All About the Glass: Low-E and Double Pane Windows



Regardless of the type of house that you have, big or small, budget or budget breaking, they will all have one thing in common. All houses have windows. Not only do windows allow light to enter your home, they also can add to, or take away from, the overall energy efficiency of your home. Even if you have the most efficient insulation, air conditioning, and heating, with poorly installed or low efficiency windows, your home will just be bleeding energy.

While the material of your window frames, and the materials used, can play a large role in the overall efficiency of your window, it will mean nothing if you’re not using the right window. Let’s face it, a single pane window just won’t be as efficient as a double pane window. And lately, a new coating has been making its way onto home windows. Originally used for commercial windows, Low-E glass is making its way to homes all across the country. And for good reason.

What is Low-E Glass?

You’re probably wondering what Low-E glass is. Low-E simply stands for low emissivity. And emissivity is “the relative power of a surface to emit heat by radiation,” as defined by the Webster’s Seventh New Collegiate Dictionary. Basically, low emissivity glass just has a low emission rate. They work on a very simple principle. Low-E glass reflects heat back to the source. In the summer, the heat of the sun will be reflected off of the outside glass, preventing most of that heat from coming into your home. In the winter, it reflects the heat from inside your home back into your home, preventing most of your heat from bleeding outside. The Two Types of Low-E Glass

Low-E glass is relatively easy to identity. It typically has a colored tint to it, or it appears to be coated. Low-E glass is created by adding metal to the glass. This can be done one of two ways, which creates two different types of Low-E glass. The two types are hard coat and soft coat. Not only do they behave differently, but they look different as well.

· Hard Coat. Hard coat Low-E glass is actually created when the glass is still a little molten. A molten layer of tin is added to the sheet of glass, which basically welds the tin to the glass. Because of how the tin is added to the glass, it’s virtually impossible to scratch or remove the tin. Hard coat Low-E glass will appear to have a blue tint.

· Soft Coat. The process for creating soft coat Low-E glass is much different. For the soft coat, silver, zinc, or tin is applied to the glass in a vacuum using an electrical charge. This coating is soft, so the coated side of the glass is placed on the inside of double pane windows. Soft coat Low-E glass is actually more efficient at reflecting heat than the hard coat.

Double Pane Windows

For the best insulation, you’ll want to use double pane windows. The best insulation comes from double pane windows that are soft coat Low-E glass with argon gas between the two panes. The argon gas actually serves double duty. It prevents the metals used in the soft coat from oxidizing, and it acts as a better insulator than just air. Out of the two types of Low-E glass, soft coat Low-E glass with argon is a significantly better insulator than hard coat Low-E glass with argon. That’s because the soft coat is better at reflecting heat, which makes soft coat Low-E glass with argon the best choice for energy efficient windows.

Paying for Efficiency

You will pay more per window for the soft coat Low-E glass with argon. However, the extra cost per window will typically be offset by the energy savings in your home. Your home will be cooler in the summer, and warmer in the winter. Low-E glass isn’t that new, but it’s gaining in popularity for home use. As you can see, that rise in popularity is well founded. Low-E glass is designed to reflect heat back toward the source, whether that heat is coming from outside of your home, or from inside your home.

As always, for the best information, you’ll always want to speak with an expert. They’ll be able to help you decide on the best windows for your needs. If you want the best energy efficient windows, though, you will want to install Low-E glass with argon.

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