総説・解説等

90% of Japanese homes do not meet the WHO housing and health guidelines for a minimum room temperature of 18℃ in winter. Promotion of warm homes by improving thermal insulation performance during new construction and renovation is expected to have the effect of preventing chronic disease, reducing frail risk and long-term care. This article introduces medical evidence on housing and health based on the nationwide intervention survey for 2,000-household / 4,000-residrnts and other large-scale studies done by authors.

本稿は建築LCAの最新状況を紹介したものである。建築LCAの研究開発は日本建築学会において1990年にスタートし、建物のLCA指針となった。その手法を応用した国、自治体の公共建築の設計に活用される気候変動緩和対策評価ツールが開発・運用され、民間企業でも幅広く利用されている。また、2007年からは戸建住宅からあらゆる用途の大規模建築までを対象とする簡易LCA手法が建築環境総合性能評価システム（CASBEE）に組み込まれ、幅広く活用されている。さらに建築LCAにおいて室内空気質汚染を始めとする室内環境による健康影響評価が行われている。

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 paper describes the outline of heatstroke risk evaluation model for aged residents based on surveys done by the Heatstroke Surveillance Committee of Japanese Association for Acute Medicine and field measurements of indoor air temperature, humidity and so on. To reduce heatstroke of aged residents, promotion of thermal insulation, sun-shading, cross ventilation, air-condition of houses and living behavior of residents are needed.