Accurate Transmittance Measurements on Hollow Glass Blocks

Michele Zinzi, ENEA-SIRE-DINT CR Casaccia
Augusto Maccari, ENEA-TML CR Casaccia
Piero Polaato, Stazione Sperimentale del Vetro
Giuseppe Rossi and Massimo Sarotto, IEN Galileo Ferraris

Keywords

Abstract

Hollow glass blocks are square shaped double glazing units available in different sizes and used for building applications. Several kinds of hollow glass blocks are commercially produced in different thickness (of the single panes and of the component), in the surface processing (obtained by acid or sand treatment), in the internal shape of the component panes and in the color. There are some intrinsic difficulties when performing optical measurements on glass block. The information available is not sufficient for a proper use of these hollow glass blocks. This work, which tries to supplement this lack of information, consists of three main experimental sections: 1) a comparison of the luminous transmittance measurements on three selected samples using two integrating spheres, 2) the mean transmittance of these samples, obtained as an interpolation of the measurements performed on several points of each block, 3) an evaluation of the bi-directional function of the luminous transmittance, by means of gonioreflectometric investigations. From an accurate knowledge of the properties of the components, the performance for the assigned application can properly be predicted.