What Is Low-E Glass?

If you are looking for a versatile material then consider glass for its surpassing solar and thermal performance. The best way to make glass efficient is through Low-E glass (Low Thermal Emissivity), which will decrease your overall heating, lighting, and cooling costs.

How Solar Energy Works 

There are three types of light that encompass the solar energy spectrum: ultraviolet, visible, and infrared light. 

The difference between the three is their wavelengths: 

  • Ultraviolet: 210-380 nanometers
  • Visible: 380-780 nanometers
  • Infrared: starts at 780 nanometers 

When you add low-e coatings to a window it will decrease the amount of infrared and ultraviolet rays, all while letting visible light through. Emissivity is when a material can radiate energy and your goal is to have low emissivity in your windows. This is a key factor when it comes to your windows insulating capabilities.

How does low-e coating work?

Believe it or not this coating is actually thinner then one strand of your hair! It will reflect low-wave infrared energy and some also reflect short wave infrared. To simplify, when the warm air in your home is trying to escape through the window, it will stop if by reflecting the heat energy back into the room and the opposite takes place in the summer.

Related Article: Choosing the Best Replacement Windows


Passive vs. Solar Control Low-e Coating

Passive low-e coatings are fused to the hot glass surface as it is being manufactured. This type of glass works well in cold climates because while it will reflect heat energy back into the room, it will also let some short infrared energy to pass through to allow heat into the room. Solar control low-e coatings are added to pre-cut glass and have higher performance in solar control. If you are in a mild to hot climate and use air conditioning then solar control is the best option.

Test for Low-E Glass

Get a match or pen light to put in front of a double pane window. You will see four reflections of the light or flame from the four glass surfaces. If your window has a low-e coating then one of the lights will be a different color. If you don’t they will all be the same color.

To ensure your window is at it’s peak performance test for low-e coating and then replace if necessary.

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