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

An energy-efficient, 22-story glass tower is currently under construction in downtown Portland, Ore. The building was designed by Zimmer, Gunsul, Frasca Architects in Portland.

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Workers install a low-emissivity glass panel. This glass has a special coating that helps reduce energy waste and has enabled architects across the country to use more glass and still meet energy codes.

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Steve Selkowitz examines the shutters at the window lab at the Department of Energy's Lawrence Berkeley National Laboratory in Berkeley, Calif. Researchers here are working on the next generation of energy-efficient windows.

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You may have noticed that clear-glass buildings are springing up in cities across the United States. The reason dates back to some 1970s-era research designed to make windows more energy-efficient.

In fact, this line of research turns out to be one of the biggest success stories to come out of the last energy crisis — and there are lessons to be learned, as America once again ramps up its energy research.

Glass Towers

The technology is called low-emissivity window coatings, and these invisible films are the reason that architects in American cities are gleefully building those transparent glass towers.

One example is on a downtown street in Portland, Ore. When the 22-story building is finished, it will be a shimmering tower, blending into the blue of the Portland sky.

Architect Glenn Justice, who helped design the tower, says it's all about creating a feel of transparency, into and out of the building.

"For the apartments, the idea was the more view the better, 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," Justice says.

The building will also be incredibly energy efficient — LEED Platinum, the industry's term for the highest level of energy efficiency. That's because the 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 towers: You'll find it in half of all new windows installed these days.

Energy Out The Window

The remarkable story of this glass starts during the last energy crisis, three decades ago, at the Department of Energy's Lawrence Berkeley National Laboratory. Steve Selkowitz was then, as now, working in the labs above the University of California's Berkeley campus.

"In the mid-'70s, people looked at energy use and said, 'OK, we need more oil, but at the same time, what can we do to reduce the need for it?'" Selkowitz says.

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. So while the Department of Energy was passing out billions of dollars for researchers to produce more fossil fuels, Selkowitz landed a very modest grant, a few million dollars, to develop more efficient windows.

"The concept actually existed, the materials existed, the patents were out there, but the pieces weren't put together in a way where you had a viable product that could be deployed at scale," Selkowitz says.

To help explain what he's talking about, Selkowitz uses a tabletop demonstration with two miniature windows. The windows look exactly the same, but one of them is coated with an invisible film that helps block infrared rays. Selkowitz puts them in front of two heat lamps and places radiometers on the other side of each window. Heat will cause these radiometers to spin. When Selkowitz turns on the heat lamps, one of the radiometers spins like crazy, while the other spins very slowly — the one beside the window with the low-emissivity coating.

Glass like this prevents a house from overheating in the summer and it holds in heat during the winter. Simple, amazing, but nobody was using it in anything bigger than an airplane cockpit window.

From The Lab To The Marketplace

Selkowitz realized that the challenge for low-emissivity, or "low-e," glass wasn't inventing it, but breaking down the barriers that kept it from the marketplace.

"The people that made the low-e glass didn't sell you windows. The window manufacturers looked back at the glass guys and said, 'This is a coating, you can't see it, you can't feel it. How do we know it works?' It's the emperor's clothes problem. How do you know something invisible really works?" Selkowitz says.

So Selkowitz had to sell the idea to the window manufacturers. To do that, the scientists made simple tools so window-makers could actually prove to themselves, and their customers, the low-e glass really worked. And the lab's experts also stepped in to settle factual disputes in the industry about whose product did what. Selkowitz calls himself and his team "the evangelists of truth of the low-e window."

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, to prod builders to use the windows.

Biggest Bang For The Buck

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.

"We now see that by continuing on a path to make our buildings more efficient, to make our lighting systems better, and to make our heating systems better, that in fact the states that embraced that are dramatically better than the national average," Kammen says.

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.

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

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. They're now working on windows with three layers of glass, to help keep sunlight out in the summer and heat in during the winter.

Energy conservation has come a long way since the dark days of the last energy crisis. Then, the advice from President Jimmy Carter was "turn down the thermostat and wear a sweater." Now, consumers want more than just energy efficiency — they want amenities, too, such as automated shutters that not only save energy, but might appeal to architects like the firm in Portland.

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