Low-E glass works by reflecting heat back to its source. It does this by utilizing a special coating which has a poor emissivity of heat and does not allow heat to be transferred through it. In the summer this helps to keep your house cooler, as the heat from objects outside is kept outside. In the winter, all objects in your home are heated (by either the sun or your furnace). This heat is also bounced back into your house by the Low-E glass. Therefore the Low-E coating glass can keep your room warm or cold, then reduce the amount of energy lost through your windows up to 75%!

There are two types of Low-E glass: hard coating and soft coating. Hard coating is the online process during glass producing, which makes Tin molten directly on the glass. The soft coating is the offline process, by the vacuum magnetron sputtering coating machine, which has better heat insulation rate because of using the multiple metal layers include silver, and the quality of Low-E film is easiler to be controlled, so the soft coating Low-E glass becomes the more popular products now. Soft coating Low-E glass is always sandwiched with another piece of glass to prevent metal layer being oxidated.