NO-94-14-3 -- A New Method for Predicting the Solar Heat Gain of Complex Fenestration Systems - 2. Detailed Description of the Matrix Layer Calculation PDF

A new method of predicting the solar heat gain through complex fenestration systems involving nonspecular layers, such as shades or blinds, has been examined in a project jointly sponsored by ASHRAE and the US Department of Energy (DOE). In this method, a scanning radiometer is used to measure the bidirectional radiative transmittance and reflectance of each layer of a fenestration system. The properties of systems containing these layers are then builtup computationally from the measured layer properties using a transmission/multiple-reflection calculation. The calculation produces the total directional-hemispherical transmittance of the fenestration system and the layer-by-layer absorptances. These properties are, in turn, combined with layer-specific measurements of the inward-flowing fractions of absorbed solar energy to produce the overall solar heat gain coefficient. A companion paper outlined the method and provided the physical derivation of the calculation. In this second of a series of related papers, the detailed development of the matrix layer calculation is presented.

KEYWORDS: calculating, solar heat gain, windows, shades, blinds, measuring, radiometry, reflection factor, transmittance, properties, optical properties, research, solar radiation.