Utilization of combined daylighting techniques for enhancement of natural lighting distribution in clear-sky residential desert buildings

Abstract

Desert buildings are exposed to clear sunny skies almost all year round. Solar rays penetrate into spaces creating a non-uniform daylight distribution and high solar heat gain; affecting both visual and thermal comfort. This paper addressed the usefulness of combing solar screens and light shelves for achievement of efficient daylight performance in a residential living room space. The objective was to harvest daylight while diffusing direct sun rays, thus, reducing artificial lighting and energy use. Simulations were conducted using the Diva-for-Rhino plug-in to interface Radiance and Daysim for the evaluation of annual Daylight Availability according to the minimum required illuminance value. The impact of combined design alternatives and techniques was tested for the purpose of increasing the "daylit" and reducing the "over lit" and "partially daylit" areas. Results showed significant improvements in daylight distribution in all orientations. In the North and South orientations, more than one combined design attained the highest value for "daylit" area, reaching95% and 85% in these orientations respectively. While in the East orientation, only one combination achieved this goal where a 67% "daylit" area was reached. Conclusions recommended alternative means of combining solar screens with light shelves for improvement of daylight distribution for each orientation.