This figure illustrates the characteristics of a typical double-glazed window with a high-transmission, Low-E glass and argon gas fill. These Low-E glass products are often referred to as pyrolitic or hard coat Low-E glass, due to the glass coating process. The properties presented here are typical of a Low-E glass product 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. This Low-E glass type is also the product of choice for passive solar design projects due to the performance attributes relative to other Low-E glass products which have been developed to reduce solar gain.

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. Low solar gain Low-E glazings are ideal for buildings located in cooling-dominated climates. Look at the energy use comparisons under Window Selection to see how different glazings perform in particular locations.