In hot arid desert environments, the solar radiation passing through windows increases the cooling loads and energy consumption of buildings. Shading of windows can reduce these loads. External perforated wooden solar screens were traditionally used for windowsâ shading. However, there is a lack in understanding their performance in a quantitative manner and unavailability of scientific means that could be used for developing new efficient designs that suit the harsh desert conditions. This thesis investigates the impact of changing screen configurations such as perforation percentage, depth, perforation openings aspect ratio and reflectivity on the energy loads, hence defining the most efficient configuration range for various window sizes and orientations. Series of experiments were conducted using the EnergyPlus simulation software for a typical residential building in the Kharga Oasis, located in the Egyptian desert. This research demonstrated that using optimum design of screen configurations could effectively achieve energy savings up to 31% of the total energy consumption in the West and South orientations. Implementing optimum perforation and depth range for solar screen shading system allowed for a larger â window to wall ratioâ that enhances daylighting and view aspects. Optimum WWR for un-screened windows in the severe desert environment of Kharga Oasis was 4%. However same energy consumption was achieved by using screens with WWR of 22%. The highest and most significant savings were achieved in screens having a depth ratio of 1 with an 80% perforation percentage in the West and North orientations, and a 90% perforation percentage in the East and South orientations. Moreover, screens openings aspect ratio was investigated. For, South, East and West orientations, significant energy savings can be achieved by using solar screen with square perforation or rectangles stretched horizontally. However, perforations stretched vertically give better energy performance in North orientation. Results scientifically confirm the effectiveness of the traditionally used colors of the old â Mashrabeyaâ , which were typically dark. Furthermore, the usefulness of utilizing external perforated solar screens in different geographical locations was demonstrated. The screens reduced energy consumption by 25% to 35% in a number of cities that lie between 14Ë N and 40Ë N. Their impact was less obvious in cities that were further north. Simulation results were then verified by conducting parametric runs using simulation-based building energy optimization software â GenOptâ . By combining Generalized Pattern Search and Particle Swarm algorithms, the hybrid GPS/PSO algorithm was employed to increase the chance of finding the minimum energy consumption .The results proved the accuracy of previous simulations. Furthermore, the use of these parametric runs generated different unusual innovative architectural solar screen configurations for each facade that could reduce energy loads considerably. This could help the design of more sustainable energy efficient buildings especially in harsh desert environments, thus adding new methods for Green Buildings design.
School of Sciences and Engineering
MS in Engineering
Committee Member 1
El Zafarany, Abbas
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(2021).Energy efficient configuration or perforated solar screens for residential desert buildings [Thesis, the American University in Cairo]. AUC Knowledge Fountain.
Arafa, Rasha. Energy efficient configuration or perforated solar screens for residential desert buildings. 2021. American University in Cairo, Thesis. AUC Knowledge Fountain.