Seasonal and diurnal variation in thermal comfort in Sri Lanka

The present work reports evidence bearing on the question whether seasonal acclimatization occurs in thermal comfort in a tropical country (Sri Lanka) where the seasonal change of temperature is small. Thermal comfort votes were taken in each of two subjects on nearly a hundred occasions over a period of 10 - 12 consecutive months. One of the subjects also had records which had been taken 12 years previously over a period of six consecutive months. The ambient temperature level which was compatible with a sensation of satisfactory thermal comfort (comfort temperature) rose in the warmer season and fell in the less warm. Evidence is also presented on the question whether there is a seasonal variation in the effect which diurnal temperature change has upon thermal comfort. The change in thermal comfort from morning to afternoon was recorded in one subject on 73 days during a 12-month period. A seasonal acclimatizational effect was detected in which the change in ambient temperature which produced thermal discomfort was found to be larger in the warmer than in the less warm months. The effective temperature scale was noticed to be no better than the dry bulb temperature in demonstrating these seasonal acclimatizational effects.