Estimation of a Building Shading Factor in an urban environment (original) (raw)
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The growing need to improve the environmental and energy sustainability of buildings involves the use of solar radiation incident on their surfaces. However, in cities, this task is complicated due to the constructive geometry that leads to shading between buildings. In this context, this work presents a study of solar access to the façades of buildings in cities. The methodology is based on the determination of the incident annual solar radiation in 121 significant points of each façade considering the twelve representative days of the year. To characterize the influence of the different city typologies on solar access, the urban solar coefficient is proposed. A study of two neighborhoods in Cordoba (Spain) with different urban settings have been analyzed. Specifically, two typologies of neighborhoods have been compared: one with "L-shaped" and "U-shaped blocks" and another with "Grouped blocks". For both of them, the Urban Solar Coefficient has been calculated, obtaining a higher mean value for the neighborhood with "L-shaped" and "U-shaped blocks" (0.317) than for the one with "Grouped blocks" (0.260). Accordingly, the results show that urban morphology can influence the Urban Solar Coefficient and solar access. Finally, a regression model for each neighborhood has been obtained in order to determine the dependence of the Urban Solar Coefficient on neighborhood geometry factors.
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Journal of Science , 2020
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International Review of Applied Sciences and Engineering, 2018
Adaptive solar shading systems have in comparison with the traditional systems of shading increased potential ability to improve the quality of the indoor environment and to increase the energy performance of buildings. Their extension allows all-around technological progress, but also the extensive application of large-scale glazing in building envelopes almost in all climatic regions. The literature review shows that the characteristics of the individual adaptive shading systems differ. Some have better performance in the sun protection or in improving the building's energy balance; others for example are better in glare elimination or in redistribution of daylight. The main purpose of this contribution is to provide a classification of the adaptive solar shading systems. In the article are compared merits and shortcomings of adaptive shading systems and are shortly analyzed assumptions of their wider application in central European climate conditions. Attention is also given ...
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Analyzing mutual shading among buildings
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A method for evaluating solar rights and shading requirements in an urban environment is presented. The method is embedded in a CAD tool developed and adapted for this purpose. With this tool one can analyze the mutual shading between buildings and other objects like trees. The purpose of this CAD tool is to allow the designer to plan efficiently the various functions of spaces among different structures, like buildings, as well as determining the location of the passive and active solar collectors. The method is a general one and allows a fast and efficient calculation of the ratio between insolated and total surface areas of any given examined object that is shaded by other irregular and nonplanar elements. The calculation of this ratio is carried out for all the months and hours for which either shading or insolation is required. The information obtained may serve as hourly input data for any dynamic simulation model which evaluates the thermal performance of the different external or internal shading systems. For a visual and a qualitative evaluation of the shadows among buildings, the suggested model permits a very realistic representation, irn which the light source is defined according to the azimuth and the altitude of the Sun at the particular time of examination. The self shading and brightness of the different surfaces and the shadows cast by the various elements at the designated time are then generated and can be evaluated visually. 0 1997 Elsevier Science Ltd. All rights reserved.
Urban morphology indicators for solar energy analysis
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Within the variation of energy performance at urban scale, the relation between solar irradiation and urban form takes a central role. The solar availability on façades which is influenced by the morphology of the urban context, is strictly related to building energy performance indeed. In this paper, we aim at identifying a set of urban morphology indicators (UMIs) that show the most accurate relations with the solar availability on façades (SI y) in the Mediterranean context. The analysis that relates to 14 urban textures of Rome and Barcelona comprises seven UMIs: gross space index, floor space index, façade-to-site ratio, average building height, volume-area ratio, building aspect ratio and sky factor of building façades. The SI y in each texture has been calculated with Heliodon2 software, using normalised models; the relation between SI y and UMIs were investigated using least-square regression analysis. Results suggest that gross space index, façade-to-site ratio and sky factor show very good correlation with SI y (R 2 = 0,91) and could be used to develop a comparative assessment tool of solar performance at fabric scale. This could ease the work of urban planners and architects in the early stage of design, reducing both data and time normally needed to perform solar analyses at urban scale.
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One of the main targets of globally aimed strategies such as the UN-supported Race to Zero campaign or the European Green Deal is the decarbonisation of the building sector. The implementation of renewable energy sources in new urban structures, as well as the complex reconstruction of existing buildings, represents a key area of sustainable urban development. Supporting this approach, this paper introduces the solar-surface-area-to-volume ratio (Rsol) and the solar performance indicator (Psol), applicable for evaluation of the energy performance of basic building shapes at early design stages. The indicators are based on the preprocessors calculated using two different mathematical models—Robinson and Stone’s cumulative sky algorithm and Kittler and Mikler’s model—which are then compared and evaluated. Contrary to the commonly used surface-area-to-volume ratio, the proposed indicators estimate the potential for energy generation by active solar appliances integrated in the building envelope and allow optimisation of building shape in relation to potential energy losses and potential solar gains simultaneously. On the basis of the mathematical models, an online application optimising building shape to maximise sun-exposed surfaces has been developed. In connection with the solar-surface-area-to-volume ratio, it facilitates the quantitative evaluation of energy efficiency of various shapes by the wider professional public. The proposed indicators, verified in a case study presented, shall result in the increased sustainability of building sector by improving the utilisation of solar energy and overall energy performance of buildings.
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