ABSTRACT
Building envelopes made of glass are established and popular in modern architecture. For economical and structural reasons, tempered glass with increased strength and thermal shock resistance is used for these high-quality façade projects. The common tempering process creates a residual stress state, which cannot be generated homogeneously over the entire glass surface, despite relatively constant tempering parameters.
Even the slightest deviations between the principal stresses generate a birefringence of light, known as anisotropy effects in the façade, under certain observing situations. These disturbing effects in the form of white or rainbow-like spots or line patterns currently lead to considerable practice problems, which cannot be solved so far. For some years now, anisotropy scanners have made it possible to control anisotropies after the tempering process quantitatively. Investigation of the correlation between the real installation situation and lighting conditions and the measurements does not yet exist. In this article, two test facilities and a concept for evaluating anisotropy effects are presented.
