CNN Article features CEE Professor Elie Bou-Zeid

March 13, 2024

Summers are becoming increasingly dangerous, especially in cities where the warming effects of tall buildings, concrete and asphalt send temperatures soaring. But there might be a simple, potentially inexpensive way to put a chill on urban heat: retroreflectors.

A study published Monday in the journal Nature Cities found when retroreflective material was installed on buildings, it decreased the surface temperature of those buildings by up to 36 degrees Fahrenheit, and air temperatures by nearly 5 degrees.

Reducing building temperature is “very, very important” for pedestrians at street level, said Elie Bou-Zeid, co-author of the study and professor of civil and environmental engineering at Princeton University, “because those walls radiate a lot of heat on you.”

Cooling those surfaces by 36 degrees “will make you feel significantly more comfortable,” he said. “It’s almost like being in the shade.”

Cities are significantly warmer than their surrounding suburbs and rural areas because of the way they are built. Tall buildings, dark roofs, asphalt and concrete absorb the sun’s rays and reflect its energy back into the environment as heat – the so-called urban heat island effect.

You can finish reading this article, written by Rachel Ramirez of CNN, at…