scholarly journals Hydrological Performance of Green Roofs at Building and City Scales under Mediterranean Conditions

2018 ◽  
Vol 10 (9) ◽  
pp. 3105 ◽  
Author(s):  
Ignacio Andrés-Doménech ◽  
Sara Perales-Momparler ◽  
Adrián Morales-Torres ◽  
Ignacio Escuder-Bueno
Keyword(s):  
Green Roof ◽  
Drainage System ◽  
Green Roofs ◽  
Hydrological Models ◽  
The Mediterranean ◽  
Dry Climates ◽  
One Year ◽  
The City ◽  
Mediterranean Conditions

Green roofs are one specific type of sustainable urban drainage system (SUDS); they aim to manage runoff at the source by storing water in its different layers, delaying the hydrological response, and restoring evapotranspiration. Evidence of their performance in the Mediterranean is still scarce. The main objective of this paper is to analyse the hydrological performance of green roofs at building and city scales under Mediterranean conditions. A green roof and a conventional roof were monitored over one year in Benaguasil (Valencia, Spain). Rainfall and flow data were recorded and analysed. Hydrological models were calibrated and validated at the building scale to analyse the hydrological long-term efficiency of the green roof and compare it against that obtained for the conventional roof. Results show that green roofs can provide good hydrological performances, even in dry climates such as the Mediterranean. In addition, their influence at the city scale is also significant, given the average runoff coefficient reduction obtained.

scholarly journals Selecting Potential Moss Species for Green Roofs in the Mediterranean Basin

Urban Science ◽  
2019 ◽  
Vol 3 (2) ◽  
pp. 57 ◽  
Author(s):  
Ricardo Cruz de Carvalho ◽  
Zulema Varela ◽  
Teresa Afonso do Paço ◽  
Cristina Branquinho
Keyword(s):  
Climate Change ◽  
Mediterranean Basin ◽  
Vascular Plants ◽  
Green Roof ◽  
Green Roofs ◽  
Potential Candidate ◽  
Moss Species ◽  
The Mediterranean ◽  
The Mediterranean Basin ◽  
Selection Of

Green roofs are important infrastructures to address the effects of climate change in urban areas. However, most studies and applications have been done in cooler and wetter regions of the northern hemisphere. Climate change will lead to more extreme weather events, such as increased drought and decreased precipitation with intense flash rain events. Increase desertification is expected especially in the Mediterranean Basin, where in summer, radiation and temperature are high and water is scarce. Therefore, while vascular plants increase water consumption in green roofs during warmer periods, mosses present themselves as potential candidates due to their poikilohydric nature, responding to the environmental availability of water, completely drying out and recovering upon rehydration. Although criteria for the selection of vascular plants adapted to the Mediterranean and suitable for green roofs have been developed, no information is available regarding the selection of mosses based on scientific criteria. Here we propose selection criteria for moss species based on ecological preferences according to Ellenberg’s values and help to define moss traits suitable for a nonirrigated, nature-based green roof that tolerates the Mediterranean climate. The main result is a table of potential candidate mosses that can be either used as standalone or in conjunction with vascular plants to decrease water usage and/or manage stormwater through an easily applicable selection methodology. For green roof practitioners, we proposed that acrocarpous mosses exhibiting turf/cushion life forms and colonist or perennial life strategies best fit the requirements for such a green infrastructure in extreme climate regions with scarce water resources.

scholarly journals Green Roof Evaluation: A Holistic ‘Long Life, Loose Fit, Low Energy’ Approach

2015 ◽  
Vol 15 (4) ◽  
pp. 76-94 ◽  
Author(s):  
Craig Langston
Keyword(s):  
Green Roof ◽  
Holistic Approach ◽  
Green Roofs ◽  
Low Energy ◽  
Environmental Criteria ◽  
Development Goals ◽  
Long Life ◽  
Social And Environmental Performance ◽  
Breakeven Point

Green roofs have potential to improve the social and environmental performance of detached housing in Australia, yet often they are overlooked due to prohibitive capital cost and a range of other perceptions that are difficult to quantify. A classic evaluation problem is invoked that must balance short and long term benefits. Using two distinct designs of the same floor area, green roof and traditional housing prototypes are analysed to determine the relative ‘breakeven’ point when long-term benefits become feasible. It is discovered that green roofs are unlikely to be viable in their own right, but when coupled with an overall design strategy of long life (durability), loose fit (adaptability) and low energy (sustainability) they can deliver least cost (affordability) over time as well as unlock valuable social and environmental rewards. This outcome can be realised within 25% of a home’s expected design life of at least one hundred years. The results demonstrate that residential green roofs, when integrated as part of a holistic approach, can be both individually and collectively justified on key economic, social and environmental criteria, and are therefore able to claim a valuable contribution towards wider sustainable development goals.

scholarly journals The native - exotic plant choice in green roof design: using a multicriteria decision framework to foster urban biodiversity

2022 ◽  
Author(s):  
Ana A. Calvino ◽  
Julia Tavella ◽  
Hernan M. Beccacece ◽  
Elizabet Estallo ◽  
Diego Fabian ◽  
...  
Keyword(s):  
Plant Species ◽  
Green Roof ◽  
Green Roofs ◽  
Exotic Plant ◽  
Beneficial Arthropods ◽  
Decision Framework ◽  
Exotic Plant Species ◽  
Multicriteria Decision ◽  
One Year ◽  
Roof Design

Green roofs are considered key elements of the urban green infrastructure since they offer several environmental benefits, including habitat provision for arthropods. To achieve these benefits and ensure green roof success, an appropriate plant selection is an important step in the design of these infrastructures, especially where green roof technology is emerging like in South American cities. So far, decisions of using native or exotic plant species in green roofs had never been evaluated taking into account the plant potential to foster beneficial arthropods. By applying an integrative multicriteria decision framework that combined the habitat template hypothesis with the potential of plants to attract floral visitors and natural enemies, we obtained a ranked set of candidate native and exotic plant species. Among the best-ranked candidate species, we further compared the performance of six native and six exotic species in 30 experimental green roofs installed in Cordoba city, Argentina. To evaluate plant success, the occurrence and cover of each species were recorded one year after establishment under two management conditions: regular watering and weeding of spontaneous plants, and no management (15 roofs each). All selected species increased their vegetative cover one year after establishment. More interestingly, native plants had an advantage over exotic plant species as they exhibited a significantly higher occurrence and a slightly higher cover with no management than exotics. Native annuals were able to reseed the following season even in the absence of management, thus highlighting the relative importance of lifespan as a useful plant trait for future studies in green roof design. Given that green roofs are one of the possible solutions to ameliorate the negative effects of urban habitat loss on arthropod diversity, the development of an integrative multicriteria decision framework that takes into account the potential of native and exotic plant species for promoting beneficial arthropods would give a new twist in plant selection processes for green roofs.

scholarly journals AN ANALYSIS ON THE EFFICIENCY OF GREEN ROOF IN MANAGING URBAN STORMWATER RUNOFF

2021 ◽  
Vol 19 (17) ◽  
Author(s):  
Shazmin Shareena Ab. Azis ◽  
Muhammad Najib Mohamed Razali ◽  
Nurul Hana Adi Maimun ◽  
Nurul Syakima Mohd Yusoff ◽  
Mohd Shahril Abdul Rahman ◽  
...  
Keyword(s):  
Flash Flood ◽  
Meta Analysis ◽  
Green Roof ◽  
Drainage System ◽  
Green Roofs ◽  
Storm Water ◽  
Water Runoff ◽  
Extensive Green Roof ◽  
Storm Water Runoff ◽  
Urban Storm

Modernization has created new impervious urban landscape contributed to major catastrophe. Urban drainage system incapable to convey the excess rainwater resulting in flash flood due to heavy rainfall. The combination of green roof on building have tremendously proved to control stormwater efficiently. This study is conducted to review the efficiency of intensive and extensive green roof in reducing urban storm water runoff. This study identifies characteristic of green roof that contributes to lessening urban storm water runoff. Data was collected based on rigorous literature reviews and analyzed using meta-analysis. Overall, findings revealed intensive green roof performed better in reducing storm water runoff compared to extensive green roof. Green roof performance increases as the depth of substrate increased. Origanum and Sedum plants are both highly effective for intensive and extensive green roofs. The performance of green roof reduces as degree of roof slope increased.

scholarly journals Modelling Green Roof Detention Performance in Cold Climates

10.29007/4rp8 ◽  
2018 ◽  
Author(s):  
Ingrid Russwurm ◽  
Birgitte Gissvold Johannessen ◽  
Ashenafi Gragne ◽  
Jardar Lohne ◽  
Tone Merete Muthanna
Keyword(s):  
Urban Areas ◽  
Low Impact Development ◽  
Green Roof ◽  
Drainage System ◽  
Green Roofs ◽  
Design Tool ◽  
Shuffled Complex Evolution ◽  
Calibration Algorithm ◽  
Event Models ◽  
Event Based

Green roofs (GRs) have become a popular sustainable drainage system (SuDS) technology in urban areas. As many countries and regions experience political encouragement and substitution schemes in implementing GRs, there is a need for reliant models that can support designing purposes. The stormwater management model’s (SWMM) Low Impact Development Green Roof (LID-GR) control is used to simulate the hydrological detention performance of two GRs, GR1 and GR2, with different drainage properties located in Oslo, Norway. This study uses event-based data to replicate GR runoff. Accordingly, four event-models were calibrated using the Shuffled Complex Evolution algorithm with the Nash-Sutcliffe criteria (NSE) as the objective function. Eight events were used for model validation. Simulation results revealed that SWMM’s LID module can capture response of the GRs even though the adequacy varies among events. During calibration two GR1 (0.55 and 0.72) and three GR2 (0.73, 0.88 and 0.51) event-models yielded NSE>0.5. However, only parameter sets of two GR2 event-models yielded NSE>0.5 when applied to the validation events. Parameter sensitivity analysis exhibited significant correlation between conductivity slope and maximum precipitation intensity. The study shows potential of SWMM as a design tool if supplemented with a calibration algorithm and some adjustments to the LID module.

scholarly journals Green Roof Design Techniques to Improve Water Use under Mediterranean Conditions

Urban Science ◽  
2019 ◽  
Vol 3 (1) ◽  
pp. 14 ◽  
Author(s):  
Teresa Paço ◽  
Ricardo Cruz de Carvalho ◽  
Pedro Arsénio ◽  
Diana Martins
Keyword(s):  
Water Use ◽  
Green Roof ◽  
Green Roofs ◽  
Climatic Conditions ◽  
Native Plant ◽  
Additional Energy ◽  
Climate Conditions ◽  
Native Plant Species ◽  
Roof Design ◽  
Mediterranean Conditions

Green roof typology can vary depending on buildings structure, climate conditions, substrate, and plants used. In regions with hot and dry summers, such as the Mediterranean region, irrigation plays an essential role, as the highest temperatures occur during the driest period of the year. Irrigation might reduce the heat island effect and improve the cooling of buildings during this period, however, the added cost of maintenance operations and additional energy consumption could outrun the benefits provided by the project. Moreover, in situations where water is scarce or primarily channelled to other uses (e.g., domestic, agriculture or industry) during drought occurrence, it is advisable to implement green roof projects with the lowest use of water possible. The objective of the present work is to investigate solutions to optimize water use in green roofs under Mediterranean conditions, such as those of southern Europe. Two case studies are presented for Portugal, and potential techniques to reduce irrigation requirements in green roofs were tested. These addressed the use of native plant species, including the extreme type of a non-irrigated green roof (Biocrust roof) and techniques for plant installation. Plant drought tolerance was found to be an advantage in green roofs under these climatic conditions and, for the species studied, aesthetic value could be maintained when irrigation decreased.

scholarly journals Socio-Ecological Dimensions of Spontaneous Plants on Green Roofs

2021 ◽  
Vol 3 ◽  
Author(s):  
Dean Schrieke ◽  
Joel Lönnqvist ◽  
Godecke-Tobias Blecken ◽  
Nicholas S. G. Williams ◽  
Claire Farrell
Keyword(s):  
Urban Communities ◽  
Open Space ◽  
Property Values ◽  
Green Roof ◽  
Green Roofs ◽  
Vegetation Coverage ◽  
Ecological Services ◽  
Housing Costs ◽  
Spontaneous Vegetation ◽  
Dry Climates

Green roofs have the potential to provide socio-ecological services in urban settings that lack vegetation and open space. However, implementation of green roofs is limited by high construction and maintenance costs. Consequently, green roof projects often disproportionately benefit wealthy communities and can further marginalise disadvantaged communities by increasing property values and housing costs. Vegetation cover on green roofs is crucial to their provisioning of socio-ecological services. Evidence suggests that green roof plantings change over time, especially with limited maintenance, and are replaced with spontaneous “weedy” species. This is often perceived as a failure of the original green roof design intent and spontaneous species are usually removed. However, where good coverage is achieved, spontaneous vegetation could provide beneficial services such as stormwater mitigation, habitat provision, and climate regulation. While social norms about “weediness” may limit the desirability of some spontaneous species, research suggests that their acceptability on green roofs increases with coverage. As spontaneous species can establish on green roofs without irrigation and fertiliser, reduced input costs could help facilitate adoption particularly in markets without an established green roof industry. Construction costs may also be reduced in hot and dry climates where deeper substrates are necessary to ensure plant survival, as many spontaneous species are able to colonise shallow substrates and can regenerate from seed. If implemented based on socio-ecological need, green roofs with spontaneous vegetation coverage may apply less pressure to property values and housing costs than conventionally planted green roofs, increasing the resilience of urban communities while limiting gentrification.

scholarly journals Substrate Depth Influences Sedum Plant Community on a Green Roof

HortScience ◽  
2009 ◽  
Vol 44 (2) ◽  
pp. 401-407 ◽  
Author(s):  
Kristin L. Getter ◽  
D. Bradley Rowe
Keyword(s):  
Plant Community ◽  
Plant Stress ◽  
Green Roof ◽  
Green Roofs ◽  
Plant Performance ◽  
Blue Spruce ◽  
Waterproofing Membrane ◽  
Substrate Moisture ◽  
Substrate Depth

Because the waterproofing membrane beneath green roofs is estimated to last at least 45 years, long-term plant performance beyond initial establishment is critical. Plants that survive initially on a green roof may not exist in the long term because of variability in climate and other factors. This study evaluated the effect of green roof substrate depth on substrate moisture, plant stress as measured by chlorophyll fluorescence, and plant community development and survival of 12 Sedum species over 4 years in a midwestern U.S. climate during 4 years of growth. Plugs of 12 species of Sedum were planted on 8 June 2005 and evaluated biweekly for absolute cover (AC). Most species exhibited greater growth and coverage at a substrate depth of 7.0 cm and 10.0 cm relative to 4.0 cm. For the species evaluated, substrate depths of at least 7.0 cm are highly recommended. AC of Sedum was significantly greater at this substrate depth than at 4.0 cm. Mean volumetric moisture content of the three substrate depths followed the same pattern as AC. When averaged over time, the 4.0-cm substrate depth held less moisture than depths of 7.0 or 10.0 cm, whereas the 7.0- and 10.0-cm substrate depths were statistically the same. Species exhibiting the greatest AC at all substrate depths were S. floriferum, S. sexangulare, S. spurium ‘John Creech’, and S. stefco. In general, species that are less suitable at these substrate depths are S. ‘Angelina’, S. cauticola ‘Lidakense’, S. ewersii, S. ochroleucum, and S. reflexum ‘Blue Spruce’.

scholarly journals Seasonal Variability of Atmospheric Aerosols in Karachi, Pakistan

2019 ◽  
Vol 10 (1) ◽  
pp. 57-63
Author(s):  
Badar Ghauri ◽  
Zahid Khalil ◽  
Muhammad Shafiq ◽  
Hussain Haider Rizvi ◽  
Jawad Nasir ◽  
...  
Keyword(s):  
Black Carbon ◽  
Optical Depth ◽  
Atmospheric Aerosols ◽  
One Year ◽  
The City ◽  
Derived Data ◽  
Carbon Concentrations ◽  
Aerosol Type

A variety of in situ and satellite-derived data of aerosols like atmospheric black carbon concentrations wereused to probe the seasonal differences of aerosol concentration in Karachi, Pakistan for one year. Daily [black carbon]varied from about 4000 to 50,000 ng/m3 with the mean maximum of 14700 ng/m3 in February, primarily duringmornings and evenings. The [black carbon] concentrations were at a maximum during winter months of November toFebruary i.e. around 12000 ng/m3 and were at minimum value during summer from June to September (3000 ng/m3).Short term and long-term variabilities were mostly affected by meteorological parameters. Apart from industrial andindiscriminate solid waste burning, most important source of BC emissions in Karachi was vehicular traffic, since overa million vehicles were registered in the city. Aerosol Optical Depth (AOD) from multi-band AOD, AERONET, andMODIS satellites showed a similar trend of its concentrations similar to BC. Aeronet 500 nm AODs were at amaximum for July (0.95 monsoons) and minimum (around 0.4) in November-February. Seasonal variation of AOD(Aeronet) was matching at other wavelengths, while the deviation in the spectral dependency of AOD was uncertain. Itimplied that a columnar spectral optical depth represented different aerosol type association having advection fromvarious directions and sources. Relevant stakeholders should play their role to reduce BC emissions to mitigate illhealth impacts in this metropolitan city.

scholarly journals Stormwater Retention and Reuse at the Residential Plot Level—Green Roof Experiment and Water Balance Computations for Long-Term Use in Cyprus

Water ◽  
2019 ◽  
Vol 11 (5) ◽  
pp. 1055 ◽  
Author(s):  
Katerina Charalambous ◽  
Adriana Bruggeman ◽  
Marinos Eliades ◽  
Corrado Camera ◽  
Loukia Vassiliou
Keyword(s):  
Water Balance ◽  
Plant Species ◽  
Rainwater Harvesting ◽  
Green Roof ◽  
Irrigation Treatment ◽  
Stormwater Runoff ◽  
Green Roofs ◽  
Roof Experiment ◽  
Stormwater Retention

Green roofs can provide various benefits to urban areas, including stormwater retention. However, semi-arid regions are a challenging environment for green roofs as long dry weather periods are met with short but intense rainfall events. This requires green roofs to retain maximum volumes of stormwater, while being tolerant to minimal irrigation supplies. The objectives of this study are (i) to quantify the stormwater retention of two substrate mixtures with two plant species under natural rainfall; (ii) to assess the performance of two plant species under two levels of deficit irrigation; and (iii) to compute stormwater runoff reduction and reuse by green roofs and rooftop water harvesting systems for three standard residential plot types in urban Nicosia, Cyprus. A rooftop experiment was carried out between February 2016 and April 2017 and results were used to compute long-term performance. Average stormwater retention of the 16 test beds was 77% of the 371-mm rainfall. A survival rate of 88% was recorded for Euphorbia veneris and 20% for Frankenia laevis, for a 30% evapotranspiration irrigation treatment. A combination of a green roof, rainwater harvesting system and 20-m3 tank for irrigation and indoor greywater use reduced stormwater runoff by 47–53%, for the 30-year water balance computations.

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