高齢化や世帯構造変化による家庭用エネルギー消費量への影響は用途間で異なるか？

抄録

 This paper investigates the effects of change in household structure on the residential energy consumption by end-use. Structural change, such as decreasing household size, is a factor for decreasing energy demand per household. On the other hand, energy consumption as a whole can be increased by losing scale economy. Moreover, as a new contribution of this paper, it was revealed that the impact of the change in household structure, compared to other end-use purposes, tends to be larger for energy consumption per household for hot water supply. The reason for this difference is that a large part of the energy consumption for hot water supply is unlikely to be shared among members of a household, so that it is likely to be affected by a change in household size. Also, single-person households tend to not fill bathtubs. In other words, energy consumption as a whole for hot water supply is hardly to be affected by change in household structure, so it is likely to be directly affected by the population change. Therefore, under the depopulation trend expected in the future, energy consumption for hot water supply is likely to decrease from the viewpoint of household structure. Meanwhile, energy consumption for space-heating per household is insensitive to change in household structure, so this energy consumption as a whole is likely to increase. This finding suggests that improving the thermal insulation performance of housing and the efficiency of appliances for space-heating is important for decarbonization in the residential sector. Although previously published studies have investigated the impact of household structure on energy consumption, this study acquired new findings by revealing that the effect can differ between end uses. Such analyses can be utilized to specify end uses having high priority for implementation of countermeasures.
 Moreover, in addition to population aging and change in household size, this study revealed that the decrease in the proportion of detached houses is also a factor for reducing energy consumption for space heating. As shown by this study, due to the increase of the proportion of collective houses, energy consumption during 2010–2015 decreased by 0.5% in the five-year period. Although previous studies have suggested an impact of the increase in collective housing on CO₂ emissions and electricity demand, this paper contributes to the literature by revealing the impact in an actual time from observed data. This suggests that compact development of cities leads to a decarbonizing of the residential sector by encouraging people in single-person households in suburban areas to move into collective housing.