| A single pane of glass used to be the only option | | | | Inert gasses are heavier and denser than air, so |
| for windows, but not anymore. Double pane | | | | their molecules do not move as easily. Having |
| windows have become very popular in new | | | | inert gasses between the panes of glass makes it |
| construction and as replacement windows over | | | | more difficult for the warmer inside air to pass |
| the years, due to their energy efficient properties | | | | through the glass to the colder outside. This helps |
| and other advantages, such as sound reduction. | | | | keep warm air from escaping during the cold |
| Double pane windows are very good insulators, | | | | winter months, saving on heating costs. |
| keeping warm air in and cold air out. What makes | | | | With lower heat loss, the window's R-Value, which |
| them such effective insulators? Part of the | | | | measures its resistance to heat flow, is increased. |
| answer lies not in the glass itself, but in the space | | | | A higher R-Value means a more energy-efficient |
| in between the two panes. | | | | window. A single pane glazed window generally |
| The space between the two panes in a double | | | | has an R-Value of about 0.85, and a double pane |
| pane window is usually about half an inch wide, | | | | glazed window without an argon fill may have an |
| and is typically filled with argon or another inert | | | | R-Value between 1.5 and 2.0. A double pane |
| gas. These gases are nontoxic, nonreactive, clear, | | | | glazed window with an argon gas fill is |
| and odorless. Argon is also inexpensive, making it | | | | considerably more energy efficient, as seen by its |
| a common choice for this purpose. | | | | higher R-Value, between 2.7 and 3.6. |
