Browsing by Author "Fitsum Gebreyohannes"

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    Context Based Design and Performance of Fixed Exterior Shading Devices for Thermal Comfort
    (A.A.U, 2021-08) Fitsum Gebreyohannes ; Helmedag Ingo
    With high incident solar radiation on the East-West building facades located especially in tropical climate regions like Ethiopia, the indoor spaces adjacent to glazed facades will become overheated. Among the various techniques of solar heat gain controls in the tropics, applications of fixed exterior shading devices play a major role in blocking incident solar radiation first hand. Through a descriptive research design, this study aims to investigate the effectiveness of such devices as a passive means of solar control as well as identify a context based shading approach that responds well during identified overheated periods in Addis Ababa. To this aim, investigations were conducted on full-glazed buildings that serve as library or office and used fixed exterior shading devices as a passive means of solar control. Questionnaires, secondary data and computer simulations were used to obtain quantitative data. These data were analyzed holistically to gain objective results. On the other hand, shading devices of selected case buildings were adopted and simulated for North, East, South, and West orientations on a mockup model to assess their performance. Their results were compared to a proposed shading design that based the identified overheated periods. This approach yielded a horizontal, Vertical, and End-profile shading angles of 820HSA, 650VSA and 380W EPA for North orientations, 650HSA, 830VSA and 600N & 550S EPA for East Orientations, 600HSA, 550VSA and 380W EPA for South Orientations, and 00HSA, 350VSA and 250N & 250S EPA for West Orientations. Proposed shadings using these shading angles were tested for each orientation on a mockup model. Simulation results showed an average shading of 57.4% North, 54% East, 75.7% South, and 84.2% West to be optimal. The results also showed a monthly total direct solar heat gain reduction ranging from 63.5KWhr/m2 -130.9KWhr/m2 for zones facing North, 73.9KWhr/m2 - 81.4KWhr/m2 for zones facing East,159.9KWhr/m2 - 162.9KWhr/m2 for zones facing South, and 159.9KWhr/m2 - 108KWhr/m2 for zones facing West. These findings can be used as shading design guidelines for radiation vulnerable glazed building facades in Addis Ababa and help improve thermal comfort.