Existing literature pointed that the economic opportunity cost of having children and gender inequality are the key factors of low fertility. Given the findings, South Korea spent more than 200 billion dollars for the last 17 years and improved gender equality significantly. However, Korea shows the lowest fertility rate in the world. To overcome the limitation of existing literature, this study reinvestigates the factors influencing the intention to have children among young individuals and hypothesizes that young people's childbearing intention is related to how much they trust other people and society, beyond economic factors. This study utilizes the ‘Young Adults Survey’ conducted by the Korean government in 2022, comprising a sample of 14, 966 individuals aged from 19 to 34. Employing logit regression analysis and finds that young adults’ perception on social trust and self-actualization possibility have significant impact on their fertility intention. In addition, all the economic factors are not significant for the intention to have two or more children. In contrast to previous studies, income, women’s labour force participation, home ownership, and population density are not significant. It implies that the current economic approaches for the fertility promotion policies would not work as expected. Social approaches should be considered to overcome the ultra-low fertility problem.

To cope with the exacerbating housing problem due to urban population increase and rapid urbanization, the number of multi-unit residential complexes (MURCs) is sharply rising. MURCs account for approximately 30% or more of housing stocks in the New York and Los Angeles metropolitan areas; and much higher in developing world, for example, 58% in Seoul, Korea. Likewise, the share of electricity consumption of MURCs in cities is increasing. Most existing literature analyzed the electricity consumption at household or house level and neglected the electricity consumption in publicly shared spaces and utilities such as outdoor lighting, parking system, elevators (vertical transportation), playgrounds, site water and sewage, management offices, security offices, and so forth. Unlike single houses, MURCs with hundreds or thousands of houses tend to be planned and built all at once, under one site plan. Therefore, urban design or site planning can crucially affect the aggregated electricity consumption at neighborhood level with different land use patterns and spatial configurations, which change light, shade, wind, heat island, reflection for individual houses and public domain. Site plan attributes can also affect residents’ choice of indoor and outdoor activities. A few simulation studies tried to examine the effect of urban design at neighborhood level, but empirical analysis can be hardly found mainly due to data limitation. This study aims to empirically investigate the effect of urban design on aggregated electricity consumption at a neighborhood level. We collected the aggregated electricity consumption data of 1122 MURCs in Seoul during the first half of 2016 and adopted the panel analysis. This study confirmed that more building coverage roads and pavements increase the aggregated electricity consumption; more green open space reduces it. Interestingly, mid-rise and mid-open plan would be the optimum design because of the effect of the number of floors. As the number of floors increases, electricity consumption for vertical transportation increases faster and offsets the benefit of high-rise and high-open plan. The study is significant, because, unlike previous studies, it empirically analyzed the collective consumption of electricity at a neighborhood level, considering the site plan features. Furthermore, this study provides evidence-based implications for sustainable urban design, especially for MURCs.