Published papers

Working from home has drawn more attention with the development of information and communications technology and the coronavirus disease 2019 pandemic. Although studies on working from home have been conducted in various academic fields, few have focused on residential environment and personality traits. In the present study, air temperature and humidity of the home workplace were measured and a questionnaire survey was conducted to understand the relationship between residential environment and personality traits and at-home work productivity. The results suggest that comprehensive productivity while working from home improved. However, when examining individual aspects of productivity, the productivity of information processing improved while that of knowledge processing and knowledge creation deteriorated. The results also suggest the importance of improving the residential environment when working from home because productivity while working from home rather than from the office improved with high evaluation of the residential environment. Moreover, productivity decreased for workers with high neuroticism and increased for those with high openness or perseverance and passion, suggesting that some personality traits are more or less suitable for working from home. To improve the productivity of all workers, these findings have practical implications for promoting appropriate maintenance of the residential environment and introducing flexible work styles that account for personality traits.

In recent years, ZEH has been drawing attention as a house that achieves a net zero annual energy consumption. In the present study, an unsteady 48-hour CFD analysis in winter was conducted to visualize the thermal environment of Nearly ZEH-M. The results showed that Nearly ZEH-M had a good thermal environment, exceeding the recommended minimum temperature range of 18°C, even in rooms without air conditioner running. It was also found that even with high insulation performance, thermal environments differed slightly by dwelling unit locations.

The Gassho-style houses in the historic villages of Shirakawa-go and Gokayama are among the most famous examples of Japanese vernacular architecture. The houses have thatched roofs that are notable not only for their design but also for their passive performance. In particular, the houses of Shirakawa Village are been well adapted to the local terrain, climate, and culture. However, no studies have considered the terrain around Shirakawa Village, particularly the topographic features of the Shohgawa River Valley, though they are likely has an effect on the houses.  In surveys conducted to date, there are many issues to address. For example, no simulations or measurements have considered the effect of topography on the wind environment, and details about heating are not yet clear. Here, the advantageous characteristics of the houses are investigated from the perspective of environmental engineering through actual measurements and computational fluid dynamics (CFD) simulations.  First, the wind environment of Shirakawa Village was evaluated by CFD analysis using a complex topography model. Visualization of the results showed that the wind flows from the north and follows the contours of the land. The wind speed increases around the center of basin and decreases in curved and narrow area. The wind speed is also decreased by dense houses. In sum, the simulation shows that Ogimachi is a low wind environment.  Second, the thermal environment in the houses in summer was investigated. The thick thatched roof prevented sharp increases in temperature and maintained a comfortable environment. The daily temperature range in the attic surrounded by the thatched roof was narrower than that on the first floor, which is framed by board walls. Within the context of sericulture, the room air temperature and wind speed in the attic represented an appropriate environment for silkworm breeding.  Third, the thermal environment of the house in winter was investigated. The effect of radiant heat from the heater was able to reach only a limited area, and the room temperature inside the houses was low. Also, snow guard fence improved the heat insulation capacity of the house, diminishing heat loss. Warm air diffused upward by convection, and the temperature tended to rise over a wide area on the second floor. Thermal sensation near the heater was improved by the increase in radiation temperature although it did not reach a comfortable level. The environment in much of the house was cold but tolerable, as the Gassho-style houses were adapted for the climate in Shirakawa Village to suit both summer and winter.  About a quarter of Shirakawa Village, covering an area larger than a city block, was targeted as the analysis region for validation. Analysis results for the wind environment of the uneven terrain were used as the boundary conditions in the analysis of the houses. In this study, the Reynolds-averaged Navier–Stokes equations were used as a turbulence model and the simulation was run using structured grid, but the use of large-eddy simulation and an unstructured grid is being considered for future research. The accuracy of the analysis remains an issue, though this method can be used to assess the influence of geography and climate in the surrounding area. The results of this research are expected to be useful for introducing passive technology into architectural design.

Efforts of local governments are essential for achieving the Sustainable Development Goals (SDGs), core elements of the 2030 agenda adopted by the United Nations in September 2015. A nationwide online questionnaire survey was conducted to collect data on the actual implementation level of the SDGs in Japan. Results showed that about 30-40% of local governments is considering/developing a plan and implementing projects towards achievement of the SDGs in Japan.

Realizing a healthy classroom environment is an essential task in sustainable development. In particular, students acquire professional skills at universities and proper design of the classroom environment is important for improving the academic performance of university students. However, there are many cases where the classroom environment is not ideal, such as when doors or windows are not opened. Many studies have analyzed the relationships between classroom environment and students' academic performance. However, few have analyzed the relationships between the spatiotemporal distribution of the classroom thermal environment and temporal changes in students' psychological sensations or concentration levels. Therefore, the main theme of this study is the exploration of the relationships between these factors. The survey was conducted in a university classroom in May 2013. All doors and windows in the classroom were closed to avoid the effects of ventilation and create the hot, humid condition of an actual classroom. The thermal environment was continuously measured at several points during the 90-min lectures, and students were asked to complete a questionnaire on their psychological sensations and concentration levels every 15 min; this allowed for collection of both physical-psychological data and spatiotemporal data of the classroom thermal environment. In the previous paper in this study (Part 1), the problems of a spatiotemporally heterogeneous thermal environment in a large classroom and students' psychological condition during a lecture were clarified. In particular, the back of the classroom tended to be hot. In this paper (Part 2), psychological questionnaire data were reanalyzed in detail from the perspective of spatiotemporal statistical analysis, which are frequently applied to city-scale studies. Local spatiotemporal autocorrelation statistics (Getis-Ord Gi*) revealed significantly hot and cold spots. The results of the analysis were visualized on 3D spatiotemporal maps. The results revealed that the number of cold spots for students' thermal sensation or tiredness level and the number of hot spots for students' concentration level in some seats in the front of the classroom decreased toward the end of the lecture. In contrast, the number of hot spots for students' thermal sensation or tiredness level and the number of cold spots for students' concentration level in some seats in the back of the classroom increased with time during the lecture. In conclusion, this paper suggests a new method for extracting features of the distribution of students with good or bad psychological condition via local spatiotemporal autocorrelation statistics. However, further efforts to enhance the validity of the newly suggested analysis method must to examine factors that specifically contribute toward improved academic performance.

The study examined the effects of the thermal environment in a terraced classroom on students' psychological sensations and concentration. The classroom thermal environment was continuously measured during 90-min lectures in May 2013. Students were asked to complete a questionnaire on their psychological sensations and concentration every 15 min during the lectures. Objective measurement data and subjective questionnaire data were analyzed. Results show that spatiotemporal heterogeneity of the classroom thermal environment was likely an important factor in students' psychological sensations and concentration.

There has been increasing interest in ESG management and movements to improve the environmental performance of real estate. Initiatives regarding SDGs (sustainable development goals) are expanding in corporate environmental behavior in answer to global environmental problems. In the United States, there are many reports showing the relationship between environmental performance certifications such as “LEED” (Leadership in Energy and Environmental Design) and rental income and real estate value, but in Japan, accumulation of comparable research is not as advanced as in Western countries. Regarding studies in Japan, target real estate comprises mainly office buildings and there are few studies analyzing the relationship between high environmental efficiency and real estate sale prices and used transaction prices for condominiums.  The principal aim of the present study is to clarify the effects of the environmental efficiency of buildings on real estate prices. Specifically, focusing on local government “CASBEE” (Comprehensive Assessment System for Built Environment Efficiency), we targeted apartment buildings certified by CASBEE Yokohama (485 buildings completed after 2006) and examined the effects of the level of each factor that composes CASBEE with regard to (1) new construction sales prices and (2) the influence on the rate of change in used transaction prices (rate of decline) by the hedonic approach. The targets of analysis were all 485 buildings in (1) and of the 80 buildings that were newly built in 2006 and 2007, those that were used transactions 5 years and 6 years after construction in (2).  The analysis results revealed the following three points.  1) When the BEE value, which is a comprehensive indicator, increases by 1 point, the average unit price increases by approximately 5.5%.  2) A 1-point increase in BEE value has a positive impact of 1.63% on the annual rate of change of the used transaction price (decline rate).  3) It is economically advantageous to purchase a condominium with a high BEE score when future sale (asset value) is taken into consideration.  It is our hope that widespread understanding of the results of the present study by concerned parties will lead to the further spread of environmentally conscious real estate. Moreover, by investigating environmental efficiency needs and willingness to pay on the customer side, we aim to clarify the differences in environmental efficiency that suppliers and consumers emphasize, leading to the future proposal of more effective environmental efficiency display and disclosure methods.

We analyzed the importance of buildings environmental performance items from the perspective of cost burden. Focusing on the evaluation items of CASBEE（Comprehensive Assessment System for Built Environment Efficiency）, we measured the importance of total of 20 items for environmental performance using conjoint analysis. It was confirmed that consumers place importance on environmental performance, where they can feel the merits of “comfort” and “convenience”. Additionally, we compared the level of each performance evaluation item of the actually supplied apartment buildings with the importance of consumers, and made a proposal for the spread of the environmental certification system.

As hubs of intellectual activity, offices are expected to promote work efficiency and support worker health. Many studies have analyzed the relationship of the office environment with work efficiency and the health of workers. However, few studies have compared the effects of various elements of the office environment on these outcomes and their economic benefits. To address this limitation, this study investigated the impact of various environmental elements on both work efficiency and health, and analyzed the economic benefits of optimizing these elements in office spaces. The impacts of each element of the office environment on work efficiency and worker health were analyzed for 1644 workers in 29 office buildings in Tokyo, Japan. Economic benefits were estimated by comparing perceived work efficiency to an ideal office and presenteeism to the absence of health-related barriers. The results showed that the office interior and furnishings provided the largest estimated economic benefits, followed by overall building sanitation and HVAC airflow. These elements produced economic benefits associated with high perceived work efficiency. The largest estimated economic benefits associated with low presenteeism was from desk lighting, which was the fourth largest economic benefit overall. The results suggest that healthy offices require not only improvements but also the removal of negative elements. These findings are expected to contribute to the realization of comfortable, healthy offices.

The impact on productivity of working from home is unclear. This study explores how the residential environment and personal attributes influence subjective productivity during winter. Indoor temperature and relative humidity were measured, and a questionnaire survey was conducted to gather information on subjective productivity, work type, work style, and personality traits. Results from 198 respondents indicated that productivity in simple tasks increased with the frequency of working from home. In addition, workers in better residential environments were 1.76 times more likely to exhibit higher productivity in simple tasks compared with those in poorer residential environments. Therefore, improving the residential environment, including temperature and humidity control, is critical to enhance productivity in simple tasks. However, workers who worked from home every day had a 0.47 times lower probability of exhibiting greater creative productivity compared with those who went to the office at least once a week, suggesting a decline in creative productivity for fully remote workers. Thus, a combination of office and remote work would be expected to increase overall productivity. Subjective productivity also varied depending on personality traits. The findings suggest that to improve productivity, workplace policies should allow for flexibility in customizing work environments according to tasks and personalities.

Previous studies investigating the relationship between indoor environmental quality and worker productivity have suggested that thermal environment has a significant impact on worker productivity. Some of these studies reported that productivity was less than optimal when the environment was thermally neutral and comfortable (i.e., PMV = 0.0). However, the analyses in those studies did not consider personal attributes, and the data hierarchy resulting from the multiple responses of survey participants was also not considered. Thus, there is no consensus on the optimal temperature for worker productivity. In this study, a measurement survey and questionnaire survey were conducted to assess worker productivity in a thermally neutral and slightly cool environment while considering the personal attributes of workers. The survey was conducted with air conditioning set to PMV = 0.0 and −0.5 for 2 weeks during late spring in Tokyo, Japan. The results of a multilevel analysis considering data hierarchy revealed that the relationship between thermal sensation and productivity differed according to gender. Men were most productive when it was cooler than thermally neutral (thermal sensation = −0.61, between“−1. slightly cool”and 0. neutral”), while women were most productive when it was warmer than thermally neutral (thermal sensation = 0.23, between“0. neutral”and“1. slightly warm”). The relationship between thermal satisfaction and productivity suggests that there may be a difference in thermal sensation that maximizes productivity and thermal satisfaction. This study provides new knowledge regarding the office thermal environment that maximizes worker productivity and thermal satisfaction.

Urban heat islands (UHIs) have been worsening, and Tokyo, Japan, is among the worst globally. The urban thermal environment requires measurement to formulate effective countermeasures. This study proposes a method for detecting roadways from infrared images of captured by a moving automobile and using deep learning to extract roadway surface temperatures from the detected roadways. Additionally, a roadway surface temperature map of Tokyo was created from 17,000 infrared images covering a route of 37 km and was then used to identify hotter and cooler areas of the city in order to validate the proposed methodology. The surface temperatures were high on wide roadways with a high sky view factor, but were lower and less variable in street canyons. Roadways perpendicular to the solar azimuth had lower temperatures due to shading by buildings. The accuracy of deep learning to detect roadway was imperfect, but a significant improvement in analytical efficiency was achieved. The method could also be applied to three-dimensional evaluation of urban surface temperatures by extracting surface temperatures for various city components, such as buildings and vegetation.

The residential environment significantly influences residents’ health, quality of life, and well-being. Therefore, it is essential to assess the residential environment and implement improvement measures when problems are identified. In this context, the use of assessment tools such as BREEAM, LEED, and CASBEE has increased rapidly in recent years. Identifying key items with these assessment tools is crucial for prioritizing improvements to residential environment. This study introduces the novel application of item response theory (IRT) to building environment engineering data in order to identify key items from the CASBEE Residential Health Checklist. The strength of IRT lies in its ability to consider variations in scores for each item and the relative relationships between items, thereby enabling the identification of significantly influential key items. Examining Japanese residences, IRT identified 6 environmental items and 7 spatial items from a total of 44 items in the CASBEE Residential Health Checklist. Additionally, these environmental and spatial components were ranked by their explanatory power for the overall assessment of the residential environment. These findings contribute to prioritizing improvements in residential environments and provide a brief assessment method. IRT can be applied to other regions and building types, potentially enabling the identification of key items unique to each case. Thus, IRT is a versatile method with broad applicability for identifying key items in residential environment assessments.