Sustainable Design Strategies for Human–Cat Shared Furniture in Compact Apartments: An Integrated SOR–Kano–FBS Approach

As urban housing becomes increasingly compact and companion animals become more deeply integrated into domestic life, human–cat cohabitation presents design challenges related to spatial efficiency, furniture wear, maintenance, and everyday coexistence. This study examines shared-interface conflicts in compact apartments and proposes an integrated SOR–Kano–FBS pathway for sustainable human–cat shared furniture design. In-home observations, semi-structured interviews, behavioral path recording, and Kano questionnaires were used to identify high-frequency activity contexts and prioritize user requirements. These requirements were translated through the FBS model into functional objectives, behavioral scripts, and structural strategies. The results indicate that ease of cleaning and maintenance, structural stability and user-perceived safety, and dedicated scratching guidance primarily represent must-be requirements. Movement-path separation, centralized storage, and aesthetic integration function as performance-enhancing requirements, whereas shared yet stratified zoning, elevated observation points, and moderate visual connection improve the cohabitation experience. Two conceptual designs—a human–cat shared living-room sofa system and a foldable work/study system—were developed. Their descriptive comprehensive acceptance indices were 0.802 and 0.794, respectively, while a combined conventional-furniture reference set scored 0.520. Because the reference set represented two conventional activity contexts, these values were used only as diagnostic, user-perception-based evidence and not as inferential proof or a direct ranking between the schemes. The findings suggest that the proposed pathway can support design-level sustainability in compact human–cat cohabitation; however, further validation through physical prototypes, long-term in-home testing, and life-cycle assessment is required.