CASBEE Certification for Buildings

1. Identify the Applicable CASBEE Tool: Determine which CASBEE tool applies to your project — New Construction, Existing Buildings, Renovation, Real Estate, Schools, Urban Development, or another variant. Each tool has specific scope and documentation requirements.\n\n2. Download the Assessment Manual: Obtain the relevant CASBEE Assessment Manual from the IBEC Download Page (ibec.or.jp). English versions are available for select tools including New Construction and Cities. The 2024 Edition of the New Construction manual is the most current.\n\n3. Engage a Registered CASBEE Assessor: Contact an accredited certification body registered with IBEC to assign a qualified CASBEE assessor to your project. Assessors must be officially registered to submit applications for formal certification.\n\n4. Conduct a Pre-Assessment / Gap Analysis: Work with your assessor and project team (architects, engineers, facility managers) to evaluate the building's current or planned performance against CASBEE criteria — energy efficiency, indoor environment, resource use, and site conditions.\n\n5. Compile Documentation: Gather all required evidence including building design drawings, energy performance calculations, material and resource use data, indoor environment quality measurements, and site assessment data aligned with the chosen CASBEE tool.\n\n6. Submit Application to Accredited Certification Body: Submit the completed documentation package to your chosen CASBEE-accredited certification body in Japan. The body will conduct a formal review and may request supplementary information or a site visit.\n\n7. Undergo Third-Party Assessment: The accredited certification body reviews submitted documentation and, where applicable, conducts site verification. The building is scored using the BEE (Built Environment Efficiency) index and assigned a rating from C (Poor) to S (Excellent).\n\n8. Receive Certification and Display Rating: Upon successful assessment, receive the official CASBEE certificate and rating label. The certification can be listed on IBEC's online registry and used in marketing materials and property disclosures.

CASBEE evaluates buildings using the Built Environment Efficiency (BEE) index, which is calculated as the ratio of Building Environmental Quality & Performance (Q) to Building Environmental Load (L). A higher BEE score indicates a more sustainable building. The rating scale runs from C (Poor, BEE < 0.5) through B− (Fairly Poor), B+ (Good), A (Very Good), to S (Excellent, BEE ≥ 3.0).

Environmental Quality & Performance (Q) — the numerator of the BEE index — covers three main categories: Q1 Indoor Environment (thermal comfort, acoustic environment, lighting and illumination, air quality), Q2 Quality of Services (functionality and usability, durability and reliability, flexibility and adaptability), and Q3 Outdoor Environment on Site (preservation and creation of biotope, townscape and landscape, local characteristics and outdoor amenities).

Environmental Load (L) — the denominator — also covers three categories: L1 Energy (building thermal load, natural energy utilization, efficiency of building systems, efficient operation), L2 Resources and Materials (water conservation, reduction in use of materials with environmental impact, avoidance of CFCs and halons), and L3 Off-site Environment (air pollution, noise and vibration, odor, sunlight obstruction, light pollution, heat island effect, load on local infrastructure).

The specific weighting and sub-criteria vary by CASBEE tool. For example, CASBEE for New Construction (2024 Edition) places particular emphasis on energy efficiency and carbon reduction in line with Japan's updated climate commitments. CASBEE for Existing Buildings focuses more on operational performance data over a 12-month period, while CASBEE for Real Estate incorporates disclosure metrics relevant to property transactions. CASBEE for Urban Development extends the framework to assess district-level environmental performance including green space, mobility, and urban heat island mitigation.

CASBEE is Japan's dominant green building rating system and the de facto national standard for building environmental performance assessment. With over 20,000 certified projects, it holds a commanding position in the Japanese market, where it is embedded in government procurement policies, municipal building regulations, and major real estate disclosure frameworks. Many of Japan's largest cities — including Tokyo, Osaka, and Nagoya — have incorporated CASBEE into local building ordinances, effectively mandating its use for large-scale developments. This regulatory integration gives CASBEE a structural advantage in Japan that few voluntary green building programs enjoy elsewhere.

Internationally, CASBEE's footprint is limited. Outside Japan, LEED (U.S. Green Building Council) and BREEAM (BRE Group) dominate the global market, and CASBEE is rarely specified by international developers or investors. The 2014 certification of a building in Tianjin, China marked the first international CASBEE certificate, and pilot tools for worldwide use have been released (notably CASBEE for Cities in 2015), but uptake beyond Japan remains modest. For multinational real estate portfolios, CASBEE is typically used alongside — not instead of — globally recognized systems.

Demand for CASBEE in Japan is growing in line with the country's ambitious carbon neutrality targets (net zero by 2050) and the government's push for ZEB (Zero Energy Buildings). The 2024 update to the New Construction assessment manual reflects evolving energy standards and climate policy. As ESG disclosure requirements tighten for Japanese listed companies under Tokyo Stock Exchange guidelines, CASBEE ratings are increasingly used as evidence of building-level sustainability performance in corporate sustainability reports and real estate investment trust (REIT) disclosures.

CASBEE was developed in 2001 by the Japan Sustainable Building Consortium (JSBC), a public-private partnership established under the Ministry of Land, Infrastructure, Transport and Tourism (MLIT). Its creation was driven by Japan's need for a nationally tailored building environmental assessment tool that could reflect Japanese construction practices, climate conditions, and regulatory frameworks — distinct from the U.S.-centric LEED system or the UK-based BREEAM. The Institute for Building Environment and Energy Conservation (IBEC) was designated as the managing body responsible for tool development, assessor training, and certification administration.

The initial CASBEE tool focused on new construction, but the family of tools expanded rapidly through the 2000s and 2010s to cover existing buildings, renovation, schools, detached houses, urban development, heat island assessment, and commercial interiors. A landmark milestone came in 2015 when IBEC released CASBEE for Cities — a pilot version for worldwide use — announced at COP21 in Paris, signaling CASBEE's ambitions beyond Japan. The 2024 edition of the New Construction assessment manual represents the most recent major update, incorporating Japan's updated energy efficiency standards and carbon reduction targets aligned with the country's 2050 carbon neutrality commitment.