Abstract
Solar radiation transmission through plastic shading nets is the most important parameter used to characterize the net type. The diffusion characteristics of solar radiation through nets are still unknown because nets are non-homogeneous materials.
In this study, transmission of solar radiation through a plastic net was characterized by determining: (i) the beam that is diffused during transmission, (ii) the unscattered beam that is transmitted through the net pores and (iii) the beam that is reflected forward on the thread surfaces specularly. Experiments to measure radiation parameters for determining these components were conducted on clear sunny days in Riyadh, Saudi Arabia. Nets with colors and porosities that are most commonly used were selected for the study. The results showed that the diffuse radiation transmitted through the selected nets was enhanced by 17-170% depending upon the structure of the net textures rather than colors. In the tested nets, the contributions of the diffused beam, the unscattered beam and of the forward specularly reflected beam to the total beam transmitted were in the ranges 0.02-0.2, 0.29-0.83 and 0.11-0.52, respectively. These values depended on the colors, texture structures and porosities of the nets. (C) 2010 Elsevier B.V. All rights reserved.