Facts about Insulated & Safety Glass

Insulated Glass

Insulated or "double-pane" glass can be found in both residential and business construction. It is required by building codes in many areas as a mandatory energy conservation measure. Insulated glass consists of two panes of glass separated by a space. The perimeter of the glass is sealed, allowing no movement of outside air into the space. The space itself can be filled with dehydrated air, or with a special gas. The type of glass, the type of spacer, and the type of gas used in the space contribute to the overall insulating efficiency of the glass, and also the total cost.If you are purchasing a new home, doing a renovation, or just adding replacement windows, you want the best insulating glass you can afford.

The glass used in the manufacture of these windows may be coated or uncoated. Coated glass is typically called "Lo E", which means low emissivity. The coating is an extremely thin layer of metallic oxide that decreases the transmission of heat through the glass. Some of these coatings also decrease the passage of ultraviolet light (UV) into your home, which is notorious for causing fading in furniture and carpets.

The gas used in the space between the panes is dehydrated air in the least expensive panes, and argon and/or krypton gas in the highest quality panes. Argon and krypton gas have qualities that decrease the movement of heat through the space, giving improved efficiency. However, these gasses increase the manufacturing cost of the windows.

The third critical factor in the efficiency of insulating glass is the spacing material. Less efficient windows use aluminum as a spacing material... a poor choice since aluminum is a very heat-conductive material. Various companies have come up with better alternatives, such as stainless steel or composite metal/rubber combinations.

The final component actually has nothing to do with the glass at all. It is the material composing the window frame. Solid metal frames and tracks produce a net energy loss, since the metal pulls heat out of the house. This effectively negates much of the value of the insulated glass. Most newer windows are made either from wood, vinyl-clad wood, or metal with an insulating "break" between the inside and outside parts, resulting in less heat transfer to the outside.

Safety Glass

Safety glass is used in automobiles. Safety glass is something many of us look through every time we ride inside a vehicle or enter a public building. There are two kinds of safety glass: Laminated and Tempered.

Automakers began using laminated safety glass, also known as auto glass, for automobile windshields in 1927. To make laminated safety glass, the manufacturer sandwiches a thin layer of flexible clear plastic film called polyvinyl butyral (PVB) between two or more pieces of glass. The plastic film holds the glass in place when the glass breaks, helping to lessen injuries from flying glass. The film also can stretch, yet the glass still sticks to it. It is also quite difficult to penetrate laminated safety glass, compared to normal window pane glass. The "sandwich with some give" that laminated safety glass is made of also helps hold the occupants in a vehicle! Laminated safety glass has two other additional benefits:

• It reduces transmission of high frequency sound.
• It blocks 97 percent of ultraviolet radiation.

Tempered safety glass is a single piece of glass that gets tempered using a process that heats, then quickly cools, the glass to harden it. The tempering process increases the strength of the glass to five to 10 times that of untempered glass. Tempered safety glass breaks differently than regular clear glass. When tempered safety glass is struck it does not break into sharp jagged pieces of shrapnel-like glass as normal window panes or mirrors do. Instead, it breaks into little pebble-like pieces, without sharp edges. It is used in the side and rear windows of automobiles. .