Development of an Optimal Machine Learning Model to Predict CO₂ Emissions at the Building Demolition Stage

The construction industry accounts for approximately 28% of global CO₂ emissions, and emission management at the building demolition stage is important for achieving carbon neutrality goals. Systematic studies on the demolition stage, however, are still lacking. In this study, research on the development of optimal machine learning (ML) models was conducted to predict CO₂ emissions at the demolition stage. CO₂ emissions were predicted by applying various ML algorithms (e.g., gradient boosting machine [GBM], decision tree, and random forest), based on the information on building features and the equipment used for demolition, as well as energy consumption data. GBM was selected as a model with optimal prediction performance. It exhibited very high accuracy with R² values of 0.997, 0.983, and 0.984 for the training, test, and validation sets, respectively. The GBM model also showed excellent results in generalization performance, and it effectively learned the data patterns without overfitting in residual analysis and mean absolute error (MAE) evaluation. It was also found that features such as the floor area, equipment, wall type, and structure significantly affect CO₂ emissions at the building demolition stage and that equipment and the floor area are key factors. The model developed in this study can be used to support decision-making at the initial design stage, evaluate sustainability, and establish carbon reduction strategies. It enables efficient data collection and processing and provides scalability for various analytical approaches compared to the existing life cycle assessment (LCA) approach. In the future, it is deemed necessary to develop ML tools that enable comprehensive assessment of the building life cycle through system boundary expansion.