Single-pane clear glass has very little insulating value. U and R values are around 1.
Double-pane clear glass cuts U-Value of a single pane in half and increases R-Value two-fold.
Double-pane glass with LowE Argon gas has low U-Values between 0.25 and 030 and R-Value of 4. This is a quadruple increase in energy efficiency over a single-pane window.
Triple-pane glass with LowE and Argon gas is a high-performance glass with U-Values between 0.19 and 0.23 and R-Value around 5. This is a 20-30% improvement in energy efficiency over double-pane glass with LowE Argon, and a whopping 500% over single pane clear glass.
Triple-pane glass with LowE and Krypton gas is among the best high-performance glazing systems available on the market today. It has U-Values between 0.15 and 0.18 and R-Value of around 7. This is a 40-50% improvement in energy efficiency over double-pane glass with LowE and Argon, and a whopping 700% over a single-pane clear glass.