Energy-Saving Windows A Legacy Of '70s Oil Crisis You can't see it, but it has saved the United States billions of dollars in wasted energy. It's an invisible window coating that keeps heat out in the summer and in during winter. And it got its start during the last energy crisis, three decades ago.

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Energy-Saving Windows A Legacy Of '70s Oil Crisis

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You know all those clear-glass buildings we're seeing in cities across the United States? Well, the special glass panels they use grew out of research in the 1970s. The big energy crisis back then led to a push to make buildings more efficient, and one of the biggest success stories to come out of that crisis was the technology to make better windows. It could hold lessons for today as energy research is ramped up once again. NPR's Richard Harris has the story.

RICHARD HARRIS: Chances are you've never heard of a technology called low-emissivity window coatings, but these invisible films are the reason that architects in American cities are gleefully building transparent glass towers these days, like this one in Portland, Oregon.

MONTAGNE: So we're standing outside of what will be a 22-story tower.

HARRIS: Architect Mark Perepelitsa watches as a crane gently hoists a panel of light-blue glass up the side of the building.

MONTAGNE: This is a piece right now that's going into place and is now being suspended and positioned.

HARRIS: When this building is done, it will be a shimmering tower blending into the blue of the Portland sky. Perepelitsa's colleague, Glenn Justice, helped design it. He says it's all about creating a feel of transparency into and out of the building.

MONTAGNE: For the apartments, the idea was the more view the better, and so we've got glass all the way down to the floor and up to the ceiling. And in Portland, Oregon, that means views of Mount Hood and Mount St. Helens, and just incredible vistas.

HARRIS: The building will be incredibly energy-efficient - LEED Platinum, in the argot. That's because this glass is amazingly good at keeping heat in during the winter and out during the summer. And this coated glass is not just in glitzy skyscrapers. You'll find it in half of all new windows installed these days. The remarkable story of this glass starts during the last energy crisis three decades ago at the Department of Energy's Lawrence Berkeley Laboratory. Steve Selkowitz was then, as now, working in the labs above the U.C. Berkeley campus.

MONTAGNE: So in the mid-'70s, people looked to energy use. And they said, OK, we need more oil, but at the same time, what can we do about reducing the need for it?

HARRIS: So Selkowitz and other physicists sat down for a brainstorming session to figure out how to reduce that need. They came back with a rather surprising answer. A huge amount of America's energy was literally going out the window, wasted. So while the Department of Energy was passing out billions of dollars for research to produce even more fossil fuels, Selkowitz landed a very modest grant, a few million dollars, to develop more efficient windows.

MONTAGNE: The concept actually existed. The materials existed. There were patents out there. There was some early exploratory work in Europe. What was missing was the pieces weren't put together in a way that you had a viable product that could be deployed at scale.

HARRIS: To help explain what he's talking about, Selkowitz takes us over to a tabletop demonstration with two miniature windows.

MONTAGNE: If you look at the two pieces of glass alone - I just pull them up here and hold them up to the light - you can't possibly tell the difference between these, right?

HARRIS: That's true.

MONTAGNE: They look just the same.

HARRIS: But then Selkowitz puts them in front of heat lamps.

MONTAGNE: So, because we have heat lamps in here representing the sun, I'm going to turn the sun on in a second with this knob. And I've got a little radiometer that spins around here. And the faster it spins, the more solar energy is coming through. And we have two kinds of glass here. So we can basically see, by just watching what the radiometer does, which of the two glasses is the best protection against the sun.


MONTAGNE: So here we go. And the one on the left is spinning like crazy, and that's just ordinary glass. And the one on the right is spinning very, very slowly.

HARRIS: And that's because the glass is coated with an invisible film that blocks half the light, the invisible infrared rays. Glass like this prevents a house from overheating in the summer, and it holds in heat in the winter. Simple, amazing, and nobody was using it in anything bigger than an airplane cockpit window. Selkowitz realized that the challenge for low-e glass wasn't inventing it, but breaking down the barriers that kept it from the marketplace.

MONTAGNE: The people that make the low-e glass don't sell you windows. The window manufacturers looked back at the glass guys and said, this is a coating, we can't see it, we can't touch it, we can't feel it. How do we know it works? How do you know it's the emperor's clothes problem? How do you know that something invisible really works?

HARRIS: So first, Selkowitz had to sell the idea to window manufacturers. To do that, his group made simple tools the window makers could use to prove to themselves, and their customers, that the low-e glass really worked. The lab's experts also stepped in to settle factual disputes in the industry about whose product did what.

MONTAGNE: We were the evangelists of truth of the low-e window.

HARRIS: All this gave the windows a foothold in the marketplace. And as more and more sold, they got cheaper. That, in turn, allowed states like California to write tougher, energy-efficient building codes in order to prod builders to use the windows. All in all, with just a few million dollars, the federal scientists became the midwives of this technology. True, it's not as sexy as inventing new gizmos to generate clean energy. But the end result is that it has saved consumers literally billions of dollars, according to a study by the National Academy of Sciences. Berkeley Professor Dan Kammen says one lesson here is that energy efficiency overall has given us by far the biggest bang for our 1970s energy research buck.

HARRIS: We now see that by continuing on a path to make our buildings more efficient, to make our lighting systems better, to make the heating systems better, that in fact the states that embraced that are just dramatically different than the national average.

HARRIS: Another secret of success here is that the Lawrence Berkeley group has somehow managed to keep working on the technology, even after the government abandoned most other energy research in the mid-1980s, when oil prices dropped and the energy crisis seemingly came to an end.

HARRIS: The classic example is that President Carter put solar panels on the White House, and President Reagan took them off.

HARRIS: Today, funding for clean energy research is about what it was in the 1960s, Kammen says. But the Berkeley lab is still working to develop the next generation of windows.

MONTAGNE: So we're walking up now to our 71T building.

HARRIS: Christian Kohler, who works with Steve Selkowitz, points up to an odd little structure with three enormous windows, all facing due south so they get maximum sunlight. They actually hate shade up here.

MONTAGNE: The gardener was like, why do you want us to cut the trees back? You know, this is the way we cut them. We're like, well, we want our south exposure.

HARRIS: Inside, researcher Eleanor Lee says there's still plenty of room to improve energy efficiency in windows. They are now working on windows with three layers of glass to help keep sunlight out in the summer and heat in in the winter. But, she adds, the goal is no longer the narrow one of energy conservation espoused by President Jimmy Carter back in the dark days of the last energy crisis.

MONTAGNE: Turn down the thermostat, wear a sweater, right? These days, people want energy efficiency with the amenity.

HARRIS: Features like automated shutters that not only save energy, but might appeal to design-savvy architects like the firm in Portland. Richard Harris, NPR News.

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