When it comes to building envelopes, the primary function of glass remains the same: letting natural light in and the eyes (and minds) of occupants out. But for decades now, scientists and glass experts have tinkered with the material, in attempts to add new functionality. Recently, two companies report advancements toward glass with energy-generating or low-maintenance features—both fueled by sunlight. It’s debatable, however, how soon you’ll find either offered in run-of-the-mill doors and windows.

AGC Interpane, a company that provides glass for everything from solar control and sound proofing, to interior applications, recently announced a product, dubbed Planibel Easy, that utilizes a pyrolytic coating and ultraviolet radiation to decompose dirt. The process, company officials say, requires five to seven days, after which decomposed dirt can be washed away by a rain shower. Officials for AGC Interpane say the product was developed with hard-to-reach locations in mind, such as the roofs of conservatories, or large areas that require a lot of time and effort to clean. Meanwhile, DWM’s editors have questions about the product. Most notably: How it manages to keep glass clean, amid a five- to seven-day process, in the event of continuous exposure (presumably to additional residue). Is the five- to seven-day process a sort of “primer,” after which dirt continuously breaks down and falls off? We also wonder if there are any restrictions or warnings about using standard cleaning methods or materials. By press time, we had not received answers to those questions. (Stay tuned for any future announcements via Twitter and Facebook.)

Powering Up

In the meantime, another company says it’s closing in on a quest to utilize sunlight for an entirely different purpose—one that DWM’s editors have been chasing down for more than a decade: energy generation. And while we spoke to Scottsdale, Ariz.-based SolarWindow Technologies as far back as 2014, at that time, we chose not to write about its product, because it was far from market ready. But several recent announcements lead us to believe that the company’s photovoltaic window coating is edging closer to deployment—including a recent influx of $25 million in capital. Company officials say the recent investment will enable SolarWindow to pursue the last phases of commercial development.

“Everything that we set out to do back in 2010 is now coming to the surface,” says John Conklin, president and CEO of SolarWindow Technologies, regarding the company’stransparent, photovoltaic coating that can be applied to glass in order to generate electricity. “We’ve made some major accomplishments in the technology,” he says, including by subjecting the product to a commercial glass fabricators’ autoclave, which Conklin says was a major milestone toward commercial production—proving that its coatings could withstand the extreme temperatures and pressures associated with manufacturing. “We shipped them out,” Conclin says of the test samples. “Our scientists received them, subjected them to a number of tests, and I got a phone call saying, ‘John, it works. It works fantastic! The autoclave did not destroy the technology.’” The product has also been cycled through extreme temperature cycles, in order to determine whether or not it can withstand thermal cycling in windows.

When applied to a 50-story skyscraper, the technology, officials say, is capable of meeting around half of the building’s total needs for electricity—producing a one-year return on investment, they claim. And those figures, officials for SolarWindow say, have been independently validated. The company’s coatings utilize an organic PV (OPV) array that’s composed of tiny solar cells that are small enough to keep glass transparent (a feature that other forms of PV glass have fallen short on over the years).

While Conklin says he cannot confirm when the product might be deployed, recent indications suggest that it could be sooner rather than later. And while the company is aiming for primarily commercial use, Conklin says there are implications for residential windows—especially when it comes to those with triple pane glass, he says.

“That’s really where our design objectives are in hitting the residential market—let’s keep the home as it is, but let’s increase the window square footage by coating other sides or faces to that glass,” he explains. “If you’re just coating [surface] two, you’ve got 15 square feet. If you coat [surface] two and [surface] three, guess what? You’ve got 30 square feet. If its triple-glazed and you’re doing [surfaces] two, four and five? You’ve got 45 square feet.”

According to information published by SolarWindow, an estimated 173,000 terawatts of solar energy strikes the Earth on a continual basis. Should both companies’ technologies pan out as claimed, that’s more than 10,000 times the world’s total energy use and a lot of clean windows.

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