Enhanced engineered calculation of the temperature distribution in architectural glazing exposed to solar radiation

The precise assessment of the temperature distribution on glass panes, whether they are single windows or façade components, is of paramount importance for the safety and durability of building skins, because many experienced breakages are due to the thermal stress resulting from solar radiation. Here, an enhanced engineered method for the calculation of the temperature field in the panel is presented, which takes into account the different heat exchange phenomena that influence the temperature distribution. The possible presence of shadows and of a contouring frame is considered by dividing the panel in regions considered to be thermally homogenous and, for each region, the time-dependent temperature is evaluated by establishing a transient energy balance. The proposed model is compared, both from a qualitative and a quantitave point of view, with the formulations of current Standards and design rules. Paradigmatic case studies are considered, taking into account the daily and seasonal variations of the external temperature and solar radiation. The effects of the size and shape of the shaded regions are also investigated in a parametric analysis. Once the temperature distribution is known, the stress state in the glass can be readily calculated with most commercial FEM codes.