Ethiopian Institute of Architecture, Building Construction and City Development

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Browsing Ethiopian Institute of Architecture, Building Construction and City Development by Subject "& sky view factor"

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    Investigating the Optimum Building Density and Lake Tana’s Breeze in the Case of Bahir Dar City, Ethiopia
    (2021-05) Ngrie, Zelalem; Assefa, Tibebu(PHD)
    The ideal built-up density for proper ventilation of Bahir Dar city is proposed using a method of performing city-scale ventilation assessment based on remote sensing, GIS, and CFD technology. The ventilation of a city depends on the location and background ventilation source. Bahir Dar is a city found south side of Lake Tana and beginning of River Abay. The ventilation background is assessed using meteorological data of wind direction and speed. The numerical simulation of ventilation potential index performance have done using roughness length (RL), sky view factor (SVF) and computational fluid dynamics (CFD). In this study, the roughness length (RL) determined the land use land cover of land sat 8 and the building morphology of existing development. The sky view factor (SVF) is estimated and calculated by using 30m high resolution digital elevation model by SAGA GIS. The general wind pattern and ventilation of the existing high rise building is evaluated by CFD simulation. Generally, the existing ventilation performance of Bahir Dar is relatively high. But in the southern part of the city ventilation is moderate (general) and low. The new structure plan of Bahir Dar city have been checked by the above criteria and the result shows high roughness length and low ventilation performance because of high density development proposal and block Lake Tana breez’s. Suitability map developed by using multiple criteria; exiting ventilation potential, major ventilation source, urban ventilation corridor buffering standard and sky view factor have been used to produce suitability map of urban ventilation corridor design. The ventilation corridor design result perform a ventilation potential index value 0.4 with low roughness value of 0.5 and high sky view factor 0.67. Accordingly, the municipality of Bahir Dar should adopt an optimal citywide development density of not more than 50%, a minimum of 15m distance between buildings, and a maximum building size (footprint) of 20m x30m.