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Please use this identifier to cite or link to this item: http://hdl.handle.net/123456789/15252
Title: IMPROVING THE THERMAL QUALITIES OF THE EXISTING STREETS OF DIRE DAWA CITY BY USING URBAN DESIGN ELEMENTS
???metadata.dc.contributor.*???: TIBEBU Assefa
AYELE, ASMAMAW
Keywords: Temperature Variation;Humidty;Wind Speed;SolarRadiation
Issue Date: Dec-2016
Publisher: Addis Ababa university
Abstract: This study discusses the contribution of street design, i.e. aspect ratio or height-to-width ratio (H/W) and solar orientation towards the development of a comfortable microclimate at street level for pedestrians. The investigation was carried out by using the three-dimensional numerical model ENVI-met, which simulates the microclimatic changes within urban environments in a high spatial and temporal resolution. Model calculations are run for a typical summer day in May 10, 2016 in Dire Dawa, Ethiopia (9.60N, 41.850E, 1200m a.s.l.), a region characterized by a hot and dry climate. Symmetrical urban canyons, with various height-to-width ratios (i.e. H/W ¼ 0.5, 1, and 2) and different solar orientations (i.e. E–W, N–S, NE–SW and NW–SE), have been studied. Special emphasis was placed on a human bio-meteorological assessment of these microclimates by using the physiologically equivalent temperature (PET). The analysis discussed the hourly temperature variation, humidity, wind speed and solar radiation in detail. Sun path and shadow length calculation for Dire Dawa city was made to compare the comfort of each street. Street width, building height, aspect ratio and street orientation were taken as major variables for the analysis. The results showed contrasting patterns of thermal comfort between shallow and deep urban streets as well as between the various orientations studied in a typical 12m street. A comparison of all streets revealed that the time and period of day during which extreme heat stress occurs, as well as the spatial distribution of PETs at street level; the comfort of pedestrian depend strongly on aspect ratio and street orientation. This is crucial since it will directly influence the design choices in relation to street usage, i.e. streets planned exclusively for pedestrian use or including motor traffic, and also the time of frequentation of urban spaces. Both investigated urban factors can mitigate extreme heat stress if appropriately combined.
Description: The Thesis entitled “Improving the Thermal Qualities of The Existing Streets of Dire Dawa City by using Urban Design Elements” is my own original work and has not been presented for a degree in any other university or institution
URI: http://hdl.handle.net/123456789/15252
Appears in Collections:Thesis - Urban Design and Development

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ACKNOWLEDGEMENT.pdfIMPROVING THE THERMAL QUALITIES OF THE EXISTING STREETS OF DIRE DAWA CITY BY USING URBAN DESIGN ELEMENTS507.74 kBAdobe PDFView/Open
chapter 1.pdf564.22 kBAdobe PDFView/Open
chapter 3.pdf2.59 MBAdobe PDFView/Open
chapter 2.pdf1.28 MBAdobe PDFView/Open
Chapter 4.pdf878.56 kBAdobe PDFView/Open
Introduction.pdf 1.pdf640.83 kBAdobe PDFView/Open
Chapter 5.pdf895.38 kBAdobe PDFView/Open
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