Spandrel glass is glass that has been rendered near opaque and glazed in wall areas covering structural columns, floors, walls, or other building elements that are intended to be concealed from outside view. Increasing standards of energy efficient initiatives are placing unique and unanticipated demands on spandrel glazing. Recently, attention has been drawn to several incidents in which spandrel glass has experienced solar-induced thermal stress breakage. This document discusses the phenomenon of thermal stress build-up, the factors that contribute to it and potential mitigation options.