Blog > Category > Posted: 2023-Jul-20, Updated: 2023-Apr-05

What is Low-e Glass?

LoE glass, also known as Low-emissivity glass or low-E glass, is a glass with properties that reflect radiant heat, thus potentially improving the thermal efficiency of a window. Emissivity is a measure of how much a glass surface transfers radiant heat through it.

Low Emissive Glass has a distinct microscopically thin layer of silver (applied to the inside-facing surface of the outside pane of window glass). This layer acts to reduce the amount of heat that can flow through the glass. Highly reflective materials have a low emissivity, while dull darker coloured materials have a high emissivity.

LoE coatings play an important role in the overall performance of a window and can significantly affect the heating, lighting and cooling costs of a home by reflecting heat in both directions - keeping heat out in the summer and in during the winter.

LoE windows can also reduce UV rays that enter the home to help in the prevention of fading on furniture, window treatments and flooring. Although UV light is reduced, Low-E glass does not adversely affect houseplants, in fact for some plant species, it actually helps boost plant growth.

There are two different types of LoE coatings: passive loE coatings and solar control LoE coatings. Passive LoE coatings are designed to maximize solar heat gain into a home to create the effect of “passive” heating and reduce reliance on artificial heating. Solar control LoE coatings are designed to limit the amount of solar heat that passes into a home for the purpose of keeping it cooler and reducing energy consumption related to air conditioning.

LoE-coated glass is available in several configurations to produce the desired balance between solar gain, light transmission and UV blocking. With the right configuration, it can also limit the amount of light coming in, thus making a room more pleasant to be in.

Below are a few LoE configurations and their corresponding benefits:

LoE 366 glass

  • High-performance solar control
  • Typically recommended for windows in the Ottawa and surrounding area
  • Best insulation option keeps heat and sun out of the home and hot & cold inside the home
  • U-factor of .29
  • Maximized solar gain of SHGC 0.27
  • Allows for 65% light transmission
  • Blocks 95% of damaging UV rays

LoE 340 glass

  • Solar and glare control
  • Best antiglare option
  • U-factor of .25
  • Maximized solar gain of SHGC 0.18
  • Allows for 39% light transmission
  • Blocks 80% of damaging UV rays

LoE 272 glass

  • All climate triple-layered tinted coatings
  • Balanced option when a room is too hot in summer and too cold in winter
  • U-factor of 0.30
  • Maximized solar gain of SHGC 0.41
  • Allows for 72% light transmission
  • Blocks 84% of damaging UV rays
  • The moderate solar gain in winter and controls heat in the summer

LoE 180 glass

  • Highest Energy Star energy rating
  • U-factor of 0.31
  • Maximized solar gain of SHGC 0.68
  • Allows for 79% light transmission
  • Blocks 70% of damaging UV rays
  • Reduces energy costs in the winter

Advantages of LoE Glass

  • Great potential insulating properties
  • Multi-seasonal indoor temperature control
  • UV Protection

Disadvantages of LoE Glass

  • Potential loss of natural light transmission depending on your preferred selection (ranging anywhere from a 25% to an 85% reduction)
  • The initial cost of installing low E glass is higher than installing standard uncoated glass

Regardless of where your home is located, choosing windows that provide you with the highest level of comfort and energy savings year-round is very important. Choosing the right glass for those windows should be the most important factor in that decision.

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