震災後の節電下における家庭の冷房使用の意識と実態

Electricity shortages prevailed in many areas of Japan after the earthquake that occurred in Tohoku on March 11, 2011. Electricity conservation was requested by government in the national interest. Excessive air-conditioning and illumination were discouraged. In summer 2012, electric utility in Kansai asked businesses and households to reduce electricity consumption by up to 10 percent, and 9 percent was reduced in households.<br> Survey on use of Air-Conditioners, electric fans and natural ventilation in summer was conducted in 2004 in southern Osaka city. Questionnaire sheets were distributed to 1,805 apartments; responded 257 of them by mail were analyzed. Another survey of the same items was conducted at the same 26 apartment buildings in the summer in 2011 when 1,765 sheets were delivered and responded 185 of them were analyzed. Weather conditions in summer in 2004 and 2011 were as normal as those of an average year.<br> Most frequent setting temperatures were 27.0°C in 2004 and 27.5°C in 2011. However, the settings were 17.0°C to 29.0°C in 2004, and were 23.5°C to 30.0°C in 2011. The mean setting temperature was 26.0°C in 2004 and 27.5°C in 2011(p<.0001). These results demonstrate the success of the COOL-BIZ government campaign, which requested that cooling temperature settings be set at 28°C. Defining the cooling charge as the difference between May and August billing amounts, results show the following for 2011 compared to 2004. Electricity charges in August were 2, 413 yen (23.0%) lower. Electricity charges in May were 515 yen (8.8%) lower. Cooling charges were 2,051 yen (43.3%) lower. Also, differences in cooling charges per 1 degree difference of setting temperature were 595 yen in 2004 and 567 yen in 2011. Differences of regression estimates of cooling charges for mean setting temperatures between 2004 and 2011 were similar to differences of mean cooling charges between those of 2004 and of 2011.<br> Comparison of 2011 data to 2004 data revealed that more respondents were satisfied with AC, orientation to AC use was higher, and awareness of cooling costs was lower. Residents depended more on AC to control indoor thermal conditions in 2011 than in 2004, and environmental consciousness was lower. Dissatisfaction with ‘high electric charge for cooling season’ decreased from 72.9% to 55.6%. The AC performance possibly improved during 2004‐2011.<br> The cooling charge increased along with disturbances by solar radiation indoors in 2004, but no relation was found in 2011. The relation between the subjective degree of apartment ventilation and the degree of window opening was stronger both when asleep and when awake in 2004, but no relation was found in 2011.<br> Respondents were less concerned about environmental issues and depended more on AC in 2011 than in 2004. Habits of controlling the indoor thermal environment according to the outdoor climate were not as strong in 2011. Most electricity conservation can be characterized as realized by higher AC temperature settings.