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Why Low-E is the Key to Energy Efficient Windows

What is Low-E glass and what can it do for your Des Moines home?

When you’re searching for energy efficient windows, “low-E” may be one of the first terms you hear. Low-E, or “low emissivity” glass is commonly used in energy efficient windows. Low emissivity plays a major role in the temperature control of your home, and thus your energy savings. It is most commonly achieved through low-E glass coatings. While low-E windows can be more expensive than the competition, they make up for it by saving your home between 12 and 33% on energy bills.


The purpose of low-E windows is to reflect heat rather than absorb it. This can be quite handy to keeping your home cool and comfortable in the heat of summer. Placing low-E coatings on the exterior glass of your windows causes harmful thermal rays to reflect off the glass. Because of this, those thermal rays won’t leak through to the interior glass and you won’t have to crank up your AC unit just to keep your home cool.

Low-E coatings can have an impact on the amount of light that your window lets through, however, so it’s important to make sure your window has strong visible transmittance (VT) performance before applying low-E coatings. Most newer, low-solar-gain low-E coatings are better able to block out harmful solar rays without diminishing the amount of natural light that the window lets through to the home.


In northern climates, low-E coatings serve a dual purpose. In the summer they work to reflect the heat from the sun away from your home’s interior. In the winter they work to keep the heat inside your home from escaping through the window. Low-E coatings are important in winter to preventing draft and high heating bills. Because window condensation can occur when cold air leaks from outside and meets the warm interior of the glass, make sure your windows have minimum air leakage. Multiple glass panes, with air or gas fillings can retard the flow of cold air into your home to prevent window condensation and work with your low-E coatings to make your home comfortable and efficient.

In the coldest weather and the hottest weather, low-E windows can help your home to feel like home and keep your energy bills in check. At Zen Windows Des Moines, we want to help to keep your windows and your home energy efficient in any way we can. Call us today at (515) 207-8789 or contact us online for a free quote.