Demand Forecasting for the Scale of Underground Space Development in Existing Urban Industrial Areas—A Case Application of Saint-Gobain Industrial Area in Xuzhou City

Against the backdrop of urban renewal, the transformation and functional enhancement of Existing Urban Industrial Areas (EUIAs) play a crucial role. Focusing on the rational development of underground space in EUIAs, this study explores forecasting methods for the development demand of such underground space, aiming to alleviate the contradiction between the protection of industrial heritage and intensive land use in EUIAs. This paper systematically sorts out the forecasting methods for the scale demand of underground space. Firstly, through a literature review, two major categories of factors influencing underground space demand—driving factors and conditional factors—are summarized, and an indicator system consisting of 23 indicators is constructed. On this basis, the modified Delphi method is employed to screen 7 dominant indicators, including the protection value of industrial heritage, the spatial distribution of industrial heritage, existing underground space, development functions, rail transit, spatial location, and surrounding supporting facilities. Based on the matrix of industrial heritage protection levels and land use nature, the development potential of underground space is evaluated, and a demand level correction model is introduced. Demand intensity is quantified through expert experience-based assignment with reference to typical domestic cases, thereby establishing a demand forecasting model for the underground space scale in EUIAs. Finally, the model is applied to the Saint-Gobain Industrial Area. Through the analysis of its industrial heritage value assessment, land use planning, and location characteristics, the areas with demand for underground space are delineated and their levels are corrected, forecasting a total underground space demand of 224,600–454,600 m2. The research results provide a theoretical basis and methodological support for the underground space planning of EUIAs, and offer references for the development practice of similar regions.