Abstract This study aims to develop a Building materials Embodied GHG Assessment Criteria and System (BEGAS) in the newly revised Korea Green Building Certification System (G-SEED). For this purpose, green building certification systems and supporting assessment systems were analyzed in order to grasp the current trend of the GHG emission assessment on building materials. The evaluands were selected by identifying the major building materials in the GHG emission assessment that meet the cut-off level of ISO 14040 for GHG emission assessment. In addition, standard quantity of GHG emissions were calculated for the G-SEED and BEGAS. An auto quantity input technique was presented using pure resource code, composed of standard work codes of the Public Procurement Service (PPS), as a medium, in order to support the easy assessment of GHG emission. Korea LCI DB, the Korean DB of environmental information on building materials, and the Korea carbon footprint labeling certificate were adopted to the database for analyzing the social features of Korea. As a result, based on the aforementioned database, the criteria of GHG emission assessment for building materials in Korea׳s G-SEED were proposed, and a web-based BEGAS was developed.