The Glass

While the material each window is constructed from is important, the reality is that most recent window-related buzzwords are all about what's inside the frame. But what do all these upgrades mean?

John Lala, president of Rycorp Construction in Virginia Beach, Va., is familiar with the gamut of efficient window options. He's built houses in all price ranges, from bare-bones-basic structures to million-dollar-plus projects for very eco-conscious clients. And after seeing everything out there and talking to lots of home buyers, he says, he ends up using windows with the same basic energy efficiency features in most of his projects.

"A double-pane window with low-E glass with a vacuum-sealed argon fill — that's what people ask for," he says. "It's an extra $40 or so per window for me to add these features, and they really do make a difference in a home's utility bills." Lala says he's found that doing anything more, such as using triple-pane glass or denser gases with greater insulative properties, "just adds cost and gives diminishing returns in efficiency."

So what exactly are you getting when you choose a window with the aforementioned options? "Low-E, argon-filled, double-paned windows provide significantly more insulation than a single-pane window," says Kendra Weinisch, a residential energy efficiency consultant in San Jose, Calif. "These windows protect the inside of the house from the sun's heat and UV rays in the summer, and they prevent heat from escaping during winter. From the standpoint of energy efficiency and value, these types of windows make a lot of sense."