TWO FAÇADE PANELS INSTALLED ON A WEST FACING WINDOW WITH DIFFERENT PERFORATION RATIOS IN KUWAIT CITY

ABSTRACT Windows directly admit the direct and diffused sunlight into the indoor space, creating a comfortable and productive environment for the occupants. However, an excessive amount of sunlight increases the cooling load demand in summers, creates high light contrast and glare, leading to an uncomfortable visual condition. Therefore, windows are internally or externally shaded to reduce the amount of sunlight at a certain time. In the present research, two façade panels are externally installed on a window. Both façade panels have circular holes of different sizes, and the holes of the two façade panels are aligned. Three sizes of holes are considered: small, medium, and large. The objective of the second façade panel is to provide additional shading to the window at a certain time that mitigates the sunlight through the window, and at the same time, it provides privacy to the occupants by blocking all views except the front view. The results indicate that the perforation ratio of the façade panels with respect to the sun depends highly on the altitude angle of the sun, which affects the heat flux from the window into the indoor space and the illuminance distribution in the indoor space. A façade panel with large holes can reduce the total heat flux into the indoor space by 26.2%, and the reduction is increased to 41% if a second façade panel with large holes is installed. The maximum heat flux reduction of 53.7% can be achieved if two façade panels with small holes are installed. A high illuminance of 692 LUX is found in the area close to the window when a façade panel with large holes is installed, and installing a second single façade panel with large holes reduces illuminance to 81 LUX. In terms of visual comfort, a façade panel with medium holes and two façade panels with large holes are the best.