Windows made of insulated glass have something other than a single pane of glass separating one side of the window from the other. They are considered essential in any serious effort to make a home or building as energy efficient as possible. There are a number of different strategies used for insulated glass in order to make it as effective as possible.
The first thing one should ask about when looking at insulated glass is the R-value. This value shows how prone the window is to losing heat. A window with an R-value of 1 is considered very inefficient. Most insulating glass units have an R-value of 2 or higher. 
However, the R-value is not the only part of the puzzle to keep in mind. In fact, while an R-value of 3 may be the sign of a very efficient window, it may not make much sense in many environments to find a window with that high of a rating. Getting up to that number can be very costly and the costs may never be realized in potential energy savings. Therefore, that may make some insulated glass windows bad investments. 
In addition to the energy savings and comfortable temperatures, insulated glass offers a number of other benefits as well. For example, insulated glass often cuts down on the amount of noise from outside. Second, the units are better guards against dust and pollen. 
The most common types of insulated glass are those with multiple panes. Most insulated glass units are double-paned units, though some are triple-paned. Again, windows with double panes are the most likely to be the ones chosen by most people in most environments.

Windows made of insulated glass have something other than a single pane of glass separating one side of the window from the other. They are considered essential in any serious effort to make a home or building as energy efficient as possible. There are a number of different strategies used for insulated glass in order to make it as effective as possible.
The first thing one should ask about when looking at insulated glass is the R-value. This value shows how prone the window is to losing heat. A window with an R-value of 1 is considered very inefficient. Most insulating glass units have an R-value of 2 or higher. 
However, the R-value is not the only part of the puzzle to keep in mind. In fact, while an R-value of 3 may be the sign of a very efficient window, it may not make much sense in many environments to find a window with that high of a rating. Getting up to that number can be very costly and the costs may never be realized in potential energy savings. Therefore, that may make some insulated glass windows bad investments. 
In addition to the energy savings and comfortable temperatures, insulated glass offers a number of other benefits as well. For example, insulated glass often cuts down on the amount of noise from outside. Second, the units are better guards against dust and pollen. 
The most common types of insulated glass are those with multiple panes. Most insulated glass units are double-paned units, though some are triple-paned. Again, windows with double panes are the most likely to be the ones chosen by most people in most environments.