Published papers

目的:成人を対象に,冬季の暖房使用と住宅内の座位行動および身体活動の関連を検討すること。方法:本研究は横断研究である。調査は沖縄県を除く46都道府県の工務店等を通して募集した断熱改修工事予定のある住宅に居住する20歳以上の成人を対象に2014年度から2017年度までの冬季(11月〜4月)に実施し,3,874名から同意を得た。加速度計は連続14日間の装着を依頼した。行動日誌から覚醒在宅時間帯を特定し,住宅内の座位行動と身体活動を評価した。コタツおよび脱衣所暖房使用の有無と住宅内の座位行動,身体活動との関連は目的変数を対数変換したうえで,日レベル(室温,オフセット項として覚醒在宅時加速度計装着時間等),個人レベル(年齢,BM等),世帯レベル(世帯年収,同居人数等)で調整した線形混合モデル(ランダム切片モデル)を男女別に実施した。非標準化偏回帰係数は指数変換し,目的変数への関連の程度を算出した。結果:有効データは3,482名であった。多変量解析の結果,コタツを使用しない場合は住宅内の座位行動時間が約2%短く[男性:exp(B)=0.98,p=0.022,女性:exp(B)=0.98,p=0.020],その中断回数は約10%多く[男性:exp(B)=1.10,p=0.001,女性:exp(B)=1.11,p<0.001],身体活動も5〜7%多かった[男性:exp(B)=1.07,p=0.005,女性:exp(B)=1.05,p=0.012]。脱衣所を暖房する場合も同様の関連が確認された。結論:コタツを使用しない人,脱衣所を暖房する人は,住宅内の座位行動時間が短く,かつ頻繁に中断し,身体活動量も多かった。局所暖房を使用せず,非居室でも暖房を行い家を暖かく保つことは,住宅内の座位行動を抑制し身体活動を促進する可能性がある。(著者抄録)

© 2018 Elsevier B.V. Numerous studies endorsed by the scientific community affirm that biophilic design in the workplace improves productivity and user well-being. However, it is necessary to go a step further and objectify the design criteria serving as an operator for productivity and well-being in design practice. In response to the challenges of how to measure the improvement of productivity and well-being through biophilic architecture design, the main contribution of this article is the development of a tool that allows to measure the predicted feature that improve productivity and well-being, based on a scientific method, which is tested by conducting a pilot experiment. A scheduled pilot experiment, as a small-scale version done in preparation for a major study, has been conducted to test a tool that quantifies the impact of biophilic design features on performance and well-being, to evaluate the influence of variables such as greenery and daylight on improving workplace performance, and look at biophilic design knowledge in greater depth. The role of natural indoor environments - understood as spaces within buildings provided with elements of nature - has received relatively little attention, compared to the number of studies evaluating occupant impact related to other characteristics of indoor environments derived from mechanical and electrical systems such as thermal factors, noise and vibration, ergonomics and office design. The present study is one of the first studies evaluating and measuring the combination of greenery and daylight into a biophilic design proposal. The results highlight an improvement in well-being, performance, creativity and health by introducing daylight and greenery into workplace design such as biophilic design features. The tool developed and tested in this pilot experiment opens a way to improve measured workplace performance to a much greater extent in contrast to the existing practice.

 The number of people needing nursing care more than doubled from 2000 to 2014, and medical expenses tend to increase yearly, in part because of the high demand for in-home care. Because elderly spend most of their time at home, the indoor thermal environment of their houses is important. The objective of this study was to investigate the relationship between perceived indoor temperature and the change in required care level among the elderly. Participants were 126 community-dwelling elderly aged 65 years or older using rehabilitation facilities in Osaka, Kochi, and Yamanashi Prefectures in Japan. A standardised questionnaire survey and indoor temperature measurements were conducted in winter to assess housing characteristics. Nursing care records from rehabilitation facilities were collected by photographing them with a camera. Spearman's rank test was conducted to assess the correlations between perceived indoor temperature, as indicated in responses to the questionnaire survey, and room temperatures measured in the living room, bedroom, and dressing room of participants. The total score from the CASBEE health checklist had the highest correlation coefficient. Participants were divided into a cold group and a warm group according to their total scores of perceived indoor temperature. The average perceived room temperature in the living room, bedroom, and dressing room was significantly lower in the cold group than in the warm group. When we compared the nursing care level in the latest survey with that from one year earlier, we found no change in most participants. The chi-square test was used to analyse the relation between perceived indoor temperature and change in required care level. We found that participants in the cold group were more likely to need a higher nursing care level than those in the warm group, at the 1% level of significance (p<0.01) Multiple logistic regression analysis was conducted by using change in care level as an objective variable. Perceived indoor temperature was significant at the 5% level of significance, and the adjusted odds ratio was 2.84 (95% CI: 1.16−6.98, p<0.05). This can be interpreted as meaning that the likelihood of the change in nursing care level from "same or lower" to "higher" was 2.84 times greater when the perceived indoor temperature changed from "warm" to "cold", indicating a high risk in the cold group that their level of nursing care would increase. The results suggest that maintaining a warm room temperature in winter helps to prevent an increase in the required nursing care level in community-dwelling elderly.

STUDY OBJECTIVES: Although associations between sleep quality and environmental factors and nutrient intake have been reported, interactions between these factors have not been elucidated in detail. Therefore, this cross-sectional study examined the effects of regular exercise and nutrient intake on sleep quality using the Pittsburgh Sleep Quality Index (PSQI), which is the most frequently used index for sleep evaluation. METHODS: The participants included 378 individuals aged 40 years or older living in Shika Town, Ishikawa Prefecture. Of these individuals, 185 met the inclusion criteria. The participants completed a self-administered questionnaire assessing lifestyle habits and frequency and duration of exercise, the PSQI, and the brief-type self-administered diet history questionnaire (BDHQ) on nutrient intake. RESULTS: A two-way analysis of covariance on regular exercise and PSQI scores indicated that protein intake (17.13% of energy) was significantly higher in the regular exercise and PSQI ≤10 groups than in the non-regular exercise or PSQI ≥11 groups (p = 0.002). In a multiple logistic regression analysis with PSQI scores (≤10 and ≥11), protein intake was a significant independent variable in any of the models adjusted for confounding factors such as age, sex, body mass index, current smoker, and current drinker (OR: 1.357, 95% CI: 1.081, 1.704, p = 0.009) in the regular exercise group but not in the non-regular exercise group.Conclusions We identified a positive relationship between sleep quality and protein intake in the regular exercise group. These findings suggest that regular exercise at least twice a week for 30 minutes or longer combined with high protein intake contributes to good sleep quality.

BACKGROUND: In countries with mild winter climates and inadequate heating, the relationship between housing conditions and health outcomes in winter have not been well studied. The purpose of present study was to evaluate the relationship between heater type and temperature factors in the bedroom and incidence of the common cold among children in Japan. METHODS: In this prospective cohort study, we distributed baseline questionnaires and temperature loggers in December 2019 and administered follow-up questionnaires in March 2020. We recruited children under age 15 years. We performed Poisson regression analysis and logistic regression analysis. RESULTS: Of 297 participants, air conditioners were the most prevalent (n=105, 35%), followed by gas or kerosene heaters (n=50, 17%) and floor heaters (n=31, 10%). Air-conditioners were associated with higher incidence of all events related to the common cold, especially having a fever (adjusted incidence rate ratio (aIRR)=1.84, 95% confidence interval (CI): 1.41-2.40). Contrary, gas or kerosene and floor heaters showed a lower incidence rate of some events related to the common cold, such as school or nursery school absence (aIRR=0.55, 95% CI: 0.37-0.82 and aIRR=0.39, 95% CI: 0.23-0.67, respectively). Whereas bedroom temperature did not show a positive association, children who always felt cold showed a higher incidence of some events related to the common cold. CONCLUSIONS: Our findings imply that the heating approach and modal thermal comfort, such as location of heating appliances, humidity, airflow, and radiant heat, may be more important for the onset of common cold in children than bedroom temperature itself.

The thermal environment of a house is a factor that affects sleep quality. Thus, for maintaining good health, it is important for houses to have an appropriate thermal environment. The influence of ventilation and air conditioning on a house's thermal environment cannot be ignored. Here, we investigated differences in ventilation and air conditioning equipment by comparing and evaluating the sleep quality of residents using individual air conditioners or central air conditioning. The results suggested that the central air conditioning group had reduced sleep latency, which might increase sleep efficiency in summer.

The practical efficiencies of existing commercial m-Si and CIS PV modules measured in reality by our group were less than 15 % because of the higher temperatures of the PV modules, and the rest of more than about 85 % of solar energy would be the exhaust heat to the environment. It was already reported in 2020 that the principle of an environmentally-friendly PV/T (Photovoltaic/Thermal) solar panel using an m-Si PV module to utilize 71.3 % solar energy for electricity and 40 °C hot water, as well as suppress heat radiation from the panel. The panel was designed to confirm the principle, i.e., it was an experimental PV/T solar panel. In this paper, a new practical environmentally-friendly PV/T solar panel is proposed for aiming the application to BIPVT (Building-integrated Photovoltaic/Thermal) systems. The new panel uses a CIS PV module, and all the functions, including a heat exchanger using flat aluminum tubes, are placed in the panel box, which is almost the same size as a simple CIS PV panel. The proposed PV/T solar panel converts 73.5 % of solar energy with 13.0 % power generation efficiency and 60.5 % heat collection efficiency at a 40 °C hot water supply in Yokohama, Japan. The efficiency is higher than the previous experimental panel. The proposed panel also can suppress heat radiation at about 50 °C even in the case of 60 °C hot water supply. The proposed PV/T solar panel can supply all residential heat demands, such as domestic hot water (DHW) and space heating or cooling, using solar heat with a lower environmental thermal load.

In 2015, the 2030 Agenda for Sustainable Development Goals (SDGs) was adopted by all United Nations Member States. The indoor environment of residences affects the health of occupants regarding SDG 3 (Good Health and Well-being). Meanwhile, a vast amount of energy is used to supply power to houses worldwide, which emit sufficient volumes of CO2 and affect climate change regarding SDG 7 (Affordable and Clean Energy) and SDG 13 (Climate Action). A key step to delivering on these SDGs is improving the thermal insulation of houses and housing equipment performance to reduce energy consumption and protect the health of the occupants by improving the indoor environment. This study presents an evaluation method for quantifying the contribution of improving housing performance toward delivering the SDGs. The proposed approach is primarily based on the results of heat load simulations. Meanwhile, blood pressure is predicted as an indicator of health by using the interior environment obtained by the simulation. A case study was performed, and the results demonstrated the effectiveness of improving the housing performance of newly constructed houses compared to heating and retrofit. The proposed method is versatile and can be adjusted for application to alternative locations, house designs, and lifestyles.

This study aimed to verify the effectiveness of a 48-h independent power outage system, evaluate the indoor thermal environment under power outage conditions, and improve residential awareness of disasters through a power outage experience. A power outage experiment was conducted in a collective residence with a 48-h independent power system. The available power for each dwelling unit was limited based on the type of heat source, at 700 and 1200 W for cogeneration (CG) and solid oxide fuel cell (SOFC) heating, respectively. The power supply was halted when the available power limit was exceeded. During the experiment, the thermal environment, temperature, humidity, amount of power generated by the CG and SOFC, and load power of the dwelling units were analyzed. We also conducted a questionnaire survey to evaluate the indoor environment and infrastructure. The results showed that home appliances could be used because all dwelling units were supplied with sufficient power, at 700 and 1200 W. The most important appliances were electric fans, refrigerators, lighting, mobile phones, and computer chargers. Therefore, the experiment demonstrated that a comfortable evacuation living condition can be realized by using CG and SOFC during a power outage in the summer.

The working space environment has a large impact on workers. To improve workplace productivity, it is important to design the office environment. In this paper, we focused on radiant air conditioning, which is attracting increasing attention for use in offices. The purpose of this study was to determine the differences in indoor environment between radiant air conditioning and convective air conditioning and evaluate their effects on workplace productivity by conducting subject experiments. Radiant air conditioning was found to reduce differences between deep body temperature and terminal skin temperature and to improve creative work performance compared with convection air conditioning.

It is important to prevent hypertension, which is a risk factor for cardiovascular disease and severe COVID-19. In addition, as more people work from home, it is desirable to improve intellectual productivity at home. Therefore, in this study, we clarify the effects of the thermal insulation performance of houses on physiological responses and productivity in remote workers. We obtained the following findings. (1) When insulation performance was higher, systolic blood pressure was lower, and the skin temperature and the blood flow rate of the feet were higher; (2) As insulation performance increased, productivity increased.

Objectives The purpose of this study was to make clear the descriptive epidemiology and the relationship between the room temperature of living room, bedroom, dressing room, and outdoor during winter, based on the climate areas in Japan. Methods This study targeted 3,781 people, survey for 5 years from 2014, based on the Smart Wellness Housing (SWH) project, which was carried out nationwide with the support of the Ministry of Land, Infrastructure, Transport and Tourism. During winter, we recorded the outdoor temperature and living room, bedroom, and dressing room temperatures at 1 m above the floor and near the floor for two weeks. Covariance structure analyses were used to clarify the relationship between room temperature and outdoor temperature based on six climate areas in Japan. The analyses were performed using SPSS22.0 and AMOS22.0 for Windows. Results The temperature near the floor inside the house was lower than the room temperature at 1 m above the floor, and both the room and near the floor temperature in the morning tended to be the lowest. The temperature disparity between the dressing room and living room was the largest. Based on climate areas, the room temperature in the Area 2 was the highest, while the room temperature in the Area 4 was the lowest. The outdoor temperature was more closely associated with the room temperature near the floor than the room temperature at 1 m above the floor, especially in the southern Areas, except Area 7. Conclusion The temperature near the floor inside the house was lower than room temperature at 1 m above the floor. The temperature disparity between dressing room and living room was the largest. The room temperature and near the floor temperature were lowest in the energy-saving Area 4. The outdoor temperature was more closely associated with the room temperature near the floor than the room temperature at 1 m above the floor, especially in the southern Areas, except Area 7.

Background: Excess winter mortality caused by cardiovascular disease is particularly profound in cold houses. Consistent with this, accumulating evidence indicates that low indoor temperatures at home increase blood pressure. However, it remains unclear whether low indoor temperatures affect other cardiovascular biomarkers. In its latest list of priority medical devices for management of cardiovascular diseases, the World Health Organization (WHO) included electrocardiography systems as capital medical devices. We therefore examined the association between indoor temperature and electrocardiogram findings. Methods: We collected electrocardiogram data from 1480 participants during health checkups. We also measured the indoor temperature in the living room and bedroom for 2 weeks in winter, and divided participants into those living in warm houses (average exposure temperature ≥ 18 °C), slightly cold houses (12–18 °C), and cold houses (< 12 °C) in accordance with guidelines issued by the WHO and United Kingdom. The association between indoor temperature (warm vs. slightly cold vs. cold houses) and electrocardiogram findings was analyzed using multivariate logistic regression models, with adjustment for confounders such as demographics (e.g., age, sex, body mass index, household income), lifestyle (e.g., eating habit, exercise, smoking, alcohol drinking), and region. Results: The average temperature at home was 14.7 °C, and 238, 924, and 318 participants lived in warm, slightly cold, and cold houses, respectively. Electrocardiogram abnormalities were observed in 17.6%, 25.4%, and 30.2% of participants living in warm, slightly cold, and cold houses, respectively (p = 0.003, chi-squared test). Compared to participants living in warm houses, the odds ratio of having electrocardiogram abnormalities was 1.79 (95% confidence interval: 1.14–2.81, p = 0.011) for those living in slightly cold houses and 2.18 (95% confidence interval: 1.27–3.75, p = 0.005) for those living in cold houses. Conclusions: In addition to blood pressure, living in cold houses may have adverse effects on electrocardiogram. Conversely, keeping the indoor thermal environment within an appropriate range through a combination of living in highly thermal insulated houses and appropriate use of heating devices may contribute to good cardiovascular health. Trial registration: The trial was retrospectively registered on 27 Dec 2017 to the University hospital Medical Information Network Clinical Trials Registry (UMIN-CTR, https://www.umin.ac.jp/ctr/, registration identifier number UMIN000030601).

Countless studies in animals have shown how housing environments and behaviors can significantly affect anxiety and brain health, giving valuable insight as to whether this is applicable in the human context. The relationship between housing, behavior, brain health, and mental wellbeing in humans remains poorly understood. We therefore explored the interaction of housing quality, weekend/holiday sedentary behavior, brain structure, and anxiety in healthy Japanese adults. Whole-brain structural magnetic resonance imaging (MRI) methods based on gray matter volume and fractional anisotropy were used as markers for brain health. Correlation tests were conducted, and then adjusted for multiple comparisons using the False Discovery Rate method. Housing quality and weekend/holiday sedentary behavior were associated with fractional anisotropy, but not with gray matter volume. Fractional anisotropy showed significant associations with anxiety. Lastly, both weekend/holiday sedentary behavior and housing quality were indirectly associated with anxiety through fractional anisotropy. These results add to the limited evidence surrounding the relationship among housing, behavior, and the brain. Furthermore, these results show that behavior and housing qualities can have an indirect impact on anxiety through neurobiological markers such as fractional anisotropy.

AbstractHome blood pressure (HBP) variability is an important factor for cardiovascular events. While several studies have examined the effects of individual attributes and lifestyle factors on reducing HBP variability, the effects of living environment remain unknown. We hypothesized that a stable home thermal environment contributes to reducing HBP variability. We conducted an epidemiological survey on HBP and indoor temperature in 3785 participants (2162 households) planning to have their houses retrofitted with insulation. HBP was measured twice in the morning and evening for 2 weeks in winter. Indoor temperature was recorded with each HBP observation. We calculated the morning-evening (ME) difference as an index of diurnal variability and the standard deviation (SD), coefficient of variation (CV), average real variability (ARV) and variability independent of the mean (VIM) as indices of day-by-day variability. The association between BP variability and temperature instability was analyzed using multiple linear regression models. The mean ME difference in indoor/outdoor temperature (a decrease in temperature overnight) was 3.2/1.5 °C, and the mean SD of indoor/outdoor temperature was 1.6/2.5 °C. Linear regression analyses showed that the ME difference in indoor temperature was closely correlated with the ME difference in systolic BP (0.85 mmHg/°C, p < 0.001). The SD of indoor temperature was also associated with the SD of systolic BP (0.61 mmHg/°C, p < 0.001). The CV, ARV, and VIM showed similar trends as the SD of BP. In contrast, outdoor temperature instability was not associated with either diurnal or day-by-day HBP variability. Therefore, residents should keep the indoor temperature stable to reduce BP variability.

Sleep disorders are drawing the attention of both medical and public health concern worldwide. In Japan, research suggests that one fifth of adults do not receive appropriate sleep and 40% of adults sleep less than 6 hours a day, and sleep rates are decreasing further year by year. Many studies show that cold indoor environments negatively affect sleep comfort and quality. Whereas these studies have focused on the effects of low bedroom temperature, few studies have focused on the effect of perception of coldness. Indoor temperature is typically much lower in Japan than in other countries. Therefore, the current study aimed to identify the effect of perception of bedroom coldness on sleep quality among Japanese adults. After controlling for covariates of age, presence of current disease and pain, smoking and consumption of alcohol (Model 1), participants who sometimes, often or always felt cold in the bedroom exhibited 0.57 (95% CI=0.32-0.83, p=<.0001), 1.08 (95% CI=0.82-1.35, p<.0001) or 2.25 (95% CI=1.83-2.67, p<.0001) higher PSQI scores compared to the group which didn't feel cold in bedroom. Our findings suggest keeping the bedroom thermal environment above a minimum limit as recommended by the World Health Organization or other organization during colder, winter nights when feeling cold during sleep. Additional deficiencies in the housing infrastructure, air quality issues due to the use of a heater, and micro bed environment need to be holistically addressed. Sleep quality can be improved by certain level via providing thermally comfortable sleeping environment.

Housing plays a critical role in human life, and the establishment of a residential environment that promotes the health of its residents is a pressing issue. Numerous studies on housing have been previously conducted in this social context; however, only a few have considered the comprehensive health risk due to the overall residential environment. In the present study, therefore, a large-scale nationwide self-rated questionnaire survey was conducted to examine the residential environment of detached houses and its impact on residents’ health status. A tool used in the Comprehensive Assessment System for Built Environment Efficiency (CASBEE), namely, the CASBEE Health Checklist, was distributed to various detached houses throughout Japan to assess the overall residential environment. The CASBEE Health Checklist covers residential environmental elements concerning thermal environment, acoustic environment, light environment, hygiene, safety, and security. Respondents were also asked about their current health status and that of family members. The questionnaire results were cross-tabulated, and odds ratios and significance probabilities (Fisher's exact test) were calculated. Results showed that the overall residential environment was likely an important determinant of health and was associated with prevalence of certain chronic diseases among residents. Odds ratios tended to be less than 1.0 in all cases, indicating that low disease prevalence was associated with a good residential environment.

CASBEE (Comprehensive Assessment System for Built Environment Efficiency) is widely used as the assessment system for green buildings in Japan. For the promotion of the low-carbon society, it is necessary to take the lead in introducing the assessment method that induces an approach to the low-carbon society into CASBEE. This paper reports the outline of this approach in the 2010 revised edition of CASBEE-NC (New Construction). © 2012 Taylor & Francis.

BACKGROUND: Previous studies using EEG (electroencephalography) as biomarker for dementia have attempted to research, but results have been inconsistent. Most of the studies have extremely small number of samples (average N = 15) and studies with large number of data do not have control group. We identified EEG features that may be biomarkers for dementia with 120 subjects (dementia 10, MCI 33, against control 77). METHODS: We recorded EEG from 120 patients with dementia as they stayed in relaxed state using a single-channel EEG device while conducting real-time noise reduction and compared them to healthy subjects. Differences in EEG between patients and controls, as well as differences in patients' severity, were examined using the ratio of power spectrum at each frequency. RESULTS: In comparing healthy controls and dementia patients, significant power spectrum differences were observed at 3 Hz, 4 Hz, and 10 Hz and higher frequencies. In patient group, differences in the power spectrum were observed between asymptomatic patients and healthy individuals, and between patients of each respective severity level and healthy individuals. CONCLUSIONS: A study with a larger sample size should be conducted to gauge reproducibility, but the results implied the effectiveness of EEG in clinical practice as a biomarker of MCI (mild cognitive impairment) and/or dementia.