THE IMPACT OF SOLAR FILM ON THE FA ADE THERMAL PERFORMANCE AND COOLING ENERGY CONSUMPTION

Abstract

Against the backdrop of global warming and increasing reliance on air conditioning, finding a cooling method that enhances thermal comfort while saving cooling energy consumption has become crucial. By taking university buildings as a research setting, this study focuses on solar film, one of the widely utilized passive cooling solutions to evaluate its impact on thermal performance and cooling energy consumption of educational building in tropical climate. The research commenced with experiments in an unoccupied room comparing scenarios with and without solar films on windows. The experiments demonstrated solar film's effectiveness in reducing the average and peak value of indoor mean radiant temperature by 0.7°C and 1.5°C respectively and reducing the short-wave radiation by 58% during the daytime. Subsequently, a parametric study using a validated EnergyPlus energy model assessed the influence of solar film on air temperature and cooling load under varying conditions of Window-to-Wall Ratio (WWR), Solar Heat Gain Coefficient (SHGC), and shading systems. The simulation results reveal that lower WWR and SHGC, coupled with shading, enhance thermal comfort, and reduce cooling energy consumption. Compared to those measures like changing WWR and provision of shading, the most notable impact on indoor air temperature and cooling load reduction is attributed to lowering the SHGC, which is achieved by installing solar films. In addition, the solar film shows superior optimization potential in the scenario with high WWR and no shading devices. Specifically, reducing SHGC from 0.8 to 0.2 using solar film in the scenario with WWR of 0.9 and no shading devices leads to a reduction in daily peak temperatures, 24h-averaged temperatures, and daytime-averaged temperatures by 4.6°C, 14.6°C and 7.2 respectively and annual cooling load by 55%, outperforming the scenarios with lower WWR and shading. A cost-effectiveness analysis was also conducted based on the cooling load result. It’s found that approximately 8 years will be taken to recover the investment of solar film through electricity savings for the E1A research room. However, in cases where external shading is not provided, the solar films can provide better economic returns. In the future, it is advisable to consider more façade factors and their interactions influencing the effectiveness of solar film and scale up the building energy model to improve the generality of the findings.