A Digital Approach to Green Information Modeling and Performance of Built Heritage: The Chuncao Mansion, Kulangsu

Green performance assessment is crucial for the conservation of built heritage. However, protected buildings often prohibit contact measurements and interior sensors, making traditional methods difficult to apply. To address this issue, we propose a method based on 3D laser scanning point clouds that relies entirely on facade scanning and aims to establish a green information model for monitoring sustainability performance. We selected Chuncao Mansion, an overseas Chinese villa on the World Heritage island of Kulangsu, as a case study; the building features typical passive design strategies. Using terrestrial laser scanning, high-precision point cloud data of the facade were obtained, registered, and denoised to build a complete 3D geometric base. We then extracted key geometric parameters from the point cloud, including veranda depth, clear height between columns, and geometric opening area ratio. These parameters were integrated into a simplified BIM model as green geometric information. Finally, we performed solar simulations based on this model, selecting the winter and summer solstices to quantify the self-shading performance of the “Chugui” curved veranda and the adjacent standard straight verandas. The results show that the mean absolute cloud-to-cloud deviation in overlapping areas is 9 mm, providing a consistent geometric basis for component-level measurement; absolute accuracy requires independent verification. For the southeast-facing veranda, local direct sunlight exposure across the analyzed surface is limited to 0–2 h on the summer solstice, while local exposure in the same area reaches 6–10 h on the winter solstice. A depth-controlled counterfactual simulation confirms that this seasonal regulation is attributed to the combined geometric configuration: the increased depth (4.44 m) secures beneficial winter solar access, while the curvature acts as a more effective lateral shading mask to reduce summer exposure compared to an equal-depth straight veranda. This study proposes a complete non-contact technical workflow covering facade scanning, green parameter extraction, BIM integration, and simulation-based solar performance assessment. The workflow is suitable for protected built heritage and can be extended to similar heritage buildings in hot–humid climate zones, providing a basis for future green assessment and potential low-carbon intervention.