To alleviate global warming effect, apartment house with long life spans have gained attention due to their ability to conserve resources and reduce $CO_2$ emissions. The purpose of the study was to develop a Sustainable Durability Design method that can quantitatively evaluate $LCCO_2$ emissions based on the durability life of apartment buildings in the early design phase. To compute $CO_2$ emissions as a function of the durability life, the durability life was determined using the durability chapter of Korea Concrete Standard Specifications, computed W/B, and thickness of concrete cover. The life cycle of the building was divided into 4 phase. For the construction phase, major $CO_2$-emitting construction materials were selected, and $CO_2$ assessment plans for 5 standard apartment housings were proposed. For the operation phase, $CO_2$ emissions were computed using the heating load calculation. For the maintenance and management phase, maintenance methods were selected according to the durability life, and $CO_2$ emissions from repair materials for each maintenance method were computed. For the disposal phase, individual $CO_2$ emissions were computed using the Standard Quantities As a result, design specifications that satisfy specific target durability life and target reductions in $LCCO_2$ were selected in the early design phase. In addition, by conducting a case analysis, 36 design specifications were selected to obtain a durability life of 100 years and a reduction in $LCCO_2$ emission of 40%.