These high-tech windows fight climate change – and will save you money

When the founders of LuxWall look through a window, they see money.

Windows offer sometimes-stunning views and natural light, but they also create a structural vulnerability that lets heat escape in winter and sneak in during summertime. Poorly insulated windows means having to consume more energy to maintain a comfortable environment. This raises utility bills and leads to the combustion of more fossil fuels, contributing significantly to carbon emissions worldwide.

Michigan-based startup LuxWall tackles this underappreciated climate challenge by fabricating vacuum-insulated glass, which it says insulates five times better than double-paned glass. The Enthermal product line holds energy about as well as fiberglass wall insulation, while providing all the aesthetic benefits of a normal window. Furthermore, the slim profile means building owners can swap out leaky old single pane windows for LuxWall without major overhauls to their window frames.

“All the single-pane windows need major work to tear out and replace with double-pane; ours can fit in the old frame,” said LuxWall board member Matt Eggers, who co-led the company’s seed round at Breakthrough Energy Ventures (BEV) and now serves as managing director at Prelude Ventures.

LuxWall opened its first commercial factory this summer in Litchfield, Michigan, with a high-profile ceremony attended by Gov. Gretchen Whitmer herself. On October 31, the company followed up with a Series B fundraise, adding another $51 million to its coffers. Climate Investment and Barclays Sustainable Impact Capital led the round, joined by earlier investors like BEV, Prelude, and Khosla Ventures.

And since LuxWall is manufacturing its product in America, it was also able to claim a $31.7 million grant from a division of the Department of Energy intended to bolster domestic supply chains. That grant will support construction of a new factory in Detroit, while the Series B pays for expanded production at the existing facility in Litchfield, about 100 miles west of Motor City.

“The orders are there,” CEO Scott Thomsen told Canary Media last week. ​“Every week we ship more.”

From the window, to the (thermal efficiency of) the wall

At a time when climate-oriented venture capitalists are throwing money after fantastical nuclear fusion contraptions and machines to siphon invisible carbon gas from the atmosphere, windows don’t typically register as a sexy cleantech breakthrough.

Nevertheless, they have a crucial role to play in decarbonizing the built environment.

“Windows are quite often the weakest link in the building envelope, particularly in climates that have significant temperature swings throughout the year,” said Panama Bartholomy, executive director of the nonprofit Building Decarbonization Coalition.

Leaky windows create cascading problems for people who wish to ditch their fossil fueled furnaces for electric heat pumps, a key step in the ​“electrify everything” strategy for decarbonization. ​“You end up paying a lot more for a larger system, because you have to pump a lot more energy for heating or cooling… and then your bills go up as well,” Bartholomy explained.

It’s bad enough if a particular household or business finds itself paying more to electrify operations. But the problem compounds further when multiplied across cities and states: Utilities have to build more clean power plants and wires to transmit the additional electricity needed to heat and cool those leaky buildings without fossil fuels. Utilities pass on those costs to customers, so society at large ultimately pays to build that extra capacity, or risks losing power amid record heat waves or cold snaps.

In short, the arduous task of electrifying America’s building stock gets considerably easier if we can neutralize the energy wasted by lousy windows. That’s where LuxWall comes in: The company sandwiches a vacuum between two thin layers of glass. That airless gap blocks a lot of heat transfer, as well as sound (in space, no one can hear you scream). That’s not to say that Thomsen is the one who invented this vacuum sandwich.

“The concept has been around for fifty years — the problem is how do you produce it,” Thomsen told me.

He decided to attempt a sturdy, cost-competitive vacuum window after a career in materials science at places like Honeywell Aerospace, and most recently at glass industry giant Guardian, where he served as chief technology officer and later as president of the Global Glass Group. Thomsen took inspiration from advances in legacy glass fabrication, as well as from low-temperature materials used in OLED televisions, and the highly automated glass printing operations pioneered by thin-film solar companies like First Solar.

Thomsen declined to fully divulge his special sauce, but it includes the materials to hermetically seal the vacuum between the two panes of glass, designs to ensure the panes don’t collapse in on the vacuum (which would ruin their insulation abilities), and the manufacturing techniques to pump those designs out at high speed with lots of robots. 

The result, Thomsen noted, is something that’s not as complicated or capital-intensive to manufacture as semiconductors or batteries, but which has ​“enough complexity to make it hard.” The technological challenge seems to have deterred pretty much anyone else from spinning up rival factories for this kind of product, even as Thomsen’s team beat their own expectations for improving the glass’s performance.

Single pane glass nets an insulation rating of around R1 — the cruddy end of the scale. That’s the kind of window that you might wake up to find coated in ice on the inside of your Iowa farmhouse, something that Eggers recalls from his childhood. Paying extra for double-pane might get you to R2 or R3. Triple pane pushes the rating higher, at great cost, while requiring structural redesigns to account for its extra thickness.

LuxWall launched in 2019 and within two and a half years was hitting R13 for its new windows, Eggers said. Since then, the company has achieved R18. That so wildly outperforms the efficiency of standard window offerings that the energy bill savings offset the upfront cost of the upgrade in two to seven years, depending on the building, per the company. New construction can pair the hyper-efficient glass with smaller HVAC units to save even more money.

“We sell on the financial payback to the property owner,” Thomsen said. ​“Our product does cost more [than double pane], but we’re delivering much more.”

Made in Michigan

LuxWall graduated from R&D to full-scale manufacturing at an auspicious time.

Leaders in Washington, D.C., embraced industrial policy after decades of dedication to free market principles that shipped factory jobs overseas. The Biden Administration prioritized clean energy manufacturing as a strategic sector for reshoring, using the Department of Energy to vet promising climate solutions and support their domestic production with loans and grants.

Michigan has emerged as a leading winner of the cleantech factory boom, which Gov. Whitmer has championed as a vehicle for the state’s economic growth; LuxWall, for instance, received $6 million in state grants to open its first factory, prior to the larger federal grant. But much of Michigan’s proposed factory buildout remains years away from completion — billion-dollar battery factories take a while to spin up and staff.

In the meantime, LuxWall delivered an early win that proves out the causal chain from federal climate policy to state-level support to construction and putting people to work on the line. It also diversifies Michigan’s cleantech sector beyond automobiles, where the Big Three automakers have been stepping back from earlier promises for a swift ramp-up in electric vehicle production.

Of course, opening a factory only accomplishes so much — the company needs to stay in business in order to deliver lasting economic vitality to the surrounding community. The recent funding ensures greater staying power for LuxWall, and means it can get cranking on the new factory in Detroit’s Delray, a historic industrial district hit hard by factory closures, where city leaders have looked for new sources of economic development.

So far, LuxWall has shipped primarily to the commercial retrofit market, Eggers said. These customers employ professional energy managers, who can calculate the savings to be had from upgrading leaky old glass. But the residential new construction market has shown stronger-than-expected demand, he added.

That early uptake could hint at pent-up demand for better window technologies. Bartholomy, the building decarbonization advocate, noted that the energy-efficient window market hasn’t undergone the kind of wholesale transformation that heat pumps have in the last six years. Heat pump product options, performance, and adoption have all experienced tremendous growth, such that heat pump sales outpaced sales for fossil fueled furnaces in the U.S. for the last two years.

“Windows have been pretty standard for a long time,” Bartholomy said. ​“The type of work LuxWall is doing is really needed innovation to deal with issues around affordability, comfort, and safety.”

If LuxWall can bite off even a sliver of U.S. window sales, it could end up serving a far larger market than the more familiar home cleantech offerings do. Buildings that can’t host solar on the roof or batteries in the garage still have windows. And even those customers who can go solar would benefit from slashing their home heating and cooling needs.