Impervious surfaces negatively affect urban hydrology by altering the depth, frequency and seasonal distribution of stormwater runoff. To assess the imperviousness of green roofs, a mathematical model was developed to simulate the stormwater response of a hypothetical green roof. The model is based on the physical processes that affect the green roof stormwater response and uses historic climate data. The results show that green roof imperviousness fluctuated according to climate conditions and precipitation sequence. Only 29% of the total precipitation received by the green roof resulted in runoff, however, the response varied substantially when evaluated at a daily interval. Runoff was eliminated during 82% of days with rain and a higher proportion of runoff disturbances were eliminated during the spring and summer compared to the fall. In comparison to an impervious surface, the green roof showed a reduction in the depth and frequency of runoff thereby improving urban hydrology.

Stormwater management is an essential aspect of urban hydrology. Urbanized areas have large amounts of impervious surface cover (ISC) and well developed sewer and drainage networks which rapidly channel water and pollutants off of streets and into local streams. This research evaluates the use of vegetated roofs as mechanisms to reduce ISC and stormwater runoff in downtown Atlanta. A 3-D model of the study site was created so that runoff rates could be measured for various rooftop scenarios under different size storm events. The results revealed a reduction in peak runoff and an increase in both the lag time and duration of response time. The results were most significant for the smallest storm event with 2/3 of the rooftops vegetated. As these experiments use a scale model for a section of downtown Atlanta, results are likely to be applicable to similar urban environments and may provide guidance for stormwater engineers.

As coberturas verdes fazem parte da arquitetura vernacular há séculos como solução para regulação térmica das edificações, retardando a transferência de calor para o ambiente interno e, no inverno, retardando as perdas de calor dos ambientes internos para o exterior da edificação (International Green Roof Association - IGRA). Em se adotando cobertura verde em edificações supõe-se haver economia no consumo de energia para se obter condições de conforto térmico nos ambientes. Baseado nessa suposição foi realizada uma pesquisa experimental onde, por meio de um estudo comparativo entre dois tipos de cobertura: a verde e a de telhas cerâmicas comprovou-se o potencial de economia de energia. A análise do comportamento térmico das coberturas verdes foi realizada por meio de coleta de dados de variáveis ambientais, durante um período de 10 meses, de um protótipo instrumentado, construído no Departamento de Engenharia de Construção Civil da Escola Politécnica da USP, São Paulo. Os dados levantados foram comparados com os dados de um segundo protótipo de mesmas dimensões e igualmente instrumentado, com cobertura cerâmica, sob as mesmas condições ambientais. A comparação dos resultados e análises em dias e episódios representativos de cada estação comprovaram a eficiência das coberturas verdes para retardar o ganho térmico da edificação. Espera-se que os resultados sejam incentivadores à larga aplicação dos telhados egetados, o que trará diversas vantagens para população. / Green roofing is been a part of the vernacular architecture for centuries as solution for constructions thermal regulation. It is known that they delay the heat transfer from the outside to the inside of the building, and during winter, they delay the heating loss from the inside to the outside of the building (International Green Roof Association - IGRA). By adopting green roofs in buildings, one assumes that there is economy in energy consumption to obtain conditions of thermal comfort in inner environments. Based on this assumption, an experimental research was accomplished where, through a comparative study between two types of roofing systems: green and ceramics, it was determined this energy saving potential of green roofs. The analysis of the green roofing thermal behavior was realized through data collection of environmental variables, during the period of ten months, from an instrumented prototype constructed at the Polytechnic School of the University of São Paulo, São Paulo. The collected data was compared to those of a second prototype with the same dimensions and equally instrumented, with ceramics roofing, under the same environmental conditions. The data comparison and analysis of specific days in each season, proved the green roof efficiency on retarding the building thermal gain. One expects that the results will encourage the application of green roofs, which will bring several advantages to the population.

As coberturas verdes fazem parte da arquitetura vernacular há séculos como solução para regulação térmica das edificações, retardando a transferência de calor para o ambiente interno e, no inverno, retardando as perdas de calor dos ambientes internos para o exterior da edificação (International Green Roof Association - IGRA). Em se adotando cobertura verde em edificações supõe-se haver economia no consumo de energia para se obter condições de conforto térmico nos ambientes. Baseado nessa suposição foi realizada uma pesquisa experimental onde, por meio de um estudo comparativo entre dois tipos de cobertura: a verde e a de telhas cerâmicas comprovou-se o potencial de economia de energia. A análise do comportamento térmico das coberturas verdes foi realizada por meio de coleta de dados de variáveis ambientais, durante um período de 10 meses, de um protótipo instrumentado, construído no Departamento de Engenharia de Construção Civil da Escola Politécnica da USP, São Paulo. Os dados levantados foram comparados com os dados de um segundo protótipo de mesmas dimensões e igualmente instrumentado, com cobertura cerâmica, sob as mesmas condições ambientais. A comparação dos resultados e análises em dias e episódios representativos de cada estação comprovaram a eficiência das coberturas verdes para retardar o ganho térmico da edificação. Espera-se que os resultados sejam incentivadores à larga aplicação dos telhados egetados, o que trará diversas vantagens para população. / Green roofing is been a part of the vernacular architecture for centuries as solution for constructions thermal regulation. It is known that they delay the heat transfer from the outside to the inside of the building, and during winter, they delay the heating loss from the inside to the outside of the building (International Green Roof Association - IGRA). By adopting green roofs in buildings, one assumes that there is economy in energy consumption to obtain conditions of thermal comfort in inner environments. Based on this assumption, an experimental research was accomplished where, through a comparative study between two types of roofing systems: green and ceramics, it was determined this energy saving potential of green roofs. The analysis of the green roofing thermal behavior was realized through data collection of environmental variables, during the period of ten months, from an instrumented prototype constructed at the Polytechnic School of the University of São Paulo, São Paulo. The collected data was compared to those of a second prototype with the same dimensions and equally instrumented, with ceramics roofing, under the same environmental conditions. The data comparison and analysis of specific days in each season, proved the green roof efficiency on retarding the building thermal gain. One expects that the results will encourage the application of green roofs, which will bring several advantages to the population.