In pursuit of Japan’s 2050 carbon neutrality goal, initiatives have begun not only to promote energy saving and renewable energy use during building operation, but also to reduce carbon dioxide and other greenhouse gas (GHG) emissions throughout the entire building life cycle—from manufacturing and construction to demolition and disposal. A new national framework is expected to be launched around fiscal year 2028 to encourage the implementation of Life Cycle CO₂ (LCCO₂) assessment for buildings.
Under this policy trend, the Institute for Built Environment and Carbon Neutral for SDGs (IBECs), supported by the Ministry of Land, Infrastructure, Transport and Tourism (MLIT), established the Zero Carbon Building (LCCO₂ Net Zero) Promotion Committee in December 2022. The Committee aims to develop and disseminate evaluation methods for “Zero Carbon Buildings,” which achieve net-zero LCCO₂ emissions through comprehensive collaboration among industry, government, and academia.
The Japan Carbon Assessment Tool (J-CAT®) was developed under this Committee as a tool for quantifying GHG emissions over the entire building life cycle. J-CAT is designed to address diverse GHG reduction strategies. While maintaining consistency with international standards, it follows Japan’s existing building LCA methodologies to enable the calculation and analysis of both upfront and whole life carbon across various building types.
The first version, released in 2024, targets non-residential buildings, with an extension to detached houses planned for 2026. J-CAT is also being linked with CASBEE for Buildings, Japan’s comprehensive environmental performance assessment tool. In addition, the tool is being continuously improved, including the creation of case studies on carbon reduction and adaptation to upcoming national systems. Future plans include developing national benchmarks with international collaboration, enhancing BIM integration, and constructing a process-based unit database.