July 2005

"Green Roof" Project at UCF Testing New Energy Performance Strategy

The University of Central Florida's Student Union is the test site for an innovative research project that has built and is now monitoring a new roof with plant media and drainage systems that allow a layer of vegetation to grow on it. The project is being led by UCF's Stormwater Management Academy. FSEC was brought in by the state's Department of Environmental Protection to team with the campus researchers to study the energy impacts of the green roof.

This building strategy can improve the facility's energy performance, air quality and the urban ecology without taking up any additional land. Green roof systems have been shown to reduce heat transfer through the roof, decrease stormwater pollutants and cut down on stormwater volume by naturally evaporating the runoff through the plant respiration process.
"Green Roof" side by side comparison.
"Green Roof" side-by-side comparison.
(Photo: Jeff Sonne)

The 3,300-square-foot roof is being used for a side-by-side comparison. One half of the roof is a conventional commercial building flat roof, while the other half of the roof is a "green roof." It's not painted green, but instead landscaped with 75 percent Florida native plants.

FSEC researchers have extensively studied building heat gain through roofs and ceilings, but planted roofs are new territory for the Center. In fact, there are only a handful of studies that have been done on green roofs in general. Simulations of the technique have found that the energy savings can range from one to 25 percent, depending on the building and the plants and soil used on the roof. FSEC's tasks will be to provide the energy-related monitoring, analysis and reporting for this project. Specifically, FSEC will study roof component temperatures, heat flux through the roof and any air temperature reductions immediately above the roof. While the roof was being constructed, FSEC researchers were able to strategically place 26 temperature sensors so that a true side-by-side comparison can be achieved.

Matt Branch adjusting pyronomiter on the green roof section.
Matt Branch adjusting the meteorological station on the green roof section.
(Photo: Jeff Sonne)

Jeff Sonne, who is heading up the FSEC effort, noted that "the sensors and data-logging equipment are now in place and automated data collection has begun." The work was completed with the help of Matt Branch, a UCF mechanical engineering student intern who is working at FSEC this summer.

This research effort extends through next fall. Sonne explained that "It will be interesting to compare next year's data once the plants have had a chance to mature and the light-colored conventional roof has somewhat reduced reflectivity."

FSEC is also working on a related building re-commissioning project on the UCF campus. Researchers are providing technical assistance to UCF's Physical Plant office in improving the efficiency of three identified campus buildings. It is hoped that the project will begin a comprehensive re-commissioning of UCF campus buildings by using the energy savings from this initial project to fund monitoring and modifications to the rest of the campus.

"GreenRroof" section at UCF.
"Green Roof" section at UCF.
(Photo: Jeff Sonne)

"One of the other outcomes of the related re-commissioning activity," according to Buildings Division chair Rob Vieira, "is that we will be providing building science training to five employees of the university's physical plant staff, and we'll also be conducting a four-course training series on these building strategies that are ideally suited for the Florida climate."

The green roof at UCF is the second green roof project sponsored by the Department of Environmental Protection. They supported one a year ago at a golf course in Bonita Bay. More information on the UCF project is available at www.stormwater.ucf.edu .