The Lawrence Technological University Greenroof Performance Evaluation Project

Lawrence Technological University is a private university located on a 120-acre campus in highly urbanized Southfield, Michigan (Detroit Metropolitan Area). The campus was primarily developed over the last several decades with limited or no stormwater controls as was customary with regulations of the time. However, the opening of a student services center in 2005 provided the opportunity for the campus to commit itself to green design and the use of low impact development (LID) techniques. The 40,000 square-foot A. Alfred Taubman Student Services Center (Center) is a Leadership in Energy and Environmental Design (LEED) Silver Certified green building that features a 10,000 square foot green roof; geothermal heating and cooling; cistern water harvesting; a bioswale, and other energy efficient technologies. As such, the Center provides a living laboratory for Lawrence Tech architecture and engineering students, local municipal officials, community planners, and design engineers to learn about LID techniques and LEED certification. Of specific interest to stormwater management, the building features a 10,000 square foot Hydrotech Garden Roof^TM and gray water cistern that recycles roof water. The presence of the green roof provided an unique opportunity to compare and contrast the hydrologic performance of a full-scale greenroof with other more traditional roofs on campus. This was accomplished by outfitting three separate roof drains (a traditional blacktop asphalt roof, a rock ballasted roof, and the green roof) with water quality and quantity sensors. Objectives of the Greenroof Performance Evaluation Project include the overall volume of precipitation retained and detained by the green roof compared to the other roofs on campus; the peak discharge and run-off coefficient reduction of the greenroof for various storm events, the nutrient loading attenuation capabilities of the greenroof; the reduction in ambient temperature associated with the greenroof; and the educational benefit of establishing a long-term monitoring station capable of determining the temporal performance of the green roof that could be integrated into the curriculum.