Abstract
Indoor thermal environment is important for maintaining comfort and health. In a tropical region, it becomes more critical when the air-conditioning system consumes excessive energy for a whole year. This study aims to clarify the impact of thermal environment on human comfort and building-related symptoms in air-conditioned offices. A field study was conducted in office spaces in Singapore and Thailand from 2017 to 2019 by installing data loggers to measure thermal variables together with a questionnaire survey. As a result, the psychometric charts of ASHRAE 55 show that most of the measured thermal environments were fitted to the 1.0 clo comfort zone, which was not recommended for people in this region. Overcooling determined the cause of high discomfort when people felt cold and preferred a warmer temperature. Based on Griffith’s method, average comfort temperatures were 24.8 °C (Singapore) and 24.0 °C (Thailand). The probit analysis illustrated that the comfort temperature range for a dissatisfaction of 20% was 23.6–26.4 °C (Singapore) and 22.9–25.6 °C (Thailand). These comfort temperature ranges which were higher than the measured values reflected the clothing adaptation and the personal complaints. Symptoms were reported in the coldest temperature group (21–22 °C), with the highest odds ratio of symptom occurrence. The thermal sensation vote defined that the higher rate of symptoms belonged to the colder-than-neutral side, whereas the thermal comfort vote could not well predict the symptom occurrence. The intention of enhancing comfort and promoting better health conditions in the offices of these regions was discussed, while considering warmer indoor temperatures.
Highlights
In tropical regions, the indoor thermal environment of an air-conditioned office building is maintained through a cooling load throughout the year (de Dear et al, 1991)
The mean room temperature of three offices in Singapore was lower than 24◦C which was the minimum recommended value for air-conditioned office spaces (S.P.R.I.N.G, 2009)
Data loggers for measuring thermal variables were installed in these offices
Summary
The indoor thermal environment of an air-conditioned office building is maintained through a cooling load throughout the year (de Dear et al, 1991). In the temperate climate zone, Japan launched a campaign for the reduction of energy consumption in buildings; this campaign was named “Coolbiz,” and it implemented setting higher temperatures of up to 28◦C during the summer People adjusted their lifestyles by wearing lighter clothes, instead of suits and ties; this dress code became a common office practice (Nakashima, 2013). The data obtained via recent studies need to be calibrated more accurately, owing to the previously limited number of field studies in hot-humid climates To address these issues, this study aims to (1) assess the on-site thermal environment and estimate the range of comfort temperature by comparing it with previous studies and (2) observe the relationship between human comfort and building-related symptoms with respect to thermal environments. It would be advantageous to consider indoor environments with regard to sustainability and the well-being of occupants to realize a promising future
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