Elderly demand for indoor thermal comfort and energy conservation is increasing in an aging society. To reveal the thermal responses of the elderly in a warm summer environment, a field study involving experimental measurements was conducted in Chongqing, China. The study included 333 subjects in 17 residential buildings and 119 subjects in 6 elderly nursing homes; it showed that elderly persons as passive users of air conditioners preferred cooling by natural ventilation. The mean thermal sensation vote was insensitive and lower than estimates obtained from the PMV model in warm environments. The physiological responses of eight elderly subjects (65 +/- 3) were measured in a climate chamber at 18 degrees C and 34 degrees C and compared with those from eight college students (22 +/- 1) and eight middle-aged subjects (50 +/- 5). In this chamber, oral temperature, blood pressure, and heart rate of elderly and middle-aged persons were determined to be almost constant as the air temperature was changed to a hot/cold environment for 30 min, a different result from that of the young subjects. However, the skin temperatures for all age groups showed dependency with air temperature conditions, suggesting skin temperature as an optimal monitoring parameter for the entire population. (C) 2019 Elsevier B.V. All rights reserved.