Window to the future
Trans World Features (TWF) | 20 Apr 2014
Window to the future
MIT Technology Review named India born Sarbajit Banerjee as one of the world’s top innovators under the age of 35. SPAN writer Jason Chiang reports

Imagine a glass window intelligent enough to block heat in the summer, yet allow it to pass through in the winter. This notion of a “smart” window may soon become a reality, thanks to the breakthrough research of Sarbajit Banerjee, an associate professor at the University at Buffalo, The State University of New York. Banerjee and his research team have pioneered an innovative window coating that blocks heat when hot and allows it to enter when cold—a potentially game-changing innovation in the ongoing struggle against global climate change.
A graduate of St. Stephen’s College in New Delhi, Banerjee arrived in the United States at the age of 21 to continue his doctoral and postdoctoral studies at Stony Brook University and Columbia University in New York. Shortly after, he was recruited to the University at Buffalo in 2007 to further his work as a solid-state chemist and materials scientist. It was here that Banerjee honed his research to focus on materials that undergo phase transitions.

Banerjee refers to these materials as being “chameleon-like,” since some sort of external stimulus drives the materials to switch from one structure to another. The most common example of a phase transition is when heat causes melting ice to undergo a transition from a solid to a liquid.

After exploring phase transitions in a variety of different materials, Banerjee’s team became particularly intrigued with the compound vanadium oxide because of its unique interaction with radiated heat. Through research, Banerjee discovered that high temperatures caused the compound’s crystalline structure to change from one that is transparent to heat to one that actually reflects it. When formed as thin nanowires, the vanadium oxide could be directly applied as a coating on glass. The result: a “smart” window capable of reflecting heat at high temperatures instead of allowing it to pass through the glass. Conversely, in colder temperatures, the coating remains transparent and allows both light and heat through to warm a building’s interior.

Banerjee’s work could not have come at a better time in the ongoing fight against global climate change. According to the United States Environmental Protection Agency, Earth’s average temperature is projected to rise another 1.1 to 6.4 degrees Celsius over the next hundred years.

In hot climates around the world, billions of dollars are spent every summer on air conditioning to cool homes, factories and vehicles, while releasing hundreds of millions of tons of harmful carbon dioxide into the Earth’s atmosphere. A 2012 report published by Transparency Market Research valued the global air conditioning market at $98.2 billion, with projected growth reaching $178.4 billion by 2018. With his heat-blocking window coating, Banerjee says his ultimate goal is to “transform windows to adapt dynamically to the external ­environment instead of being static, immutable structures” that are “gluttonous” in their energy consumption.

Banerjee is currently in the process of licensing his heat-blocking window coating to industrial partners in the United States. He also has a partnership with Tata Steel in Mumbai to explore how to use the coating to deflect heat from the corrugated steel roofs in India and other parts of the developing world. As he works to make these materials commercially available, Banerjee predicts that it will cost just 50 cents per square foot—much cheaper than the expensive tinted windows that also block out natural sunlight.

The exciting progress of Banerjee’s innovative “smart” windows has not gone unnoticed by his scientific peers. In 2012, MIT Technology Review named Banerjee as one of the world’s top innovators under the age of 35. Judging from his excitement in exploring new materials, Banerjee is far from finished in his quest to make the world a cooler place.


Sarbajit Banerjee shared some of his experiences in an interview with SPAN.

What drew you to research in the United States? What were the biggest adjustments to make when you arrived?

I was attracted by the research infrastructure and the open intellectual culture of the U.S. The general qualities of U.S. academia and research environment that I’ve come to appreciate over the years include openness to new ideas, a healthy irreverence for tradition, and the tremendous opportunities provided to young people. The biggest adjustment for me, having been born in Kolkata and having gone to college in Delhi, was getting used to living in American suburbia. The cold snowy winters in New York also took a lot of getting used to.

What are some of the biggest challenges you’ve encountered along the way in your research?

The U.S. research environment, while being extremely open to new ideas, is also very competitive. The biggest challenge one faces is securing the resources—funding and equipment—to pursue new ideas. We have been fortunate to secure some federal, philanthropic and industrial support, but it is a constant struggle to ensure that there are enough resources available to fund students and to pursue new research directions.

What advice would you give to those aspiring to follow your path in materials science?

1. Ignore traditional disciplinary boundaries as much as possible—our urgent technological challenges today are across disciplines.
2. Try to talk to people from all walks of life—it never ceases to surprise me how much one can learn from a casual conversation.
3. Passion and interest can only take you places if you are willing to put in the hard work.