Intervention study of the effect of insulation retrofitting on home blood pressure in winter: a nationwide Smart Wellness Housing survey

Abstract

Objective: The WHO's Housing and health guidelines (2018) listed ‘low indoor temperatures and insulation’ as one of five priority areas, and indicated insulation retrofitting to help mitigate the effect of low indoor temperatures on health. However, there is still not enough evidence for the effect of insulation retrofitting based on an objective index. Methods: We conducted a nonrandomized controlled trial comparing home blood pressure (HBP) between insulation retrofitting (942 households and 1578 participants) and noninsulation retrofitting groups (67 households and 107 participants). HBP and indoor temperature were measured for 2 weeks before and after the intervention in winter. To examine the influence of insulation retrofitting on HBP, we used multiple linear regression analysis. Results: The analyses showed that indoor temperature in the morning rose by 1.4°C after insulation retrofitting, despite a slight decrease in outdoor temperature by 0.2°C. Insulation retrofitting significantly reduced morning home SBP (HSBP) by 3.1 mmHg [95% confidence interval (95% CI): 1.5–4.6], morning home DBP (HDBP) by 2.1 mmHg (95% CI: 1.1–3.2), evening HSBP by 1.8 mmHg (95% CI: 0.2–3.4) and evening HDBP by 1.5 mmHg (95% CI: 0.4–2.6). In addition, there was a dose–response relationship between indoor temperature and HBP, indicating the effectiveness of a significant improvement in the indoor thermal environment. Furthermore, there was heterogeneity in the effect of insulation retrofitting on morning HSBP in hypertensive patients compared with normotensive occupants (–7.7 versus –2.2 mmHg, P for interaction = 0.043). Conclusion: Insulation retrofitting significantly reduced HBP and was more beneficial for reducing the morning HSBP of hypertensive patients.

A Systematic Review of Associations between Energy Use, Fuel Poverty, Energy Efficiency Improvements and Health

“…Except for one office study [ 43 ], eight studies were performed in residential buildings ( Table A10 ). Some studies reported that energy efficiency intervention in homes can improve asthma [ 77 , 78 ], respiratory symptoms [ 77 , 78 , 79 , 81 ], sinusitis [ 80 ], general health [ 80 , 83 ], satisfaction [ 80 , 81 ], and reduce blood pressure [ 84 ]. Furthermore, an improved mechanical ventilation rate in office buildings can improve SBS symptoms, productivity, and perceived indoor air quality [ 43 ].…”

“… Francisco et al [ 83 ] 2017 United States Weatherization services Intervention Residential buildings General health 72 households 178 children and adults Energy efficiency retrofits can improve self-reported health. Umishio et al [ 84 ] 2020 Japan installation of outer walls, floor and/or roof insulation and replacement of windows Intervention Residential buildings Blood pressure 1009 households 1685 adults Energy efficiency insulation retrofitting in homes can reduce home blood pressure and reduce morning home systolic blood pressure of hypertensive patients. …”

Impact of indoor temperature instability on diurnal and day-by-day variability of home blood pressure in winter: a nationwide Smart Wellness Housing survey in Japan

“…A randomized controlled trial [ 32 ] indicated that instruction in home heating reduced morning SBP by 4.4 mmHg. Furthermore, an intervention study [ 33 ] revealed that insulation retrofitting of houses significantly reduced morning home SBP by 3.1 mmHg. Based on these results, heating use and highly insulated houses are both important for reducing BP levels.…”

Influence of residential performance on residents' health status (part II): Nationwide survey of environmental performance of apartment buildings and residents' health status

“…The thermal insulation and airtightness of houses affect the health of residents. [1][2][3][4][5][6][19][20][21][22] In New Zealand, a large-scale study of 4407 low-income residents (1350 households) revealed that residents living in houses with better insulation had higher self-assessments of their health status, fewer absences from school and work, and fewer hospitalizations for respiratory diseases. 1,2 Regarding airtightness, apartment buildings are more airtight than detached houses, resulting in increased condensation, mold, and dampness.…”

“…For example, a room in an apartment is surrounded by other dwelling units; therefore, the outer surface area is small, resulting in better heat insulation and airtightness compared with detached houses. The thermal insulation and airtightness of houses affect the health of residents 1‐6,19‐22 . In New Zealand, a large‐scale study of 4407 low‐income residents (1350 households) revealed that residents living in houses with better insulation had higher self‐assessments of their health status, fewer absences from school and work, and fewer hospitalizations for respiratory diseases 1,2 .…”