Low-E is the sunscreen your home needs

August 29, 2011

UV rays not only damage our skin cells when we go outside unprotected, but they can also damage the valuables in our homes--furniture, artwork, etc--if the windows are not properly protected. Low-Emissivity, or low-E, glass is a technology that has been in development since the late 1970s and now, like double-paned glass windows or argon gas-filled windows, it is usually available as a standard feature.

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Low-E is a metallic coating on the glass that filters out UV light. The effect is that less UV radiation is likely to enter your home, which not only protects the life of artwork, furniture, and other possessions, but it can help keep your home warm in the winter and cool in the summer. Essentially, low-E window glass is your home's sun shield.

Choosing low-E replacement windows

Most high quality replacement windows come with some form of low-e coating. Choosing low-E glass does not usually affect style or design options, and these three leading manufacturers sell replacement windows that go beyond the standard:

  1. Andersen Windows: Low-E4 are windows that are coated with titanium dioxide, and in addition to the energy savings, the company says that the coating helps the windows look cleaner and reduces water spots.
  2. Marvin: Low-EII or Low-EII with argon are rated as energy-efficient by EnergyStar.
  3. Milgard: SunCoatMAX offers the best protection in comparison to Milgard's line of energy-efficient windows.

These are good options to consider if you live in an area where heating and cooling costs are big concern.

Low-E glass is designed differently for different climates, so if you are putting replacement windows in your home, make sure they are rated for your geographic area. If you live in a cooler, northern climate, for example, the low-E coating might still allow some UV light to enter your home to help with passive solar warming in the winter. In warmer, southern climates, the coating might block more UV radiation to help make cooling your home more effective.

Low-E replacement windows cost and value

According to the U.S. Department of Energy, low-E windows cost about 10 to 15 percent more than regular windows. However, reducing UV light in your home can reduce your energy costs by 30 to 50 percent. The main reason for this is that low-E coating reduces a window's U-factor, which is a measurement of the amount of energy lost or gained through the glass. A lower U-factor means a more energy-efficient window.

When you compare the factors between cost and value, investing in increased sun protection for your house will likely ensure your savings are increased, too.


U.S. Department of Energy • Low-Emissivity Window Glazing or Glass  

Milgard Windows • Milgard SunCoat Low-E Glass 

Andersen Windows • Low-E4  

Marvin Windows • Maintenance, Performance and Energy Efficiency

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