A new value of average beam solar heat gain coefficient for innovative daylighting systems

The majority of the fenestration systems are available in the market today are of the type whose solar gain properties can be determined through the u se of a computational procedure. However there is a class of fenestration s ystems (or attachments) that cannot be handled with the conventional proced ures like solar path diagrams and shading masks. This class includes the da ylight systems. These systems are an innovative technology for sunlight red irection or sunlight exclusion. A new formula for the solar heat gain coeff icient (SHGC) is introduced, which can help in the discussion process conce rning the optimization of solar gains through the above mentioned systems. This formula is solar positioned and radiation weighted value and can provi de an accurate way to estimate the energy flux through the window and can b e used as a performance rating methodology for the above mentioned systems. (C) 2001 Elsevier Science B.V. All rights reserved.