AeroShield's clear, lightweight material, when sandwiched between two panes of glass, produces highly efficient windows.
AeroShield's clear, lightweight material, when sandwiched between two panes of glass, produces highly efficient windows. Credit: AeroShield / Courtesy

A new material developed in Massachusetts could someday help make super-efficient windows more affordable for home and business owners.

A Cambridge startup called AeroShield has developed a clear, lightweight material that, when sandwiched between two panes of glass, produces windows that are more insulating than even bulkier, more expensive options.

Early research by the company indicates that windows incorporating its material could cut residential heating and cooling costs by 20%. The first prototypes could be installed in demonstration projects by the end of 2022, and products could hit the wider market in 2023 or 2024.

“We’re really excited by a change we could start in the industry by enabling some better designs and some better products,” said co-founder Elise Strobach.

As the country grapples with the urgent need to lower greenhouse gas emissions, the energy consumption of buildings is a key problem to solve. Fossil fuel combustion in buildings accounted for about 29% of greenhouse gas emissions in the United States in 2018, according to a report from the Center for Climate and Energy Solutions, a Virginia-based climate and clean energy nonprofit.

Lowering these emissions will require switching from fossil fuels to electricity wherever possible, generating cleaner electricity on the grid, and reducing overall power usage. And a key strategy for decreasing energy consumption is to create extremely tight building envelopes.

Windows, however, have always posed a challenge to achieving high levels of efficiency: Heat lost or gained through windows is responsible for up to 30% of the energy used to heat or cool a home, the federal Department of Energy estimates.

The vast majority of windows sold in the United States are double-glazed, meaning they are constructed of two panes of glass with a thin space between them filled with air or another gas. These windows are highly efficient, but there is general consensus that windows will need to perform even better to meet climate and energy goals. Triple-glazed windows are an energy-saving step up but significantly bulkier and more expensive than the standard double-glazed window.

Researchers have been attempting to develop even more efficient windows in several ways, said Stephen Selkowitz, a building materials scientist who spent 40 years working at Lawrence Berkeley National Laboratory in California. Some are trying various combinations of gas between panes and thin coatings on the glass. Others are trying to remove all the air from between panes, creating an insulating vacuum in the middle of the window.

Strobach expects AeroShield will allow double-glazed windows to be more insulating than triple-glazed, but with a lighter weight and a lower price. AeroShield windows might also be more resilient than vacuum-sealed windows, which would lose most of their thermal impact if even a small crack in a pane broke the vacuum.

“It’s not too much to say that they are basically revolutionizing window technology — if you can make this product commercial-ready, you can really change the game,” said Emily Reichert, chief executive of Greentown Labs, a technology incubator where AeroShield has done much of its work.

Getting the glass right

AeroShield began with research Strobach conducted for her doctorate work at the Massachusetts Institute of Technology, searching for ways to better insulate solar panels so they would generate power more efficiently. She looked to silica aerogel which, despite what its name suggests, is not sticky or oozy. It is a very light, highly porous solid glass that is such a good insulator that NASA has used it to protect critical equipment.

First invented in 1931, aerogels are not a new technology. However, silica aerogel has always been a cloudy, pale blue color, too opaque to let sufficient sunlight pass through to solar panels. Strobach’s goal was to figure out how to make the material transparent.

“It’s one of the most insulating materials in the world,” Strobach said. “But it had never been clear.”

Her research succeeded even beyond her original goal. The material she created not only let adequate sunlight pass, but it was also clear enough to see through. Essentially, she explained, her team made nanoparticles of glass and the pores between them smaller than the wavelength of visible light, so, in the final material, the light doesn't interact with the material.

The effect of the extremely tiny particles and pores, she explained, is similar to walking through rain: Small raindrops with ample space between them provide essentially no resistance to the moving body.

This unexpected level of transparency got Strobach and her fellow researchers thinking about other possible applications for her aerogel. That’s when they had the idea of sandwiching it inside double-paned windows to super-charge their insulating qualities.

Strobach switched the focus of her doctoral work to optimize the aerogel for windows and began to think about the logistics of manufacturing and selling the material. As she talked to people in the window industry, she realized she was on to something.

“The industry was very open to sharing the problems that they’d faced,” she said. “Not only is this a problem we could solve, but it’s a really tough problem to solve without us.”

Strobach and business partner Kyle Wilke launched AeroShield at the end of 2019, shortly before Strobach completed her Ph.D. in early 2020. The company immediately attracted the attention of the Massachusetts Clean Energy Center, a quasi-public agency that helps fund and support clean energy businesses in the state. Since 2019, the clean energy center has awarded the company more than $400,000 in grants to support the development of prototypes, to help it stay afloat during the pandemic-induced economic downturn, and to start scaling up its manufacturing process.

“She is coming out with top-tier science,” said Ariel Horowitz, senior program director at the clean energy center. “[Windows] wouldn’t necessarily strike you as a sexy application, but it is so impactful — so needed.”

Going to market

In 2020, AeroShield joined the incubator space at Greentown Labs, received a $256,000 National Science Foundation grant, and was selected for an Activate fellowship, which helps support technology entrepreneurs as they turn their research into businesses. Most recently, the company was selected to participate in the Healthy Buildings Challenge, a program to nurture businesses that aim to create more comfortable and environmentally friendly buildings. The funding from the challenge will help Aeroshield plan its production launch.

“They’re commercializing a lot faster than we would have expected for a manufactured building material,” Horowitz said.

Still, hurdles remain before AeroShield can make it to market.

Regularly producing sheets of the aerogel — which is very fragile — in the sizes necessary for windows has been an early challenge. However, the company has recently developed a process for successfully producing intact sheets of its material that are 20 inches by 14 inches, an industry-standard window size.

The next step is to work with industry partners to put these sheets in actual windows and do rigorous testing to validate the durability and thermal qualities of the material, Strobach said.

She expects AeroShield to end up working with the manufacturers who make the glass panes for windows, rather than the companies that build the full windows, including sash and frame. Her reasons are both practical and environmental.

“The first partner we need is the person making insulated glass,” she said. “The most energy-efficient way to make things better seems like it’s to use the knowledge and the equipment we’ve got.”

The market for highly efficient windows, however, could be tricky, said Rick Dunn, product manager of emerging technologies for the Northwest Energy Efficiency Alliance.

Often, when presented with new energy-saving technologies, manufacturers can be reluctant to devote too much money and equipment to a product without a proven level of demand. By producing only a small amount of a new product, however, they keep prices high, which lowers demand. Breaking that cycle is a challenge for any new entrant offering energy-efficient building materials, Dunn said.

Eventually, though, outside forces will help drive demand, he noted. Building codes in many places are slowly starting to call for greater energy efficiency, and the federal EnergyStar program is in the process of raising its performance standards for insulating windows.

For now, AeroShield will be focusing on getting to market with windows for residential buildings, but Strobach envisions a future in which the material will be standard for windows of all types.

“I think AeroShield hopes one day to be a part of all new windows,” she said. “When we talk about our energy technology, we do see it as the piece of a bigger puzzle.”

Sarah is a longtime journalist who covers business, technology, sustainability, and the places they all meet. She has covered the workings of small-town government in New Hampshire, the doings of alleged swindlers and con men, and the minutiae of local food systems. Her work has appeared in the Guardian, the Boston Globe,, Slate, and other publications. Based in Gloucester, Sarah covers New England.