A team of materials scientists at the U.S. Department of Energy’s Lawrence Berkeley National Laboratory recently announced a breakthrough in smart-window technology that could have major implications on buildings’ artificial lighting and temperature-control costs.
The spray-on smart glass material offers users the ability to control not only the amount of visible light streaming through a window, but also to mitigate heat-producing near-infrared (NIR) light. The functionalities can be used independently or together, allowing the user to tailor the technology to the climate and maximize energy savings.
According to the Department of Energy’s ARPA-E, buildings swallow 40 percent of all energy used in the U.S., and typical windows can over-inflate energy bills by as much as 25 percent. The scientists behind the Berkeley Lab’s innovation say their smart windows could shrink those numbers considerably.
Here’s how the technology works:
- The coating is made of a composite material that combines two different functionalities: nanocrystals of indium tin oxide are embedded in a glassy matrix of niobium oxide. Indium tin oxide—also used to make touchscreens in iPhones and similar devices—absorbs light’s heat when electricity passes through it. Both indium oxide and niobium oxide are electrochromatic, which means they change color when a current passes through them.
- A small negative current of electricity tells the indium tin oxide nanocrystals to absorb heat; a stronger negative charge helps the niobium oxide to change color and provide some shade.
- The Berkeley Lab team published a report detailing how the technology works in the current issue of Nature.
An Oakland, California-based start-up called Heliotrope Technologies is partnering with the Berkeley Lab to bring the technology to market. Heliotrope, which is primarily focused on developing low-cost smart-window technology, is a product of the Berkeley Lab’s Molecular Foundry, and two of its co-founders—Delia Milliron and Guillermo Garcia—are also co-authors on the Nature paper describing the Berkeley Lab’s breakthrough. Last year, the Berkeley Lab was awarded $3 million from ARPA-E to develop the technology; Heliotrope was listed as a partner on that project.
Heliotrope, an LBNL Molecular Foundry spinoff company, won the top cash prize award of $50,000 at the Saint-Gobain Innovaton Competition in 2012 held at the Greenbuild International Conference in San Francisco. The company was also awarded $150,000 by the DOE in January of this year. It was seeking $750,000 in new funding as of December 2012, when it presented at the NREL Industry Growth Forum.
Heliotrope focuses on the $13.1 billion global commercial building fenestration market and lists its key competitive advantage as being improved occupant comfort, building aesthetics and energy performace at 1/5 the price. Its competitors include: SAGE Electrochromics, Soladigm, EControl-Glas, Chromogenics, Gesimat, Pleotint, RavenBrick, Kinestral Technologies, Research Frontiers, Switch Materials.
To read more about the research breakthrough in the journal Nature, click here
To read the LBNL press release, click here
To view Heliotrope’s video presentation at the Saint-Gobain Innovaton Competition (posted on Facebook), click here