Specialty gases such as krypton, xenon, neon, and rare gas mixtures used to fill items made of glass in order to improve their performance or make them function. Specifically, krypton is used as a filler in the production of double and triple-pane insulated windows. Major advantages of using krypton are reducing heat loss, increasing heat transfer resistance in the unit, and reducing levels of solar radiation. You can also increase the R-value or decrease the U-factor for window and door insulation with krypton, xenon and rare gas mixtures. These rare gases are also used to fill light bulbs and neon lighting.