Thermal analysis of architectural glazing in uneven conditions based on Biot's variational principle: Part II-validation and case-studies

The thermal state in architectural glazed panes strongly depends on the properties of the components, on inclination, on solar radiation and, most of all, on projected shadows on the surface. The unevenness of temperature distribution in the pane, often referred to as "thermal shock", can produce stresses leading to breakage. Determining the temperature field is therefore of primary interest in the design. In Part I of this work, a semianalytical FEM formulation, based on Biot's variational principle for heat transfer (hence, called in short BVM-FEM) has been presented. Here, the BVM-FEM formulation is first validated by means of comparison with the direct solution of the differential form of the thermal problem, analyzed under either fixed or variable outdoor conditions. Successively, it is used to calculate the temperature field in the paradigmatic examples of rectangular monolithic glass panes, with cast shadows and contour frames. The worked case-studies emphasize the importance of heat exchange by conduction between regions receiving a different amount of solar radiation, which is found to be localized in narrow strips across the interface. The code recognizes the temperature and heat-flux peaks occurring at the corners of differently irradiated regions, which pose the greatest risk to glass integrity.