Low-e glass has a low emissivity, which enhances its thermal insulation, and a highly reflective, ultra-thin coating, which reduces the amount of the sun's ultra-violet and infrared rays that pass through. This reflective coating does not affect the amount of visible light that passes through.
Glass radiates thermal or heat energy. A low-e or low-emissivity glass radiates even less thermal energy. During winter, less heat energy from a home's insides passes through low-e glass windows to its exterior, trapping more heat inside for a warmer environment, resulting in reduced heating expenditure for the household. Less heat from the outside passes through low-e glass windows during summer. This makes the insides cooler, resulting in less air-conditioning expense. A reduced amount of ultra-violet rays, which can cause fabric colors to fade and harm a person's skin, passes through low-e glass during sunny days.