Seasonal Asymmetry in Thermal Adaptation Among Residents of Traditional Dwellings in Eastern Hunan: An aPMV-Based Field Study of Winter Adaptation

Adaptive thermal-comfort parameters for Chinese hot-summer and cold-winter rammed-earth dwellings, occupied exclusively by residents aged 60 and over, remain poorly quantified. Two seasonal field campaigns were run in Weishan Village, Liling City, eastern Hunan, in 2026, giving 100 valid vote–measurement pairs in winter (8–14 January) and 100 in summer (15–21 July) from residents aged 60 and over. Air and globe temperature, relative humidity and air velocity were measured at three heights; thermal sensation used the ASHRAE 55 seven-point scale. Observations were binned into 0.2 °C intervals, and λ was estimated from interval mean votes with vote-count weighting. Winter λ = −0.61 (95% CI [−0.76, −0.47], p < 0.001) was significantly negative and robust, whereas summer λ = +0.07 (95% CI [−0.10, +0.24], p = 0.425) was not significant; the two differ significantly (λw − λs = −0.68, p < 0.001). Winter AMV lay above PMV at every interval, whereas the summer lines crossed at 29.2 °C. Although 12 of the 23 winter intervals lie below −2, beyond the range in which PMV was validated, restricting the estimate to the validated range |PMV| ≤ 2 leaves the winter coefficient at −0.67 (95% CI [−0.85, −0.50]) and the summer coefficient at +0.09 (95% CI [−0.13, +0.31]), so extrapolation does not explain the winter result. Seasonal asymmetry is established, but its form is winter adaptation demonstrated and summer adaptation not demonstrated.