Green roofs have been used as a stormwater Best Management Practice (BMP) for more than 20 years in Germany and have been used in the United States for over decade. However, common acceptance of greenroofs as a structural BMP has been slow in many communities. One reason is the lack of published data on their performance, especially in the United States. A recent literature search on greenroofs yields very few published U.S. studies on the water quantity and quality benefits associated with greenroofs, only two of which were conducted in a university setting (Penn State University and North Carolina State University). In both cases, while the greenroofs being evaluated were constructed at full scale, the constructed roofs were small and constructed primarily for research purposes.
The green roof constructed at Lawrence Tech was designed as a stormwater BMP in a high-density urban environment, which makes performance data critical. There is also a need to conduct research on green roofs at a variety of locations throughout the United States. Regional differences in hydrology, climate, plant material, and background water quality make the transference of results from one region to another questionable. Finally, there are numerous green roof design configurations and data needed to evaluate the effectiveness of different designs. All of these factors indicate the necessity of more research studies on green roof performance.