Decarbonization in green building rating systems: A systematic review on embodied and operational carbon credits

The construction industry is a major contributor to global carbon emissions. Although Green Building Rating Systems (GBRS) are widely used to promote sustainability, their treatment of whole-life carbon remains uneven, with operational carbon generally receiving greater emphasis than embodied carbon associated with material production, transportation, and end-of-life stages. While life cycle assessment (LCA) is well established at the building-project level, its incorporation within GBRS remains fragmented. Existing GBRS literature primarily compares high-level sustainability categories and does not systematically map carbon-related credits to life-cycle stages or examine differences in LCA boundary definitions, governance structures, and verification mechanisms across systems. This study is the first to conduct a standardized life-cycle carbon mapping of carbon-related criteria across major GBRS and to evaluate their capacity to function as whole-life carbon accounting and governance frameworks for both embodied and operational emissions. In addition, this review explicitly reports the relative weighting of embodied versus operational carbon across GBRS, highlighting that most systems strongly prioritize operational carbon, while embodied carbon remains underrepresented, and that DGNB is the only system allocating more than 50% of its carbon-related credits to embodied emissions, alongside key inter-system differences in boundary coverage, Environmental Product Declaration use, and governance maturity. Based on these findings, the study outlines pathways to strengthen GBRS by integrating cradle-to-site LCA, improving material transparency, and supporting low-carbon design and construction strategies across the building life cycle. Overall, this review provides evidence-based insights to support the integration of embodied and operational carbon within GBRS and to enhance their role in advancing whole-life decarbonization of the built environment.