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Window Technologies: Glazing Types - Double Low-E Glazing

Double-Glazed, High-solar-gain Low-E Glass

This figure illustrates the characteristics of a typical double-glazed window with a high-solar gain low-E glass with argon gas fill. These windows are designed to reduce heat loss but admit solar gain. High-solar-gain low-E glass products are best suited for buildings located in heating-dominated climates and are the product of choice for passive solar design projects.

High-solar-gain low-E glass is often made with pyrolytic low-E coatings, although sputtered high-solar-gain low-E is also available.

Double HSG Low-E

Center of Glass Properties

Note: These values are for the center of glass only. They should only be used to compare the effect of different glazing types, not to compare total window products. Frame choice can drastically affect performance. These values represent double glazing with a 1/2" air gap.

Whole Window Properties - Double-Glazed, High-solar-gain Low-E Glass

  Metal Frame Metal Frame Non-metal Non-metal
Frame Metal Frame Metal Frame with Thermal Break Non-metal Frame Non-metal Frame, Thermally Improved
U-Factor 0.56-0.70 0.41-0.55 0.41-0.55 0.23-0.30
SHGC >0.60 0.41-0.60 0.41-0.60 0.41-0.60
VT >0.60 0.51-0.60 0.51-0.60 0.51-0.60
Note: The thermal performance properties of specific glazings and frames can vary depending on product design and materials.
The results presented here are averages. Consult specific manufacturers for NFRC rated U-factors and SHGCs for products of interest.

Double-Glazed, Medium-solar-gain Low-E Glass

This figure illustrates the characteristics of a typical double-glazed window with a moderate-solar-gain low-E glass with argon gas fill. These windows are often referred to as spectrally selective low-E glass due to their ability to reduce solar heat gain while retaining high visible transmittance. Such coatings reduce heat loss and let in a reduced amount of solar gain making them suitable for climates with both heating and cooling

Medium-solar-gain low-E glass is often made with sputtered low-E coatings, although pyrolytic moderate-solar-gain low-E is also available.

Double MSG low-E

Center of Glass Properties

Note: These values are for the center of glass only. They should only be used to compare the effect of different glazing types, not to compare total window products. Frame choice can drastically affect performance. These values represent double glazing with a 1/2" air gap.

Whole Window Properties - Double-Glazed, Medium-solar-gain Low-E Glass

  Metal Frame Metal Frame Non-metal Non-metal
Frame Metal Frame Metal Frame with Thermal Break Non-metal Frame Non-metal Frame, Thermally Improved
U-Factor 0.56-0.70 0.41-0.55 0.41-0.55 0.23-0.30
SHGC 0.26-0.40 0.26-0.40 0.26-0.40 0.26-0.40
VT 0.51-0.60 0.51-0.60 0.51-0.60 0.51-0.60
Note: The thermal performance properties of specific glazings and frames can vary depending on product design and materials.
The results presented here are averages. Consult specific manufacturers for NFRC rated U-factors and SHGCs for products of interest.

Double-Glazed, Low-solar-gain Low-E Glass

This figure illustrates the characteristics of a typical double-glazed window with a low-solar-gain low-E glass with argon gas fill. As with moderate-solar-gain low-E glass, these windows are often referred to as spectrally selective low-E glass due to their ability to reduce solar heat gain while retaining high visible transmittance. Compared to most tinted and reflective glazings, this low-E glass provides a higher level of visible light transmission for a given amount of solar heat reduction. Variants on low-solar-gain low-E coatings have also been developed which may appear slightly tinted. This type of low-E product reduces heat loss in winter and substantially reduces solar heat gain both in winter and in summer. Thus, low-solar-gain low-E glazings are ideal for buildings located in cooling-dominated climates.

Low-solar-gain low-E glass is typically made with sputtered low-E coatings consisting of either two or three layers of silver (also called double-silver or triple-silver low-E).

Double LSG low-E

Center of Glass Properties

Note: These values are for the center of glass only. They should only be used to compare the effect of different glazing types, not to compare total window products. Frame choice can drastically affect performance. These values represent double glazing with a 1/2" air gap.

Whole Window Properties - Double-Glazed, Low-solar-gain Low-E Glass

  Metal Frame Metal Frame Non-metal Non-metal
Frame Metal Frame Metal Frame with Thermal Break Non-metal Frame Non-metal Frame, Thermally Improved
U-Factor 0.56-0.70 0.41-0.55 0.41-0.55 0.23-0.30
SHGC ≤0.25 ≤0.25 ≤0.25 ≤0.25
VT 0.51-0.60 0.51-0.60 0.51-0.60 0.41-0.50
Note: The thermal performance properties of specific glazings and frames can vary depending on product design and materials.
The results presented here are averages. Consult specific manufacturers for NFRC rated U-factors and SHGCs for products of interest.

 

 

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