COMFORT TEMPERATURE AND ADAPTIVE MODEL FOR HOUSES IN THE NAGASAKI PREFECTURE IN A WARM CLIMATIC REGION IN JAPAN

Abstract

 To determine the comfort temperature in houses in warm climatic regions and examine the locality of adaptive model of houses, a thermal comfort field survey, integrated with measurements and questionnaires, was conducted in 12 houses of the Nagasaki Prefecture, which has a warm climate, in summer, autumn, and winter seasons from 2015 to 2018. The 12 houses comprised 6 detached houses and 6 apartment houses. Most of the houses had minimal insulation and airtightness.

 Here, the thermal environment measurements were carried out. These included the temperature and relative humidity in living room and bathroom at 1.1 m above the floor surface; the temperature in living room at 0.1 m above the floor surface; the globe temperature in living room; and the outdoor temperature. Each item was measured every 10 min by a small data logger. During the measurement, the occupants were asked to assess their living environment for thermal sensation, preference, thermal acceptability, humidity sensation, draft sensation, sweat sensation, general comfort, activity 15 min before, window and door openings, heating and cooling systems’ operation, electric fan operation, and clothing, and they were asked to vote up to three times a day when their thermal sensations were neutral. To evaluate the thermal sensation, two scales, i.e., the ASHRAE seven-point thermal sensation scale (TSV) and the modified seven-point TSV (mTSV), were employed. The collected voting sheet was classified into three modes: free running (FR), cooling (CL), and heating (HT) modes. In this survey, the thermal sensation based on mTSV was used because their correlation coefficients with thermal preference vote, indoor temperature, and globe temperature were higher than those of TSV. In this survey, the indoor temperature at which an occupant voted the thermal sensation as ‘neutral’ was defined as the “comfort temperature,”, and the indoor temperature at which an occupant voted the thermal sensation as ‘slightly cold,’ ‘neutral,’ or ‘slightly hot’ was defined as the “semi-comfort temperature.” In addition to this, the comfort temperature was calculated and examined using another method, the Griffiths’ method.

 It was found that the comfort temperature extracted from the voting sheet was approximately same as that calculated using the Griffiths’ method. Therefore, an adaptive model with the comfort temperature, calculated using the Griffiths’ method in this study, was proposed for houses in the Nagasaki Prefecture for comparison with other areas. On comparison based on building type, structure, age, gender, and temperature preference, some differences were observed in the adaptive models depending on the building type and occupant attributes. Although the adaptive model also considered the running mean outdoor humidity ratio in addition to the running mean outdoor temperature in this study, it was confirmed that the accuracy of the model did not change when only the running mean outdoor temperature was used as an explanatory variable. The adaptive model in the Nagasaki Prefecture was then compared with that in the Kanto region. Based on this comparison, it was observed that the regression equations used to calculate the comfort temperature from the running mean outdoor temperature were approximately similar, except that the regression coefficients in FR mode tended to be slightly different. Consequently, it is thought that it is necessary to set the target of the housing adaptation model in detail by region and by housing and occupant attribute in order to achieve efficient energy saving for houses.