Duhwan Lee

This study summarizes the technology level and economic feasibility of two small 500 m² public office buildings that achieved a first-class Zero Energy Buildings (ZEB) certification for the first time in Korea. In addition, a Life Cycle Assessment (LCA) reflecting the ZEB performance in the operation stage was analyzed, and the LCA factors considering the characteristics of small buildings were reviewed. Moreover, an economic analysis was performed through a Net Present Value (NPV) by reflecting the ZEB and LCA, and the results showed little economic feasibility. However, adding the environmental costs calculated through the LCA to the existing energy-saving costs could offset an additional 11.6–11.7%. Therefore, including the environmental impact and cost through these LCA evaluation techniques could be a positive step toward increasing the effectiveness of ZEB applications. This study is significant in that it conducted a comprehensive analysis through ZEB and LCA in terms of carbon reduction for small buildings that achieved a first-class ZEB certification, but it is limited to only two cases.

In this study, the economic feasibility of green remodeling (GR), which could improve the health, safety, and energy of elderly households considering social cost, was analyzed. As a result, the net present value of GR was ‘−10,267 USD (49.7%)’, which was found to be uneconomical compared to the total construction cost (20,981 USD, 100%) despite benefits of energy saving, carbon reduction, and air pollutant reduction. Based on this result, in order to expand GR for low-income elderly households, who cannot afford to perform GR, a GR support measure linked to the currently implemented energy conversion and old-age housing support policies was proposed. It allows the government to perform GR for low-income elderly households with 1/4 of the total construction cost. This result could revitalize GR to reduce greenhouse gas and contribute to housing stability for low-income elderly households who are vulnerable to COVID-19 and climate change.

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.