Effects of Retrofitting Living Rooms with Thermal Insulation on the Health of the Elderly

INTRODUCTION Human life expectancy is affected by numerous factors, including heredity and disease, which have been studied in considerable detail. However, other factors influencing human health and life expectancy have not been studied quite as extensively. The quality of housing affects human health, but little is known about the specific health effects of the indoor environment. People spend most of their time indoors, mostly in their own homes, and thus, improving the quality of housing could potentially aid in the prevention of ill health. The elderly spend most of their time in their living rooms; therefore, in the present study, we investigated the effects of retrofitting living rooms with thermal insulation on the indoor environment and the health of elderly residents.

METHODS Most areas of Japan have a temperate climate, with mean winter daytime temperatures ranging from -8°C in the north to 17°C in the south. The mean winter daytime temperature in Tokyo is 6°C (mean values from 1981-2010). This study was carried out in two areas of Tokyo as well as Saitama, a prefecture adjacent to Tokyo. The participants were living in 10 households in Saitama and four households in Tokyo. The four houses in Tokyo were conventional wooden structures built between 1941 and 1952 (mean age of structure, 63.5 years). In Saitama, eight houses were wooden structures and the other two were light-gauge steel framed; these 10 houses were an average of 26.6 years old. All houses had no or poor insulation. Most of the residents usually heated only their living rooms and occasionally their bedrooms. The living room of each house was retrofitted with one of the following four insulation levels: 1) replacing single-pane with double-pane windows (Tokyo, n=3); 2) replacing single-pane with double-pane windows and retrofitting the living room walls and floor with thermal insulation (Tokyo, n=1); 3) replacing single-pane with double-pane windows, installing thermal insulation in the living room walls and floor, and installing a floor heating system (Saitama, n=5); and 4) the same changes as level 3 except that vacuum insulation panels were used to retrofit the walls (Saitama, n=5). Residents comprised six elderly males and 12 elderly females (mean age, 67.9 years; age range, 59-85 years). All residents were in good health and were not taking antihypertensive drugs. The initial indoor environment and residents' health were assessed from October to December 2011 (baseline), before the thermal insulation retrofitting. After the retrofitting, the indoor environment and residents' health variables were assessed as outcomes in the following two measurement periods: the first winter (January to February 2012) and the second autumn/winter (October to December 2012). In this study, we focused on outcomes measured during the second autumn/winter (follow-up), which were obtained in the same seasons as the baseline measures. For each house, temperatures and relative humidity were measured every 10 minutes in the living room, the bedroom, the bathroom, and the changing area, and outside of the house for 4 weeks in each measurement period. Each participant's blood pressure was automatically measured every 30 minutes for 24 hours by a portable automated sphygmomanometer (TM-2431C, A&D Co. Ltd., Tokyo, Japan) once in each measurement period. Participants measured their own blood pressure five times per day (after waking, after breakfast, after lunch, after dinner, and before bedtime) and recorded the number of hospital visits and daily frequency of defecation and urination for 4 weeks in each measurement period. Each resident was interviewed at home and answered a questionnaire composed of the following scale items: subjective view of health; WHO-5 well-being index1); Overactive Bladder Symptom Score (OABSS)2); St. George's Respiratory Questionnaire (SGRQ); Pittsburgh Sleep Quality Index (PSQI)3); Rhinoconjunctivitis Quality of Life Questionnaire Japanese Version (JRQLQ No.1)4); thermal sensation; thermal comfort; humidity sensitivity; and clothing insulation value (CLO). Residents completed this questionnaire once for each measurement period.

RESULTS and DISUSSION The mean outdoor temperatures were 16.5±1.19°C in autumn/winter 2011 and 11.7±1.51°C in autumn/winter 2012. Autumn/winter 2011 was significantly warmer than autumn/winter of 2012 (P<0.01). The mean temperatures of the residents' living rooms were 20.3±0.76°C at baseline and 18.7±1.49°C at follow-up (P<0.01). The mean temperatures of the residents' bedrooms, bathrooms, and changing areas were lower in 2012 than in 2011 by 3.6°C, 3.5°C, and 3.7°C, respectively. Although the mean living room temperature was lower in 2011 than in 2012, residents started using heating appliances in their living rooms 1 to 2 weeks later in 2012. On the contrary, they turned the heater on in their bedrooms 4 or 5 days earlier in 2012 than in 2011. No significant differences were observed in thermal sensation, thermal comfort, humidity sensitivity or clothing insulation between baseline and follow-up. The difference in the timing of heating appliance use in the living room might be attributed to factors other than temperature and relative humidity, such as sensitivity to drafts. No significant changes were seen in blood pressure measured every 30 minutes for 24 hours before and after the thermal insulation retrofitting. Coefficients of variance of self-assessed blood pressure, which were obtained by dividing the standard deviation by the mean value across 4 weeks, were significantly smaller at follow-up than at baseline, indicating relative stability in the residents' blood pressure after the retrofitting. Significant improvements were evident in PSQI and JRQLQ items after the retrofitting. Furthermore, in personal interviews, residents reported that they perceived better thermal conditions, greater anti-noise effects, and less dew condensation in their living rooms after the retrofitting. These results suggest that retrofitting living rooms with thermal insulation improves some aspects of the health of elderly residents.