Carbon-Conscious Environmental Building Design - Performance Verification of Tokyo Office Building -

Abstract This study demonstrates that integrated environmental building design can overcome the traditional trade-off between operational and embodied carbon emissions. In recent years, due to advancing climate change and energy resource constraints, the need to achieve carbon neutrality in the construction sector has become increasingly urgent. To address this challenge, a holistic optimization approach through cross-domain integration is essential, rather than partial optimization by individual domains such as architectural design, structural/mechanical engineering, and production. As a practical initiative, we developed a staggered layered precast concrete shear wall structure and implemented it in a Tokyo urban office building. The outer shell structure itself provides environmental performance through solar control, natural ventilation, and reflected light introduction, enabling coordination between architectural passive elements and high-efficiency mechanical systems to achieve both comfort and energy efficiency. This paper presents the results of a comparative analysis of the relationships among comfort, energy efficiency, and upfront carbon in whole-life carbon reduction, examining the completed design, advanced proposals, and conventional structural solutions using this implemented environmental design methodology.