Misuse of windows can be a pane

Scientific advances help to warm homes, cut down on bills


Do you use your windows as the maker intended?

That's not as dumb a question as it sounds. Windows were designed to perform certain functions, and we, as users, don't always make the most of what they are made to provide.

For example, windows are designed to bring in natural light during the day, yet we cover them with curtains and blinds, and rely instead on electric lighting, which costs a lot more money than the sun charges for the same service.

There are some valid arguments for blocking sunlight, which accelerates the fading of materials such as paint and cloth. It also increases the temperature of a home's interior on hot days.

On the other hand, modern window glass can let in lots of light without heat, and is much more energy-efficient.

Double-pane windows with low-e (emissivity) coating can reduce heating bills by 34 percent in cold climates, compared with uncoated, single-pane windows, says the Alliance to Save Energy, a Washington-based nonprofit advocacy group.

These low-e coatings are spectrally selective, letting in visible light but blocking radiant-heat losses to cut heating bills.

The Efficient Window Collaborative, a group of insulation and window manufacturers that complies with federal energy requirements, says the invisible gas filler in a double-pane window is critical to energy efficiency. Instead of plain air, high-efficiency models use argon or krypton gas, which conduct little heat and help the window's insulating properties.

Traditionally, the material used to create the separation between the two panes of glass, called a thermal break, was metal. New materials insulate better and make the overall window more efficient.

Window frames also are insulated for greater efficiency.

Security issues have altered the function of windows in urban areas because, though windows are the eyes on the world, the world can see in, too.

Windows are locked, bolted and barred, especially in crime-ridden neighborhoods. Instead of being the "eyes of the house," windows are considered weak points.

But having to close them robs a home's occupants of such benefits as cross-ventilation, and increases the use and cost of air-conditioning and fans.

All that aside, windows remain working components of building skins, and manufacturers have been quick to develop new technologies that improve visibility, security and comfort.

The consumer's main concern is getting the results of these new technologies properly installed.

Leakage around windows is so widespread, for example, that the American Society for Testing and Materials International has developed industry standards for installation.

After a century in the business, Andersen Windows continues to consider them "the home's main interface with the outside world," although it is unlikely that anyone used the word "interface" 100 years ago.

The manufacturer introduced some ideas about the future use of its product at the builders show in Las Vegas in January.

The purpose of its Project Odyssey was "to envision the home of the future and to examine the role that windows play in people's lives," Andersen's Cameron Snyder said.

The three-year project "yielded a simple, yet surprising vision for the home of tomorrow: that it may look more like the home of the past than the home of today," Snyder said.

What that means is that the new technologies rapidly becoming part of everyday life might be incorporated into window design.

This would help free homeowners of "much of the clutter and complexity filling the home today and once again rely upon the window as the interface for light, air, information and security," Snyder said.

These products are far from being ready for the market - indeed, Andersen did not even have photographs of the prototypes on display at its show booth - but they do represent some interesting thinking.

ClearSite, which Andersen has dubbed "the invisible insect screen," is designed to provide a much clearer view of the outdoors and increase curb appeal.

The technology used in ClearSite manages light transmission and reflection for better outdoor views, and increases the amount of air and light entering while preventing even tiny insects from passing through.

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