Subdivided switchable sun protection glazing

The facade, as an interface between the interior and the exterior environment, performs multiple tasks. On one hand it has to ensure the highest possible comfort for building occupants, on the other hand it should contribute to minimizing the energy demand of the building. The detailed requirements on a facade depend on its orientation, local climatic conditions and the building use. Since surrounding conditions vary, an invariant facade system cannot react properly to this variability. In order to overcome this limitation, the authors are developing a switchable glazing unit with adjustable light and energy transmission properties. The functional principle is based on the use of liquid crystal materials. The main component of the switchable glazing is a thin switchable cell which is embedded in an insulating glazing unit. The cell area can be substructured into independently tintable pixels. This ensures maximum utility of the glazing. Currently, a prototype glazing is investigated under real conditions. A floor-to-ceiling glazing is assembled using small sized cells (310 mm x 286 mm) arranged in nine rows and six columns. The cell size is currently limited by the restrictions of the available production capabilities. However, cell integration in other insulating glazing units is possible as well. An effective daylight and shading control can be provided within these glazing units. In order to enhance the effectiveness of the system, the authors are developing different control strategies. The switchable glazing system and its simulation-based performance analysis will be presented in the paper.