Analysis of transparent building envelope renovations for indoor thermal comfort in an educational building

Purpose - The buildings should be designed by respecting the environmental and climatic conditions they are in and their orientation. Then, the characteristics of the building envelope (BE) play an important role in building energy consumption and user comfort. In fact, the type and material of glazing is one of the crucial parameters for BE. The transparency ratio of BE also determines the facade performance. The aim of this study is to analyze the different renovation scenarios for BE with high transparency of an educational building (EB) in hot summer weather to obtain indoor thermal comfort (ITC) for users. Design/methodology/approach - The methodology includes thorough measurement of existing ITC using TESTO-440 and simulation of each retrofit scenario using DesignBuilder building energy modeling (BEM) simulation software with Energyplus to determine optimal thermal comfort. Since the study focuses on the impact of the transparent BE on summer ITC, four main scenarios, naturally ventilated (NV) facade, film-coated glass facade, replacement of glazing with opaque units, sun-controlled facade with overhang and solar shading, were simulated. The results were analyzed comparatively on both performance and cost to find the best renovation solutions. Findings - A total of 7 different renovation scenarios were tested. Simulation results show that passive systems such as NV have limited contribution to indoor air temperature (IAT) improvement, achieving only a 4 degrees C reduction while offering the lowest cost. A film coating resulted in a reduction of 3-6 degrees C, but these applications have the highest cost and least impact on ITC. It was found that exterior coating leads to better results in film coating. Preventing and limiting the increase in IAT was achieved by reducing the transparency ratio of BE. The best results were obtained in these scenarios, and it was possible to reduce IAT by more than 10 degrees C. The best performance/cost value were also obtained by decreasing transparency ratio of roof and sun control. Research limitations/implications - Since the high transparency ratio has a negative impact on summer comfort, especially in hot climate zones, summer ITC was prioritized in the renovation solutions for the case building. Originality/value - The study's findings present a range of solutions for improving the ITC of highly transparent buildings. The solutions can help building managers see the differences in renovation costs and their impacts on ITC to decrease the cooling load of the existing buildings.