What are Low-E Coatings?

What are Low-E Coatings?
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2 months ago
Reviewed by Bryan Baeumler

Low-E coatings can be a great addition to your window quality. However, before we get into why, let's first go over what you need to know about Low-E coatings and how they work.

Everything You Need to Know About Low-E Coating

Low-E (low emissivity) glass coating is an invisible metallic layer that is added to glass surfaces to help with energy efficiency. The metallic layer allows short-wave solar energy to pass through the glass while reflecting long-wave infrared energy. This is important as it will enable you to gain heat from the sun's energy while limiting the heat trying to leave the home.

This kind of coating is extremely beneficial in winter climates when you are trying to keep heat in to avoid running your furnace or electric heat. Although there is a slight loss in solar gains to your home due to the coating, the reduced solar heat loss makes up for it during the evening.

Essentially, solar heat is reflected off the glass in the summer, which keeps your house a little cooler. While the coating reflects heat, it also filters out harmful UV rays, which can slowly fade curtains, rugs, and furniture over time.

In comparison, in the winter, it allows visible light in and retains radiant heat trying to escape to the outside environment.

In terms of measuring the effectiveness of Low-e coatings, there are a few ways in which you may see it advertised.

  • Solar Heat Gain Coefficient (SHGC) - The SHGC is the fraction of incident solar radiation that comes through the window. This fraction may be either radiated inward or transmitted and absorbed. 1 is the maximum amount of solar heat allowed through the window, and 0 is the least amount.

  • U-Value - This rating is based on how much heat loss a specific window provides. A 0.1 U-value is very little heat loss, while a 1.0 would be high heat loss.

  • Visible Light Transmittance (VLT) - VLT measures how much visible light can pass through a given window. 0 means that no visible light can pass through, and 1 allows all visible light.

  • Light to Solar Gain (LSG) - LSG is the ratio between the VLT and SHGC. A high LSD means more sunlight entering the room with less solar gain.

Low-E Coated Windows

In terms of Low-e coating glass, there are two specific ways it is done.

The first is passive Low-E coatings, otherwise called a hard-coat. This Low-E coating process uses the pyrolytic process and creates a pyrolytic coating. Essentially, the coating is applied to the glass ribbon as it is being produced on the float line. This process allows the coating to fuse to the hot glass surface, which is very durable.

The other way you can coat glass is through solar control, otherwise called a soft coat. Companies that produce soft coats use a Magnetron Sputtering Vapor Deposition process. The Low-E coating material is applied off-line to pre-cut glass in a vacuum change at room temperature. This coating needs to be sealed in an insulated glass or laminated unit to work. However, this coating has lower emissivity and the highest performing solar control.

There are three primary ratings for Low-E coatings for windows from these processes.

  1. The LoE 180 is the standard low-emissivity coating that will help keep the heat in and reduces the number of EV rays entering the home. Most companies suggest this kind of coating on any window in the house.

  2. The LoE 272 is a more advanced coating that performs better than the LoE 180. This kind of coating is perfect for pretty much any window in the home.

  3. Finally, the LoE 366 provides the same insulating values as the LoE 272, but with the added reduction of up to 95 percent of UV radiation. Window companies generally suggest using this coating on unshaded south and west-facing windows.

Finding the Right Window for You

When it comes to finding the perfect winding for you, it does come down to your location and what you are looking for in terms of energy efficiency. Low-E coatings are a great way to strengthen your overall home efficiency while creating a brighter and cozier home.

However, your choice is going to depend on your exact location. If you are in the prairies or up North, a hard-coat Low-E coating might be best. These freezing climates are ideally suited for a hard coat, which will allow for some of the sun's short-wave infrared energy to get through, helping heat your home a little during the winter. At the same time, your Low-E coating will keep the interior long-wave heat energy back on the inside.

However, if you are on the coast of British Columbia where winter is an optional activity or in Ontario, where you get both a cold and hot climate, then a soft coat Low-e solution might be best. This is because it is a bit of the best of both worlds, where you get better UV protection and overall U-value but not as much efficiency in heating your home in the winter.

Here at Canadian Choice Windows and Doors, we proudly carry various Low-E glass coating options. Our main option is our LoE 189, which improves the LoE 180 without the costs associated with LoE 270.

Our LoE 189 is not an add-on feature for our clients but rather a standard, ensuring that all of our windows include a Low-E glass coating. Our custom windows come with a Low-E coating, whether you are looking for awning, bay, or even architectural windows.

Cost for window replacement


Is it worth getting Low-E glass?

Yes, Low-E glass ensures that your home can stay cool in the summer and warm in the winter.

How do I know if my windows have a Low-E coating?

If you buy your windows from Canadian Choice Windows and Doors, all of your windows will have a Low-E glass coating. You can also check if you have a Low-E coating inside or out by holding a match to your window and seeing if any of the four (if you have double-paned glass) reflections are slightly clearer and a somewhat different colour.

How long does Low-E coating last?

Low-e coating lasts the lifetime of the window.

Julia Gurevich
Julia Gurevich

Julia Gurevich is a versatile content writer with a passion for delivering captivating narratives through a diverse and attentive approach. Her eye for detail helps her craft content that resonates with audiences across varied home improvement industries, capturing the perfect balance between information and entertainment. As a content coordinator, Julia takes pride in delivering content that leaves a lasting impact through her ability to navigate seamless content strategies and collaborative projects between teams. In her free time, she enjoys exploring Toronto’s cultural landscape, visiting local parks, and getting to know members of the community through events and activities.

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Reviewed by Bryan Baeumler

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