The evolution of your double pane windows starts with ancient history

January 08, 2012

As common as glass windows are today, glass itself is still somewhat magical. Clear, flat, rigid and sparkling, its formula seems to defy possibility--silica and soda ash heated to the point of liquefying the components. Egyptians used that formula 3500 years ago for making bottles. In about 250 B.C.E. the Babylonians discovered that glass could be blown to make drinking goblets and other vessels.

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From bottles to windows…

Eventually in northern Europe hot, blown glass was sliced open, flattened, and made into small panes. Scores of ancient European cathedrals featured this type of glass connected together with molten lead to create glowing masterpieces.

In colder northern regions homes often had a hole, or "wind eye" in the house roof for ventilation. Wall openings were covered by wooden shutters, paper, hides or other materials to keep out wind, precipitation, and unfortunately, light. In the late 17th century the French learned to grind and polish flat glass sheets, and technology for producing plate glass improved throughout the 19th century. Pittsburgh Plate Glass Company was the first in the U.S. to automate that process. Plate glass became affordable for all, and home shutters were replaced with glass "wind eyes," now called "windows."

From single to double pane windows…

The true evolution of double pane windows originated in 1913 when the Andersen Lumber Co. became the first to manufacture wood window frames. In 1932 they added the sash and hardware, and two years later, even the glazing. Making the entire factory-squared, tight-fitting assembly was the first step in laying the groundwork for what would become today's double pane windows for the home. In 1952, they introduced a Welded Insulated Glass window, and the double pane window was born.

To energy-efficient, window glass enhancements

Since the entire window assembly, and not just the glass, is critical to energy efficiency, Andersen later developed the Perma-Shield® Cladding system, which had a low-maintenance, tough, vinyl cladding that covered the exterior wood frame and sashes. Innovations since then include a non-conductive, sealed-air or inert gas space between the panes. Triple panes are common for large expanses of glass or extreme weather climates.

Transparent microscopic interior metal coatings enhance windows' abilities to reflect exterior temperatures and retain interior temperatures, as the season requires. Coatings now vary to meet each region's climate. The U.S. Department of Energy and the National Fenestration Rating Council put labels with ratings on Energy Star-rated windows to guide consumers.

The magic of glass continues. Its sound-dampening capability is well-known. Impact-resistant and wind-resistant double pane windows for the home are widely available. But more is sure to come: There's no reason to believe the magic show is over.


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