What Is Low-E Glass?

Low-E stands for "low emissivity". Low-E windows contain glass that has been coated in invisible layers of metallic oxide. This coating allows natural light to enter the home while deflecting UV rays and infrared light back out into the environment. Why is this important?

UV rays are invisible rays of light emitted by the sun. UV rays are responsible for fading upholstery, burning skin and, over the course of many years, damaging building materials. Infrared light is heat that warms your home during the winter. By deflecting both types of light back out into the environment, low-E coatings help keep your home warm in winter and cool in summer

How Does It Work?

In a way, low-E coatings sound almost too good to be true. How can glass enable light to enter or exit the home, while preventing heat loss in the winter and heat entry in the summer?

Low-E coatings are not visible to the naked eye. However, they are still reflective, just like the silver coating on the inside of a thermos. This reduces the emissivity of the glass and prevents certain types of light from entering or exiting the home. Low-E coatings are selectively reflective, and only allow light of a certain wavelength and frequency to pass through glass

What Are the Benefits?

Low-E coatings are beneficial to homeowners in a variety of ways:

• Dramatic reduction in heat loss. Stop heat transfer and reduce heat loss in the home by as much as 50%.

• Cost Savings. Homeowners will see reduction in energy bills by using low-E glass.

• Invisible. Low-E glass is not visible to people.

• Durable. Low-E coatings cannot be wiped away, scratched off or damaged because the coating is applied to the inside of the glass.

• Protection of furniture, flooring material and upholstery. UV rays are prevented from penetrating and damaging furniture.

What Is the Science Behind It?

Light takes many forms, but visible light occupies only a fraction of the spectrum. Other parts of the light spectrum include short-wave solar energy (UV rays) and long-wave infrared (heat).

Low-E glass has a coating that reflects short and long-wave infrared rays. The only light that passes through low-E coatings is visible light. Low emissivity glass prevents heat transfer and ensures that visible light is able to pass through the glass in both directions.

Does It Perform in Different Season/Climate?

During the summer, this reflective coat sends heat back into the atmosphere instead of allowing it to enter into the home via the glass. During the winter, the reflective coat sends heat back into the home to keep the interior of the house comfortable. This innovative coating, along with the space between the panes of glass, serves as an excellent insulator for residential homes 

Can Low-E Glass Help Lower Energy Costs?

Low-E glass can help reduce energy costs by reducing the amount of heat that leaves and enters the home on a summer or winter day. During the summer, low-E glass shuts hot air out of the home. During the winter, low-E glass keeps warm air in the home to reduce the burden on the furnace.