Evaluation of thermal performance for a smart switchable adaptive polymer dispersed liquid crystal (PDLC) glazing

Abstract

A new class of smart window technologies are gaining interest as they have the functionality to control dynamic solar radiation, shading, ventilation and energy production. They are capable of improving buildings’ energy performance by adapting to different climate conditions and bring thermal and visual comfort for occupants. Polymer-dispersed liquid crystal (PDLC) is a smart switchable window that changes its optical transmissions from translucent to transparent when an alternating electric current stimulus is introduced. The present paper discusses the results of an indoor investigation for the optical and thermal performance of a PDLC glazing system. The spectral transmittance of the investigated PDLC was evaluated for both the translucent and transparent states using UV–vis–NIR (1050) spectrophotometer. In addition, the thermal investigation was carried out in an indoor condition utilising a test cell equipped with a small scale of PDLC glazing, which was exposed to (1000, 800, 600, 400 W/m2) solar radiation for 180 min. The optical evaluation showed that the investigated PDLC glazing offered low transmission for UV (8%) and NIR (44%) in the translucent state, respectively. The result of SHGC was 0.68 and 0.63 for the transparent and translucent states, respectively, which indicates that the investigated sample could be more effective in reducing heat loads in a cold dominated climate. The U-value for the PDLC glazing was 2.79 W/m2 for the transparent and 2.44 W/m2 translucent.