日本の住宅建設がもたらすCO2排出量を定量化〜建設工法と建物階数の違いに着目〜

2026-02-16 九州大学

図1．2015年における日本の住宅建設の工法別・階数別のCO2排出構造

＜関連情報＞

• https://www.kyushu-u.ac.jp/ja/researches/view/1418
• https://www.mdpi.com/1996-1073/19/3/783

日本の住宅におけるカーボンフットプリント分析 Carbon Footprint Analysis of Residential Buildings in Japan

Ai Nagata,Sora Matsushima and  Shigemi Kagaw
Energies  Published:2 February 2026
DOI:https://doi.org/10.3390/en19030783

Abstract

The decarbonization of the building sector is a critical challenge for achieving Japan’s net-zero targets. However, comprehensive assessments comparing residential construction methods and building heights at the national scale remain limited. This study applies Environmentally Extended Input–Output Analysis (EEIOA) to evaluate the embodied CO₂ emissions associated with four distinct residential construction methods. The results reveal that, when accounting for carbon storage, the net CO₂ emissions per unit of floor area were significantly lower for wooden houses (195 kg-CO₂/m²) compared to steel-reinforced concrete (1109 kg-CO₂/m²), reinforced concrete (857 kg-CO₂/m²), and steel-framed houses (803 kg-CO₂/m²). A further analysis based on building height indicates a structural divergence: while wooden houses account for the majority of emissions in one- to three-story buildings due to their high market share, reinforced concrete houses dominate emissions in four- to nine-story buildings driven by their high carbon intensity. These findings suggest that promoting timber construction, particularly in taller buildings, is a vital strategy for climate change mitigation. Consequently, policy support focusing on technological advancement, cost reduction, and consumer awareness is essential to accelerate the adoption of wooden architecture.