Green Roof - A Thing of the Future ... and the Present

Iowa State University has a total of five green roofs on top of campus buildings - more than any other state university in Iowa.

Green roofs were developed for buildings with flat rooftops that can be partially or completely covered with some sort of vegetation.

While the cost of implementing a green roof may be expensive, the advantages offset the disadvantages. Not only do green roofs absorb rainwater and reduce water runoff, they provide insulation to the building, reduce noise and add to the overall appearance of a building or structure.

CALS students helped to implement a new green roof on top of the Memorial Union during the spring of 2012. More than 50 students and volunteers helped with the project, including the horticulture student who came up with the idea, Miles Thompson.

The 855-square-foot roof was installed primarily for its aesthetic value because it is in a highly visible location. But before the horticulture students could actually start planting, the original roof needed to be re-roofed and flood tested for precautionary measures.

The roof consists of a variety of sedums, which are a winter-hardy, perennial plant. Roof Top Sedums, LLC, a regional grower and distributor in Davenport, Iowa, grew the plants installed on the green roof. The founders of the company are ISU alumni, with degrees in horticulture and landscape architecture. Along with Roof Top Sedums, Central States Roofing of Ames oversaw the installation by student volunteers.

Placed on the second story on the east side of the Memorial Union, the green roof can be viewed from the Multicultural Center hallway. A television is mounted at the end of this hallway with a slideshow of horticulture students planting the green roof and showing the incredible amount of work they put in.

How's the Memorial Union green roof doing? Its implementation has reduced temperature fluctuation inside that part of the building, as well as deadening the sound from that area. The location also is partially shaded, so the plants don't bake in the summer heat.

The Horticulture Club has volunteered to do maintenance during the school year. Campus Services takes over maintenance during the summers. Maintenance is kept simple with inspections done monthly for weeds and pests. Watering isn't as essential because the roofs are designed to effectively absorb rainwater. Kerry Dixon-Fox, the project manager, said, "It has improved the quality of the water running off the roof during rain events because it does filter out particulates - it would be nice to do more of the flat roofs, but funding is an issue at this time. I'm very happy with the condition of the roof right now - it looks great!"

Other ISU buildings that occupy a green roof include the College of Design's King Pavilion, State Gym, Horticulture Hall and the Bissell Road CyRide stop. Troxel Hall, one of Iowa State's newest buildings, will also be implementing a green roof upon completion.