NEWARK, Del. – On a warm fall day in 2008, Annette Shine sat in a classroom teaching a course.

Her group of University of Delaware chemical engineering students struggled to learn the difficult material in a sweaty, 86-degree room.

The building’s ventilation system had been switched over to heat for the winter, so forget about air conditioning. Shine opened a window, but construction nearby made too much noise. So she and her students treated it as an engineering problem, and eventually, they came up with a solution.

Grow a garden on the roof.

This fall, people looking over a one-story wing jutting out from the south side of Colburn Laboratory will see an array of colorful plants covering the flat tar roof.

Recent temperature readings on the roof have revealed a greater benefit. Aside from cooling Colburn, the plants cause the peak temperature on the roof to occur later in the day. Instead of the high heat of the day radiating into the rooms around 1:30 p.m., it will be delayed until 3:30 or 4 p.m. in places where the dirt is 4 inches deep and around 6:30 p.m. where it’s 8 inches thick.

“That could be very useful to us because we don’t have that many classes at that time of night,” Shine said.

Shine, her engineering students and an assistant professor of landscape design, Chad Nelson, worked on the green roof, UD’s first.

The process required a structural engineering study to ensure the roof wouldn’t collapse under the weight of the garden, and facilities personnel wanted assurances that the plants would not become a maintenance hassle.

After some study, Nelson chose durable plants that grow year-round and require little attention beyond some occasional weeding. The plants, a natural heat shield, absorb and deflect the sun’s rays. On a hot day, Shine and her students predict, the plants will lower the temperature inside by 5 or 6 degrees.

Nelson hopes the visibility of the Colburn Lab project will inspire more greening elsewhere in the university.

“We wanted the first one to be in a visible place to kind of market it to the rest of campus,” Nelson said.