Thermal loads in triple glazing — experimental and numerical case study

Abstract

Increasing demands with regard to size, energy efficiency and user comfort result in complex façade elements, often consisting of multi-pane insulating glass units with thermal or solar control glass and shading elements. This leads to numerous structural and environmental factors which influence the development of temperatures in glass panes and thus thermal stress. Glass breakage due to thermal stress is already experienced in practice. Nevertheless, there are no generally valid and introduced engineering approaches for determining thermal loads under affecting all significant key influence factors for complex façade elements or triple glazing. In this contribution to the subject, the temperatures of triple glazing with a functional coating and various shading elements was investigated under outdoor exposure. The environmental parameters and temperatures of the glass panes were recorded and validated by transient simulation. This paper outlines the experimental monitoring and presents the validation of the simulation results. The heat transfer coefficient has proven to be one of the most influential factor in the simulation of glass temperatures. Since the heat transfer coefficient cannot be directly determined by measurement, a number of calculation approaches were evaluated, leading to dimensioning assumptions for the simulation of thermal loads in triple glazing.