Published papers

睡眠の質低下を引き起こす要因の一つとしては、夏季の蒸し暑さが挙げられ、冷房を使用した適切な暑さ緩和対策が求められている。既報においては、冷房の連続運転が睡眠に与える影響を検証し、入眠時および睡眠中の後半に適切な温熱環境が異なる可能性及びタイマー運転の検証の必要性を示唆した。そこで本研究では、非定常温熱環境制御が睡眠の質に与える影響を明確にするため、被験者実験を実施し、非定常温熱環境制御が睡眠の質向上に寄与する可能性を示した。

睡眠の問題は重大な健康被害をもたらす。近年、室内温熱環境と睡眠の関係に注目が集まりつつあるが、季節を通して調査を行った例は少なく、その検証は不十分である。そこで本研究では、夏季・冬季の室内温熱環境が睡眠に及ぼす影響を明らかにすることを目的として、2014年の夏季と冬季に実態調査を行った。マルチレベル分析の結果、夏季は寝室の室温1℃上昇に伴い0.2%睡眠効率が低下し、冬季は室温1℃低下に伴い0.8%睡眠効率が低下することが示された。

Residents themselves are responsible for controlling their living environment, and their perception of coldness is important to protect their health. Although previous studies examined the association between perceived coldness and indoor temperature, they did not consider the spatial-temporal differences in indoor temperatures. This study, conducted in Japan, measured indoor temperatures in 1,553 houses across several rooms (living room, changing room, and bedroom) and heights (at 1 m above the floor and near the floor) over two weeks and obtained the perceived coldness from 2,793 participants during winter. Results showed substantial temperature differences between rooms (horizontal differences): 3.8 °C between living and changing rooms, and 4.1 °C between living rooms and bedrooms. The average vertical and diel (evening-morning) temperature differences in the living room were 3.1 °C and 3.0 °C, respectively. Regional analysis revealed that the Tohoku region experienced larger horizontal and diel indoor temperature differences, primarily due to its practice of intermittent and partial heating in living rooms only, in contrast to Hokkaido's approach of heating the entire house continuously. Despite Hokkaido's comprehensive heating system, it exhibited the largest vertical temperature difference of 5.1 °C in living rooms, highlighting the insufficiency of heating alone and the necessity for enhanced thermal insulation. The multivariate logistic regression analyses showed that average temperatures and vertical temperature differences were associated with perceived coldness, while horizontal and diel differences did not show a significant association, further emphasizing the importance of improved thermal insulation. Moreover, factors like individual attributes (age and gender), and lifestyle choices (meal quantity, exercise habits, alcohol consumption, and clothing amount) were significantly associated with coldness perception. Notably, older adults were less likely to perceive coldness but more vulnerable to the health impacts of low temperatures, underscoring the necessity of not solely relying on human perception for indoor temperature management to protect cold-related health problems.

Improvements in workplace productivity bring significant benefits to companies, and so previous research has focused on how the indoor office environment affects workplace productivity. Recently, the effect of support spaces, such as “refresh corners”, on workplace productivity has been investigated. Light and the visual environment also affect the fatigue and sleepiness of workers through the autonomic nervous system. Hence, support spaces could improve workplace productivity by alleviating fatigue and sleepiness. In this study, we conducted a human subject experiment in the autumn of 2013. The working efficiency of participants was measured during simulated work while they used a support space with different light and visual environments. In addition, the participants wore a heart rate monitor to measure their autonomic nervous state and they answered a questionnaire on fatigue and sleepiness before and after support space use. An open support space activated the parasympathetic nervous system and reduced fatigue. Moreover, having blinds open to allow daylight in also activated the sympathetic nervous system and decreased sleepiness. Lower levels of sleepiness before work improved working efficiency for idea generation. These results suggest that using open support spaces with daylight reduces fatigue and sleepiness, and increases workplace productivity.

ENEMANEHOUSE2014, a contest in which 5 universities design, construct, and measure Zero-Energy-Houses (ZEH), was held as a part of a project by Agency for Natural Resources and Energy. The University of Tokyo established a consortium with various enterprises and proposed a ZEH prototype of city apartment called “CITY-ECOX”. CITY-ECOX has flexible spatial structure and technologies that can be customized according to the climate of a construction site and lifestyles of house owners. A real size CITY-ECOX was built in Tokyo, January 2014, and its environmental performance was measured. This paper shows design of CITY-ECOX and result of its operation.

As a neutral academic institution, we introduce a new environmental model for interpreting the overall impacts of buildings and propose what can be done in a wide variety of activities in the architectural and construction fields. This proposal is based on the two-year discussion in the 'Subcommittee on Sustainable Buildings' of the 'Committee on the Global Environment' of the Architectural Institute of Japan.

国土交通省は2014年度より、厚生労働省と連携して「スマートウェルネス(健康・省エネ)住宅等推進事業調査」を実施しており、著者はこの調査を行っている医学・建築学の専門家約90名で構成される委員会の幹事と調査解析小委員会の委員長を務めている。同事業調査では、断熱改修等による住まいの改善が居住者の健康に与える影響に関する2千世帯・4千人規模の全国調査(SWH全国調査)を実施し、2023年6月現在で医学系原著論文11編が刊行されている。本稿では、それらの概要と著者らによるその他の成果について紹介した。SWH全国調査では、亜熱帯の沖縄県を除く全国2190世帯の居間、寝室、脱衣所の冬季室温を測定した。その結果、WHO勧告冬期最低室温18℃以上を、在宅中の居間平均室温で満たさない住まいが9割を占めることが明らかになった。その他、断熱改修による暖かい住まいが、高血圧緩和、血圧変動緩和、心電図異常所見の予防、脂質異常症の予防、過活動膀胱の予防、睡眠の質向上、健康関連QOLの向上、座りすぎ生活の減少、につながることについて概説した。

Optimal control of HVAC system is required because of its considerable influence on workplace-productivity, health and global environment. In this study, we developed an optimal HVAC control system using Response Surface Method by Spline, which calculates optimal control conditions on the basis of cause-and-effect model of thermal comfort, outdoor environment and control parameters created by building's operational data. Experimental study was conducted to verify the effectiveness of developed method by applying it on optimization problem of thermal comfort in several zones. We concluded that our method is practicable and efficient to achieve multi-objective optimization control on HVAC system.

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.

Current countermeasures for preventing hypertension emphasize only improvements to lifestyle. Recently, improving life environment has attracted attention, in parallel with publication of the WHO Housing and health guidelines. We quantitatively evaluated the relationship between housing thermal environment and blood pressure (BP) in a real-world setting. We conducted a nationwide, prospective intervention study-the Smart Wellness Housing survey-in Japan, as a non-randomized controlled trial. The intervention was the retrofitting of thermal insulation in houses. Participant recruitment was done by construction companies in all 47 prefectures of Japan. Measurements of home BP and indoor temperature at 1.0 m above the floor in the living room, changing room, and bedroom were taken for 2 weeks before and after the intervention each winter (November-March) of FY 2014-2019. As of July 2022, over 2500 households and 5000 participants were registered in the database. We found that (1) about 90% of Japanese lived in cold homes (minimum indoor temperature <18 °C), (2) indoor temperature was non-linearly associated with home BP, (3) morning systolic BP (SBP) was more sensitive than evening SBP to changes in indoor temperature, (4) SBP was influenced by indoor temperature change particularly in older participants and women, (5) unstable indoor temperature was associated with large BP variability, and (6) insulation retrofitting intervention significantly reduced home BP, especially in hypertensive patients. We proposed that the BP reduction effect of the life-environment is comparable to that achievable by lifestyle.

This study examined the seasonal patterns of physical activity (PA) and sedentary behavior (SB) and the relationship between PA and SB and the indoor thermal environment in each season. 98 of 131 the participants were analyzed. 1) Daily moderate-to-vigorous PA was significantly greater in fall than in winter. 2) Adjusting the accelerometer wearing time, outdoor PA and SB were not significantly related to season, but indoor moderate-to-vigorous PA were significantly greater in fall and summer than in winter. 3) Using a kotatsu in winter was associated with longer SB and less light-intensity PA than using an air conditioner.

Aim: Some studies have reported a higher incidence of falls during winter with similar proportions of indoor and outdoor falls. We investigated the relationship between indoor temperature during winter and falls at home in the past year among community-dwelling older adults. Methods: This cross-sectional study enrolled 964 individuals of ≥65 years of age in Japan. Participants answered questions about falls (including trips) at home within the past year, and the living room temperature was measured for 2 weeks during winter. Participants were divided into those living in cold (mean temperature near the floor <12̊C), slightly cold (12-17.9℃), and warm (≥18̊C) houses. The association between indoor temperature (cold vs. slightly cold vs. warm houses) and falls at home in the past year was examined using a logistic regression analysis adjusted for potential confounding factors. Results: Valid data were obtained from 907 participants (mean age: 72.0±6.3 years), of whom 265,553, and 89 lived in cold, slightly cold, and warm houses, respectively. In the past year, falls occurred once in 325 (35.8%) participants and multiple times in 148 (16.3%) participants. In warm houses, the odds ratio of falling once and multiple times in the past year was 0.49 (p=0.032) and 0.34 (p=0.035), respectively, in comparison to cold houses. Conclusions: Living in cold houses may be associated with an increased risk of falling at home among older adults. Maintaining an appropriate indoor thermal environment during winter may reduce the risk of falling among individuals who spend most of their time at home.

近年、地域や職場等を通じた健康増進への働きかけが注目されている。この流れより執務環境の主観評価ツールであるCASBEE-OHCの開発とそのチェックリストを用いたWEBアンケート調査が行われた。しかし現在、オフィス環境やワーカーを取り巻く環境の変化が予想される。そこで本研究では、現在の環境について新たな知見を得るため、再度調査を実施した。結果として、現在、執務者の健康には住まいの環境や家での執務環境の影響が関係していることが確認された。

The purpose of this study was to clarify the effect of winter indoor thermal environment on the health for Child-Rearing Age Women. Follow-up surveys on Residents' health and indoor thermal environment were conducted in winter(2015-2022) before, after and 5-6years after moving to houses with thermal insulation performance. Repeated measure analysis of variance showed that increased indoor temperature reduce the symptoms such as cough and phlegm, stuffy or runny nose, stiff shoulders, back pain, cold extremities, injury, and catching a cold. It also improved subjective sleep quality and subjective health status.

Improvement of living environment quality of life (QOL) is increasingly attracting attention as a factor in disease prevention. We administered questionnaires to adult residents of a suburb of Kitakyushu City, Japan, in October 2009 and October 2011, with the aim of evaluating chronological changes in resident health and changes in the housing and regional environment over those two years. Cause-and-effect relations were considered through structural equation modeling (SEM) using a cross-lagged effects model and a synchronous effects model. Analysis of the results indicates that the housing and regional environment affects resident health. The present study quantified living environment value according to reported resident satisfaction. In addition, further studies with an increased sample size may be beneficial. Topics for future research include evaluation using objective indicators to strictly elucidate the causal relationship between resident health and living environment.