Considering that environmental sustainability is a defining issue of the 21st century, Penn is dedicated to promoting a sustainable culture and implementing environmentally conscious policies. Penn believes that higher education can play a leadership role in addressing global climate change, through research, teaching and operational practices. The use of green roof technologies is one of several sustainable development strategies. Green roofs are an attractive sustainable technology, especially in densely developed urban areas like Penn. One of the most significant environmental challenges facing Philadelphia is the pollution of its rivers. Like many of America's oldest cities, Philadelphia has a combined sewer/stormwater system, in which underground sewer pipes also carry away excess rainwater after a rain. During significant rainfall events, excess stormwater from city rooftops, streets, and parking lots can overwhelm wastewater treatment plants, resulting in untreated wastewater flowing directly into the Schuylkill and Delaware Rivers. Since a good portion of the city is made up of rooftops, one of the key strategies for reducing stormwater runoff is the use of green roofs to slow the passage of stormwater into the sewer system. However, uncertainty remains regarding their benefit in reducing water runoff attenuation on roofs. To help the university learn more about the stormwater benefits of green roofs, this report provides guidelines and monitoring information to support a uniform monitoring approach for green roofs on campus, with a specific case study of the site. With uniform monitoring approaches, the effects of green roofs on stormwater runoff hydrology can be more accurately compared from site to site. These comparisons can therefore support… half of the paper… the amount of runoff water collects different types of wastes, natural or man-made, and discharges them into different water bodies, i.e. lakes, rivers, and springs of drinking water. Amazingly, green roofs can absorb between 50 and 100% of the precipitation that falls on the roof, significantly increase the filtration time of rainwater, and significantly reduce the volume of rainwater flowing into streams and systems. drainage.2.3 USE OF GREEN ROOFS IN UNIVERSITY OF PENNSYLVANIA ENVIRONMENTS With an ambitious goal of becoming the greenest city, the City of Philadelphia ranked fourth in green roof growth in 2012 and 2011, according to annual reports of Green Roofs for Healthy Cities (GRHC). In collaboration with the Philadelphia Water Department Office of Watersheds, Penn is showcasing best sustainability practices by installing green roofs on a number of buildings across campus: