Green roof hydrologic performance and modeling: a review

2013 ◽  
Vol 69 (4) ◽  
pp. 727-738 ◽  
Author(s):  
Yanling Li ◽  
Roger W. Babcock
Keyword(s):  
Peak Flow ◽  
Green Roof ◽  
Field Measurements ◽  
Green Roofs ◽  
Economic Benefits ◽  
Design Parameters ◽  
Technical Literature ◽  
Factors Affecting ◽  
Model Soil ◽  
Runoff Volume

Green roofs reduce runoff from impervious surfaces in urban development. This paper reviews the technical literature on green roof hydrology. Laboratory experiments and field measurements have shown that green roofs can reduce stormwater runoff volume by 30 to 86%, reduce peak flow rate by 22 to 93% and delay the peak flow by 0 to 30 min and thereby decrease pollution, flooding and erosion during precipitation events. However, the effectiveness can vary substantially due to design characteristics making performance predictions difficult. Evaluation of the most recently published study findings indicates that the major factors affecting green roof hydrology are precipitation volume, precipitation dynamics, antecedent conditions, growth medium, plant species, and roof slope. This paper also evaluates the computer models commonly used to simulate hydrologic processes for green roofs, including stormwater management model, soil water atmosphere and plant, SWMS-2D, HYDRUS, and other models that are shown to be effective for predicting precipitation response and economic benefits. The review findings indicate that green roofs are effective for reduction of runoff volume and peak flow, and delay of peak flow, however, no tool or model is available to predict expected performance for any given anticipated system based on design parameters that directly affect green roof hydrology.

scholarly journals Space variability of hydrological responses of Nature-Based Solutions and the resulting uncertainty

2020 ◽  
Author(s):  
Yangzi Qiu ◽  
Igor da Silva Rocha Paz ◽  
Feihu Chen ◽  
Pierre-Antoine Versini ◽  
Daniel Schertzer ◽  
...  
Keyword(s):  
Spatial Variability ◽  
Peak Flow ◽  
Hydrological Cycle ◽  
Green Roof ◽  
Spatial Arrangement ◽  
Intersection Theorem ◽  
Runoff Volume ◽  
Hydrological Responses ◽  
Total Runoff ◽  
The Impact

Abstract. During the last decades, the urban hydrological cycle has been strongly modified by the built environment, resulting in fast runoff and increasing the risk of waterlogging. Nature-Based Solutions (NBS), which apply green infrastructures, have been more and more widely considered as a sustainable approach for urban stormwater management. However, the assessment of NBS performance still requires further modelling development because of their hydrological responses sensitively depends on the representation of multiscale space variability of both the rainfall and the NBS distribution. Indeed, we initially argue this issue with the help of the multifractal intersection theorem. To illustrate the importance of this question, the spatial heterogeneous distributions of two series of NBS scenarios (porous pavement, rain garden, green roof, and combined) are quantified with the help of their fractal dimension. We point out consequences of their estimates. Then, a fully-distributed and physically-based hydrological model (Multi-Hydro) was applied to consider the studied catchment and these NBS scenarios with a spatial resolution of 10 m under two different types of rainfall: distributed and uniform, and for three rainfall events. These simulations show that the impact of spatial variability of rainfall on the uncertainty of peak flow of NBS scenarios ranges from about 8 % to 17 %, which is more pronounced than those of the total runoff volume. In addition, the spatial variability of the rainfall intensity at the largest rainfall peak responds almost linearly to the uncertainty of the peak flow of NBS scenarios. However, the hydrological responses of NBS scenarios are less affected by the spatial distribution of NBS. Finally, the intersection effects of the spatial variability of rainfall and the spatial arrangement of NBS seem more pronounced for the peak flow of green roof scenarios and the total runoff volume of combined scenarios.

scholarly journals Effects of Extensive Green Roofs on Energy Performance of School Buildings in Four North American Climates

Water ◽  
2019 ◽  
Vol 12 (1) ◽  
pp. 6 ◽  
Author(s):  
Milad Mahmoodzadeh ◽  
Phalguni Mukhopadhyaya ◽  
Caterina Valeo
Keyword(s):  
Leaf Area Index ◽  
Leaf Area ◽  
Plant Height ◽  
Green Roof ◽  
Green Roofs ◽  
Energy Performance ◽  
Design Parameters ◽  
Soil Thickness ◽  
Area Index ◽  
Roof Design

A comprehensive parametric analysis was conducted to evaluate the influence of the green roof design parameters on the thermal or energy performance of a secondary school building in four distinctively different climate zones in North America (i.e., Toronto, ON, Canada; Vancouver, BC, Canada; Las Vegas, NV, USA and Miami, FL, USA). Soil moisture content, soil thermal properties, leaf area index, plant height, leaf albedo, thermal insulation thickness and soil thickness were used as design variables. Optimal parameters of green roofs were found to be functionally related to meteorological conditions in each city. In terms of energy savings, the results showed that the light-weight substrate had better thermal performance for the uninsulated green roof. Additionally, the recommended soil thickness and leaf area index for all four cities were 15 cm and 5 respectively. The optimal plant height for the cooling dominated climates is 30 cm and for the heating dominated cities is 10 cm. The plant albedo had the least impact on the energy consumption while it was effective in mitigating the heat island effect. Finally, unlike the cooling load, which was largely influenced by the substrate and vegetation, the heating load was considerably affected by the thermal insulation instead of green roof design parameters.

scholarly journals Physical Characteristics of and Seed Germination in Commercial Green Roof Substrates

2015 ◽  
Vol 25 (2) ◽  
pp. 221-227 ◽  
Author(s):  
Derald A. Harp ◽  
Cheng Chen ◽  
Curtis Jones
Keyword(s):  
Seed Germination ◽  
Block Design ◽  
Green Roof ◽  
Chemical Properties ◽  
Green Roofs ◽  
Economic Benefits ◽  
Physical Characteristics ◽  
Internal Cooling ◽  
Pinto Bean ◽  
Expanded Shale

Green roofs provide multiple environmental and economic benefits, such as roof surface temperature reduction, reduced internal cooling needs, storm water management, and extended life span of roofing materials. However, green roof substrates must be relatively lightweight, so it is typically coarse with limited water holding capacity. We hypothesize the physical characteristics that make the substrates successful on a roof are likely to reduce seed germination. For this study, we tested the germination of three perennial species and one annual: shasta daisy (Leucanthemum ×superbum), yarrow (Achillea millefolium), and indian blanket (Gaillardia pulchella), and pinto bean (Phaseolus vulgaris) (as a control) across five different substrates: peat/perlite/large expanded shale, compost/sand/expanded shale, compost/black dirt/expanded shale, compost/expanded shale, and peat/perlite (control). Substrate physical and chemical properties were analyzed, and a germination test conducted using a randomized complete block design, with each species/substrate combination appearing once per block. Germination was defined as seedling emergence, and monitored every 7 days for 28 days. Pinto bean had the highest germination (76.2%) across all substrates, compared with 43.4% for indian blanket, 40.4% for yarrow, and 23.0% for shasta daisy. Seed germination, across all species, was lower in green roof substrates. Germination success was very strongly correlated with seed length, seed width, and seed area, while no relationship was found between seed germination and substrate pH or electrical conductivity (EC). Therefore, it is likely that the physical characteristics of green roof substrates create poor conditions for seed germination.

scholarly journals Site Conditions, Maintenance Costs, and Plant Performance of 10 Extensive Green Roofs in the Research Triangle Area of Central North Carolina

2020 ◽  
Vol 30 (6) ◽  
pp. 761-769
Author(s):  
Julieta Trevino Sherk ◽  
Wenyan Fu ◽  
Joseph C. Neal
Keyword(s):  
North Carolina ◽  
Plant Cover ◽  
Green Roof ◽  
Green Roofs ◽  
Economic Benefits ◽  
Plant Performance ◽  
Site Conditions ◽  
Maintenance Costs ◽  
Research Triangle ◽  
Highly Correlated

Compared with traditional roofing, green roofs (GRs) have quantifiable environmental and economic benefits, yet limited research exists on GR plant survival, maintenance practices, and costs related to plant performance. The objective of this study was to assess plant cover, site conditions, and maintenance practices on 10 extensive GRs in the Research Triangle Area of North Carolina. Green roof maintenance professionals were surveyed to assess plant performance, maintenance practices, and maintenance costs. Vegetation cover on each site was characterized. Relationships among plant performance and environmental and physical site characteristics, and maintenance practices were evaluated. Survey respondents ranked weed control as the most problematic maintenance task, followed by irrigation, pruning, and debris removal. No single design or maintenance factor was highly correlated with increased plant cover. Green roof age, substrate organic matter, and modular planting methods were not correlated with greater plant cover. Results showed a trend that irrigation increased plant cover. Plants persisting on GRs included several species of stonecrop (Sedum sp.), but flame flower (Talium calycinum) and ice plant (Delosperma basuticum) were also present in high populations on at least one roof each. Green roof maintenance costs ranged from $0.13/ft2 to $3.45/ft2 per year, and were greater on sites with more weeds and frequent hand watering.

Research of Extensive Green Roof (Spring) for Create Comfortable Environment in Taiwan City

2015 ◽  
Vol 749 ◽  
pp. 420-424
Author(s):  
Chiou Chuan Chen
Keyword(s):  
Energy Saving ◽  
Air Conditioning ◽  
Room Temperature ◽  
Green Roof ◽  
Electricity Consumption ◽  
Green Roofs ◽  
Economic Benefits ◽  
Control Area ◽  
Building Roof ◽  
Extensive Green Roof

March to May at noon control area (exposed roof) temperature of 37.56°C, test below (green roofs) surface only 24.69°C, 24.79°C room temperature on the second floor, planting mean temperature of 27.6°C, effectively prevent the roof surface temperature rise, and thus reduce the interior roof of the second temperature 12.77°C . Building extensive green roofs to cooling, mainly to reduce the building room temperature of 3.76°C;reducing air conditioning electricity consumption , accomplish cooling and energy-saving benefits.March to May at noon (12:00-13:00), ANOVA analysis of cooling efficiency, the temperature difference between the building control area as the dependent variable, compare independent variables, and found that different monitoring areas of solar radiation cooling effect,2 floor indoor cooling temperature 13.9083°C, efficiency the most significant.Roofs of buildings spring will be applied as extensive green roof in spring, creating building roof thermal comfort (24.88°C) and Auliciems (1981) estimate room comfort temperature (24.55°C) are similar, significant benefits to achieve room thermal comfort.Buildings is applied for green roofs in the spring can reduce home power consumption (reducing air conditioning systems use frequency), to energy-saving (58.17%) of the economic benefits.

scholarly journals Influence of environmental factors on retention of extensive green roofs with different substrate composition

2019 ◽  
Vol 86 ◽  
pp. 00026 ◽  
Author(s):  
Anna Baryła ◽  
Agnieszka Karczmarczyk ◽  
Agnieszka Bus ◽  
Edyta Hewelke
Keyword(s):  
Environmental Factors ◽  
Green Infrastructure ◽  
Urban Areas ◽  
Green Roof ◽  
Green Roofs ◽  
Statistical Regression ◽  
Climate Conditions ◽  
Factors Affecting ◽  
Organic Mineral ◽  
Local Ecosystem

Increasing recognition is being given to the adaption of green roofs in urban areas to enhance the local ecosystem. Green roofs may bring several benefits to urban areas including flood mitigation Analysis of environmental factors affecting the outflow of green roofs is the subject of many studies. The work assessed how environmental factors moisture of structural layers and antecedent dry weather period influence the retention on two types of green roof substrates. The monitoring of environmental factors and amount of runoff was carried out on two models of green roofs covered by extensive vegetation (mosssedum-herbs) with substrates of an organic-mineral and mineral composition for 8 months. A statistical regression approach identified potential antecedent meteorological factors and moisture indicators of extensive green-roof retention. Continuous field monitoring data revealed the combined effects of rainfall depth and antecedent dry weather period to explain the measured stormwater retention under a moderate climate conditions regime. It is important to incorporate site-specific planning and assessment prior to green infrastructure design.

Study on Landscape Design of Roof Garden

2013 ◽  
Vol 838-841 ◽  
pp. 2993-2996
Author(s):  
Ying Sun ◽  
Guang Lin Gao
Keyword(s):  
Green Roof ◽  
Complex Form ◽  
Green Roofs ◽  
Economic Benefits ◽  
Landscape Design ◽  
Garden Design ◽  
Performance Arts ◽  
And Performance ◽  
Roof Design ◽  
Roof Garden

The roof garden is a complex form of roofs landscape. Advanced green roof design played a huge ecological and economic benefits gradually being recognized for the significance of green roofs and classification, this paper study the roof garden design principles and key technologies for preliminary summary and discussion, proposed green roof functioning and performance arts beautiful landscape design methods.

INVESTIGATING THE ENVIRONMENTAL IMPACTS OF GREEN ROOF INSTALLATION

2015 ◽  
Vol 76 (1) ◽  
Author(s):  
Amir Mahdiyar ◽  
Arham Abdullah ◽  
Sanaz Tabatabaee ◽  
Leily Mahdiyar ◽  
Saeed Reza Mohandes
Keyword(s):  
Urban Areas ◽  
Green Roof ◽  
Environmental Issues ◽  
Green Roofs ◽  
Developed Countries ◽  
Economic Benefits ◽  
Environmental Benefits ◽  
Adverse Impacts ◽  
Increasing Trend ◽  
Rural Places

Green roof installation has been used as a sustainable approach for many years in order to reduce the adverse impacts of environmental issues all around the world. These environmental issues include: global warming, air pollution, flood, carbon footprint and so on. Green roofs are practical as a sustainable approach, especially in developed countries; however, there is an increasing trend of implementing green roofs in developing countries. This paper is reviewing the benefits of green roof installation and how green roof might contribute to reduce the negative environmental issues. The environmental problems that can be solved or reduced by these benefits are discussed separately in this paper. It is concluded that due to the environmental benefits of green roof installation, it leads to many economic benefits. Moreover, green roof implementation is beneficial in both urban areas and rural places.

scholarly journals Space variability impacts on hydrological responses of nature-based solutions and the resulting uncertainty: a case study of Guyancourt (France)

2021 ◽  
Vol 25 (6) ◽  
pp. 3137-3162
Author(s):  
Yangzi Qiu ◽  
Igor da Silva Rocha Paz ◽  
Feihu Chen ◽  
Pierre-Antoine Versini ◽  
Daniel Schertzer ◽  
...  
Keyword(s):  
Spatial Variability ◽  
Peak Flow ◽  
Hydrological Cycle ◽  
Green Roof ◽  
Spatial Arrangement ◽  
Intersection Theorem ◽  
Runoff Volume ◽  
Hydrological Responses ◽  
Total Runoff ◽  
The Impact

Abstract. During the last few decades, the urban hydrological cycle has been strongly modified by the built environment, resulting in fast runoff and increasing the risk of waterlogging. Nature-based solutions (NBSs), which apply green infrastructures, have been more and more widely considered as a sustainable approach for urban storm water management. However, the assessment of NBS performance still requires further modelling development because of hydrological modelling results strongly depend on the representation of the multiscale space variability of both the rainfall and the NBS distributions. Indeed, we initially argue this issue with the help of the multifractal intersection theorem. To illustrate the importance of this question, the spatial heterogeneous distributions of two series of NBS scenarios (porous pavement, rain garden, green roof, and combined) are quantified with the help of their fractal dimension. We point out the consequences of their estimates. Then, a fully distributed and physically based hydrological model (Multi-Hydro) was applied to consider the studied catchment and these NBS scenarios with a spatial resolution of 10 m. A total of two approaches for processing the rainfall data were considered for three rainfall events, namely gridded and catchment averaged. These simulations show that the impact of the spatial variability in rainfall on the uncertainty of peak flow of NBS scenarios ranges from about 8 % to 18 %, which is more significant than those of the total runoff volume. In addition, the spatial variability in the rainfall intensity at the largest rainfall peak responds almost linearly to the uncertainty of the peak flow of NBS scenarios. However, the hydrological responses of NBS scenarios are less affected by the spatial distribution of NBSs. Finally, the intersection of the spatial variability in rainfall and the spatial arrangement of NBSs produces a somewhat significant effect on the peak flow of green roof scenarios and the total runoff volume of combined scenarios.

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