1 – ClimaTech insulated glass The optional ClimaTech insulated glass package combines multi-layered low-emissivity (Low-E) glass and argon gas. In the winter, it lets in solar heat and holds the warm air inside. In summer, it repels heat and glare while filtering out ultraviolet rays which can fade carpet, furniture, artwork and painted or stained wood. 2 – Intercept® Warm-Edge Spacer System The PPG Intercept Spacer System features a unique, one-piece metal alloy, U-channel design that creates an effective thermal barrier to help reduce conducted heat loss through the window. It’s sealed, one-piece design makes Intercept spacers stronger and better at retaining insulating gas than many conventional designs. Intercept spacers are so energy-efficient that they keep the edges of the window glass warmer, so your home feels more comfortable in the winter. ThermD™ Stainless Steel Intercept Warm-Edge Spacer ClimaTech ThermD features insulating Low-E glass, argon gas and a stainless steel Intercept Warm-Edge Spacer for even greater thermal efficiency with the unique Intercept design.  Through its stainless steel alloy, ThermD advances performance to the highest level.  Stainless steel – known for its unsurpassed strength, durability and resistance to corrosion – is also impervious to gas transmission, which improves insulating gas retention in the window unit and increases its overall thermal performance. The stainless steel spacer also incorporates flex, for low stress on the sealant bond to offset effects of temperature changes and helps to prevent seal failure.  ThermD Stainless Steel Spacer delivers thermal performance, structural integrity and reliability to maximize your new window investment. 3 – Insulating Argon Gas Argon gas is a colorless, odorless, nonflammable, nontoxic, and above all, safe inert gas that is heavier than air. When the air between two window panes is replaced with argon gas, the energy efficiency of the window increases. Additionally, it acts as a sound barrier to help make your home quieter.