar Heat Gain: the window's ability to resist warming from sunlight.
• Visible Light Transmittance: how much light passes through the glass.
• Air Leakage: how well the window seals operate.

To get the run-down on what windows to buy for what region of the U.S. you live in, visit the Efficient Windows Collaborative Web site. The site is loaded with charts, graphs and clear explanations of approximate energy savings related to the type of windows you choose. Calculate for yourself the kind of window that would save you the most, keeping in mind that the higher tech windows are no doubt the costliest.

Before you purchase, visit the manufacturer's Web site. Then visit your favorite do-it-yourself store, window installer or licensed contractor. If you plan on doing the installation yourself, read and follow the manufacturer's instructions to the letter to comply with strict warranty guidelines. "Make sure you read the fine print," says John Gillstrom of Andersen Windows. "Many warranties are prorated and are not transferable. Unlike Andersen's." Oh, and one more thing, if your Uncle Guss, the one with the tools and the know-how is available for the first install, you'd be wise to invite him over to spend the weekend.