Ruey Lung Hwang

Thermal Comfort Requirements for Occupants of Semi-Outdoor and Outdoor Environments in Hot-Humid Regions

Abstract Providing thermally comfortable semi-outdoor and outdoor environments is essential to multi-functional public spaces such as museums, cultural centers and university campuses. Given the difficulty of controlling the thermal conditions, individuals may have reduced expectations regarding the thermal comfort of outdoor environments. An extensive field survey of five public places in Taiwan obtained 8077 sets of data. This study discussed thermal sensitivity and proposed thermal comfort ranges, neutral temperatures, and preferred temperatures for semi-outdoor and outdoor environments. The results show that occupants of semioutdoor and outdoor environments are more tolerant regarding thermal comfort than are occupants of indoor environments. Furthermore, global radiation appears to have greater potential to change subject thermal sensation than air movement. In a hothumid region such as Taiwan, semi-outdoor and outdoor environments, applied with sunshine eliminating design strategies, can effectively increase occupant thermal comfort.

Investigating the adaptive model of thermal comfort for naturally ventilated school buildings in Taiwan.

Divergence in the acceptability to people in different regions of naturally ventilated thermal environments raises a concern over the extent to which the ASHRAE Standard 55 may be applied as a universal criterion of thermal comfort. In this study, the ASHRAE 55 adaptive model of thermal comfort was investigated for its applicability to a hot and humid climate through a long-term field survey performed in central Taiwan among local students attending 14 elementary and high schools during September to January. Adaptive behaviors, thermal neutrality, and thermal comfort zones are explored. A probit analysis of thermal acceptability responses from students was performed in place of the conventional linear regression of thermal sensation votes against operative temperature to investigate the limits of comfort zones for 90% and 80% acceptability; the corresponding comfort zones were found to occur at 20.1–28.4°C and 17.6–30.0°C, respectively. In comparison with the yearly comfort zones recommended by the adaptive model for naturally ventilated spaces in the ASHRAE Standard 55, those observed in this study differ in the lower limit for 80% acceptability, with the observed level being 1.7°C lower than the ASHRAE-recommended value. These findings can be generalized to the population of school children, thus providing information that can supplement ASHRAE Standard 55 in evaluating the thermal performance of naturally ventilated school buildings, particularly in hot-humid areas such as Taiwan.

Thermal Comfort for Urban Parks in Subtropics: Understanding Visitor’s Perceptions, Behavior and Attendance

The paper is an effort toward thermal comfort assessment for urban parks under the climatic conditions of Taiwan to help architects achieve better climatic design. Field interviews, observations, and micrometeorological measurements were conducted in this study. The WBGT was used as the thermophysiological index to investigate the effects of thermal conditions on visitor’s thermal perception and adaptive behavior in outdoor urban spaces. In this study, behavioral adaptations used by visitors as a means of achieving comfort were evaluated. Observational results showed that the overall attendance was influenced by sun and thermal conditions. There was a robust relationship between thermal sensation votes, as well as thermal acceptability, and thermal environment, in terms of WBGT. The upper and lower limits of 80% acceptability are 26°C WBGT and 20°C WBGT, respectively.

Outdoor thermal comfort characteristics in the hot and humid region from a gender perspective

Thermal comfort is a subjective psychological perception of people based also on physiological thermoregulation mechanisms when the human body is exposed to a combination of various environmental factors including air temperature, air humidity, wind speed, and radiation conditions. Due to the importance of gender in the issue of outdoor thermal comfort, this study compared and examined the thermal comfort-related differences between male and female subjects using previous data from Taiwanese questionnaire survey. Compared with males, the results indicated that females in Taiwan are less tolerant to hot conditions and intensely protect themselves from sun exposure. Our analytical results are inconsistent with the findings of previous physiological studies concerning thermal comfort indicating that females have superior thermal physiological tolerance than males. On the contrary, our findings can be interpreted on psychological level. Environmental behavioral learning theory was adopted in this study to elucidate this observed contradiction between the autonomic thermal physiological and psychological–behavioral aspects. Women might desire for a light skin tone through social learning processes, such as observation and education, which is subsequently reflected in their psychological perceptions (fears of heat and sun exposure) and behavioral adjustments (carrying umbrellas or searching for shade). Hence, these unique psychological and behavioral phenomena cannot be directly explained by autonomic physiological thermoregulation mechanisms. The findings of this study serve as a reference for designing spaces that accommodates gender-specific thermal comfort characteristics. Recommendations include providing additional suitable sheltered areas in open areas, such as city squares and parks, to satisfy the thermal comfort needs of females.

Field Experiments on Thermal Comfort Requirements for Campus Dormitories in Taiwan

A long-term field experiment project has been launched to investigate thermal comfort requirements for classrooms, dormitories and outdoor spaces of universities in Taiwan. This study presents the research findings achieved in Phase II of this research project. Data for the experimental survey are gathered from two student dormitories of two universities in Central Taiwan, one of which is naturally ventilated and the other is air-conditioned. Results obtained from logistic regression analysis reveal that, despite different thermal conditions in the two dormitories, all students report similar neutral temperature, preferred temperature and upper limit of thermal acceptability. The operative temperatures of thermal neutrality and thermal preference for student dormitories fell at 25.4 and 24.8°C respectively. The upper limit of thermal acceptability obtained via indirect investigation

Passenger thermal perceptions, thermal comfort requirements, and adaptations in short- and long-haul vehicles

While thermal comfort in mass transportation vehicles is relevant to service quality and energy consumption, benchmarks for such comfort that reflect the thermal adaptations of passengers are currently lacking. This study reports a field experiment involving simultaneous physical measurements and a questionnaire survey, collecting data from 2,129 respondents, that evaluated thermal comfort in short- and long-haul buses and trains. Experimental results indicate that high air temperature, strong solar radiation, and low air movement explain why passengers feel thermally uncomfortable. The overall insulation of clothing worn by passengers and thermal adaptive behaviour in vehicles differ from those in their living and working spaces. Passengers in short-haul vehicles habitually adjust the air outlets to increase thermal comfort, while passengers in long-haul vehicles prefer to draw the drapes to reduce discomfort from extended exposure to solar radiation. The neutral temperatures for short- and long-haul vehicles are 26.2°C and 27.4°C, while the comfort zones are 22.4–28.9°C and 22.4–30.1°C, respectively. The results of this study provide a valuable reference for practitioners involved in determining the adequate control and management of in-vehicle thermal environments, as well as facilitating design of buses and trains, ultimately contributing to efforts to achieve a balance between the thermal comfort satisfaction of passengers and energy conserving measures for air-conditioning in mass transportation vehicles.