Dr. Joel G. Burken, Curators Distinguished Professor in Civil, Architectural, and Environmental Engineering at the Missouri University of Science and Technology, will be seminar speaker on Monday, April 10 from 4-5 pm. His talk, entitled “Reconnecting Urban Hydrology with Green Roofs and Infrastructure – Understanding the Benefits,” is part of the Environmental Engineering Seminar Series and is co-sponsored by the Department of Civil and Environmental Engineering.

Reconnecting Urban Hydrology with Green Roofs and Infrastructure – Understanding the Benefits

Abstract: Green roofs use vegetation, soils, and natural processes to restore natural hydrologic benefits urban environments, providing traditional roof services and alternative stormwater management technologies. Numerous other benefits and impacts are not yet fully understood or valued appropriately. Research conducted assesses specific stormwater benefits of green roofs and analyzes potential energy benefits through side-by-side comparisons of full-scale white, traditional black rubber, and green roofs in the mid-continent Missouri climate. The 54% of stormwater retention demonstrated in this green roof research reveals aid in urban watershed management and an observed 15 mm of storage capacity also provides an opportunity for energy dissipation via evapotranspiration (ET). Water and energy models are combined to illustrate impacts of ET on green roof temperatures and urban heat island mitigation. As ET is dependent on a variety of climate parameters including temperature, humidity, wind speed, and solar radiation, the potential to dissipate energy from a roof surface by means of water vaporization was modeled, with 10.9 MJ/m2 of energy dissipated for 4.8 mm of ET.

The US EPA details urban temperatures 12°C warmer than rural surroundings. During daytime, the green roof displayed surface temperatures 35°C less than the black roof and 20°C less than its “cool roofs” competitor, the white roof. Models using climate data to estimate potential ET may be used as predictive tools on impacts of green roof design. The modeling also calibrated ‘crop coefficients’ for the various greenroof media and is related to standardized testing of different greenroof media to aid in design of greenroofs to maximize benefits for different climates. The models will also be predictive in sustainable stormwater management, allowing green roofs to maximize runoff reduction, peak flow attenuation, and urban heat island mitigation, which results in projecting value and economic savings benefits.