Change of Summer Thermal Control Use in Homes after Electricity Shortage Caused by 3.11 Disaster in Japan

Electricity has been shortened in Japan after the Earthquake occurred in Tohoku in March 11 in 2011. Fukushima atomic electric generating station stopped and exploded because tidal waves after the earthquake washed away the cooling plants of the station. Safety of atomic electric generation is suspected and almost atomic electric generating stations were stopped after the disaster.

Electricity saving was required for the nation by government. Excessive illuminations and air-conditioning were accused. Circumstances were more serious in Kansai area where half of the electricity generation depended on atomic power generation. Electricity saving up to 15 percent was appealed to business sections and households in Kansai area by electric power company in summer season in 2011.

We carried out a questionnaire survey of air conditioner use in summer for apartment house occupants in the south of Osaka city in Kansai area in 2004. The surveyed items were number of air-conditioners, setting temperatures, electricity use and charge in May and August, subjective degree of air-conditioner use and consciousness for using air-conditioners and so on. Usage of electric fan and natural ventilation were also surveyed. We carried out another survey of the same items for the same apartment buildings just after the period of electricity saving in 2011, though the occupants were not the same.

Electric charge difference between August and May decreased by 43% and electric use difference between August and May decreased by 46%. Mean setting temperature of air conditioners increased from 25.9 in 2004 degree to 27.5 degree in 2011.

Number of air conditioners, living style such as regularity of living time, almost constitution such as duration to heat or perspiration and environmental consciousness of the respondents such as preference of natural wind or anxiety of global warming were not different between 2004 and 2011. On the other hand evaluation of air conditioner performance, consciousness of electric cost, positive or negative thinking toward air conditioner use changed significantly. Subjective frequency of natural ventilation use both in daytime and nighttime did not changed, though air conditioner and electric fan use changed significantly. Subjective evaluation of ventilation, noise in buildings, moldiness, sunshine heat and sunshine glare of the apartments were significantly different between 2004 and 2011.

Correlation between subjective electric saving and frequency of opening windows in daytime and frequency of electric fan use, correlation between air pollution and window opening in nighttime, correlation between outside noise and window opening in daytime disappeared in 2011.