Wellness Offices in Japan: An Empirical Analysis Based on CASBEE-Wellness Office

In recent years, with the global expansion of environmental, social, and governance (ESG) investment, the adoption of certification systems that evaluate not only the environmental performance but also wellness aspects of buildings has gained increasing attention. While WELL and Fitwel have become widely adopted certifications focusing primarily on health and comfort, in Japan, CASBEE-WO (Comprehensive Assessment System for Built Environment Efficiency-Wellness Office) was introduced in June 2019. CASBEE-WO is distinctive in that, in addition to worker health, workplace productivity, it incorporates resilience, safety, disaster preparedness, reflecting Japan's particularly high exposure to natural hazards. This study investigates the status of CASBEE-WO and the characteristics of certified properties, five years after its launch, with 209 certifications as of August 2025. Of these, 176 properties with sufficient data were analyzed. In addition to overall scores and category-specific evaluations, building attributes such as certification rank and certification pattern were examined. The results show that, within Qw.1 (Health and Comfort), , "Interior planning of common space" received the highest evaluations, and the spatial and interior design categories generally scored highly. By contrast, comfort-related items such as "Smoke isolation and prohibition", "Room temperature", and "Natural ventilation performance" tended to receive relatively lower scores. The relationship between rank and total score indicated that many properties were concentrated near the threshold values for rank divisions, suggesting that applicants are highly conscious of rank acquisition. Scale-based analysis further revealed that large-scale buildings (over 16,529 m2) achieved higher scores than medium-scale buildings, and that most properties exceeding 150,000 m2 obtained the highest rank, S. In conclusion, compared with comfort-related measures, aspects more visible to building occupants, such as interior planning, tended to be prioritized. Moreover, the findings confirm that, particularly in large-scale buildings, S-rank certification is strategically pursued as a form of brand value, indicating that CASBEE-WO has been recognized as a credible structure for assessing wellness and resilience in office buildings.