A field study on seasonal adaptive thermal comfort of the elderly in nursing homes in Xi'an, China

Abstract

To derive deeper insight into the dynamic thermal comfort demands of the elderly in response to the seasonal climate shift, 213 people aged above 60 years in nursing homes were surveyed in a long-term field investigation conducted in Xi'an, China. A subjective questionnaire of thermal comfort and objective physical environment tests was administered, and 834 valid questionnaires were collected. Human thermal responses to seasonal climate shift, and their correlations with indoor operative temperatures were analyzed. Seasonal and yearly adaptive thermal comfort models for the elderly were then developed. Results show that clothing regulation during the transition season was most sensitive to temperature changes. Neutral temperatures during winter, transition season, and summer were 19.4 °C, 22.6 °C, and 24.1 °C, respectively. The acceptable temperature ranges that 80% and 90% respondents accepted were 14.9°C-30.4 °C and 17.7°C-27.7 °C, respectively. Nearly half the older respondents expected indoor temperature to remain unchanged during all seasons, but the percentage of respondents who wanted warmer or cooler indoor temperatures varied in different seasons. The yearly adaptive comfort model for elderly differed from models in ASHRAE 55 and EN 15251, as well as the models for elderly in Shanghai and young people in Xi'an. The results indicate that elderly in Xi'an actively adapt to the indoor thermal environment through behavioral adjustment. Moreover, they have higher acceptability and lower psychological expectations on the thermal environment. The model established in this study may have some limitations for the sample size, but can serve as references while designing comfortable and healthy indoor thermal environments for nursing homes.