Thermal-Preference Profiles Reveal Individual Differences in Residential Outdoor Thermal Comfort Under a Hot-Humid Climate: A Case Study for Age-Friendly Architectural Design Using Explainable Machine Learning

Individual differences in outdoor thermal comfort (OTC) are critical to the healthy use of urban public spaces, yet whether thermal preference can shape OTC independently of demographic characteristics remains largely unexamined. Using residential outdoor spaces in Fuzhou, a representative hot-humid city in China, as a case, this study combines field measurements and questionnaire data from 296 respondents (72.6% aged 60 or above) with explainable machine learning and K-Modes clustering to examine how thermal preference drives individual differences in OTC. Three stable preference profiles were identified—heat-sensitive (56.4%), wind-seeking (20.3%), and heat-tolerant (23.3%)—which exhibit markedly different thermal responses. The neutral globe temperature ranges from 29.90 °C for the heat-sensitive profile to 35.85 °C for the heat-tolerant profile, a difference of 5.95 °C, whereas the comfort bandwidth is widest for the heat-sensitive profile (9.03 °C) and narrowest for the heat-tolerant profile (4.13 °C), the former being 2.2 times the latter. The profiles are independent of sex and BMI and only weakly correlated with age, yet their explanatory power for the variance in thermal comfort vote (TCV) (η2 = 0.254) is 4.9 to 23.1 times that of the demographic variables. The thermal environment contributes far more to TCV than the visual environment (74.4% versus 25.6%), with globe temperature (Tg) as the strongest single factor. Overall, differentiated design that adopts the most heat-sensitive profile as the constraint boundary covers the comfort needs of a broad population more effectively than demographic stratification. The novelty of this study lies in introducing psychologically grounded thermal-preference profiles as an operational stratification dimension for architectural design, offering age-friendly hot-humid residential environments a preference-oriented pathway toward refined, human-centered outdoor space design.