scholarly journals Hydrologic Performance of Experimental Green Roofs Stands as the Effect of Climate Condition

2021 ◽  
Vol 1203 (2) ◽  
pp. 022124
Author(s):  
Zuzana Miňová ◽  
Pavol Purcz ◽  
Lukáš Takal
Keyword(s):  
Storage Capacity ◽  
Green Roof ◽  
Green Roofs ◽  
Runoff Coefficient ◽  
Climate Condition ◽  
Water Storage Capacity ◽  
Dimensionless Coefficient ◽  
High Runoff ◽  
Guidelines And Standards ◽  
Hydrologic Performance

Abstract The water storage capacity of a green roof forms several benefits for the building and its environment. The hydrologic performance is traditionally expressed by the runou coefficient, according to international guidelines and standards. The runoff coefficient is a dimensionless coefficient relating the amount of runoff to the amount of precipitation received. It is a larger value for areas with low infiltration and high runoff (pavement, steep gradient), and lower for permeable, well vegetated areas (forest, flat land). The paper is presenting 3 experimental stands of green roofs. Each stand is unique in terms of its construction. The aim of this paper is to highlight how green roof responds to real clima events. The experiment provides mathematical graphs and behaviour of the geen roof stands from 03/2019 to 01/2021.

scholarly journals Hydrologic Performance of an Extensive Green Roof under Intensive Rain Events: Results from a Rain-Chamber Simulation

2021 ◽  
Vol 13 (6) ◽  
pp. 3078
Author(s):  
Elena Giacomello ◽  
Jacopo Gaspari
Keyword(s):  
Water Retention ◽  
Green Roof ◽  
Green Roofs ◽  
International Standards ◽  
Dimensionless Number ◽  
Runoff Coefficient ◽  
Retention Performance ◽  
Extensive Green Roof ◽  
Rain Events ◽  
Hydrologic Performance

The water storage capacity of a green roof generates several benefits for the building conterminous environment. The hydrologic performance is conventionally expressed by the runoff coefficient, according to international standards and guidelines. The runoff coefficient is a dimensionless number and defines the water retention performance over a long period. At the scale of single rain events, characterized by varying intensity and duration, the reaction of the green roof is scarcely investigated. The purpose of this study is to highlight how an extensive green roof—having a supposed minimum water performance, compared to an intensive one—responds to real and repetitive rain events, simulated in a rain chamber with controlled rain and runoff data. The experiment provides, through cumulative curve graphs, the behavior of the green roof sample during four rainy days. The simulated rain events are based on a statistical study (summarized in the paper) of 25 years of rain data for a specific location in North Italy characterized by an average rain/year of 1100 mm. The results prove the active response of the substrate, although thin and mineral, and quick draining, in terms of water retention and detention during intense rain events. The study raises questions about how to better express the water performance of green roofs.

scholarly journals Comparative Analysis of Green Roof Guidelines and Standards In Europe and North America

2011 ◽  
Vol 6 (2) ◽  
pp. 170-191 ◽  
Author(s):  
Bruce Dvorak
Keyword(s):  
North America ◽  
North American ◽  
Green Roof ◽  
Performance Standards ◽  
Green Roofs ◽  
Growth Media ◽  
Root Barriers ◽  
Root Barrier ◽  
New Guidelines ◽  
Guidelines And Standards

The German FLL Guidelines for green roofs are designed to inform about state-of-the-art performance expectations for green roofs. North America is experiencing steady growth in the green roof market and has no single-source set of standards or guidelines; therefore there is a need to identify what type of guidance may be lacking. Seven domains of knowledge from the FLL Guidelines are compared to similar areas of content in North American documents. It was found that although there are several North American green roof guidelines in use, compared to the FLL Guidelines there are areas where knowledge is lacking: guidance for compatibility of system components, slope application, filter fabrics, root barriers, surface and subsurface drainage, growth media, and erosion control, as well as standards or postconstruction testing requirements for fabrics, bulk density of growth media, root barrier performance, drainage media, and growth media. A case study of the Chicago City Hall green roof examines its content compliance with FLL performance standards. Recommendations for further advancement of North American guidelines include the need for more collaborative research and development in efforts to advance existing and new guidelines across ecoregions.

scholarly journals Limitations in using runoff coefficients for green and gray roof design

2020 ◽  
Vol 51 (2) ◽  
pp. 339-350
Author(s):  
Lotte Askeland Schärer ◽  
Jan Ove Busklein ◽  
Edvard Sivertsen ◽  
Tone M. Muthanna
Keyword(s):  
Green Infrastructure ◽  
Field Experiments ◽  
Green Roof ◽  
Drainage System ◽  
Green Roofs ◽  
Field Studies ◽  
Urban Drainage ◽  
Runoff Coefficient ◽  
Different Types ◽  
Roof Design

Abstract Climate change combined with urbanization increases the performance demand on urban drainage systems. Green roofs are one of the most used green infrastructure measures to alleviate the pressure on the urban drainage system through the detention and retention of runoff. The rational method with the runoff coefficient (C) is one of the most commonly used design tools for stormwater design in Norway. This method relies on a runoff coefficient being available for green roofs, which is typically not the case. This paper compares laboratory and experimental field studies to investigate runoff coefficients from different types of detention-based roofs. The methodology described in the German ‘FLL Guideline’, one of the world's most commonly used green roof standards, was used to measure the runoff coefficients for the different components making up a typical green roof. The contribution from each layer is reflected in the runoff coefficients. The runoff coefficients from the field experiments were calculated using observed precipitation and runoff from existing green roofs in Oslo, Trondheim, Sandnes, and Bergen, Norway. Events that had a cumulative precipitation comparable to the laboratory events, but longer durations, were selected. These events gave significantly lower and varying runoff coefficients, clearly demonstrating the limitation of choosing a suitable runoff coefficient for a given roof. However, laboratory experiments are important in understanding the underlying flow processes in the different layers in a detention-based roof.

scholarly journals Model Details, Parametrization, and Accuracy in Daily Scale Green Roof Hydrological Conceptual Simulation

Atmosphere ◽  
2020 ◽  
Vol 11 (6) ◽  
pp. 575 ◽  
Author(s):  
Mirka Mobilia ◽  
Antonia Longobardi
Keyword(s):  
Conceptual Models ◽  
Good Accuracy ◽  
Storage Capacity ◽  
Potential Evapotranspiration ◽  
Green Roof ◽  
Hydrological Models ◽  
Water Storage Capacity ◽  
Capacity Model ◽  
Daily Scale ◽  
Maximum Water

In time, several models with different complexity have been proposed to predict the retention performances of a green roof. In the current study three conceptual models of increasing complexity in descriptive details, are calibrated and compared to experimental data. The proposed approaches consist of daily scale hydrological models, based on water balance equations, where the main processes and variables accounted for are the precipitation input, the evapotranspiration losses, and the maximum water storage capacity. Model detail increase is achieved moving from an approach using potential evapotranspiration and constant storage threshold to an approach using actual evapotranspiration and a variable storage threshold. The main findings confirm on one side the role played by evapotranspiration modeling and, on the other side, the good accuracy achieved, in a minimal calibration requirement approach, through the modeling of basic and elemental processes.

Drainage and water storage capacity of insulation cork board applied as a layer on green roofs

2019 ◽  
Vol 209 ◽  
pp. 52-65 ◽  
Author(s):  
António Tadeu ◽  
Nuno Simões ◽  
Ricardo Almeida ◽  
Carlos Manuel
Keyword(s):  
Storage Capacity ◽  
Water Storage ◽  
Green Roofs ◽  
Water Storage Capacity

scholarly journals Development of different herbaceous perennial species on the experimental extensive green roof of Corvinus University Budapest

2006 ◽  
Vol 12 (1) ◽  
Author(s):  
Zs. Fejes ◽  
L. Gerzson
Keyword(s):  
Plant Species ◽  
Storage Capacity ◽  
Green Roof ◽  
Herbaceous Plant ◽  
Perennial Species ◽  
Water Storage Capacity ◽  
Extensive Green Roof ◽  
Different Types ◽  
Sedum Acre ◽  
Herbaceous Perennial

During 2003-2004 six "traditional" herbaceous plant species (Sedum reflexum, Sedum acre 'Aureum', Sedun spurium„Sedum floriferum, Festuca glauca) and six "new" plant species (Sedum pulchellum, Prunus tenella, fivericum polyphyllum, CeraiTtignIct plumbaginoides, Dianthus plumarius and Phlox subulala) were tried on four different types of roof insulation on the 100 m large experimental extensive green roof of the Building K of Corvinus University Budapest, at Villányi street, Budapest. According to the results obtained so far, the viability and good decoration values of all the "traditional" plants were proved. From the six "new" plants Ceratostigma plumbaginoides, Dianthus plumarius and Sedum pulchellum (with some restrictions) proved to be suitable. A significantly poorer development was showed by the remaining "new" species (Phlox subulata, 1-1yericum polyphyllum, Prunus tenella) than the "traditional" ones. As for the different types of roof insulation, the best was with the direct order of layers, and drainage layer with water storage capacity.

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