AbstractPrefabrication and modular construction is promoted globally as a sustainable and efficient construction method. The greenhouse gas (GHG) emissions from prefabricated and modular construction have been widely studied and the focus has mainly remained on the measurement of GHG emissions. There has been limited emphasis on the activity-level emission data analysis, and current methods lack a dynamic approach in the analysis of GHG emissions. These limitations contribute to the lack of GHG emissions evaluation and optimization strategies in prefabrication and modular construction projects. To address this knowledge gap, an earned green value management (EGVM) model based on the earned value management theory is developed for setting up a benchmark for evaluating the GHG emissions. Additionally, a two-phase GHG emissions optimization method based on the EGVM model is proposed. This EGVM model and the GHG emission optimization method were applied in a real prefabricated building project. The results demonstrate that this new approach can facilitate GHG emissions management and can improve decision-making in prefabrication and modular construction projects.