This study aims to investigate the eco-friendly planning methods for a sustainable apartment houses in the Metropolitan area of Seoul. Eco-friendly plans that considers the environmental issues were attempted from the beginning of 2000s, and since then, many apartment houses in Korea were built using this concept. They were, however, generally focusing on the physical and spatial aspects of the site plan. After the Seoul C40 weather summit conference in 2009, the low carbon green housing standard has been emphasized and thus the chemical concept was added to the existing physical planning methods. Under such a background, this study intends to investigate the eco-friendly plans for the apartment houses in the 2000s. This includes an ecological network plan, an ecological base plan, a building greening plan, a water treatment plan, and an energy saving plan. Based on the analysis and synthesis of these planning methods in the early 21st century, it would be possible to set up a proper future plan to enhance the sustainable built environment in the housing industry in the coming years.