A Smart Window Assembled with Energy Storage and Optical Modulation Capability for Building Energy Saving

Abstract

Phase change materials (PCM) hold promise for enhancing the performance of building transparent envelope. Using PCM alone in window lacks the ability to adjust the indoor light environment, a drawback that photochromic materials can address. Herein, a novel light-modulating PCM called SPCM@PC-film was synthesized via spinning drop method from shaped phase change material (SPCM) and photochromic film (PC film). The transmittance of SPCM@PC-film for high temperature could reach 62.10 % for indoor lighting needs and compared with SPCM, transmittance of SPCM@PC-film was smaller for infrared and ultraviolet rays, showing good light blocking performance. By comparing the adjustment effects of SPCM smart window (W1) and SPCM@PC-film smart window (W2 and W3) on indoor thermal and optical environment, it was found W2 performed best, which faced the PC film to the outdoor side. W2 could reduce indoor temperature and maintain indoor illumination. Furthermore, under simulated outdoor conditions in summer, W2 reduced indoor temperature by up to 1.66 ℃ and kept indoor illumination stable within 2000 lx. Moreover, at noon, W2 cut indoor temperature by 2.75 ℃ at most and illumination by 1088 lx, maintaining at 1704 lx, demonstrating it had ability to create a more comfortable indoor thermal and optical environment.

Keywords: Phase Change Material, Photochromic film, Smart windows, Light modulation, Thermal and optical comfort, Energy saving.