Double-Glazed with Low-Solar-Gain Low-E* Glass, Argon/Krypton Gas

This figure illustrates the characteristics of a typical double-glazed window with a low solar gain Low-E glass and argon/krypton gas fill. These Low-E products are often referred to as sputtered (or soft-coat) due to the glass coating process. (Note: Moderate solar gain Low-E products are also sputtered coatings.) This type of Low-E product, sometimes called spectrally selective Low-E glass, reduces heat loss in winter but also reduces heat gain in summer. 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.

Low solar gain Low-E glazings are ideal for buildings located in cooling-dominated climates. In heating-dominated climates with a modest amount of cooling or climates where both heating and cooling are required, Low-E coatings with high, moderate or low solar gains may result in similar annual energy costs depending on the house design and operation. While the high solar gain glazing performs better in winter, the low solar gain performs better in summer. Look at the energy use comparisons under Window Selection to see how different glazings perform in particular locations.

Variants on low solar gain Low-E coatings have also been developed which lower solar gains even further. However this further decrease in solar gains is achieved by reducing the visible transmittance as well - such coatings, which may appear slightly tinted, are best suited for applications where cooling is the dominant factor and where a slightly tinted effect is desired.

*Spectrally Selective

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.