CO2 emissions have a major negative impact on global climate. Buildings are the main contributors to this emission. Several green building rating systems (GBRS) have been developed worldwide to improve building sustainability performance. One of the main criteria in these systems is to minimize carbon emissions. However, there is a significant challenge in standardizing the indicators used to measure and assess these emissions due to varying regional practices and system requirements. This study analysed eight widely used sustainable building assessment systems using a structured procedure to evaluate the efficiency and the level of which these systems measure and assess carbon emissions. The comparison of different practices highlights substantial variations and a lack of consensus, not only regarding the type and optimal number of indicators used in a system, but also concerning the extent and scope of coverage of various sustainable building attributes (SB). Generally, the results show that most of the examined rating systems reflect a low comprehensive coverage. However, the highest coverage of carbon emission related indicators is found in the materials category. On the other hand, most of the examined systems reveal very low representative coverage.