Home > Windows > Guide To Low-E Glass | Energy Efficiency & How it Works

Guide To Low-E Glass | Energy Efficiency & How it Works

Updated Nov 16, 2022

Updated Nov 16, 2022

Home > Windows > Guide To Low-E Glass | Energy Efficiency & How it Works

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Your home’s windows are influential to the indoor temperature, which is why there are many types of glass materials available. One example, that we’ll be exploring today, is low-E glass — a coating that enhances thermal performance and prevents indoor energy loss.

Contact any of the providers below to receive a free quote on getting low-e glass installed in your home.

What Is a Low-E Glass Window?

Low-E glass (low energy efficiency) features a thin, transparent coating that’s even thinner than a strand of human hair. Low-E coatings reflect long-wave infrared energy to prevent heat loss inside during winter and allow hot air to escape during summer.

Low-E coatings have two types: soft coat and hard coat. The former consists of silver, zinc, or tin that’s fixed onto the glass in a vacuum and provides excellent heat insulation.

Depending on how these coatings are attached to your new windows, they can make the glass appear tinted. However, this tint shouldn’t impact your visibility out of the window, though it’ll deflect UV rays.

How Does Low-E Glass Work?

Energy-efficient windows have a coating (that the human eye can’t detect) that’s reflective. This coating prevents certain light forms from entering or leaving the home. In fact, this coating only allows the light of a particular wavelength and frequency to penetrate the glass.

Furthermore, the only light that passes through is visible light, which it can do so in both directions. Low-E glass windows also prevent heat transfer to allow visible light to pass through.

What Makes Low-E Glass Energy Efficient?

This type of glass can reduce your energy costs and prevent hot air from inside your home from escaping. Around 25–30 percent of your heating and cooling compensates for heat gain or heat loss through your home’s windows. 

Benefits of Low-E Glass

There are many reasons why homeowners switch to E-glass, and here are some of the advantages.

Enjoy Energy Savings

Low-E glass can cut your energy costs by up to 30 percent by keeping your home at the optimal temperature, so you don’t need to use an air cooling system or switch on your central heating as often. In fact, this energy-efficiency glass prevents the sun’s harsh rays from penetrating the windows to control the temperature inside of your home. Best of all, double-pane glass further controls your home’s climate and prevents air from leaking outside.

Low-E windows keep your home hot in winter and cool in summer and increase the amount of visible light and brightness that enters your home. This means that you can use natural lighting and not have to switch on the indoor lights.

Reduce UV Damage to Your Belongings

The sun’s rays can penetrate through glass, damaging your household items and fabrics. This harsh sunlight exposure can make your sofa look more worn and cause pictures to fade. Low-E windows block UV radiation to protect your upholstery and items, keeping them looking brighter and in tip-top condition for longer.

Prevent the Sun’s Glare

On a sunny day, do you have to draw the curtains so you can view the TV or see your computer screen clearly? This low-emissivity glass deflects infrared light to reduce glare and allows you to work and watch TV without having to adjust your position or close the blinds.

Less Condensation

Condensation can form on glass windows due to hot air coming into contact with a cold window pane. This is particularly common during the colder months when you have the heating on inside. Condensation doesn’t seem like a big issue, but it can contribute to mold and mildew buildup, which has health implications.

Increase Window Durability

For safety reasons, your windows must act as a reliable, solid barrier for the inside of your home and the outside world. While low-E glass has a thin coating, it’s exceptionally strong, which helps to increase your window’s strength.

This feature is advantageous to keeping you feel safe in your home, and it’s also worth the investment if you live in a climate that’s prone to hurricanes.

Low-E Coating Types

These are two types of low-E glass available.

Passive Low-E Coatings

This coating allows some of the sun’s infrared energy to enter the home, helping to keep the heat inside. Passive low-E coatings are ideal for colder climates.

Solar Control Low-E Coatings

These coatings limit the amount of solar energy that enters your home, keeping buildings cool and reducing the need for air conditioning.

How To Choose a Low-E Coating Glass Type

The main difference between these two types of coatings is whether you want your home to feel warm or cool. Here’s how to decide which coating is best for you.

Light Penetrated Through

Solar control coating blocks infrared radiation from penetrating through the glass into your home. This allows only visible light to pass through the glass.

Energy Efficiency

Solar control coating is more energy-efficient, helping you to save more money on your energy costs. It works by allowing heat to escape outside when it’s summer and welcoming in heat in the winter.

Find a local contractor to help with low-e glass installation:

How To Tell if You Have Low-E Glass

If you’re unsure about whether your home has low-E glass installed on the windows, here’s how to recognize if you do.

  • Light a match, and hold it up to the window.
  • You’ll see four reflections of the flame against the window.
  • If you have double-pane windows, the four images will appear the same shade.
  • If you have low-E glass, one of the four reflections will appear a slightly different color than the rest.

You may also notice a slight blue/green shade on the glass at certain angles.

Our Top Recommendations for Low-E Glass Windows

Here are our top picks for low-E glass windows.

Stanek Comfort-Gard Xtreme

This glass consists of triple glazing, two layers of argon gas, and two layers of low-E.


JELD-WEN’s low-E windows and doors are available in various glass types: SunResist, SunStable, SunFlow, HeatSave, and Turtle Glass. Decide between single-, double-, and triple-coating.

Turtle Glass, in particular, reduces glare. HeatSave focuses on keeping heat inside your home, and SunStable blocks harmful UV rays while allowing some sunlight to shine through.

Low-E Windows vs. Double- or Triple-Pane Windows

Double-glazing windows are thicker than low-E glass, which keeps your home quieter. This is ideal if you live on a busy road or near a school. In fact, double-glazed windows can reduce 60 percent more sound than single glazing.

Moreover, triple-pane windows retain even more heat from inside your home than double-glazing and low-E windows.

If you’re replacing your windows to retain heat, low-E glass won’t allow natural sunlight to penetrate through, which can leave some areas of your home slightly cold. On the other hand, double-glazing allows natural sunlight in, keeping the windows and rooms warmer, which is perfect for winter.

However, if you want your windows to deflect heat, low-E glass is great because it doesn’t allow as much heat to enter the room due to the glass coating. This can be highly beneficial in the summer.

Low-E Windows Cost

Expect $120–$1,200 per window, depending on the size, craftsmanship, and material. It’ll also cost around $40 per hour for a professional to install these replacement windows.

Final Verdict: Are Low-E Glass Windows Worth It?

These energy-efficient glasses have so many advantages to them with the most obvious being retaining hot or cold air inside to keep you comfortable indoors. As a result, low-E glass can save you money on your heating and cooling costs. Best of all, the coatings appear thin to the human eye, but they’re long-lasting and durable.

Frequently Asked Questions

What are the disadvantages of Low-E windows?

This type of glass is more expensive and, therefore, considered a luxury item. Low-E windows can also diminish the amount of natural light that enters.

How long do Low-E windows last?

The average life expectancy of low-E glass is 10–15 years. The climate in your area can affect the lifespan.

Do Low-E windows scratch easily?

The coating is durable and more difficult to scratch than glass.

Why do Low-E windows look green?

This is due to the reflective coating. This can be based on the number of coats and the glass’s thickness.

Do Low-E windows fail?

As windows age, the coating on the interior might weaken, making low-E windows less effective.

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