Clera Windows + Doors Blog

What is a low-E coating and why does it matter?


If you have ever been window shopping and seen the term low-E coating, you may have wondered what it is. It would be wise to familiarize with the phrase, because windows that have a low-E coat are the best to purchase when replacing your old ones. Contrary to popular belief, less is better when it comes to this factor. An E coating refers to a window’s “emittance” ability. Thus a low-emittance window is one that is equipped with a reflective coating that works well to keep light and incoming heat out.

Think of the reflectors you place in your car to keep the heat out. This is essentially the same thing; low E-coatings are virtually transparent, and are comprised of very small metal particles that operate to prevent external energy from coming in. Many people assume this is not a good thing, especially if they live in a colder climate. Windows that have these coatings do an excellent job at letting heat in as well; you just have to select the proper size for the climate you live in.

The benefits of low-e coating

  • Energy savings
  • Protection from harmful UV rays
  • Condensation reduction

If you live in a region that is very hot, a low-E coated window that is designed to maximize the suppression of radiated heat will work best. They can greatly reduce the amount of heat that will come into your home, which will in turn keep you from having to run your air conditioning unit. However, the internal panes are also coated with the same material, which means they will work to trap the heat inside your home when winter time comes around.

Low-E coated windows block ultraviolet radiation, which can damage materials (carpet, leather furniture). If you have ever noticed a faded appearance on items in your home that are placed near the windows, this is the culprit. Low-E coatings keep these rays from ever coming in, but they still allow the heat to pass through the glass.

Condensation can be a very annoying and detrimental problem, and it is caused when warm air meets cold glass. The resulting moisture that is released becomes condensation, which can damage the window itself and materials in the vicinity. You don’t have to worry about these problems nearly as much with windows that have low-E coatings in place.

No matter where you live, choosing a window that will save you money on your heating and cooling bill is one worth investing in. Low-E coated windows are designed for this purpose, but they also provide many other benefits. There are many styles and types to choose from, so be sure to consult with your window company when making the decision to replace your windows.



  • Avatar for Sam Sam says:

    How much energy can I expect to receive with these windows? Do they differ much from other energy-efficient models? Thanks for the helpful insight!

  • Avatar for Martha Martha says:

    I liked the comparison to car reflectors; many people don’t think the same rules apply to the windows in their home. It is always a good idea to be informed.

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