Spatial and temporal changes of outdoor thermal stress: influence of urban land cover types

Green infrastructure (GI) has emerged as a feasible strategy for promoting adaptive capacities of cities to climate change by alleviating urban heat island (UHI) and thus heat stress for humans. However, GI can also intensify the winter cold stress. To understand the extent of UHI within a city as well as the link between outdoor thermal stress both diurnally and seasonally, we carried out an empirical study in Würzburg, Germany from 2018 to 2020. At sub-urban sites, relative humidity and wind speed (WS) was considerably higher and air temperature (AT) lower compared to the inner city sites. Mean AT of inner city sites were higher by 1.3 °C during summer and 5 °C during winter compared to sub-urban sites. The magnitude followed the spatial land use patterns, in particular the amount of buildings. Consequently, out of 97 hot days (AT > 30 °C) in 3 years, 9 days above the extreme threshold of wet bulb globe temperature of 35 °C were recorded at a centre location compared to none at a sub-urban site. Extreme heat stress could be halved with 30–40% cover of greenspaces including grass lawns, green roofs, and green walls with little compromise in increasing winter cold stress.

EVALUATION OF THE POTENTIAL OF GREEN ROOFS APPLIED TO AN URBAN FABRIC USING GIS AND REMOTE SENSING DATA CASE OF THE NADOR CITY / MOROCCO

Accelerated urban growth has affected many of the planet's natural processes. In cities, most of the surface is covered with asphalt and cement, which has changed the water and air cycles. To restore the balance of urban ecosystems, cities must find the means to create green spaces in an increasingly gray world. Green spaces provide the city and its inhabitants a better living environment. This article uses Nador city as a case study area, this project consists in studying the possibility for the roofs to receive vegetation. The first axis of this project is the quantification of the current vegetation cover at ground level by calculating the Normalized Difference Vegetation Index (NDVI) based on Satellite images Landsat 8, then the classification of the LiDAR point cloud, and the generation of a digital surface model (DSM) of the urban area. This type of derived data was used as the basis for the various stages of estimating the potential plant cover at the roof level. In order to study the different possible scenarios, a set of criteria was applied, such as the minimum roof area, the inclination and the duration of the sunshine on the roof, which is calculated using the linear model of angstrom Prescott based on solar radiation. The study shows that in the most conservative scenario, 21771 suitable buildings that had to be redeveloped into green roofs, with an appropriate surface area of 369.26Ha allowing a 63,40% increase in the city's green space by compared to the current state contributing to the improvement of the quality of life and urban comfort. The average budget for the installation of green roofs in a building with a surface area of 100 m2 varies between 60000dh and 170000dh depending on the type of green roofs used, extensive or intensive. These results would enable planners and researchers in green architecture sciences to carry out more detailed planning analyzes.

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

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.

Passive Design Strategies for Energy Efficient Buildings in the Arabian Desert

This study aims to assess passive design features through the extensive modifications of building envelopes to affect the energy efficiency of residential buildings in hot arid climates. In support of the aim of this research, the annual electric energy bill of a typical residential building in Sharurah was collected and analyzed. Then, the DesignBuilder simulation program was used to investigate how different modifications of building envelopes could affect the energy consumption of the residential buildings under common scenarios. Varied thermal insulation, different types of glass, shading devices, and green roof were investigated with this perspective. The simulation results show that thermal insulation can significantly reduce annual energy consumption by as high as 23.6%, followed by green roofs. In contrast, shading devices and glazing system types were fewer superiors. The results also indicate that the effective combination of certain strategies can reduce total energy consumption by 35.4% relative to the base case (BC) of this research.

ANALYSIS FOR IMPLEMENTING GREEN ROOFS ON REINFORCED CONCRETE SLABS. A CASE STUDY IN THE CITY OF TUXTLA GUTIERREZ, CHIAPAS, MEXICO

En la búsqueda de asumir métodos que brinden un mejor confort en el sistema de vivienda, éstos requieren de mejores prestaciones estructurales en las edificaciones actuales. Las prácticas constructivas en la región se han ido desprestigiando con el paso del tiempo, concibiendo edificaciones vulnerables, que dejan expuesto a quienes las habitan. El objetivo de esta investigación fue analizar de forma integral las características técnicas, constructivas y de diseño de losas de concreto armado, en su implementación como estructura de soporte para techos verdes en la ciudad de Tuxtla Gutiérrez, Chiapas, México. Para realizar el análisis se consideraron las propiedades intrínsecas del miembro de soporte (losas), el estado actual en las que estas se encuentran y su diseño bajo regímenes de durabilidad. Tras realizar la investigación se encontró que los espesores de la losa y las cuantías de acero son menores para claros promedio, según lo estipulado por las normas técnicas correspondientes. Los daños por corrosión del acero son esperados y se encuentran bajo un régimen de diseño inadecuado, aunado a la deficiencia durante el proceso constructivo. Las construcciones analizadas y desarrolladas por procesos de construcción formal o de autoconstrucción evidencian patologías similares. La falta de centros de capacitación para los propietarios y los obreros que adopten los métodos de autoconstrucción, así como el poco rigor de las autoridades en el cumplimiento de los reglamentos de construcción se han convertido en una brecha del conocimiento clave. Finalmente, es poco probable la implementación de techos verdes en estas estructuras sin antes realizar cambios significativos en toda la construcción.

Policies for Smart and Sustainable Renovation of Urban Blocks

The objective of this chapter is to recognize the fundamental issues for the low levels of efficiency of the strategies for the energy renovation of the building stock in Greece. The regulatory framework for the energy efficiency and energy renovation is analysed, and the main policies that have been adopted for upgrading the building stock are summarized. Strategies for the energy renovation of buildings have often led to the further deterioration of the built environment as the Greek city is still characterized by the low quality of life and the low energy efficiency of buildings. A tool for assessing the overall benefits of renovation strategies at the urban block scale is presented as a means for the optimization of the efforts and profits. A smart strategy of renovation including thermal insulation, passive design, and green roofs should be context based considering urban form, urban geometry, and climate.

Sensoriamento Remoto aplicado na Avaliação do Impacto do Armazenamento da Água de Chuva no Sistema de Drenagem Urbana

O processo de urbanização, com intensificação no número de construções, resulta na impermeabilização das superfícies na redução da infiltração e do escoamento subterrâneo, e consequente aumento do escoamento superficial. Neste contexto, pesquisadores buscam tecnologias para minimizar tais problemas ambientais, visando a melhoria não só da conjuntura atual, mas também das próximas gerações. Assim, se inserem as tecnologias verdes para mitigação dos problemas ambientais, com destaque para os telhados verdes. Tal cenário de crescimento urbanístico e de problemas ambientais é evidenciado nos grandes centros urbanos, a exemplo do município de Recife-PE, especificamente na Região Político Administrativa RPA2, no bairro de Dois Unidos. Para identificar áreas verdes e urbanizadas, foi empregada a tecnologia do Sensoriamento Remoto com o emprego do Índice de Construção por Diferença Normalizada (NDBI) e, para identificar os pontos baixos das vias e realizar a análise de alagamento foi utilizado o Modelo Digital de Elevação (MDE) com a geração das curvas de nível. Os resultados indicaram que as duas ações investigadas, telhados verdes e caixas d’água, conjuntamente, foram ineficientes na resolução dos alagamentos e que os custos da adaptação dos telhados para implantação das coberturas verdes foram mais onerosos que a aquisição de caixas d’água de 500 L. Por outro lado, tais ações podem contribuir para a redução das dimensões do projeto de drenagem urbana reduzindo o volume de água pluvial excedente (acima da capacidade de escoamento da sarjeta) em cerca de 45% (de 46.033,30 m3 para 20.902,23 m3). Remote Sensing applied to the Impact Assessment of Rainwater Storage in the Urban Drainage SystemA B S T R A C TThe urbanization process, with an increase in the number of constructions, results in the waterproofing of surfaces, reducing infiltration and underground runoff, and a consequent increase in surface runoff. In this context, researchers are looking for technologies to minimize such environmental problems, aiming to improve not only the current situation, but also the next generations. Thus, green technologies are included to mitigate environmental problems, with an emphasis on green roofs. Such a scenario of urban growth and environmental problems is evidenced in large urban centers, such as the municipality of Recife-PE, specifically in the Administrative Political Region RPA2, in the neighborhood of Dois Unidos. To identify green and urbanized areas, Remote Sensing technology was used with the use of the Normalized Difference Construction Index (NDBI) and, to identify the low points of the roads and perform the flood analysis, the Digital Elevation Model was used (MDE) with the generation of contour lines. The results indicated that the two actions investigated, green roofs and water tanks, together, were inefficient in resolving the floods and that the costs of adapting the roofs for the implementation of green roofs were more expensive than the purchase of water tanks from 500 L. On the other hand, such actions can contribute to reducing the dimensions of the urban drainage project by reducing the volume of excess rainwater (above the drainage capacity of the gutter) by about 45% (from 46,033.30 m3 to 20,902.23 m3).Keywords: urban drainage, green roof, water tanks.