Preliminary assessment of visual performance of novel switchable glazing assemblies for glare control in a mediterranean climate

Abstract The control of glare in office environments is often improvised retrospectively using shading devices, typically internal blinds. Consequently, views are blocked, and artificial lighting loads are increased. Today’s glazing technology, particularly that of the IGU (insulated glazing unit) delivers much of the expected performance in terms of heat transfer and indoor natural lighting, but occupant glare discomfort is commonplace, particularly in climates with high solar insolation. This paper provides a preliminary assessment of the visual performance of a novel glazing assembly comprising of two, independently switchable solar-PDLC (solar Polymer Dispersed Liquid Crystal) and SPD (Suspended Particle Device). These switchable interlayer films are intended to control the visible light transmittance into an indoor space. The outcomes of this study will guide the order and assembly combination of a prototype IGU for future full-scale testing from both visual and thermal comfort perspectives. Using a novel scale model approach to represent a typical indoor space with a high glazing ratio and a luminance photometer, the Daylight Glare Probability (DGP) provided by the different states and positioning of the switchable glazing are compared to that provided by conventional static glass under identical field test conditions. Comparisons of the visual appearance of the potential combinations of these technologies were also investigated relative to an unshaded glazing configuration, to assess the ability of switchable films to instantly convert transparent openings into opaque, wall-like elements. The results indicate that the scale-model approach was effective for such preliminary investigations and that more specifically, such a combined switchable glazing assembly does have the potential for reducing glare, and thus merits further investigation in a full-scale study.