Performance evaluation and optimization of a phase-change material -integrated thermochromic glazing for office buildings

This study focused on developing and optimizing a novel smart phase-change material integrated with thermochromic glazing (PCM-TCG) system specifically designed for buildings operated in the hot-summer-cold winter climate zone in China. The optimal integration of these materials for buildings has not been evaluated previously. The thermal and daylighting performance were evaluated with EnergyPlus and Radiance, respectively. The optimization model was established with MATLAB. The optimal solutions identified by NSGA II were further analyzed with Fluent and Radiance. The results indicated that the best solution for each orientation (south, west and east) shared similar features. The phase-change temperature of the phase-change material layer was 25 °C, which is close to the indoor air temperature in summer. The transition temperature of thermochromic glazing (TCG) was around 20 °C. The solar transmittance of TCG was low (around 50% in clear state and 30% in tinted state). The highest visible transmittance of TCG was measured within the feasible range (70%). The optimal thickness of the PCM layer was 11–13 mm to provide adequate thermal mass. The optimal PCM-TCG can reduce annual energy demand by at least 11.3% and improve spatial daylight autonomy by at least 32.7%, compared to low-E glazing.