This study strives to determine ways to increase the use of outdoor spaces, particularly spaces that have an abundance of natural elements, in environmentally friendly housing developments. Empirical data were obtained by observing residents' behaviors (445 observations) and interviewing 61 residents in Kuemhwa Greenvill, a new housing project in Giheung Sanggal, South Korea. The outdoor natural environments were classified into four categories: reserved natural environment, built environment with a natural appearance, built environment as a green buffer, and built environment with natural elements. The survey revealed that, typically, the natural environments were utilized less than the non-natural environments. Because natural environments did not support various outdoor activities, only persons in certain limited age groups (adults and adults with children) and small groups of one or two people used them. In particular, children's play activities and social gatherings rarely occurred in the natural environments. Apart from physical, psychological, and social accessibility issues, the residents' preferences for the use of non-natural environments were related to their needs and the physical features of the environments.