Effect Of Thermal History On Human Thermal Comfort,health And Work Performance

The indoor environment should guarantee occupants' comfort,health,and work performance as people spend most of their time indoors.Exploring the effect of longterm thermal history and short-term thermal history on comfort,health,and work performance is important for designing the indoor environment and drafting standard.In this research,systematic field studies were conducted to determine the effect of long-term thermal history on thermal comfort and physiological responses.Meanwhile,based on field studies and chamber experiments,short-term thermal history was explored in terms of human health,thermal comfort,and work performance,and the mechanism behind the physiological and psychological responses was investigated.The main research work and findings include:(1)Field studies were conducted in split air-conditioned(SAC)and naturally ventilated(NV)dormitory buildings.The effect of long-term thermal history on thermal comfort and physiological responses was determined,and the mechanism behind thermal adaptation and long-term thermal history was revealed.Compared to the split air-conditioned buildings,thermal environment was poorer and occupants felt less comfortable in naturally ventilated buildings.Also,the neutral temperature was higher in naturally ventilated buildings than that in split air-conditioned buildings.The indoor thermal history had no significant effect on physiological acclimatization and induced psychological adaptation.(2)Based on field studies,the applicability of adaptive comfort model and PMV model was explored in split air-conditioned office buildings.Comfort temperature,acceptable temperature range,and preferred temperature were determined.The results indicated that occupants preferred a “cooler” temperature,which was lower than the neutral temperature.Compared to the PMV model,the adaptive comfort model was more applicable to split air-conditioned office buildings.(3)A long-term field study was conducted in split air-conditioned dormitory buildings.Indoor thermal environment,physiological responses,and subjective thermal perception were investigated.The effect of short-term thermal history on thermal comfort and physiological responses was explored.Compared to the occupants who stayed in the building for more than 30 min,the occupants,who stayed in the building for less than 30 min,had a lower neutral temperature and a higher percentage of acceptability with the cool environment.Meanwhile,the upper extremity skin temperatures were highly correlated with thermal sensation.(4)Chamber experiment was conducted to explore the effect of short-term thermal history on human thermal comfort,health,and physiological responses in radiant environment.The relationship between subjective thermal perception and physiological responses was determined.The results indicated that thermal perception,skin temperature,and heart rate variety changed significantly under temperature stepchanges.The asymmetry of thermal comfort and physiological responses occurred in opposite temperature step-change direction.Skin temperature was highly correlated with overall thermal sensation.The overall thermal perception was highly correlated with local thermal perception.(5)Chamber experiment was conducted to explore the effect of short-term thermal history,induced by metabolic rate change and temperature step-change,on indoor work performance,thermal perception,and health.Also,the mechanism behind the effect of short-term thermal history and work performance was revealed.The results showed that the short-term thermal history induced by temperature had no significant effect on work performance.While the exposure time had a significant effect on work performance.The longer exposure time,the higher performance.This may be caused by the short-term thermal history induced by the metabolic rate change.