Age differences in thermal comfort and physiological responses in thermal environments with temperature ramp

The well-being of the elderly is critical in today's aging society. However, the age difference in thermal comfort in buildings with unstable thermal environments is poorly understood. In this study, 32 gender-balanced elderly and young participants were recruited to investigate differences in thermal perceptions and physiological responses to thermal environments with temperature ramps between 34 °C and 18 °C (up and down) in a climate chamber. We found that the elderly have a time lag and smaller variation in thermal responses than the young group when air temperature changes, especially in non-neutral conditions. The elderly reported less thermal discomfort (P < 0.05) and fewer complaints of sick building syndrome (SBS) and perceived air quality (PAQ). Local thermal sensation vote (TSV) and local skin temperature (LST) results also revealed age differences in the coldest local body parts and TSV-LST relationships. The LST of the arms and head of the elderly was lower in some conditions, indicating that health risks should be considered more carefully. The elderly had significantly higher blood pressure and were more sensitive to temperature ramps than the young. Thermal perceptions and physiological responses were affected by both air temperature values and ramp direction. Linear regressions were performed to predict TSV as a function of PMV and temperature ramp rate ΔT for the elderly and young groups, respectively. Therefore, age should be considered when evaluating the thermal comfort of older adults in unstable environments.