Green roofs received increased scientific attention with respect to climate adaptation in urban environments for their hydrological, biodiversity and insulative capacities. Yet, the thermal properties of roofs with an additional water layer underneath the vegetation substrate (blue-green roofs) are not well represented in scientific research. In this field study, we examined the impact of surface temperatures, indoor temperature and insulative properties of blue-green, green, and conventional gravel/bitumen roofs in the city of Amsterdam for early 20th century buildings. Temperature sensor (IButtons) results indicate that outside surface temperatures of blue-green roofs were more stable than for conventional roofs. For instance, for three warm periods during summer (2021) surface substrate temperatures peaked much higher for gravel roofs (+8 oC) or bitumen roofs (+18 oC) than for blue-green roofs. On top of that, during a cold period in winter average water crate layer temperatures remained 3.0 oC higher and much more stable than substrate temperatures of blue-green roofs and conventional roofs, implicating that the blue layer functions as an extra temperature buffer. The effect of lower daily variation of surface temperatures in winter and summer is also reflected by inside air temperatures. Inside temperatures showed that locations with blue-green roofs are less sensitive to outside air temperatures, as daily temperature fluctuations (standard deviations) were 0.19 and 0.23 oC lower for warm and cold periods, respectively, compared to conventional roofs. This effect seems rather small but comprises a relatively large proportion of the total daily variation of 24% and 64% of warm and cold periods respectively.
This article will explore the Cradle to Cradle (C2C) framework for urban environments, focusing on the perception, utilization and maintenance of parks. The case study explores the perception of urban flora and the value of greenery in everyday life in The Netherlands. The reflection section addresses the difference between conventional and C2C approaches to greenery on the one hand and current green management policies and public opinion on the other hand. The author reflects on how urban planning policies can be better geared towards public awareness of C2C, and towards the implementation of ecologically benign management of urban flora. It is proposed that an implementation of urban green management consistent with C2C is feasible and desirable. It is feasible given the favorable shifts in public opinion in relation to urban sustainability, and it is desirable due to the basic cost-benefit analysis and increased need for urban sustainability. This is a post-peer-review, pre-copyedit version of an article published in Urban Ecosystems. The final authenticated version is available online at: https://doi.org/10.1007/s11252-015-0468-2 https://www.linkedin.com/in/helenkopnina/
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