Bassist and scholar George Ban-Weiss
His willingness to push boundaries has made him a much in-demand musician. Ban-Weiss has appeared on dozens of albums, toured and played with scores of bands with different sounds and styles.
“Improvised music has shown me the value of letting go, pushing creative frontiers, and not worrying about possibly failing in the end,” Ban-Weiss said. “In my mind, the best results come from being willing to take risks and not being hampered by one’s own comfort zone.”
A Can-Do Spirit
He has taken that same can-do spirit to academia. The assistant professor at USC Viterbi's Sonny Astani Department of Civil and Environmental Engineering tackles major research projects with policy implications such as climate change and urban air quality. The 33-year-old has already made an indelible impression. In August, “MIT Technology Review” selected Ban-Weiss as one of the world’s "35 top innovators under the age of 35."
“It’s quite a distinction to be on a list of recipients with people like [Facebook’s] Mark Zuckerberg and [Google’s] Larry Page and Sergey Brin,” he said. “These are people who have transformed people’s everyday lives.”
Ban-Weiss has much to feel happy about these days. He has undertaken groundbreaking research on how dark and other non-reflecting residential roofs contribute to “urban heat islands,” a phenomenon in which cities are several degrees warmer than surrounding areas. His research on roofs, which began four years ago at the Lawrence Berkeley Lab, also appears to have influenced local policymakers.
Scientists have long known that dark roofs absorb lots of heat, transfer it to homes and heat them up, leading to blasting ACs and wasted energy. For people without air conditioners, especially the elderly, scorching days can pose health risks. Dark roofs also transfer heat to the air above, making it warmer and in some cases exacerbating air pollutants like ground-level ozone.
Until now, there was no good way to measure the solar heat absorbing properties of roofs at the city scale, Ban-Weiss said. Researchers could potentially go building-to-building with special instrumentation, a time-consuming process that would require permissions from building owners, who aren’t always forthcoming. Or they could rely on “coarse” satellite imagery that measured too large of an area to distinguish roofs from other urban surfaces.
A Better Way
Ban-Weiss thought there had to be a better way.
After a lengthy search, he found highly detailed aerial imagery taken by a subcontractor of the U.S. Department of Agriculture. That same company, he later learned, had employed a special sensor that could measure light intensity at four different wavelengths, similar to sensors found on satellites. While the data was originally acquired for other purposes (and at a high cost), Ban-Weiss developed methods to convert that information into solar reflectance data, which is the fraction of sunlight that is reflected away from the roof.
Ban-Weiss leveraged that knowledge to create a map of Los Angeles that showed all roofs, along with their sunlight absorption properties. The imagery revealed that roofs cover about 20 percent of the city. And the majority of those roofs were very absorptive and inefficient.
Armed with his large map of LA’s rooftops, Ban-Weiss made a presentation about his work at a spring 2013 conference, organized by the advocacy group Climate Resolve, on ways to improve the city’s climate resilience. He told the assembled that replacing dark roofs with lighter or reflective ones could cut air conditioning usage by 10 percent to 20 percent and position the city to better deal with climate change. Then-Mayor Antonio Villaraigosa gave the opening remarks at the event.
“The maps that I created made it very clear that the current state of residential roofs in Los Angeles is very inefficient and that there’s room for a lot of improvement,” he said.
Through his staff, Villaraigosa was already aware of Ban-Weiss’ research, said Craig Tranby, environmental supervisor at the Los Angeles Department of Water and Power. A few months after the conference, the Los Angeles City Council passed an ordinance, signed in January by Mayor Eric Garcetti, mandating that roofs on new homes have light roofs or ones that reflect in the near-infrared part of the spectrum so that they maintain their dark appearance without absorbing heat.
“George definitely played a role in all this,” Tranby said.
Later this year, Ban-Weiss plans to publish a research paper that takes an in-depth look at roofs throughout California. Although most cities regulate roofs on commercial buildings, most regions do not control residential roofs, Ban-Weiss said. He hopes his research findings might encourage other cities in the state to follow Los Angeles’ lead in regulating them to make them cooler. LA is the first major city in the nation to pass legislation on residential roofs.
“It’s fulfilling to know that the research I’m doing could have an impact on actual policy and help result in reductions in air conditioning energy use and heat in cities,” Ban Weiss said. He is currently researching ways to mitigate dark pavements’ impact on city warming.
Ban-Weiss has long brought creativity to understanding complex environmental issues. As a Ph.D. student at UC Berkeley, he studied particulate matter emissions from combustion sources, which are harmful to human health and impact global climate. As part of that research, Ban-Weiss wanted to measure how emissions from diesel trucks varied. Until then, nobody had solid data about which trucks were responsible for the most pollution.
To answer that question, he set up instruments in the exhaust ducts of a traffic tunnel to measure black carbon emissions from individual trucks. Black carbon is thought to be the second most important cause of global warming after carbon dioxide and is a human carcinogen. As he would later do with residential rooftops, Ban-Weiss came up with a policy-relevant and nuanced way to present the data.
His findings: the 10 percent highest emitting “dirty trucks” were responsible for about 40 percent of black carbon emissions, suggesting that policy should require retrofitting these high emitters and not solely focus on emissions from new trucks. The California Air Resources Board is now phasing in policy requiring the retrofitting of older trucks.
“George’s role was key in initiating this very productive line of research in my group, which two subsequent generations of Ph.D. students have continued to use,” said Robert Harley, Ban-Weiss’ Ph.D. advisor and the C.W. Johnson Professor of Civil and Environmental Engineering at UC Berkeley.
Ban-Weiss joined the USC faculty in August 2013. He said he has found his colleagues “extremely supportive, collaborative, friendly, and excellent partners for research.” He also feels excited to join a department that he said is rapidly growing.
Fear of Flying
Growing up in Davis, Calif., Ban-Weiss exhibited the same fearless streak that would later make him a rising star in academia. As a young child, watching 747s take off fascinated him and sparked an interest in engineering. However, airplanes also terrified him because of his fear of flying. No matter. Ban-Weiss not only overcame his phobia, he has logged hundreds of flight hours after receiving his pilot’s license at age 17.
“I wouldn’t call myself fearless. I’m afraid of a lot of things,” he said. “But when I get a bee in my bonnet, I go for it 100 percent until I really make it happen.”