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Golden Scholars: UC Berkeley investigates cool roofs and how birds fly

A "chicken or the egg" question about how chicks fly and how cool roofs cut down on greenhouse gas emissions and money burned on AC.

How did birds like this guy learn to fly?
How did birds like this guy learn to fly?
Russ Isabella-US PRESSWIRE

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A mini-tour of the renovations at Lower Sproul.

In other construction news, this summer was spent touching up the esplanade at the Campanile in anticipation of its 100th birthday.

Berkeley Lab and Advanced Light Source's biggest four-year-old fan just got a sweet behind-the-scenes tour. Consider your heart warmed.

Berkeley Lab thinks they have a material to challenge the almighty graphene.

An analysis of Pacific and California water shows no sign of radiation from Fukushima.

My E45 (Properties of Materials) professor Ramamoorthy Ramesh has been named Berkeley Lab's Associate Laboratory Director at Energy Technologies.

Cal alumnus, professor emeritus of chemistry, and member of the Manhattan Project Robert E. Connick passed away at the age of 97. We send our condolences to his friends and family.

Cool roof, bro

The extent of my knowledge of architecture is the dude from 500 Days of Summer and the girl from Inception. (Such a gender binary view of the world.) But there may be new considerations for them when it comes to designing buildings: how cool are those roofs?

Berkeley Lab took a look at seven buildings in China that have the coolest roofs they could findroofs that cut down on the need for the God-send that is air conditioning and, consequently, the emissions of greenhouse gases by virtue of simply having a light color.

By reflecting more sunlight, cool roofs reduce heat flow into the building, which lowers energy consumption and power-plant emissions if the building is air-conditioned. For buildings without air conditioning, the sunlight absorbed by a dark roof heats the space below, making it less comfortable. Hot, dark roofs on any building also warm the city air, aggravating what is known as the urban heat island effect. Additionally, while nearly 80 percent of the sunlight reflected from a roof can escape to outer space, the "thermal infrared" energy radiated by a hot, dark roof is trapped by greenhouse gases, such as CO2 and water vapor, warming the atmosphere.

The monetary savings with cool roofs are increased for business buildings (vs. residential). Appealing to the bottom line is probably critical for this design strategy to gain footing with big businesses.

Annual reductions in emissions of CO2, the principal climate-warming gas released by burning fossil fuels, ranged from 1.1 to 3.4 kilograms per square meter of roof in the four warmer cities. A small office building in Guangzhou with a 1,500-square meter cool roof would save 5 metric tons of CO2 each year, about the same as taking a car off the road for the year. Annual savings in emissions of NOx and SO2, two pollutants associated with major health concerns, ranged from 2.9 to 13 grams of NOx per square meter of roof, and from 5.4 to 33 grams of SO2 per square meter of roof.

In the office building experiment in Chongqing, the researchers found that a white roof reduced air conditioning use on a summer day by 9 percent. For the factory in Foshan, which did not have air conditioning, summer measurements showed that the cool roof reduced the indoor air temperature by 1 to 3 degrees Celsius, and also reduced roof heat flow into the building by two-thirds.

One of the cons of cool roofs is that they basically cut both ways. By reflecting sunlight in the summer, they also reflect sunlight in the winter. Meaning they can end up increasing costs and gas emissions for buildings that suffer get to enjoy icy, cold winters.

And to thinkparents always try to tell you that being cool doesn't matter.

Chicken or the egg for the chicken wing?

Biologists have long wondered about the origin of flying. Did some avian ancestor start running and flapping his arms, suddenly becoming airborne? Or did it jump off a building "to save his nephew" and start wildly flailing his arms to discover fight? Well, a UC Berkeley study by Dennis Evangelista and Roberty Dudley on newborn chukar partridges believes to have solved the mystery.

[They] found that even ungainly, day-old baby birds successfully use their flapping wings to right themselves when they fall from a nest, a skill that improves with age until they become coordinated and graceful flyers.

"From day one, post-hatching, 25 percent of these birds can basically roll in midair and land on their feet when you drop them," said Dudley, who also is affiliated with the Smithsonian Tropical Research Institute in Balboa, Panama. "This suggests that even rudimentary wings can serve a very useful aerodynamic purpose."

Another dagger in the "running while flapping" theory is based on developments of flight and baby maturation. Unfortunately, the news article just kinda throws at us the fact that midair maneuverability was important in the early stages of flight development, without really explaining why. In addition, they have inferred the importance of flapping midair after observing those aerial adjustments in chicks that were merely a few days old.

The new study shows that aerial righting using uncoordinated, asymmetric wing flapping is a very early development.

Righting behavior probably evolved because "nobody wants to be upside down, and it's particularly dangerous if you're falling in midair," Dudley said. "But once animals without wings have this innate aerial righting behavior, when wings came along it became easier, quicker and more efficient."

On the other hand, you can stare at a chick while it runs on an incline and never see its wings flap.