Impact of green retrofits on heating energy consumption of apartment buildings based on nationwide energy database in South Korea

In South Korea, apartment buildings account for 63% of residential buildings and approximately 40% of apartment buildings were built before 2000, which leads to the growing demand for green retrofits of old apartment buildings. In this study, heating energy consumption of apartment complexes in Seoul and Busan was analyzed using a nationwide database, in order to evaluate the current energy status of apartment complexes. The energy consumption trend with building age were analyzed by classifying the heating bill data into four groups by construction year of apartment complexes. Based on these data, a simulation model of an old apart-ment building was developed to predict energy performance improvement through green retrofits. The results clearly showed that heating energy consumption increased with building age regardless of heating degree days in both regions. In particular, a significant difference in energy consumption was found in apartment complexes constructed before and after 2000, which implied the necessity of green retrofits for old apartments. The results of green retrofit simulation showed that heating energy consumption was reduced by up to 31.6% and 32% in Seoul and Busan, respectively. The method and results of this study can be applied to establish a green retrofit strategy based on a nationwide database of residential energy.