Low emissivity (low e or low thermal emissivity) refers to a surface condition that emits low levels of radiant thermal (heat) energy.

Low e glass illustration

How Low-e Glass Works

Glass is one of the most popular and versatile building materials used today, due in part to its constantly improving solar and thermal performance by using passive and solar control low-e coatings. 

So, what is low-e glass?

To understand coatings, it’s important to understand the solar energy spectrum or energy from the sun. Ultraviolet (UV) light, visible light (VL), and infrared (IR) light all occupy different parts of the solar spectrum – the differences between the three are determined by their wavelengths.

Low-E coatings have been developed to minimize the amount of ultraviolet and infrared light that can pass through glass without compromising the amount of visible light that is transmitted.

When heat or light energy is absorbed by glass, it is either shifted away by moving air or re-radiated by the glass surface. The ability of a material to radiate energy is known as emissivity. In general, highly reflective materials have a low emissivity and dull darker colored materials have a high emissivity.

Radiant energy is one of the important ways heat transfers occur with windows. Reducing the emissivity of one or more of the window glass surfaces improves a window’s insulating properties.

This is where low emissivity (or low-e glass) coatings come into play. Low-E glass has a microscopically thin, transparent coating—it is much thinner than a human hair—that reflects long-wave infrared energy (or heat).

Low-e glass works the same way as a thermos. A thermos has a silver lining, which reflects the temperature of the drink it contains, and the temperature is maintained because of the constant reflection that occurs. Since low-e glass consists of extremely thin layers of silver or other low emissivity materials, the silver low-e coating reflects the interior temperatures back inside, keeping the room warm or cold.

low-e glass windows

FB Doors showroom of low-e glass hurricane impact windows

Top Benefits of Low-E Glass

  1. Insulating

Due to their coating, Low-E windows are more insulative than standard non-coated glass. 

The coating helps reflect heat back to the outside in the summer, and keep properties better insulated.

  1. Reducing Energy Costs

Somewhere between 10-50% of all energy loss in a home happens through non-coated windows and doors. Low-E glass can help cut back on some of that loss.

Low-E windows help reduce energy costs associated with the heat transfer that happens thru windows. 

  1. Allowing Natural Light to Flow

Even though Low-E windows block UV rays and infrared light, they still allow plenty of natural light to pass through because the coating is tintless and nearly colorless.

While the light might be slightly less visible than it would be through a completely clear pane of glass, Low-E glass windows still allow plenty of natural light to flow throughout a home.

This gives homeowners all the benefits of natural light without the drawbacks.

  1. Non-Toxic and Safe

The coating on Low-E glass windows is safe and non-toxic, so homeowners don’t have to worry about dangerous chemicals or harmful effects on them, their children, or their pets.

  1. Long-Lasting and Cost-Effective

The Low-E coating is strong and applied evenly to the entire surface of the glass. Moreover, Low-E glass windows are typically just a couple of dollars more than regular glass windows. The extra cost generally pays for itself in energy savings.


When thinking of window designs: size, tint and other aesthetic qualities come to mind. 

However, low-e coatings play an equally important role and significantly affect the overall performance of a window or door. 

Avoid the popular misconception that tinted windows are like just installing Low-E glass windows.

That’s not true, and Low-E coating is typically just a couple more dollars than regular tinted glass windows.

With our efficient glass choices, you will feel the difference with more consistent temperature throughout your home and see the difference in your energy cost savings.

Low-e glass offers better UV protection, reduces solar gain, increases comfort, and cuts back on energy use.

So, make a great investment installing Hurricane Impact Windows and Doors w/ Low-E with FB Doors Corp.

Schedule a complementary consultation here.