Typical double-pane windows have hardly changed since their invention a century ago. Filling them with inert gases or adding coatings to reflect or let in heat has made them more effective. But it’s still generally accepted that, all other things being equal, your home’s energy bills will go up or down based on how many windows you have, and how big they are.

“Windows are always viewed as the problem, because windows typically lose 10 to 20 times more energy per square foot than a well-insulated wall,” says Stephen Selkowitz, an affiliate at the Lawrence Berkeley National Laboratory and a dean in the field of building energy efficiency. The Energy Department estimates that U.S. households each waste $200 to $400 a year on energy bills due to drafts, leaks and inefficiencies, for a total of at least $25 billion a year.

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These new three- and four-pane windows can be even better insulators than the walls around them, but cost only about 20% more than standard energy-efficient windows. Installing them could bring big energy savings for those ready to retrofit, and could enable the construction of new homes that are so well-insulated that even when the power goes out in a winter storm, they stay warm for days. Another variant of these windows can meet the most stringent hurricane-related building codes in the country, while being significantly lighter than conventional stormproof windows.

The bad news is that Joe and Jane Consumer won’t be able to buy these kinds of windows at the local home-supply store—at least not yet. While the primary manufacturer of this type of window is offering its tech to other window makers, it’s only opened up U.S. production in the past few months, and it’s still scaling up manufacturing.

Bringing the panes

Scientists have long known the key to more efficient windows is similar to the relationship between razorblades and a closer shave: More is better. But it was hard to translate that into a product that could be mass manufactured, at a price that people would be willing to pay, says Selkowitz.

Enter Corning, maker of the thin, tough Gorilla Glass that has helped make possible today’s mobile devices. In order to win over Steve Jobs and land Apple as a client when it first started making iPhones, Corning offered Apple a fresh twist on its existing process for making glass for LCD displays and other applications, which yielded a new kind of chemically strengthened glass.

Traditional glass, called soda-lime glass, is made by floating molten glass on top of molten tin, which is a cheap and effective process but leaves microscopic flaws. With Gorilla Glass, molten glass with different additives than soda-lime glass cascades in a waterfall as thin as half a millimeter, which rapidly cools and is cut to size, yielding glass that is nearly flawless. The glass is also chemically strengthened, making it resistant to scratches and chipping.

As the smartphone industry ramped up, Corning built more factories to meet demand for Gorilla Glass. Some of these factories now use the same process, with a slightly modified chemistry, to create far larger sheets of similarly tough glass, for windows instead of hand-held devices. These sheets of glass are thinner than a credit card, yet they can be bigger than a queen-size mattress, says Ron Verkleeren, senior vice president of Corning’s emerging-innovations group.

This architectural glass doesn’t yet have a compelling name like Gorilla Glass, but they’re working on it, he adds. (“Orangutan Glass” has my vote.)

When three or even four layers of glass are put together, with inert gas in between, only the interior panes are the super-thin Corning panes, and they add little weight to the finished product. 

When you go from a single air gap to the two or three that are possible with triple- and quad-pane windows, the insulating ability of a window can skyrocket, says Selkowitz, who has collaborated at the federally funded Lawrence Berkeley lab with Alpen, a Colorado-based maker of specialty windows, to research their capabilities.

Efficiency and more

Alpen’s windows have long been favored by architects who want to build super energy-efficient homes. Corning began collaborating with Alpen about five years ago, and now the company is ready to mass-manufacture reinforced windows at two facilities, one in Colorado and one in Pennsylvania. The first wave will be windows in standard sizes, says Andrew Zech, Alpen’s CEO. Key to keeping costs down are the company’s new automated, high-throughput assembly lines for making the windows, he adds.

David Schleicher, managing director of Kala, a high-performance builder in Kansas City, Mo., has been living with a wall of triple-pane windows comparable to Alpen’s on the south side of his home since 2015. Typically, such a vast expanse of glass—a total of 16 feet by 7—would create an unpleasantly cold patch during the winter. But this glass is so well insulated, it actually creates warmth in his living room: It admits the radiant heat of the low winter sun but prevents conductive heat loss through the window, says Schleicher.

“With the right glass in my house, my heat won’t even be running on a winter day, as long as the sun is shining and it’s coming in the window,” he says. “It is crazy—I will be in shorts and a T-shirt and it’s 20 degrees outside. Meanwhile, my neighbors are paying out the nose in heating and cooling bills.”

Whether or not these innovative new windows take off depends largely on the demand from builders, homeowners and landlords.

Historically, the biggest reason that energy-efficient technologies get adopted is that building codes require them, says Schleicher. Without explicit regulations that enforce minimum standards, builders often seek deals on materials so that they can maximize profits, and businesses and individuals who rent out properties often have little incentive to reduce tenants’ month-to-month energy bills.

Slashing home energy bills is just the next chapter for the tech that brought us smartphone glass.

Miter Brands is producing windows in North Venice, Fla. in which it layers Corning’s tough glass onto windows designed to withstand hurricane-force winds. Previously, the company’s impact-resistant glass doors weighed up to 600 pounds; using Corning thin glass inside has cut the weight by up to 40%, says Dean Ruark, vice president of engineering and innovation at Miter subsidiary PGT Innovations.

Despite being lighter, these new doors can pass the most stringent hurricane testing in the country: Miami Dade’s building codes for hurricane resistance. This involves withstanding ??air pressure equivalent to a major hurricane, and a two-by-four fired from a cannon at 34 miles an hour…twice.