Window Specs You Should Know About
It is important to know a glass window's specifications before purchase. Probably the first thing that a cost conscious homeowner wants to know (besides the price) is how well a window insulates. A window's ability to insulate is measure by something called its U-value. The U-value does not measure how much heat goes through the multiple panes of glass, but measures the ability of the entire window, properly caulked, to restrict the flow of energy from one side to the other. This means that the lower the U-value the better. A zero (which is impossible) would mean that there is absolutely no loss of energy. While a 1.00 would be a total loss of energy - an open space.
Many communities set minimum standards for glass windows in new built structures and additions. Be sure to check with your local permit office for what U-value is required. The U-value is highly dependent on what kind of glass, how thick the glass is, how many panes of glass you have and what kind of gas, if any, is between the panes. (Argon gas will improve the insulation quality of the window.)
Many manufacturers use special glass that limits the admission of Ultra Violet light and also deflects a certain amount of the heat of sunlight. Most people prefer clear glass, but there are many kinds of textured glass that can be used in windows made for special purposes such as bathrooms. Glass can also be tempered (for strength), laminated (for noise reduction), and even tinted. All of these additional features will naturally incur additional costs.
Most window frames are made of vinyl. This is a high quality material that works well for most purposes. At one time glass window frames were primarily made of wood, and high-quality wood frames are still made and used. They have proved their value as a good insulator. But they are subject to rot and need more maintenance than vinyl. Wood can also be expensive because it is harder for the manufacturer to work with than vinyl - though there is no real difference in the installation process. Today vinyl can be made to look like wood or can be clad with wood on the interior. Aluminum was once a popular and inexpensive alternative to wood, it is not as frequently used today in homes. Fiberglass is becoming more popular because of its insulation qualities due to the fact that it does not shrink and expand very much with temperature changes and its strong structural qualities.
Of course, you are going to have lengths and widths to worry about. These numbers describe the opening the window will fit into. It does NOT describe the pane of glass or the moveable part of the window. Also know the depth of the wall (usually 4 or 6 inches). Windows are made specifically for various types of construction.
Armed with this information, you should be able to make informed decisions when purchasing windows.