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Thermal comfort is crucial in satisfaction and maintaining quality sleep for occupants. In this study, we investigated the comfort temperature in the bedroom at night and sleep quality for Indonesian students during summer and winter. Eighteen male Indonesian students aged 29 ± 4 years participated in this study. The participants had stayed in Japan for about six months. We evaluated the sleep parameters using actigraphy performed during summer and winter. All participants completed the survey regarding thermal sensation, physical conditions, and subjective sleepiness before sleep. The temperature and relative humidity of participants’ bedrooms were also measured. We found that the duration on the bed during winter was significantly longer than that during summer. However, sleeping efficiency during winter was significantly worse than that during summer. The bedroom temperature of the participants was in the range of comfort temperature in Indonesia. With the average bedroom air temperature of 22.2 °C, most of the participants still preferred “warm” and felt “slightly comfortable” during winter. The average comfort temperature each season calculated using the Griffiths method was 28.1 °C during summer and 23.5 °C during winter. In conclusion, differences in adaptive action affect bedroom thermal conditions. Furthermore, habits encourage the sleep performance of Indonesian students.

The field survey on indoor thermal environment was conducted in real‐life 22 houses occupied by 29 middle‐aged men and women in the suburbs of Kuala Lumpur, Malaysia. 18 had air conditioners (AC) in the master bedroom, and 4 had natural ventilation (NV), though all homes had ceiling or standing fans. During nighttime sleeping hours, the average air temperature (Ta) in the participants' bedrooms ranged from 22.6°C to 32.2°C, with relative humidity (Rh) varying between 32% and 80% and airflow between 0.1 and 1.3 m/s. Based on the ET* values, the participants were divided into three groups (A, 20.9°C–24.9°C ET*; B, 25.0°C–27.9°C ET*; and C, 28.0°C–32.5°C ET*), and sleep variables were then compared among the three groups. Group B had the shortest time to fall asleep, whereas group C had the longest awakening time during sleep. The sleep efficiency index (SEI) revealed that sleep quality in group C was inferior to that in group A. No differences were observed in subjective sleep sensations and thermal comfort among the groups, except for humidity sensation. This study demonstrates the importance of using activity meters to measure objective sleep variables in daily life.

A filtering method for observable point clouds from travel path is proposed to improve the efficiency of each point in the point cloud map for self-localization of autonomous mobile robots. The method involves retaining only the point clouds along the planned travel path of the mobile robot that can be observed by it. These points constitute the observable point cloud map. By performing ray casting from the position of the depth sensor along the travel path, observable regions are extracted whereas unobserved point clouds, such as those behind obstacles or out of the sensor range, are removed. The effectiveness of the method is evaluated through comparative experiments involving self-localization using both an original wide-area point cloud map and the observable point cloud maps. A new metric called localization contribution per point is introduced to quantify the contribution of each point, in the point cloud map, to self-localization. The experimental results demonstrate the efficiency of the observable point cloud map when used for self-localization.

Psychological adaptation to ambient temperatures is fascinating and critical, both theoretically and practically, for energy efficiency in temperate climates. In this study, we investigated and compared the brain response (event-related potentials with a late positive component and latency ~300 milliseconds; labeled “P300” in the present study) and reaction times of Indonesian participants (n = 11), as tropical natives living in Japan, and Japanese participants (n = 9) in natural (i.e., hot during the summer and cold during the winter) and comfort conditions (with cooling and heating). Thermal comfort under contrasting conditions was studied using both instruments and subjective ratings. P300 potential and reaction time were measured before and after a Uchida–Kraepelin (U–K) test (30 summation lines). The results showed that P300 potential and latency did not change between the pre- and post-U–K test among conditions in any of the groups. Furthermore, Indonesian participants showed lower P300 potential (hot conditions) and slower P300 latency (hot and cooling conditions) than Japanese participants. We also found that the reaction time of the Indonesian group significantly differed between the pre- and post-U–K test in an air-conditioned environment, with either cooling or heating. In this study, Indonesian participants demonstrated a resistance to P300 and worse reaction times during work in a thermally unfamiliar season, specifically indicated by the indifferent performances among contrasting environmental conditions. Indonesian participants also showed similar thermal and comfort sensations to Japanese participants among the conditions. In the winter, when the Indonesian neutral temperature is higher than Japanese’s, the energy consumption may increase.

The effects of season on sleep and skin temperature (Tsk) in 19 healthy, elderly volunteers were investigated. Measurements were obtained in summer, winter, and fall, and activity levels were monitored using a wrist actigraph system for five consecutive days. The temperature and humidity of the bedrooms of the subjects' homes were measured continuously for five days. During actigraphic measurement, Tsk during sleep was measured for two nights. The bedroom temperature and humidity significantly increased in summer compared to winter and fall. In summer, the total sleep time decreased (mean ± SE min; summer, 350.8 ± 15.7; winter, 426.5 ± 14.2; fall, 403.2 ± 16.4) and wakefulness increased (P < 0.003) compared to those in fall or winter. The sleep efficiency index that was derived from wrist actigraphy was significantly decreased (P < 0.001) in summer (81.4 ± 2.9%) compared with winter (91.6 ± 1.3%) or fall (90.2 ± 1.2%). The forehead Tsk significantly increased, while the chest and thigh Tsks were decreased in summer compared to those in fall or winter. These results suggest that, in the elderly, sleep is disturbed in summer more than in other seasons, and that this disturbance is related to fluctuations in Tsk.

This study aimed to investigate the thermal environment and thermal comfort of elderly occupants living in elder care facilities and to compare the quality of sleep, in all four seasons, of these elderly occupants. A total of 16 healthy participants with a mean age of 80 ± 5 years (range, 70–87 years) were recruited in two elderly facilities, of which, 13 participated in all four measurements. The sleep parameter was measured by a wrist actigraph which the participants were requested to wear and analyzed with commercial software using the Cole–Kripke algorithm, to assign scores for sleeping and waking patterns. Both ambient temperature (Ta) and relative humidity (Rh) levels were found to be lower in the winter and higher in the summer. The Ta in the summer and Rh in the winter were not within the scope of the Japanese Standard for Maintenance of Sanitation in Buildings, as the central HVAC and air conditioners were turned off due to the absence of facility managers. More than 50% of the elderly occupants used fans and increased airflow by opening windows during the summer nights as an adaptive thermal approach. The slope of the relationship between prevailing mean outdoor temperature and indoor Ta determined in this study was similar to the adaptive model and the regression line lies over the upper limits of the adaptive model. No significant difference was found in the sleep parameter among the four seasons; however, a sex difference was found in the sleep latency and length of waking period during the sleep. The sleep parameters such as sleep efficiency indexes were significantly better for elderly women than men. The adaptive approach is not enough to improve the sleep efficiency of sleeping elderly people even within the acceptable temperature range based on the thermal comfort, especially for elderly men.

The mainstream approach employing light detection and ranging (LiDAR) estimates the self-position of mobile robot by matching the point cloud acquired during navigation with that recorded in advance, in order to autonomously navigate to the goal point. However, this method is problematic in that it is vulnerable to environmental changes and that much effort and expenses are required to construct and update the point cloud map. Thus, in this paper, we propose an autonomous navigation method that does not require constructing a point cloud map by visiting the site in advance and is robust against environmental changes. The proposed method carries out autonomous navigation by using RTK-GNSS, and deep-learning algorithm of semantic segmentation and YOLO, A * algorithm for path planning, and pure pursuit algorithm for path navigation. Furthermore, obstacle avoidance is carried out using semantic segmentation, YOLO, and kernel density estimation. We conducted a navigation experiment, in which a 300 m section was autonomously navigated, thus verifying the validity of proposed method.

Comfort temperature is important to investigate because the chosen office indoor temperatures affect the energy used in a building, and a thermally comfortable environment makes the occupants be more productive. The effects of temperature on comfort are broadly recognized for thermal comfort. Japanese office buildings are well equipped with air-conditioning systems to improve the thermal comfort of the occupants. The main objectives of this research were to compare the winter comfort temperature in mixed mode (MM) and heating, ventilation and air-conditioning (HVAC) office buildings and to investigate the relationship between the comfort temperature and the indoor air temperature. This study measured the thermal environmental conditions of the office buildings and surveyed the thermal comfort of the occupants. The field survey was conducted during winter in seven office buildings located in the Aichi prefecture of Japan. In total, 4466 subjective votes were collected from 46 occupants. The result suggested that the occupants were found to be more satisfied with the thermal environment of MM buildings than that of HVAC office buildings. Overall, 95% of comfort temperatures were in the range 22~28 °C in MM and HVAC buildings, which were higher than the indoor temperature of 20 °C recommended by the Japanese government. The comfort temperature was highly correlated to the indoor air temperature of the MM buildings than to that of HVAC buildings. This indicated that the occupants were more adapted towards the given thermal environment of MM buildings.

A field survey of indoor environmental measurements and questionnaires on thermal sensation, overall comfort, and behaviors was conducted in four office buildings in Japan by visiting each office every month over a duration of more than a year during the coronavirus disease 2019 (COVID-19) pandemic. The indoor environment was measured concurrently. We obtained 1047 votes from office workers in their 20s to 60s. The regression and Griffiths’ methods were used to calculate the indoor comfort temperature. A logistic regression analysis was used to develop the occupant behavior model. Over 70% of the occupants found the indoor environment comfortable at a mean comfort temperature of 23.2 to 25.9 °C. Gender differences were observed in thermal sensation and overall comfort, but a gender difference was observed only in the cooling mode for the indoor comfort temperature. An adaptive model was developed for the office buildings in Nagasaki city to predict the indoor comfort temperature from the outdoor air temperature. The proportions of heating, cooling, and fan usage can be predicted from the outdoor air temperature using a logistic regression analysis. The adaptive model and occupant behavior model are useful for the indoor temperature control of the existing buildings and thermal simulation of the new building design.

A summer field study was conducted in two university dormitories in the Tokai region of Central Japan. The study aimed at understanding the correlation between subjective thermal responses as well as whether nationality was affecting the responses. It was observed that nationality significantly affected thermal sensitivity and preference. The occupants’ acceptance for thermal stress was invariably above 90%. Despite the high levels of humidity observed, the multiple regression model showed that only the indoor air temperature was significant for explaining the variability of thermal sensation for both Japanese and non-Japanese students. The highest probability of voting neutral for university students in dormitory buildings in the Tokai region of Japan was estimated within 24~26.5 °C (by probit analysis). Japanese students were more sensitive to their indoor environment as opposed to the international students. The adjusted linear regression coefficient yielded from the room-wise day-wise averages were 0.48/K and 0.35/K for Japanese sensitivity and international sensitivity, respectively. In our study, the Griffiths’ model of estimating comfort temperature (or thermal neutrality) showed weak predictability and notable differences from the actually voted comfort. The neutral and comfort temperature observed and estimated in the study remained invariably below the recommended temperature threshold for Japan in summer leading to believe that that threshold is worth reevaluating.