Guide to Buying Energy Efficient Windows
The first step to buying energy efficient windows is to look at the design of your home. In what direction do the windows face, and how large are the windows in your home? In heat-dominated areas, windows that face the south should be heavily glazed and possess a solar heat gain coefficient of more than .6 in order to make efficient use of solar heat during cold months, but a U-factor of less than .35 so that heat transfer is reduced during the summer.
In cooling-dominated climates, the focus should be on the north-facing windows with low solar heat gain coefficient, while south-facing windows should be shaded by porches or trees to reduce the intrusion of sunlight and heat. Tinted and reflective windows are not encouraged in these areas because they reduce the SHGC and permit more heat during the summer and spring.
It doesn’t hurt to familiarize yourself with Energy Star ratings prior to buying energy efficient windows so you will be comfortable with looking at selections and making decisions. These ratings are designed to help you choose windows that will maximize the efficiency of your home without detracting from the aesthetic benefits provided by sunlight and open floor plans.
The next step to buying energy efficient windows is to look at your choice of frames. In years past, aluminum frames were most popular, but aluminum conducts heat far more easily than other frames and can be detrimental in cooling-dominated climates. A better choice would be a composite or fiberglass frame that can be insulated against heat transfer and won’t conduct as much heat from the interior to the exterior of the home. Additionally, wood frames should be avoided in areas with high fluctuation in temperature because the material will expand and contract. Wood laminate frames would be a better choice and lend the same aesthetic appeal.
There are also about five types of glazing or glass that you should consider before buying energy efficient windows. This is what makes up the bulk of your window and will ultimately determine how much energy you conserve. Glass-filled windows, for example, are popular in heating-dominated climates because they provide more insulation and reduce the U-factor considerably. Tinted glass is also popular, but if you have a green thumb, you should note that a tint of greater than 70 percent may cause inside plants to die from lack of conducted sunlight.
You might also consider glaze options when buying energy efficient windows, which simply means that there are multiple panes of glass. These are most popular in cooling-dominated climates where heat transfer is highest, and therefore where heat needs to be absorbed. Double-pane and triple-pane windows are far more expensive than the single-pain variety, but last indefinitely and can significantly reduce cooling costs in the summer.
You can also look at alternatives to buying energy efficient windows if you are concerned about the cost. Solar screens, for example, are popular in the south as a deterrent to heat conduction through the glass, and can also provide privacy for those who enjoy keeping the windows open. Light is permitted into the room, but heat is reduced by the screen.
