In Korea, it is also mandatory for most buildings to receive energy efficiency rating certification from 2020 for the purpose of reducing greenhouse gas emissions and expanding green buildings. However, the issue of the accuracy of the ECO2 program continues to be raised, and comparisons have been made with dynamic energy analysis programs in a single type of building according to a single area. However, comparisons between multiple building types and multiple areas are insufficient. Therefore, in this study, cooling and heating loads according to multiple building types and multiple areas were analyzed through ECO2 and TRNSYS programs. The regions were supposed to be Seoul, Daejeon, Gwangju, and Busan and the building types were supposed to be office buildings and apartment houses. The annual average building load values from ECO2 were higher than those from TRNSYS. Among residential buildings across the four regions, the largest discrepancy was 41.4% in Seoul. Conversely, for commercial buildings, the most significant difference in annual average loads was noted in Gwangju, at 37.9%.

The air temperature is gradually increasing owing to global warming, especially in summer, therefore, the performance of an air source heat pump (ASHP) is expected to be decreased. Accordingly, the performance gap between the ASHP and ground source heat pump (GSHP) should be increased, however, the quantitative comparison has not been yet investigated. In this study, impact of global warming on the performance of the ASHP and GSHP is investigated based on the climate data for 1930, 1980, and 2030. The coefficient of performance (COP) as well as annual power consumption of the ASHP and GSHP are compared and analyzed. In the case of COP, the COP of GSHP hardly changes over the years owing to the constant ground temperature, while that of ASHP decreases by 3.7% for cooling and increases by 0.71% for heating. In the case of annual power consumption, the cooling and heating power consumption of GSHP increases by 12.69% and decreases by 15.58%, respectively, over the year owing to the changes in heating and cooling loads. As for the ASHP, the cooling and heating power consumption increases by 16.64% and decreases by 17.8%, respectively. For a more accurate comparison, power consumption ratio is introduced and shows that total annual power consumption of the GSHP to ASHP decreased from 68% in 1930 to 65% in 2030. Therefore, as global warming accelerates, the effect of reducing power consumption by using GSHP compared to ASHP is expected to be increasing.

Green-remodeling is to improve the energy performance of existing buildings that have been aged for more than 15 years since completion. In order to achieve the national greenhouse gas emission reduction plan in the building sector, it is necessary to analyze the carbon reduction effect by considering the internal carbon emissions that may occur during green-remodeling of old buildings. This study analyzed the effects of energy reduction and carbon emission reduction when green-remodeling was applied to old health centers constructed in 1992. When applying green-remodeling, the carbon emission reduction effect considered the embodied carbon emission of the improvement items and the carbon emission at the building operation stage. When applying green-remodeling to existing buildings, energy consumption was reduced by 39.3%, and carbon emissions were reduced by 48.9% after 27 years of green-remodeling. In order to reduce carbon emissions, it was important to apply a renewable system as an item to improve the performance of green-remodeling. In particular, it was confirmed that it is very important to consider the photovoltaic system as a top priority for the carbon emission reduction.

The Government the Republic of Korea is showing a lot of interest in net zero-energy buildings (NZEBs) to reduce energy consumption of buildings and to promote green growth policy in construction sector. The application of building passive technologies and renewable energies is essential to achieving NZEBs. Green remodeling reinforced the insulation of the exterior walls and roofs of the buildings and replaced high-efficiency windows and doors. In this study, the energy performance before and after green remodeling applied in a detached house was comparatively analyzed for baseline scenario and three different ones, ALT 1, ALT 2 and ALT 3. A building modeling and simulation software (DesignBuilder V7.0) with EnergyPlus (V9.4) calculation engine was used to calculate the energy demand and energy consumption for each scenario. Based on the calculation results of the building's energy demand for baseline, it was determined that the target building required more heating energy than cooling energy. The simulation results also showed that the implementation of building envelope performance improvement technologies (ALT 1) could notably decrease the heating energy consumption of the building. After the remodeling (ALT 1), the source energy consumption per unit floor area was assessed to be reduced by 65.2%, compared to prior remodeling of 338.7 kWh/m² -y. Meanwhile, ALT 2 can achieve energy savings of 67.7% and ALT 3 can achieve savings of 73.1%. Following completion of the remodeling project, actual construction costs, and on-site measurements and verification results will be gathered and compared with the simulation results. Additionally, economic analysis including construction costs and payback period will be conducted using actual site data.

This study analyzes the energy performance of a elderly care center building and the applicability of a ground source heat pump (GSHP) system through simulation approach. For this purpose, a building information modeling (BIM) program and an energy performance calculation program were used. The impact of the mechanical ventilation system on the energy requirements of the heating and cooling system and the indoor environment was also analyzed, focusing on the change in indoor carbon dioxide (CO₂) concentration, which is a representative indicator of the indoor environment (air quality). The simulation results showed that the target building exceeds Level 7 in terms of simulated primary energy consumption or actual energy consumption. In addition, it was analyzed that the target building could not maintain the indoor CO₂ concentration below the standard concentration by natural ventilation through window opening alone. Combining the GSHP system with the mechanical ventilation system (Case B and Case C) can further reduce the overall energy consumption by reducing the amount of outdoor air introduced by opening windows. The cost savings compared to the baseline case are estimated to be 67.3% for Case A, 63.7% for Case B, 65.5% for Case C, and 42.5% for Case D. It is necessary to analyze the impact of various renewable energy technologies and passive ones on the energy performance and indoor environment of elderly care centers.