Spectral, visual, thermal, energy and circadian assessment of PDLC glazing in warm and humid climate

Abstract

This paper detailed the experimental investigation of the Polymer Dispersed Liquid Crystal (PDLC) glazing over visual comfort, thermal performance, circadian entrainment, and energy consumption of an office room in a warm and humid climate. In addition, an elaborated study was carried out on the PDLC glazing's spectral, visual, thermal, and circadian characteristics. The thermal evaluation was carried out with a test cell of size 0.3*0.4 m. It was observed that the internal glass surface temperature was comparatively higher than the external glass temperature. It indicates the high solar gain of PDLC glazing. Under opaque and transparent states, the Correlated Colour Temperature (CCT) and a Colour Rendering Index (CRI, Ra) were almost identical. For an ultraviolet (UV) lamp source, PDLC film reflects most of the radiation under an opaque condition. Circadian Stimulus is 10–20 % more under clear states than the opaque state. A real-time experiment was performed in a test room at Manipal, where the PDLC sheet was pasted on the west-oriented window. Colour rendering and circadian effectiveness were satisfactory. CS was always above 0.3, the minimum requirement for circadian entrainment. Due to the milky appearance of the opaque state, a low solar elevation angle induces more reflection on the workspace, and hence more daylight comes into the interior. Under these conditions, uniformity is less. It is observed that PDLC is most suitable in the south and the north orientation windows for the southern tropical climate. The energy consumption was observed as 0.5 kWh /day.