The purpose of this study is to analyze the scope of the expected improvement effect of office buildings and educational research facilities according to green remodeling. Thus, in order to quantitatively grasp the architectural performance of the existing buildings, the building thermal performance, the airtightness, the indoor environment, and the air quality were measured using equipment. The analysis indicated that the envelope performance and the indoor environment were unsatisfactory compared to the current legal standards, and for indoor air quality, CO2 and formaldehyde were measured to be dissatisfactory in some buildings. The energy analysis results indicated that the improvement range differed according to the renovation history for each building, resulting in differences in the energy-saving rate for each alternative. The reduction rates of primary energy consumption using energy simulation were 38.5–67.4% for office buildings and 23.7–66.3% for educational research facilities, and the payback periods were 14 to 27 years for office buildings and 12 to 30 years for educational research facilities. These results are expected to contribute to the activation of green remodeling because they can be used as indicators to predict the expected construction cost, the payback period, and the expected effect required for green remodeling.