Spending lots of time staring out your window? Soon, that could become a different experience.

Windows that double as television screens, computer monitors or stereo systems are being unveiled today, on the first day of the International Builders' Show in Las Vegas, by Andersen Corp., the country's largest window manufacturer.

The new windows are the latest advance in a growing industry, fueled by record new-home sales, bigger and bigger houses, and a burgeoning remodeling industry. In 2002, 56 million windows were produced in the country, up from 47.9 million in 1996, according to the Window and Door Manufacturers Association. New windows are purchased in about equal numbers for new homes and remodeling projects, according to the association.

Minnesota-based Andersen's new entrant, which isn't for sale yet, is a bay window that doubles as a home entertainment center. A low-voltage electric current runs through the window. When the current is on, the window is clear. But flip a switch to turn the current off and the glass goes opaque, allowing it to be used as a projection screen for watching television or DVDs. The flanking casement windows become the speakers.

The company is also showing a window featuring an embedded touch-screen computer that slides into a pocket in the window frame when not in use. Andersen and other large window manufacturers are also introducing several other designs in windows and screens at the annual trade show, which runs through this week.

Windows may seem simple enough -- glass in a frame -- but a lot of technology has gone into them in recent years, mostly to improve energy efficiency.

The National Association of Home Builders estimates that windows are, at the very least, an $8 billion-a-year industry. Precise figures are hard to come by because the majority of the nation's window manufacturers and marketers are privately held companies that don't release public sales figures.

What is clear, though, is that Americans have more and more windows in their homes. Fifteen years ago, the average American home had 12 windows, according to research conducted by the builders group. Now, as homes get bigger and windows become more popular, the average home has 16 windows. Upscale houses of between 4,000 and 5,000 square feet have about 20 windows.

"The trend is toward more windows and bigger windows," said Gopal Ahluwalia, head of research at the builders association. "Consumers want more light and more use of glass in their homes."

But do we really need our windows to turn into televisions?

"These are gimmicks," Ahluwalia said. "People like these types of things as topics of discussion. It's the 'We have it and only we have it' type of mentality. Only people with a lot of money will want them." He predicted the new multimedia windows will end up only in houses priced at $1.5 million and higher.

"It depends on the consumer, but generally what people are looking for in windows is aesthetics, energy efficiency and convenience," said Chris Simpson, vice president of marketing and sales for Pella Corp., another large window manufacturer.

Andersen executives say that the entertainment-center windows are prototypes and that the company hasn't put a price tag on them. They say they came up with the design after several years of research and countless focus groups.

"Homeowners want the conveniences and benefits of new technologies, but they don't want them to be so invasive or ubiquitous in their homes," said Phil Donaldson, senior vice president of product development for Andersen.

"When you look at a traditional home, there's a lot of conflict. The TV is in conflict with the fireplace and with your view of outside. It's difficult to position the furniture. With these windows, you can enjoy your backyard and your television from the same position."

The company envisions the windows being bought for the kitchen or family room of the house. The projector, the hard drive of the computer or the stereo is elsewhere -- connected to the bay window but hidden in its seat or in other furniture in the room. The entire system is set up so that when the window is turned to opaque, the speakers go on.

The speaker windows have drivers -- the disc-like woofers and tweeters that are the actual speaker parts inside speaker cabinets -- embedded into the window sash on the side and hidden by a small decorative metal cover. The speaker windows can also turn opaque.

"It's pretty remarkable," said Sandy Isenstadt, a professor of architecture at Yale University who has seen the new windows. "The transformation is pretty startling. One minute you're looking out your bay window at your neighbor's back yard, and the next you're watching Tom Cruise and 'Top Gun.' "

However, Isenstadt said it was hard to tell whether the windows would appeal to homeowners. Windows that switch from transparent to opaque were introduced years ago by several window manufacturers, but they never caught on with consumers.

"It remains to be seen whether it's worth it," Isenstadt said. "It'll have a novelty value for a while."

Andersen is also unveiling an "invisible insect screen" at the show, a window screen the company says is visible only from up close.

Pella will show new retractable screens for patio doors, in which the screens roll into the frame of a sliding door when not in use. The company already sells retractable screens for windows.

They are also unveiling new cordless within-the-window shades. These are blinds and shades that fit between the glass that can be lowered and raised without cords hanging down the sides of the windows. The Iowa-based company is already selling within-the-window shades with pull cords.

One innovation that buyers would really go for, manufacturers say, is a true self-cleaning window -- covered with a protective surface similar to a car wax. Moisture would bead, rinse away and take the dirt with it. Although the technology is there, it hasn't been perfected, said Simpson of Pella.

"Self-cleaning windows are the ideal," he said. "They wouldn't be a hard sell at all."

Pella Corp. created windows with blinds that fit between the glass and can be lowered and raised without external cords.