Abstract:Various tools that assess life cycle CO 2 (LCCO 2 ) emissions are currently being developed throughout the international community. However, most building LCCO 2 emissions assessment tools use a bill of quantities (BOQ), which is calculated after starting a building's construction. Thus, it is difficult to assess building LCCO 2 emissions during the early design phase, even though this capability would be highly effective in reducing LCCO 2 emissions. Therefore, the purpose of this study is to develop a Building Simplified LCCO 2 emissions Assessment Tool (B-SCAT) for application in the early design phase of low-carbon buildings in South Korea, in order to facilitate efficient decision-making. To that end, in the construction stage, the BOQ and building drawings were analyzed, and a database of quantities and equations describing the finished area were conducted for each building element. In the operation stage, the "Korea Energy Census Report" and the "Korea Building Energy Efficiency Rating Certification System" were analyzed, and three kinds of models to evaluate CO 2 emissions were proposed. These analyses enabled the development of the B-SCAT. A case study compared the assessment results performed using the B-SCAT against a conventional assessment model based on the actual BOQ of the evaluated building. These values closely approximated the conventional assessment results with error rates of less than 3%.