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.

Thermal comfort in office buildings is instrumental in improving the productivity of employees while maintaining their health. The primary objectives of this research were to analyze the comfort temperature in Japanese office buildings and investigate its relationship with outdoor air temperature. Additionally, we examined the differences in comfort temperatures with respect to closed and opened windows to factor in the increase in the opening of windows during the COVID-19 pandemic when air-conditioning systems were operated. We investigated the environmental conditions of office buildings and the thermal comfort of the occupants through monthly visits to each office building over a year. Field data were collected from four office buildings located in Nagasaki City, with 1047 votes obtained from 143 participants. The survey indicated that the occupants were highly satisfied with the thermal environment in their offices. The correlation between indoor comfort temperature and outdoor temperature was high in the FR mode. Based on the analysis, we developed an adaptive model for office buildings in Nagasaki City and compared it with existing adaptive models used for buildings in other regions of Japan. The proposed model is useful for energy-saving designs that bring out human adaptive capacity.

This paper focused on the impact of lifestyle changes in response to the novel coronavirus infection (COVID-19) on the electricity demand of 1339 detached houses from October 2020 to March 2021. Analyzing with the lifestyle questionnaire survey, twelve months after the first state of emergency for COVID-19 at April 2020, “working from home” was the only factor that increased household power consumption for 11% and the other factors were gone. Space heating power consumption in this period did not increase significantly. Lifestyle changes have affected household timely electricity demand and increased self-consumption of renewable energy of photovoltaic power generation systems.