Optimizing the evaluation of building envelope design for thermal performance using a BIM-based overall thermal transfer value calculation

The thermal performance of building envelopes has a profound effect on maintaining indoor environmental conditions and is critical in obtaining an energy-efficient design. Choosing appropriate building envelope materials is one of the most effective ways to manage heat flows, prevent excessive building energy consumption, and maintain a comfortable temperature for occupants. The OTTV standards are popularly used worldwide for assessing the rate of heat transfer through building envelopes. However, manual calculation methods for OTTV are involved functions with various variables and coefficients that need to be considered. Furthermore, computing multiple functions using manual calculation method can be time-consuming and human error can be occurred throughout the completion of the calculation process. Accessing materials' thermal properties from BIM potentially reduce the time required to derive coefficients for the OTTV measurement. Therefore, this research presents a BIM-based approach to provide an automatic assessment of the OTTVs of building envelopes. This study proposes integrating BIM and a developed visual scripting to automatically extract thermal and physical properties from the BIM database for supporting thermal transfer value calculation. The applicability of the proposed system is validated in a BIM model of an office building. The proposed system provides a valuable decision support system for designers to select an appropriate envelope material to achieve an optimum OTTV for optimizing energy-efficient building design. This study proposes integrating BIM and a developed visual scripting to automatically extract thermal and physical properties from the BIM database, and provide a realtime thermal transfer value calculation.