Argon and Krypton Gas-Filled Insulated Glass

Argon and Krypton are inert gases that are used to insulate windows

One of the most sought after qualities in a replacement window is energy-efficiency. Most people however wouldn't know how energy-efficiency can be achieved with different window options and configurations. For instance, did you know that some windows are made with certain types of gas between the panes of glass, and that the type of gas can greatly affect how energy-efficient your windows are? The two common types of gas used in replacement windows are argon and krypton.

Argon and krypton are known to make a measurable difference in replacement window energy-efficiency ratings. The most common measurements of energy-efficiency in a replacement window are U-value, R-value, and Solar Heat Gain Coefficient (SHGC).

  • U-value is the rate of heat flow through a window; the lower the value, the better the insulating quality. Most commonly the U-value is used to measure a window's total insulating value.
  • R-value is the resistance of a material to heat flow; the higher this number, the better the insulating value.
  • SHGC is an energy performance rating that measures the fraction of incident solar radiation admitted through the total window unit. The lower the window's SHGC, the less solar heat transmits through it.

So what's the difference?

Argon - Abundant and Cost Effective

Argon is a common gas with approximately 9,300 PPM in the atmosphere, making it more abundant than carbon dioxide. Argon is about 25% more dense than air. Argon's higher density adds more insulation than air. Argon is also an inert gas, which means it does not react with many other elements. Great insulation along with low reactivity is what makes argon a great solution for energy-efficient replacement windows. The addition of argon gives certain applications like Lang Exterior's Enhanced Glass Package a U-value of .30 and an SHGC Value of .30, commonly referred to in the industry as 30/30 windows, which are very energy-efficient.


Krypton occurs only in trace amounts in the atmosphere. In fact the name "krypton" comes from the Greek word meaning "the hidden one." Krypton is a denser gas than argon, making it a better insulator. Like argon, krypton is chemically non-reactive. This gas is known for being energy-efficient in many different industries. At Lang Exterior we use krypton in our most energy-efficient window, the "R5." Our R5 windows are triple-paned windows, with krypton gas between the panes. With this gas along with other enhancements we are able to achieve an R-value of 5 and a U-value of .20!


Take a look at more info on selected Lang Exterior products and glass options with argon and krypton gas fill: