Project

Green infrastructures / green roofs

Goal: Green infrastructures - resilient cities.
Assessment of plant species and susbstrates to be used in green roofs.
Evaluation of green roofs to support stormwater management and water reuse.

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Cristina Sousa Coutinho Calheiros
added 3 research items
Green roofs are gaining interest as nature-based solutions (NBS) to counteract with several environmental and socio-economic problems associated to urban sprawl and climate change. The challenge is to transform the built environment through the inclusion of NBS. Taking advantage of the existing space in the top of the buildings, the integration of green roofs will support the cities’ transition towards circularity and resilience. They provide several ecosystem services and can act as multifunctional and decentralized units. In order to boost these services, green roofs need to be effectively incorporated and replicated in the urban landscape. Different configuration of systems may be considered depending on the challenges that the city foresees. To fully implement green roofs, it is important that (i) barriers are identified and overcome, (ii) standardization is set to grant liability, (iii) policies, incentives, and strategies are properly established, (iv) organizations delivering NBS services are leveraged, and (v) awareness and dissemination promotion, as investment in education, are considered. This paper intends to give an overview of the importance of green roof integration in the urban environment considering the dimensions of the building and the city, having underlined their contribution to circularity and cities’ resilience.
Water in the city is typically exploited in a linear process, in which most of it is polluted, treated, and discharged; during this process, valuable nutrients are lost in the treatment process instead of being cycled back and used in urban agriculture or green space. The purpose of this paper is to advance a new paradigm to close water cycles in cities via the implementation of nature-based solutions units (NBS_u), with a particular focus on building greening elements, such as green roofs (GRs) and vertical greening systems (VGS). The hypothesis is that such “circular systems” can provide substantial ecosystem services and minimize environmental degradation. Our method is twofold: we first examine these systems from a life-cycle point of view, assessing not only the inputs of conventional and alternative materials, but the ongoing input of water that is required for irrigation. Secondly, the evapotranspiration performance of VGS in Copenhagen, Berlin, Lisbon, Rome, Istanbul, and Tel Aviv, cities with different climatic, architectural, and sociocultural contexts have been simulated using a verticalized ET0 approach, assessing rainwater runoff and greywater as irrigation resources. The water cycling performance of VGS in the mentioned cities would be sufficient at recycling 44% (Lisbon) to 100% (Berlin, Istanbul) of all accruing rainwater roof–runoff, if water shortages in dry months are bridged by greywater. Then, 27–53% of the greywater accruing in a building could be managed on its greened surface. In conclusion, we address the gaps in the current knowledge and policies identified in the different stages of analyses, such as the lack of comprehensive life cycle assessment studies that quantify the complete “water footprint” of building greening systems.
Green building–integrated systems and technologies (e.g., green roofs (GR) and walls (GW)) are classified as nature-based solutions (NBS) in the context of urban green infrastructure (GI), which contribute to add both natural elements and processes, as a result of locally designed, resource-efficient, and systemic interventions in cities. They have also been considered to address several urban challenges towards cities’ circularity. The European Union (EU) Biodiversity Strategy and the Action Plan recently adopted by the European Commission, represent a comprehensive long-term programme aspiring to protect nature and reversing the ecosystem degradation by 2030. Sustainable and resilient societies under the challenge ‘innovating with nature’ are the leading aim of the EU Research and Innovation (R&I) policy agenda goals on NBS and re-naturing urban areas. The European GI/NBS Associations build the bridge to provide a network among stakeholders from academia, municipalities, entrepreneurs and private-sector entities and other non-governmental organisations, by creating a platform to build and share knowledge and create collaboration on sustainable GI/NBS, regarding building-integrated vegetation approaches as well as related policies, regulations and technical guidelines. The commitments of the foundations to encourage and promote the advanced adoption of green urban infrastructure practice and planning as part of the built environment, drive active efforts to support NBS innovation objectives and the transition from ‘grey to green’ infrastructure. The present manuscript aims at reflecting the crucial role of the Associations on GI/NBS, mainly GR and GW, to develop local frameworks applying innovative plans of action, and allocate R&I opportunities implementing relevant and inclusive urban regeneration solutions. Within this context, it will be highlighted the example of the Portuguese National Association of Green Roofs.
Carla Pimentel-Rodrigues
added a research item
Nowadays it is imperative to assess the effects of climate change and develop mitigation and adaptation measures, particularly in urban environments, as cities will comprise 2/3 of the world's population by 2050, according to the UN. The use of rainwater in buildings can be a good solution to reduce flood peaks of stormwater in public areas, which may increase as a result of climate change, but also to increase water efficiency in buildings. Indeed, hydric stress is increasing on a global scale (especially in the Mediterranean basin) and it is imperative to search for measures to face these consequences. On the other hand, the use of green roofs (GR) in buildings can also bring many advantages, since it also cushions peak flows of stormwater in cities and increases the number of green infrastructures as well as all its associated benefits. Thus, it is possible to state that the GR technology combined with rainwater harvesting systems (RHS) is particularly promising, pointing to the importance of developing studies that help the combined design of these systems, specifically runoff coefficients. The contributions of roofs to environmental sustainability can be further enhanced by the inclusion, for example, of photovoltaic panels, which conduces mitigation of climate change by increasing the production of renewable energy. In Portugal, a project is under development for modular roofs involving these three technologies, seeking to contribute to greater future sustainability in urban environments. The project involves research related to these different technologies and their integration, and in this paper we present the first results obtained in relation to runoff coefficients, in view of the combination of the green roof with a rainwater harvesting system in regions with a Mediterranean climate. The theoretical results show low values and wide variations in the runoff coefficients, with a minimum of 0.04 and maximum of 0.14, in terms of annual averages, which are significantly lower than the values that are usually suggested in the bibliography. Experimental tests to validate these results are in progress.
Cristina Sousa Coutinho Calheiros
added a research item
Questions arise concerning the way ecosystems inspire the design of the environment that undergoes human intervention. Planting vegetation on rooftops, as green roofs, brings numerous environmental, economic and social benefits. In order to better understand and to manage green roofs as sustainable urban ecosystems it is important to consider an interdisciplinary approach at a higher education level. This manuscript presents an exercise designed to support the understanding of green roofs as urban ecosystems through a conceptual model, acting as a facilitator tool to communicate across different disciplines and enabling to communicate and convey information in a graphic language. The exercise was implemented during an Erasmus Plus Project workshop and 16 participants with different backgrounds were engaged. Diverse outcomes were achieved in accordance with the participants’ background, allowing the connection of diverse areas of expertise. As a result, the study shows how conceptual modelling can contribute to an interdisciplinary approach and therefore promoting a better integrated solution for socio-ecological problems. As such the study gives step forward in the practice of an Education for Sustainable Development. Keywords: green roofs, ecosystem services, conceptual modelling, education for sustainability, higher education
Cristina Sousa Coutinho Calheiros
added a research item
As paisagens são expressões territoriais assumidas pela natureza. As paisagens urbanas não são mais do que o reflexo centralizado da imposição das tendências do homem sobre elas ao longo do tempo, que reflete também a sua identidade. Atualmente evidenciam-se processos de perda, fragmentação e descontinuidade de habitats na cidade e a degradação da qualidade de vida em territórios urbanos. Para além disso a sua vulnerabilidade é exacerbada pelos impactos de eventos climáticos extremos como ondas de calor e pluviosidade. Paisagens urbanas sustentáveis terão que evoluir a partir da inventariação das paisagens existentes num contexto económico, ambiental e social.
Cristina Sousa Coutinho Calheiros
added a research item
Green roofs are an increasingly trend in urban areas as they provide unquestionable ecosystem services. The environmental benefits they provide derive from their functioning as ecosystems so, the substrates and plant species selected to be used in green roofs can greatly influence their performances. In the present research three substrate types: a standard substrate (S) (expanded clay and vegetable soil); a technical substrate (T), and a recycled substrate (R) were tested in mesocosms. Each of these mesocosms were planted with two plants of: Sedum album (Sa), Armeria maritima (Am) and Rosmarinus officinalis var. prostratus (Rp). Substrate characterization showed a superior water retention capacity of S, the lower particle density and a porosity close to that of T (47.7%). Determination of cover areas for Sa and Am and determination of stems and branches growth of Rp was made to monitor plants development. The plants did not show better growth in S, and Sa even grew better in T and R. Microfauna density varied with substrate and time. This suggests substrate composition may be designed to meet specific requirements that contribute for the development of a desirable microfauna to enhance plants development.
Cristina Sousa Coutinho Calheiros
added a research item
Green roofs have been described as technical solutions to overcome urban environmental problems, such as decrease of vegetation and stormwater management. In the present study, two pilot 20 m2 extensive green roofs were implemented in an urban Mediterranean region, at a 1st storey on a warehouse building structure, in order to test the adequacy of different substrates for supporting aromatic plants (Lavandula dentata, Helichrysum italicum, Satureja montana, Thymus caespititius and Thymus pseudolanuginosus). Experimental substrates included expanded clay and granulated cork as main components, supplemented with organic matter and crushed egg shell. A commercial substrate that obeys to FLL guidelines was also tested. Plant growth was assessed and compared within each platform. All experimental substrates proved to be adequate for vegetation growth, with the combination of 70% expanded clay, 15% organic matter and 15% crushed egg shell showing the best results regarding plant establishment and growth over time. Water runoff quality parameters - turbidity, pH, conductivity, NH4+, NO3−, PO43− - met standard values required for water reuse for non-potable purposes, such as toilet flushing or irrigation. Preliminary qualitative thermographic measurements comparing surface temperature of different plant species and the substrate showed that temperature of vegetation surface was lower than substrate, reinforcing green roofs benefits of lowering air temperature in their surroundings. The present research shows that aromatic vegetation combined with clay substrates are suitable for green roofs located in countries of the Mediterranean region.
Cristina Sousa Coutinho Calheiros
added a research item
Green infrastructures – The trend of green roofs in cities The current trend is to conceive urban management strategies that envisage green infrastructures comprising a multifunctional landscape. In turn, it is intended that they give answer to the societal challenges, considering also the potential of natural capital with high resilience to the climate conditions and be economically feasible. Green roofs play, in this perspective, a central role. Engineering may give an important contribution in this field.
Cristina Sousa Coutinho Calheiros
added a research item
Green roofs (GRs) are becoming a trend in urban areas, favouring thermal performance of buildings, promoting removal of atmospheric pollutants, and acting as possible water collection spots. Rainwater harvesting systems in buildings can also contribute to the management of stormwater runoff reducing flood peaks. These technologies should be enhanced in Mediterranean countries where water scarcity is increasing and the occurrence of extreme events is becoming very significant, as a result of climate change. An extensive pilot GR with three aromatic plant species, Satureja montana, Thymus caespititius and Thymus pseudolanuginosus, designed to study several parameters affecting rainwater runoff, has been in operation for 12 months. Physico-chemical analyses of roof water runoff (turbidity, pH, conductivity, NH4(+), NO3(-), PO4(3-), chemical oxygen demand) have shown that water was of sufficient quality for non-potable uses in buildings, such as toilet flushing. An innovative approach allowed for the development of an expression to predict a 'monthly runoff coefficient' of the GR system. This parameter is essential when planning and designing GRs combined with rainwater harvesting systems in a Mediterranean climate. This study is a contribution to improving the basis for the design of rainwater harvesting systems in buildings with extensive GRs under a Mediterranean climate.
Cristina Sousa Coutinho Calheiros
added a project goal
Green infrastructures - resilient cities.
Assessment of plant species and susbstrates to be used in green roofs.
Evaluation of green roofs to support stormwater management and water reuse.