A new method for calculating the embodied carbon emissions from buildings in schematic design: Taking building element as basic unit

In the schematic design stage, accounting for the embodied carbon emissions (ECEs) from buildings during design optimization is indispensable for saving energy and reducing emissions from the source. Since the traditional inventory analysis method is more widely applied in the mature construction drawing design stage or with a detailed bill of quantities, developing a method suitable to provide design feedback during the schematic design stage is urgently needed. The key issues of the method that need to be solved are the lack of design information and the difficulty in obtaining quantities. To address the limitations, this paper proposes a BIM-based calculation method that takes the building element (BE) as the basic unit, and the accuracy is verified by a frame-structure case study. For this method, it is imperative to create carbon emission factors (CEFs) of the BEs as the basis of calculation combined with the quantities extracted from the model schedules by encoding, which can significantly contribute to the calculation. The results show that this method has good accuracy and high efficiency and can identify potential hotspots of ECEs, which conforms to design process and habits and provides design feedback function for carbon emission reduction (CER). At the schematic design stage, the application of this method can quantitatively evaluate the ECEs and optimize the design from the BE level so that the concept of low carbon design can be truly put into practice and the energy savings and emission reductions of buildings can be controlled as early as possible.