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Ecoroofs, also known as green roofs, are becoming widely installed with relatively little data collected on their in situ performance. For this study, three large ecoroof portions (280-500 m 2 ) located on two different buildings in Portland, OR, USA were instrumented and monitored continuously for more almost 3 years. For the Broadway Building, a student dormitory on the campus of Portland State University, measurement of ecoroof energy conservation and rainwater discharge abatement helped qualify the building for its Leadership in Energy and Environmental Design silver award. Using an electromagnetic flowmeter, stormwater discharge was monitored and compared to rainfall. Over a 3-year period, rainwater discharge was reduced by about 25%. Rooftop heat flux was simultaneously measured using an array of temperature sensors. When compared to a rock ballast roof exposed to the same weather conditions, the ecoroof heat flux was reduced by 13% in winter and 72% in summer. Retrofit ecoroof installations on the Multnomah County Building, an office building, were also monitored for almost 3 years for two separate ecoroof sections with different plantings, using similar electromagnetic flow meters and a rain gauge. Overall reductions of rainwater discharge were 12% and 17% for those two ecoroofs. For all three ecoroofs, discharge reductions varied widely by month due to seasonal differences in the amount of rainfall. Based on the measurements taken in this study, ecoroofs in Portland, OR, USA appear to offer some performance advantages.

Vegetated roofs are becoming more commonly deployed as a means of mitigating stormflow in urban areas. A greenroof performance comparison of stormwater runoff has yet to be conducted with controlled rain events and quantifiable antecedent soil moisture. This study aimed to investigate the rainwater management provided by various greenroof design schemes. Runoff retention, peak flow lagtime, conductivity, and pH of ten different small-scale greenroof schemes were observed and analyzed under repeatable rain simulations in a pilot-scale study. Sedum rupestre Angelina, Sedum hispanicum, Trifolium repens (white clover), Trifolium pratense (red clover), Vinca major (Big-Leaf Periwinkle), and Lolium multiflorum (ryegrass) were grown in the same type of soil media but separate 2′ × 2′ trays at depths of 5 cm and 14 cm to observe how soil depth and root zone development affects stormwater flow through for each plant type. Results showed that increased green roof soil depth improved water retention and runoff lagtime; the effect of plant type was mixed and inconclusive. Runoff conductivity test results depended primarily on soil depth and the existence or absence of vegetation. Testing results show that pH normalization provided by a greenroof does not depend significantly with the substrate depth.

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