Context Based Design and Performance of Fixed Exterior Shading Devices for Thermal Comfort
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Date
2021-08
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A.A.U
Abstract
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.
Description
Keywords
Fixed Exterior Shading Devices, Glazing, Shading Design, Simulation, Solar Control, Solar Radiation, Thermal Comfort