Role Of Green Roofs Research Articles

The Role of Green Roofs in Mitigating Urban Heat Islands in Berlin, Germany

Urban heat islands (UHIs) pose significant environmental and social challenges for cities, particularly in the context of climate change and rapid urbanization. In Berlin, green roofs have emerged as a sustainable solution to mitigate UHIs, offering benefits such as temperature regulation, stormwater management, and improved air quality. This paper explores the environmental impact of green roofs in Berlin, focusing on their ability to reduce urban temperatures and enhance microclimates. It also examines the city’s policies and incentives that promote green roof adoption, alongside successful local projects. However, challenges such as economic constraints, technical barriers, and public engagement limitations hinder widespread implementation. Comparative perspectives from cities like Singapore, Toronto, and Copenhagen provide insights into overcoming these obstacles. By adopting tailored strategies and learning from global examples, Berlin can optimize its green roof programs to address urban challenges and enhance sustainability.

Using Plants of Novel Ecosystems as Resources to Create Green Roofs in Cities’ Adaptation to the Climate Change Process

Using local wild plant resources to create green roofs in urban areas is a sustainable solution that supports cities' adaptation strategies to climate change. Creating extensive green roofs, in accordance with the Nature-Based Solutions concept, supports minimizing the effects of climate change, loss of biodiversity and human health. The aim of this paper is to identify, based on an analysis of published research results, the main criteria for selecting vegetation introduced to green roofs and the role of green roofs in minimizing the effects of climate change in the context of NBS. The data were collected by analyzing the results of studies published in the last 10 years, focusing on plant selection. It was found that species selection often fails to consider plant functional traits. The potential of wild plants in urban-industrial areas for creating green infrastructure and optimizing ecosystem services remains largely unrecognized. However, certain plants with desirable functional traits, originating e.g. from habitats such as post-industrial coal mining waste heaps, show promise in providing functional support to urban ecosystems in minimizing the effects of climate change.

Role of green roofs in urban connectivity, an exploratory approach using landscape graphs in the city of Paris, France

Green roofs provide many ecosystem services, but little is known about the way they contribute to urban functional connectivity. This paper has the following four objectives: (1) to compare the potential green roofs’ role to connectivity in relation to other urban green spaces, (2) to specify the green roofs contribution’s type, (3) to explore the influence of building height integration method and finally (4) to assess the impact on connectivity of simulated greening new roofs. Using a landscape graph approach, we modeled ecological networks of three species groups with different dispersion capacities in the Paris region (France). Then, we computed several connectivity metrics to assess the potential contribution of green roofs to functional connectivity. At a large scale (metropole scale), our results show that green roofs can slightly improve the global connectivity largely through the connections rather than the addition of habitat area. More than a stepping stone function, green roofs would have a dispersion flux function at a local scale. Furthermore, when the difficulty of crossing movement is exponential to the height of buildings, green roofs over 20 m high are mostly disconnected from the ecological networks. In addition to the green roof’s height, our analysis highlights the very strong role played by buildings’ configuration. This study raises promising directions for the integration of building height into the analysis of urban connectivity. Detailed research and long-term biological data from green roofs and green spaces are needed to confirm our results.

The role of green roofs in post COVID-19 confinement: An analysis of willingness to pay

Urban population is becoming less likely to contact with nature. Yet, green infrastructure, as green roofs, provide multiple ecosystem services, as promoting citizens physical and psychological well-being. With the Coronavirus 19 world pandemic public spaces, like parks and other recreational areas, were closed and most citizens were confined to their dwellings. In this context, the need for outdoor space in the housing environment became more necessary than ever. This study is based on a survey performed to citizens living in 35 different countries to identify their access and value given to existing green areas in the home environment during and after confinement, and their willingness to pay (WTP) for an accessible green roof. Results indicate that 68% of respondents missed having a garden during the confinement and the outdoor space value increased after the confinement. Most are willing to pay for a medium sized accessible green roof and their WTP increases if the green area is bigger. WTP for medium sized green roofs is higher in other countries than in Portugal but not significantly different for larger green roofs. To promote private investment in green roofs, citizens WTP should be considered when designing new urban green infrastructure incentive policies.

Drainage flux simulation of green roofs under wet conditions

The role of green roofs in reducing drainage fluxes is known, but despite extensive analysis in the literature, methods to predict the hydrologic performance for a given green roof composition are scarce. These methods are useful for the hydraulic design and for planning regulations that impose specific hydrological responses. This research investigates on the prediction of the drainage fluxes produced below a green roof with initial water content equal to its water retention capacity (worst-case scenario). Laboratory tests were performed to analyse the rainfall-drainage relationship for green-roof and single components (growing media and drainage storage layers) under specific rainfall intensities. Two types of largely used drainage/storage layers and growth media were analysed, both singularly and in combination. The experiments consider two rainfall events lasting 10 min with constant intensity. The results indicate that the Curve Number (CN) method (U.S. Soil Conservation Service) with a simple adaptation can be used to reproduce the green-roof hydrologic behaviour under antecedent moisture conditions comparable with those of the experiments. In fact, the water retention capacity, controlling the water-output initiation below the green roof, can be used as threshold variable of a step function, above which the CN method is applicable and below which drainage fluxes are practically null. Through this position, the CN assignment for a composite greenroof can be consistently estimated using the proprieties of the single components (drainage/storage layer and growing medium) and it provides values that are very close to those of waterproof media and quite higher than those suggested in companion researches. Drainage amounts are predicted with a standard error equal to 1.50 mm, which corresponds to 5.7% of the mean value observed. After rain initiation, the steady state condition of the drainage flux has proved to be markedly affected by the growing medium and drainage layer composing the system, which result effective in discriminating the green roof performance.

Role of green roofs in reducing heat stress in vulnerable urban communities—a multidisciplinary approach

Green infrastructure, such as green roofs, is increasingly being used to reduce ‘heat stresses’ associated with urban heat island effects. This article discusses strategies to identify vulnerable neighborhoods in the City of Chicago, where green roofs could achieve multiple goals to mitigate urban heat-related challenges. Numerical simulations were performed using the urbanized version of the Advanced Research Weather Research and Forecasting model to predict rooftop temperatures, a representative variable for exposure in this study. The model was dynamically coupled with a physically-based green rooftop algorithm as a part of the urban parameterization within the model. Our approach integrates information from multiple sources: social vulnerability indices (a function of exposure, sensitivity, and adaptive capacity), high-resolution temperature simulations over the urban area, and observed electricity (air conditioning) consumption data. The social vulnerability indicators were used to develop a quantitative heat vulnerability index for Chicago. We found that an analysis of multiple drivers is needed to identify neighborhoods that will likely benefit from mitigation strategies like green roofs. Our case study identified a large number of census tracts in south and west Chicago, along with isolated tracts throughout the city that would strongly benefit from green roof implementation. The tools and methodology from this study can be easily adopted for other urban regions and would be informative for stakeholders and managers, in general, in making adaptation strategies for extreme heat management.

The role of green roofs in mitigating Urban Heat Island effects in the metropolitan area of Adelaide, South Australia

Changing an urban environment and replacing vegetated surfaces with low albedo materials is one of the reasons for increasing temperatures in an urban environment and consequently also one of the key causes of urban heat island effects. In this study, an experimental investigation at the micro-scale and also a numerical simulation at the macro-scale of a typical urban environment in Adelaide were conducted to estimate the potential for mitigating the UHI effect. The results showed that existing low albedo materials such as asphalt, metal roofs and brick pavements contribute to the heat island potential. Also, urban development and a lack of natural vegetation contribute to increased temperatures in cities. The ability of two types of extensive and intensive green roofs to reduce the surrounding micro-climate temperature were monitored. The results showed that they have significant cooling effects in summer time and could behave as an insulation layer to keep buildings warmer in the winter. Furthermore, different scenarios of adding green roofs to the Adelaide urban environment were investigated using the Envi–MET model. The scenario modelling of adding green roofs in a typical urban area in Adelaide, Australia, supported the hypothesis that this can lead to reductions in energy consumption in the Adelaide urban environment. Also an increased use of other water sensitive urban design technologies such as green walls and street trees together with the adoption of high albedo materials is recommended for achieving the optimum efficiency in terms of reducing urban temperatures and mitigating urban heat island effects.

The role of green roofs in sustainable development

Nowadays, due to this fact that city and urbanity have been increasingly expanded, the destruction process of urban green space is developing with more speed which this process makes numerous problems among which we can refer to increase in level of air pollution, reducing urban landscape, increase in respiratory diseases, etc. The green roofs, the gardens which are built in the houses’ roof instead of the land, nowadays have been replaced with urban green space or parks in most of the advanced and overcrowded cities which are faced with shortage of space because of increased construction and reduced surface of land. In this article, first sustainable development, urban green space and its role in sustainable development have been defined and then the green roof and its types and components have been studied and finally two sample of types of green roof have been compared.

Balancing water demand reduction and rainfall runoff minimisation: modelling green roofs, rainwater harvesting and greywater reuse systems

Recent years have seen a growing interest in more distributed approaches towards stormwater management, often integrated with other forms of distributed management of urban water such as water demand management technologies. This paper focuses on the role of green roofs (GR), rainwater harvesting (RWH) and greywater reuse and their integration at the building level. A number of models were developed to simulate these systems, and provide design curves able to simultaneously minimise both total runoff volumes and the amount of potable water used in the building (for irrigation and toilet flushing). The models developed were applied to the design of stormwater infrastructure for the building of the National Gallery, in Athens, Greece. A sensitivity analysis of various model parameters was conducted, with results suggesting, inter alia: (i) a significant decrease of total runoff volumes for rainfalls of medium-to-small return periods; (ii) a significant influence of the plant factor on water requirements (with implications for selecting vegetation for GR in a Mediterranean climate); and (iii) a significant impact of latent heat peaking during the months of June and July. The trade-off, on runoff volumes, between percentage of green roof area and the dimensions of the water storage tank was also investigated. The results suggest that the most preferable solution for conserving potable water was RWH combined with greywater recycling, while for runoff minimisation the best option was the combination of green roof and greywater recycling.

The Role of Green Roofs as a Source/sink of Pollutants in Storm Water Outflows

Green roofs are increasingly used as sustainable urban drainage systems due to their retention and detention capacity; however, the impact of green roofs in term of water quality is still a debated issue among researchers. A monitoring programme was carried out at the University of Genoa on a full-scale experimental site to assess the quality of storm water outflows. As for rainfall, the bulk deposition (dry and wet fractions) is collected to evaluate the role of the overall atmospheric deposition in altering storm water quality. The pollutant load observed in the green roof outflow is limited; concentration values for solids and metals are lower than those generally observed in storm water runoff from impervious surfaces. Suspended solids and Chemical Oxygen Demand (COD) are below respectively 10 and 20 mg/l, on average; as for heavy metals, copper and zinc are equal to 30 μg/l on average, while iron is equal to 120 μg/l. The Event Mean Concentration (EMC) statistics of the pollutant loads associated with the rainfall and outflow have been compared and discussed. The observed green roof behaviour as a sink/source of pollutants with respect to the atmospheric deposition is also investigated based on both concentration and mass. Results demonstrate that: green roof behaves as a source with respect to solids, COD and potassium while zinc and mainly copper are retained within the green roof stratigraphy. The resulting mass delivery behaviour reveals that no significant first flush occurs for pollutant constituents irrespective of the hydrologic characteristics and pollutant sources.

The role of Green Roofs on Reducing Heating and Cooling Loads: A Database across Chinese Climates

This paper aims to use detailed modelling techniques and develop a database for assessing in a quick and easy way the energy performance of green roof designs across a range of Chinese climates. The focus is on heating and cooling loads by calculating indoor temperatures using the EnergyPlus simulation tool. The study covers 5328 configurations by varying model parameters such as location, climate, seasonal periods, glazing type, wall insulation levels, roof insulation, soil thickness and condition, and vegetation density characteristics. It was found from the results that green roofs can offer significant energy savings for heating and cooling loads if they are applied on roofs without insulation but only limited energy savings where heavy insulation on the roof is also applied. This database can prove to be a useful tool to the practitioners who want to perform rapid assessments of the potential energy savings that could be gained from a green roof installation in a Chinese location.