ARPA-E: Designing a SHIELD for single-pane windows

Photo Credit: EPA

In this four-part series, we are examining the environmental government research agency ARPA-E and how its work intersects with the interests of the commercial real estate sector. We began with a high-level look at ARPA-E as an agency before delving into three specific programs that relate to building efficiency: SHIELD, DELTA, and BEETIT. These programs coordinate a constellation of long-shot research projects related to window-pane insulation, heating and cooling localization, and HVAC efficiency, respectively.

Check out part one, America’s Green Innovation Engine; part three, Managing Buildings’ Heat DELTAsand part four, If you can’t take the heat, just BEETIT. Don’t forget to sign up for our newsletter at the bottom of this page to receive weekly updates!

Despite consistent improvements in efficiency over the past several decades, windows remain a stubborn cause of energy loss in U.S. buildings. Under the auspices of Dr. Eric Schiff, ARPA-E’s SHIELD program is working on innovative solutions for retrofitting the U.S.’s existing stock of single pane windows and that could someday make windows comparable to walls in thermal insulation, or in some cases even better.

It makes sense that the program would focus on existing single pane windows: Only a few years ago, single pane windows made up a sizeable chunk of all residential windows and more than half of commercial ones, according to Ducker research cited by the agency. In total, there were 7.6 billion square feet of single pane windows in use. While some progress has been made, windows are a long-lived component, meaning that single pane windows still make up a massive portion of the overall market.

Why is this important? Windows cost U.S. residents and businesses approximately $50 billion per year for the five quads that they waste in heating and cooling. Because single pane windows lose considerably more heat in the winter and allow in more heat in the summer, they contribute the most to this loss of energy. This means that they also represent an important opportunity for energy savings. Schiff estimates that, if his project is successful, U.S. building owners will save a collective $10 billion per year.


Running an ARPA-E Program

Dr. Schiff has worked as a professor of physics at Syracuse University since 1981, with stints as a visiting consultant and professor at Brown University, Innovalight, and the Xerox Palo Alto Research Center. Interestingly, his work has focused on solar cells and other semiconductors and not the metamaterials and nanofoams that SHIELD is primarily concerned with.

“For a long time – literally decades – I’ve been troubled by the security, economic, and environmental consequences of our enormous energy usage in the U.S.,” Schiff told Aquicore. “While looking for program ideas to propose at ARPA-E, I discovered that several percent of all energy used in the U.S. is needed to compensate for heat losses just through windows. I also realized from fairly recent research that the time might be right for developing some new, interesting, and inexpensive materials for retrofitting single pane windows.”

Currently, there are thirteen programs under Schiff’s stewardship, totally an investment of almost $28.8 million. The costliest program, an effort by Triton Systems, Inc. to produce a window glazing system that combines a nanoparticle-polymer composite film with an insulating layer of air-filled porous material, weighs in at $3,224,500. The least costly, at $859,886, is a Virginia Commonwealth University attempt to make transparent, polymer-reinforced aerogel panes that can be fixed to the outsides of windows to the same effect.

“There are very early stage projects, translating science into new technology, and we always respect that this is taxpayer supported,” said Schiff. “We provide advice where we can. Sometimes we ‘pivot’ projects into more promising directions. Sometimes a project reaches a dead end and is canceled. …. We are supporting some truly innovative research.”


Working with ARPA-E

The work that ARPA-E program directors and staff put in is all geared around enabling cutting-edge scientists to do what they do best: science.

Judging by my conversation with Dr. Massimo Bertino, a professor at Virginia Commonwealth University and the lead researcher on the second project mentioned above, they are succeeding. Bertino was animated and excited to discuss the successes and challenges involved with his work.

Bertino’s team is using freeze drying to remove water from the aerogel during the manufacturing process. There are challenges associated with applying this process, but Dr. Bertino is confident that it will help them to cut the cost of manufacturing significantly while retaining the qualities that the project demands. The other two options, ambient drying and supercritical drying, have greater downsides.

Ambient drying results in aerogel that is fractured into chunks, which destroys the transparency needed for windows. Supercritical drying allows for good transparency, but requires extremely high pressures, making it prohibitively expensive at scale. Freeze drying – a process that involves freezing the gel and allowing water vapor to sublimate off under very low pressures – may be the key to a successful manufacturing process.

Another challenge is durability.

“You poke a little bit into these things and they crumble,” said Bertino. “So what we do is we add a little bit of polymer reinforcement, and the trick is not to compromise the transparency while using the polymer. And that’s really the trick we are mastering.”

When I asked whether the product would be flexible, Dr. Bertino revealed a curiosity that becomes a scientist doing what is still essentially blue skies research.

“No, this stuff is rather rigid. I mean… can we make it flexible? Oh, maybe. Well, right now it’s rigid!”

Though he stressed that it is still at the proof-of-concept stage, the value of the project were it to become a commercial reality is clear. The aerogel that Dr. Bertino’s team is working with has a thermal resistivity of R-7 to R-10. The higher the r-value, the harder it is for heat to penetrate through the material. For contrast, the average single pane window has an r-value of about R-0.9, so window panes bolstered by a durable, low-cost aerogel could save buildings collective billions in heating and cooling costs.

“Working with ARPA-E, they have been very professional, they are very involved, they follow us, Bertino said. Laughing, he added, “sometimes, too much. But they are very supportive. … The advantage they have is, when something is promising, they can make the phone calls for me. Because of course, if the federal government calls of if I call, you get different results.”

Among other projects supported under the SHIELD umbrella are a cellulose nanocrystal film, a nanobubble thermal barrier, and a transparent nanofoam polymer. The SHIELD program began in mid-May of last year, so it’s still extremely new even by ARPA-E standards. The fruits of the projects supported under the program likely won’t find their way into commercial and residential buildings for some time, but they represent an investment in the future of building efficiency that is almost indisputably valuable.

Check out part one, America’s Green Innovation Engine; part three, Managing Buildings’ Heat DELTAsand part four, If you can’t take the heat, just BEETIT. Don’t forget to sign up for our newsletter at the bottom of this page to receive weekly updates!

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