A type of beetle that can regulate its body temperature in some of the hottest places on Earth inspired a new cooling material that doesn’t need energy, researchers say.

The work could have major implications for cooling everything from buildings to electronic devices in an environmentally friendly manner.

“Anywhere that needs cooling, this can help.”

New information about a species of longicorn beetle that can cool its body enough to survive in volcanic areas in Southeast Asia led to researchers to create a photonic film based on the beetle’s wing structure. They used common, flexible materials that are mechanically strong and can be manufactured on a large scale.

The film passively cools, meaning it doesn’t take up energy like the systems we use to keep temperatures down in our cars and buildings.

The findings appear in the journal Proceedings of the National Academy of Sciences.

“Anywhere that needs cooling, this can help,” says Yuebing Zheng, an associate professor in the mechanical engineering department at the University of Texas at Austin. “Refrigerators, air conditioners, and other methods consume large amounts of energy, but this is cooling by itself.”

The team found that its film reduced temperatures of items in direct sunlight by as much as 5.1 degrees Celsius, more than 9 degrees Fahrenheit.

Lots of uses for the cooling material

The film, which would work as a coating on top of objects, could have a wide array of uses. It could be put on top of windows in office and apartment buildings to reflect sunlight and keep energy bills down. It could protect solar panels from being degraded by constant sunlight exposure. It could be wrapped around cars to keep them cool while parked. And it could be a key ingredient in novel cooling fabrics, wearables, and personal electronics.

The US Energy Information Administration projects a significant jump in air conditioning consumption by 2050—a 59% growth in the residential sector and a 17% increase in commercial use. As the need for more cooling rises, so does the necessity for a new solution that doesn’t consume mass amounts of energy or put a strain on the environment.

The cooling prowess of the beetle was previously known, but what made it so effective at regulating its temperature remained a mystery. The team found that the triangular “fluffs” on its wings play an important role, reflecting sunlight while helping shed internal body heat at the same time.

Longicorn beetles, also known as longhorn beetles, stand out because of their long antennae, sometimes three times the length of the rest of their bodies. There are more than 26,000 species of longicorn beetles.

This research focuses on a specific species of the beetle, Neocerambyx Gigas. It can survive in scorching hot climates near active volcanoes in Thailand and Indonesia, where summer temperatures frequently top 40 degrees Celsius (105 degrees Fahrenheit), and the ground heats up to 70 C (158 F). When it gets hot, the beetles remain still and stop foraging to avoid taking on any excess heat from movement.

Avoiding manufacturing problems

The film the team created is made of PDMS, a flexible, widely used polymer, along with some high throughput ceramic particles.

Because of the common materials used and the simple process for manufacturing the film, known as micro-stamping, Zheng believes the project will succeed where some other research seeking to replicate biological effects has failed.

“A lot of time, mimicking the biology doesn’t work at a larger scale because of high costs and stringent manufacturing requirements,” Zheng says.

Going forward, the research team is working to further optimize the manufacturing process for large-scale production. They will also seek commercialization opportunities in several areas, including energy-efficient buildings, water cooling systems, thermal fabrics, desert dew water harvesting devices, and supplemental cooling systems for power plants.

Additional researchers from UT Austin, Shanghai Jiao Tong University in China, and KTH Royal Institute of Technology in Sweden contributed to the work.

Source: UT Austin

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A new system monitors people’s faces to maintain the temperature of indoor spaces.

Heating and cooling are the largest consumer of energy in American homes and commercial buildings. There’s a need for smarter, more flexible climate control that keeps us comfortable without heating and cooling entire empty buildings.

Researchers at the University of Michigan have developed a solution that could do away with the wall-mounted thermostats we’re accustomed to. They describe Human Embodied Autonomous Thermostat, or “HEAT,” in a study in the journal Building and Environment.

The system pairs thermal cameras with three-dimensional video cameras to measure whether occupants are hot or cold by tracking their facial temperature. It then feeds the temperature data to a predictive model, which compares it with information about occupants’ thermal preferences.

Finally, the system determines the temperature that will keep the largest number of occupants comfortable with minimum energy expenditure. The new study shows how the system can effectively and efficiently maintain the comfort of 10 occupants in a lab setting.

“COVID presents a variety of new climate control challenges, as buildings are occupied less consistently and people struggle to stay comfortable while wearing masks and other protective gear,” says project principal investigator and study coauthor Carol Menassa, associate professor of civil and environmental engineering.

“HEAT could provide an unobtrusive way to maximize comfort while using less energy. The key innovation here is that we’re able to measure comfort without requiring users to wear any detection devices and without the need for a separate camera for each occupant.”

HEAT works a bit like today’s internet-enabled learning thermostats. When it’s newly installed, occupants teach the system about their preferences by periodically giving it feedback from their smartphones on a three-point scale: “too hot,” “too cold,” or “comfortable.” After a few days, HEAT learns their preferences and operates independently.

The research team is working with power company Southern Power to begin testing HEAT in its Alabama offices, where test cameras will be mounted on tripods in the corners of rooms. Menassa explains that cameras would be less obtrusive in a permanent installation. The cameras collect temperature data without identifying individuals, and all footage deletes immediately after processing, usually within a few seconds.

A second test, also with Southern Power, will place the system in an Alabama community of newly constructed smart homes. The team estimates that they could have a residential system on the market within the next five years.

Facial temperature is a good predictor of comfort, Menassa says. When we’re too hot, the blood vessels expand to radiate additional heat, raising facial temperature; when we’re too cold, they constrict, cooling the face. While earlier iterations of the system also used body temperature to predict comfort, they required users to wear wristbands that measured body temperature directly, and to provide frequent feedback about their comfort level.

“The cameras we’re using are common and inexpensive, and the model works very well in a residential context,” says study coauthor Vineet Kamat, professor of civil and environmental engineering, and electrical engineering and computer science. “Internet-enabled thermostats that detect you and learn from you have sort of built a platform for the next phase, where there’s no visible thermostat at all.”

Coauthor Eunshin Byon, an associate professor of industrial operations and engineering, built HEAT’s predictive model. She believes that tweaks to the model could make the system useful in applications beyond homes and offices—in hospitals, for example, where care providers struggle to stay comfortable under masks and other protective equipment.

“The COVID-19 pandemic requires nurses and other hospital workers to wear a lot of protective gear, and they’ve struggled to stay comfortable in the fast-faced hospital environment,” Byon says. “The HEAT system could be adapted to help them stay comfortable by adjusting room temperature or even by signaling to them when they need to take a break.”

In partnership with the school of nursing, Menassa’s research group has already conducted a pilot study that explored how the system can provide personalized thermal comfort for nurses working in healthcare environments such as chemotherapy administration units.

HEAT is available as a licensable technology through the university’s Office of Technology Transfer.

The National Science Foundation supported the research. The team has filed patent applications related to the technology.

Source: University of Michigan

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