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The Difference in the Pane:
Energy-Efficient Window Glass
 I'll tell you the truth: when I redid my home, I didn't even think about the windows. Whatever the contractor put in was just fine with me. I had enough on my head without worrying about the different types of window glass, thank you. Once I started to do some research, though, I began to wonder if I had made a mistake in being so blasé.
All types of window glass were not created equal, and many of them include features that can reduce your energy bills significantly. Features that enhance insulation or reduce harmful sunlight can make a big difference in the effectiveness of your windows, and the numbers on your energy bills.
Once you have an idea of what type of features you're looking for, you can try to find a combination of features that best fits your needs. Windows do not have to be one-size-fits-all; you can mix and match features and styles accordingly.
Window Glass Features
- Insulating Glass - Insulating glass really consists of two layers of glass, with an air space in between. Sometimes the space is injected with an inert gas, making it an even more effective insulator. Insulating glass reduces energy bills, as well as outside noise.
- Low-e Coatings - Low-e coatings are virtually invisible coatings that are applied to window glass in different ways. These coatings are instrumental in enhancing energy efficiency and screening out ultraviolet rays (see below). Softcoat low-e is applied to the interior side of insulating glass; although it is the more effective type of low-e, it is vulnerable to climactic conditions and window-washing. Hardcoat low-e can be used even on regular, single-pane glass, but is considered to be the less efficient option.
- Tinted Glass - Tinted glass runs the gamut from light tints designed to reduce sun glare, to tints dark enough to preclude the use of shades or blinds. Particularly in warm, sunny climates, tinting can be a simple and cost-effective way to reduce energy bills.
- Safety/Tempered Glass - Although not an energy-saving feature per se, safety glass can be an invaluable feature should your window ever break. Rather than splintering, safety glass shatters into shards, leaving no sharp edges. Building regulations may require it under certain circumstances.
The Funny Numbers
Construction materials, windows included, often have ratings listed on the packaging. Buyers know that these numbers tell you something about the product's effectiveness and quality, but goodness only knows what!
When describing the energy efficiency of glass windows or doors, here are some terms to keep in mind:
- U-Factor - This is a measurement for heat transfer through the glass. The numbers typically run between .20 and 1.20. Lower U-Factor numbers mean better insulation.
- R-Value - Almost the opposite of U-Factor, R-Value shows the ability of the glass to resist heat transfer. Look for higher R-Value numbers for better insulation.
- SHGC (Solar Heat Gain Coefficient) - This number indicates the amount of heat that gets generated from sunlight shining through the glass. The range of measurement runs from 0 to 1. Lower numbers mean less heat, and are a boon for reducing air conditioning bills in warm climates.
- VT (Visible Light Transmittance) - The VT measurement refers to the percentage of light that passes through the window. The higher the number, the brighter the light that passes through into the interior.
- UV (Ultraviolet) Light Transmittance - Although UV rays are not visible, they do cause fading to exposed furniture, carpeting and paintings. The lower the UV rating, the lower the percentage of UV rays entering the building.
As with any construction project, be sure to enlist the help of the experts in making your choice. Ask your contractor or dealer for the best deals and the best combination of options. Between your research and the experts' advice, you're sure to get a better window for your home.
Another article brought to you by HomeImprovementExpo.com.
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