City of Tempe, ASU working on creating technology to keep bus stops cool

New technology being created to keep bus stops cool

The City of Tempe, ASU and 3M are collaborating on evaluating new technologies to keep bus stops cool during the summer.

TEMPE, Ariz. - The heat in the valley can be unbearable at times, especially when waiting for public transportation.

"It's so hot. It would be nice to have some sort of shade."

"When I ride the bus and I stand by the shade."

To reduce the urban heat island effect, a team of Arizona State University researchers have collaborated with the City of Tempe and 3M to evaluate different technologies that will help keep bus shelters cooler.

"This latest technology is one that really just became possible over the last 5 years or so. Known as passive daytime radiative cooling materials so these are materials that are both very highly reflective to the suns' energy but also highly emissive of their own energies," said ASU professor David Sailor.

Sailor says six bus shelters in Tempe are being used for this experiment.

Three are controlled with conventional materials and the other three have radiative film cooling technology. All have six sensors to compare.

"Could you actually have material that was sub-ambient all hours which means it's always taking heat out of the air and pumping it out into space. And we found that this particular product got us most of the way there. It doesn't stabilize ambient every hour of the year, but the vast majority of the time is below ambient temperature."

After collecting data for eight months, the team was impressed with what they found.

"We've seen about 10 to 20 degrees Fahrenheit difference in surface temperatures between the traditional bus shelter roof and the innovative cooling film," Sailor said.

Sailor says they don't expect much of an impact across the city by modifying three bus shelters, but "the idea is to prove the technology and then to start deploying it much more broadly so it can not only go on every bus shelter rooftops, it can go on building rooftops, it can go on other artificial shade structures. It has the potential to really provide some really substantial cooling benefit."

Sailor and his team are finalizing their analysis and will be working on publishing their findings.