Picture windows are fixed windows that do not open. They are usually installed in difficult to reach places to let in light. For unobstructed views where ventilation is not a concern, picture windows are ideal. Picture windows create a portrait-like space on walls - hence the word "picture" in their name. Picture windows are also a popular choice for letting in natural light without cold air in areas of a room that may be most susceptible to drafts. In picture windows, insulated glass is a great option for added performance and increased comfort in the home. Insulated glass is a combination of two or more panes of glass with a hermetically sealed air space between them. Optional inert gases, like argon, may be used between panes to further improve thermal performance and energy savings.