Blue-green roofs have been utilized and studied for their enhanced water storage capacity compared to conventional roofs or extensive green roofs. Nonetheless, research about the thermal effect of blue-green roofs is lacking. The goal of this research is to study the thermal effect of blue-green roofs in order to assess their potential for shielding the indoor environment from outdoor temperature extremes (cold- and heat-waves). In this field study, we examined the differences between blue-green roofs and conventional gravel roofs from the perspective of the roof surface temperatures and the indoor temperatures in the city of Amsterdam for late 20th century buildings. Temperature sensor (iButtons) values indicate that outside surface temperatures for blue-green roofs are lower in summer and fluctuate less during the whole year than temperatures of conventional roofs. Results show that for three warm periods during summer in 2021 surface substrate temperatures peaked on average 5°C higher for gravel roofs than for blue-green roofs. Second, during both warm and cold periods, the temperature inside the water crate layer was more stable than the roof surface temperatures. During a cold period in winter, minimum water crate layer temperatures remained 3.0 o C higher than other outdoor surface temperatures. Finally, also the variation of the indoor temperature fluctuations of locations with and without blue-green roofs have been studied. Locations with blue-green roofs are less sensitive to outside air temperature changes, as daily temperature fluctuations (standard deviations) were systematically lower compared to conventional roofs for both warm and cold periods.
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Many nature-based solutions are seen as favourable and effective measures to increase urban resilience during more extreme weather events, by for example decrease high temperatures in summer. Since space is often scarce in urban environments, roofs have received increased attention in mitigating the consequences of climate change in urban areas. This resulted in a variety of roof systems of green and blue-green roofs designed as an integral part of the built environment due to their hydrological, insulative and biodiverse capacities. This study examined the impact of blue-green, and conventional roofs on roof surface temperatures, indoor temperatures and insulative properties of the building. Temperature sensors (IButtons) have been used for summer and winter measurements on roofs for early 20th century buildings in the city of Amsterdam (NL).The results indicate the strongest effect of blue-green roofs on surface temperatures in summer, with significantly lower surface temperatures (2-3°C) than for conventional roofs. During winter days, the surface temperatures were not significantly different on blue-green roofs than on conventional roofs. The measurements in the water crate layers of blue-green roofs show an all year-round temperature buffering effect. During hot summer days, the temperature in the water storage of the blue-green roof was much lower than other measured surfaces (up to 12 °C and 7 °C compared to gravel roofs and the blue-green roof substrate, respectively) and also experienced the least diurnal variation. Similarly, the empty water crate layer showed up to 3 °C higher minimum temperatures during cold winter nights. The measurements also show a small positive systematic effect on the indoor environment under a blue-green roof compared to traditional gravel roof type. The variation in indoor temperature is smaller underneath the blue-green roofs compared to the reference roofs during both warm and cold periods (0.19 – 0.35 °C reduction in STD). This suggests that rooms located under a blue-green roof are less sensitive to the outside air temperature and its natural diurnal variation.Although the effect on indoor thermal comfort seems to be small, blue-green roofs contribute to overall greening of the city. Second, thanks to the water storage the potential for growing biodiverse vegetation is higher than on extensive green roofs.
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Online knowledge-sharing platforms could potentially contribute to an accelerated climate adaptation by promoting more green and blue spaces in urban areas. The implementation of small-scale nature-based solutions (NBS) such as bio(swales), green roofs, and green walls requires the involvement and enthusiasm of multiple stakeholders. This paper discusses how online citizen science platforms can stimulate stakeholder engagement and promote NBS, which is illustrated with the case of ClimateScan. Three main concerns related to online platforms are addressed: the period of relevance of the platform, the lack of knowledge about the inclusiveness and characteristics of the contributors, and the ability of sustaining a well-functioning community with limited resources. ClimateScan has adopted a “bottom–up” approach in which users have much freedom to create and update content. Within six years, this has resulted in an illustrated map with over 5000 NBS projects around the globe and an average of more than 100 visitors a day. However, points of concern are identified regarding the data quality and the aspect of community-building. Although the numbers of users are rising, only a few users have remained involved. Learning from these remaining top users and their motivations, we draw general lessons and make suggestions for stimulating long-term engagement on online knowledge-sharing platforms
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The Caribbean Netherlands are dealing with a situation where imported vegetables and fruits are mostly imported and hardly affordable. This leads to consuming unhealthy food and high obesities rates as a consequence. A lack of good agricultural practices with regard to water-smart and nature inclusive agriculture, as well as limited coping capacities to deal with hazards and climate change, results in very limited local production and interest. Initiatives that focused only on agrotechnological solutions for food resilient futures turned out to be ineffective due to a lack of local ownership, which jeopardizes sustainability. Moreover, the 'green' and 'blue' domains are not seen as attractive career perspectives among youth, hampering a bright future for those domains.
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In today’s city environments, extreme weather conditions are a fact oflife. Amsterdam, Mumbai, Nairobi or Sydney… climate change issuesneed to be tackled all around the world.In the last couple of decades, Amsterdam has dealt with largeramounts of rainwater, severe heat stress and a decreased biodiversity.In order to strengthen urban resilience to climate change, blue-green(BG) roofs are increasingly being introduced. BG roofs placean additional water layer underneath the green layer. The idea is thatthese roofs reduce runoff after rainfall by retaining precipitation andmitigate heat stress, caused by increased evapotranspiration (the sumof evaporation from the land surface and transpiration from plants)and a higher albedo effect (the ability of surfaces to reflect sunlight).
MULTIFILE
There is a clear demand for collaborative, knowledge sharing tools for urban resilienceprojects. Climatescan is an interactive, web-based map application for international knowledge exchange on ‘blue-green’ projects around the globe. The tool was applied during the Adaptation Futures & The Water Institute of Southern Africa (WISA)conferences, June 2018, in Cape Town. The use of climatescan by different stakeholders during the event led to recommendations for a better application of the web-based map in Africa and around the world.
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''There is a clear demand for a collaborative knowledge-sharing on climate adaptation and mitigation. As a consequence of urban expansion, green spaces are lost and the available areas for pervious green areas are decreasing. Many cities will experience greater impacts from flooding and heatstress due to climate change. Blue-green and small scale Nature-based solutions (NBS) such as bio swales, raingardens and wetlands offer opportunities to adapt urban areas to the impacts of climate change, but their multiple benefits are often unknown to the wider public. Research suggests that effective management of mitigate flood events and heat stress will be achieved by applying a range of NBS measures at different locations in cities [Majidi et al 2019]. Mapping of these (potential) locations for NBS will raise awareness and contribute to capacity building on climate adaptation. Some open source Climate Change Adaptation Platforms (CCAPs) allow mapping of NBS by citizen science and can help to inform and inspire different stakeholders on the topic of climate adaptation in respective region. The aim of most CCAPs is to facilitate an open and free exchange of knowledge on an international scale. Raising awareness about climate adaptation in urban areas and promoting NBS are also key aims.''
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The concept of Smart Healthy Age-Friendly Environments (SHAFE) emphasises the comprehensive person-centred experience as essential to promoting living environments. SHAFE takes an interdisciplinary approach, conceptualising complete and multidisciplinary solutions for an inclusive society. From this approach, we promote participation, health, and well-being experiences by finding the best possible combinations of social, physical, and digital solutions in the community. This initiative emerged bottom-up in Europe from the dream and conviction that innovation can improve health equity, foster caring communities, and sustainable development. Smart, adaptable, and inclusive solutions can promote and support independence and autonomy throughout the lifespan, regardless of age, gender, disabilities, cultural differences, and personal choices, as well as promote happier and fairer living places.
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Over recent years, there has been an explosion in the number and diversity of projects undertaken to address urban resilience and climate proofing. Sharing the knowledge gained from these projects demands increasingly innovative and accessible methods. This paper details the outcomes of one such initiative: an interactive web-based map application that provides an entry point to gain detailed information of various ‘blue-green’ projects. The climatescan.nl has proven to be a successful tool in several international workshops, not only for field-based practitioners but also for those involved in teaching and research. Further upscaling is needed however if the full potential of such an application is to be achieved.
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