Kumagai Gumi Co., Ltd. and Sumitomo Forestry Co., Ltd. have completed an environmentally friendly commercial building in Tokyo, combining energy-saving architecture with newly developed mass timber construction technologies. Designed and constructed under "with TREE"—the joint mid-to-large-scale timber building brand managed by both companies—the project marks the completion of "KiGi AKIHABARA," the first nine-story hybrid timber and steel structure developed for real estate firm The Sankei Building Co., Ltd. Construction was finalized on May 29, 2026, and the building officially opened on July 22, 2026.

Located in Higashi-Kanda, Chiyoda Ward, Tokyo, the nine-story structure features a combined steel and timber frame (partially timber-framed) with a total floor area of approximately 1,072 square meters. Aimed at establishing a rational and optimal "hybrid timber office" model tailored for contemporary urban environments, the development incorporates advanced structural, fireproof, and aesthetic innovations.

The project utilized 61.7 cubic meters of structural timber. To minimize embodied carbon emissions generated during construction, maintenance, and eventual demolition, the structural framework incorporates electric arc furnace (EAF) steel, achieving an estimated 380-ton reduction in carbon dioxide emissions during the design evaluation phase. For operational carbon, the facility obtained "ZEB Ready" certification at the design stage, achieving a 50% reduction in operational energy consumption. Over an assumed 60-year operational lifecycle, total emission reductions are projected to reach 4,371 metric tons. (2026/08/03)