Increased Thermal Load in Insulated Glass Units

The oil crises of the 1970s increased the awareness of energy efficiency. Over the past forty years, single- and double-glazed windows have evolved into a range of modern insulating glass solutions for windows and facades. In the mid-1990s the climatic loading of double-glazed units (DGUs) was investigated and design rules were developed for use in practice. Even though those rules were at the time developed for DGUs, they have recently also been used for the design of modern triple-glazed units (TGUs) and multilayer facade systems. So far, no research has posed the question whether this design process, and in particular the temperature differences that have been determined for DGUs, can be applied to other systems. It is therefore the aim of this paper to determine the governing temperatures in insulated glass units (IGUs) under modern boundary conditions. To do this, the thermal behavior of TGUs, multilayer facade systems and solar shading is investigated in detail. A simple calculation model is developed, which can be used to determine the glass temperatures in various facade configurations in accordance with the relevant standards. The results show that while parts of the existing requirements are still valid, there are distinct differences in the requirements for more modern applications.