Low-E glass : energy efficiency & other benefits (2024)

Low Emissivity (low-E) glass helps keep your interior spaces warm during colder periods. Depending on your needs, it can allow passive heat to assist your heating system during the winter, or in the summer months can help limit the overheating of your interior by limiting the amount of solar energy passing through the glazing. All of this while letting natural light in.

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  • What are the benefits of low-E glass?
  • What is low-E glass and how do we use it?
  • A solution for every climate and need
  • Applications and uses of low-E glass
  • Tips to see if you have low-E glass in your windows
  • Our low-E product solutions

What are the benefits of low-E glass?

Low-E glass : energy efficiency & other benefits (1)

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Protect homes from cold and hot weather

Low-E glass helps limit the transfer of heat through the glazing (from the interior to the exterior) and helps maintain the heat inside a home during the colder months. When desired, it can let passive heat in to benefit from the free heat from the sun. Alternatively, in warmer climates or for south-facing windows where the priority is to provide protection from solar energy and prevent your interior from overheating, low-E glass with solar control properties can be used to help limit the solar energy entering a building through the glazing.

Low-E glass : energy efficiency & other benefits (2)

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Let the light in

Low-E glass lets a high proportion of the visible light inside. Due to its thermal efficiency, low-E glass can allow larger glazed areas to be created without having to compromise on the thermal comfort of building occupants. Natural light can offer visual comfort and contribute to well-being. Large-glazed areas provide views to the outside and can help connect you to nature and the surrounding environment.

Low-E glass : energy efficiency & other benefits (3)

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Improve energy efficiency

Low-E glass can help keep the interior temperature of a home comfortable at all times of the year, while helping to lower the demand on the heating and/or air-conditioning systems, thus contributing to improving the energy efficiency of a building or home.

Low-E glass : energy efficiency & other benefits (4)

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Protect the colors of your furniture and floors

Low-E glass helps preserve the color of your interior furniture and floors for longer, as it filters up to 78%* of harmful ultraviolet (UV) rays, which can be responsible for up to 50% of the color fading of materials and fabrics. When combined with laminated glass, it can block up to 99% of damaging UV rays.

*for a triple insulating glass unit with two ClimaGuard Premium2 coated glass

What is low-E glass and how do we use it?

How is low-E glass made?

Low-E glass is a coated glass. Very thin, transparent low-E coatings are applied to the surface of the glass. The process used at Guardian Glass to apply low-E coatings on float glass is the sputter process. This process allows the deposition of multiple layers, resulting in a permanent, nearly-invisible and ultra-thin coating (approx. 1/500th of the thickness of a sheet of paper). Windows with low-E coatings limit the amount of heat that is transmitted through the glass. The coatings are made up of a series of almost invisible layers of various materials and rely on one or more precious metal layers (e.g. silver) to reflect interior heat.

See more in this video how glass is coated:

Insulated Glass Unit (IGU)

Low-E glass must be used in a double or triple insulated glass unit (IGU), and the coating must be positioned inside the IGU cavity. The cavity of the IGU is hermetically sealed and protects the coating from external elements that could deteriorate the coating, which is sensitive to humidity. Low-E coatings are positioned on surface #3 of a double IGU, closer to the interior environment, where the heat can be reflected back into the room. In triple IG Units, low-E coatings are positioned on surfaces #3 and #5, (one coating in each cavity).

See more about how an Insulating Glass Unit works and how to improve its performance.

How is the thermal insulation performance of low-E glass measured?

The U-Value describes the energy transfer caused by an air temperature difference between the inside and the outside of a building. The lower the U-Value, the better the thermal insulation performance of the glazing. For example, using a low-E thermal insulating glass in double glazing can bring the U-Value down to 1.0 W/m2K compared to 2.7 W/m2K for double glazing with standard float glass*. This value can be further improved to 0.5 W/m2K in triple glazing.

*4mm glass - 16mm interspace - 4 mm glass

A solution adapted to the climate and need

Low-E glass products provide thermal insulation, while some also have solar control properties. Depending on the climate, as well as the window orientation and size, the glass option chosen may be different. It is important to take all these elements into consideration to select the glass that will best meet your needs. You can also add additional benefits to your window glass by combining it with laminated glass, for example, to improve sound reduction and/or the safety and security of your windows. We have created a simple tool that can help you understand which glass would be the most appropriate for your windows. You just need to answer a few questions to receive a recommendation.

Answer a few questions and receive your window glass recommendation

Our low-E product solutions

Low-E glass : energy efficiency & other benefits (2024)

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