Study on Griffiths constant for elderly people at different ages

To investigate the thermal sensitivity differences in elderly people at different ages in indoor thermal environments in summer, and broaden the applicability of the traditional Griffiths constant in elderly people at different ages, 44 elderly people aged 60 and above in a pensioners’ building in Baoding are selected as subjects for field tests, and 3 666 sets of subjective and objective index data are obtained. Firstly, these elderly people are divided into three age groups (60-74, 75-88、≥89), and the thermal neutral skin temperature of elderly people is calculated according to the correlation between the thermal sensation vote and the mean skin temperature of elderly people from different age groups. Secondly, the distribution characteristics of the thermal sensation vote of elderly people from different age groups at different ambient temperatures are analysed, thus the thermal neutral temperature of elderly people from different age groups is obtained. Finally, based on the improvement and supplement of the traditional Griffiths constant (0.5 ℃-1), the age-specific subjective Griffiths constant and objective Griffiths constant are proposed. The results show that the thermal neutral skin temperatures of elderly people from the three age groups are 35.4, 35.7, and 36.2 ℃, and the skin temperature comfort intervals are 34.8-35.9, 34.9-36.4, and 35.1-37.4 ℃, respectively. The thermal neutral temperatures of the three age groups are 27.8, 27.9, and 28.5 ℃, and the temperature comfort intervals are 24.5-31.1, 24.1-31.8, and 24.3-32.7 ℃, respectively. The subjective Griffiths constants of the three age groups gradually decrease, which are 0.60, 0.43, and 0.35 ℃-1, respectively. The objective Griffiths constants also gradually decrease, which are 0.54, 0.38, and 0.14, respectively. This paper can provide a theoretical basis for the thermal comfort study and environmental difference control for elderly people.