Upfront carbon (UC) assessment of structures during the design stage of buildings is an important perspective, also related to the seismic performance of buildings. Previous studies have evaluated UC for multiple pre-designed cases and analyzed their characteristics. However, during the design stage, sufficient quantity and specification information is often unavailable for UC evaluation. This study identifies key points and perspectives for setting input conditions and calculation parameters in UC assessment during the "design stage," particularly focusing on structural type classification based on seismic performance and ground/foundation conditions in Japan. Through parametric analysis, it examines not only UC emissions but also analyzes their distribution by above-ground, below-ground, and foundation components to understand their respective impacts.Furthermore, it demonstrated the potential contribution of extending building lifespans through the adoption of seismic isolation and vibration control structures to reducing whole-life carbon emissions.This suggests that considering the ratio of above-ground, underground, and foundation components, along with improving structural durability, is an effective design strategy for reducing environmental impact.