Analysis of the Lifecycle Carbon Reduction Effects of Public Daycare Centers through Green Remodeling

In the Republic of Korea, 42.6% of buildings are 30 years old or older. Most were constructed before the strengthening of energy-saving design standards, making improvements in energy performance essential to meet carbon-neutrality targets. "Green remodeling" refers to environmentally friendly retrofits of aging buildings to improve energy performance and efficiency and enhance indoor comfort. Accordingly, the Korean government is promoting green remodeling for aged public buildings, prioritizing facilities for vulnerable groups such as children. In green remodeling, the before-and-after energy-saving effect is critical, and current policy in Korea recommends achieving at least 30% energy savings. However, achieving carbon neutrality requires whole-building life cycle assessment (LCA) of carbon emissions, whereas most domestic efforts still focus only on reducing operational energy use. Therefore, this study analyzes emission-reduction effects not only during operation but across the entire life cycle of a green-remodeled building. A public daycare center over 30 years old was selected, and passive measures, including thermal insulation, low-emissivity glazing, and airtight insulated doors, were applied. The embodied carbon of the materials used was calculated using the national LCI database, and life cycle assessment across production, transportation, construction, and demolition stages was performed in accordance with ISO 14040 and ISO 21930. The operational effects of the green remodeling were analyzed using the DesignBuilder program. According to the results, the carbon emissions generated by the green remodeling works for a public daycare center over 30 years old were 32.078 tCO2eq, and during the operational stage the emissions decreased from 12.558 tCO2eq to 11.225 tCO2eq, representing a reduction of approximately 10.6%. These results indicate that carbon payback begins 24.1 years after the green remodeling, and that full offset can be achieved at 48.2 years. Therefore, the findings suggest that energy savings are feasible for green-remodeled buildings not only during operation but also from a whole life-cycle perspective, and they are expected to serve as a basis for future carbon-reduction analyses and policy development.