Global warming is increasing, and buildings with glass envelopes are one of its contributing factors. Glass increases visual comfort but can also increase heat gain, which results in increased energy needs. Indonesian National Standard (SNI) 6389:2020 provides energy conservation strategies for building envelopes, including using external shading devices to reduce the Overall Thermal Transfer Value (OTTV). On the other hand, this strategy can reduce the intensity of natural lighting, thereby increasing the energy needed for artificial lighting. Therefore, optimization is required. This study aimed to evaluate the types and configurations of shading devices that can optimize OTTV and natural lighting performance and to identify how much influence the OTTV variables and natural lighting performance have. The method used was quantitative, with experiments using the Ecotect and Ladybug Tools simulation programs. The results showed that the combination type of external shading device could reduce OTTV to a maximum limit of 16% and maintain the intensity of natural lighting (sDA) within the threshold of 61.8% and free from glare (sGA) by 94.9%. There is a correlation between OTTV and natural lighting performance. The increase in OTTV is directly proportional to the intensity of natural lighting and glare. The highest correlation was found in the vertical type, followed by the horizontal type, and the lowest in the combination.
Hidayat et al. (Fri,) studied this question.