The emission quota of 26.9% was allocated to the architectural sector according to the greenhouse gas(GHG) emission reduction goal of the government. It has become inevitable to change the architectural structures in a low-energy consumption and sustainable manner for new and existing house. The introduction of various legal systems and deregulation have been attempted to promote the low carbon emission and sustainable energy conversion. Although overall emission reduction goal has been set for 6.7 million units of existing houses, there has been a lack of standards and directions for the emission reduction measures. This study was intended to present the most economic and effective green technology improvement measures based on the investigation into the current conditions through direct visit to the selected architectural structures and the repeated simulation of relevant technical elements.