Age differences in thermal comfort and sensitivity under contact local body cooling

Global climate change presents challenges to comfort and health of the elderly. Contact-based local thermal regulation offers a potential solution to enhance their thermal comfort, yet lacks practical application guidelines. To investigate the impact of local regulation on overall thermal perception, this study recruited 16 elderly individuals (66.7 ± 4.2 years) and 16 young individuals (23.3 ± 1.0 years), exposing them to local cooling of 12 body parts in hot indoor environments. Subjective questionnaires and skin temperature were collected. The results indicate that in a stable thermal environment, elderly individuals reported lower thermal sensation votes (TSV), higher thermal comfort votes (TCV), and weaker willingness to change the environment. While young participants preferred cooling the trunk, the elderly preferred cooling of the head and neck. Under local cooling, most of the body parts did not show significant differences in local TSV between the two groups, but the elderly group exhibited significantly higher local TCV. Cooling of the core body parts (head, neck, chest, upper back, abdomen, and lower back) had a greater impact on reducing overall TSV and increasing overall TCV among the elderly. The elderly showed higher acceptance of local cooling, particularly favoring cooling of the head and neck, which are the most thermally sensitive area. Thermal sensitivity significantly decreased with age. Based on the results, local cooling of 26 °C to the head, neck, chest, and upper back is the recommended solution for local regulation in hot environments. This research provides valuable insights for developing targeted strategies to improve thermal comfort for the elderly.