This study presents a methodology and process to establish a mandatory policy of zero-energy buildings (ZEBs) in Korea. To determine the mandatory level to acquire the rating of a ZEB in Korea, this study was conducted under the assumption that the criteria of ZEB was a top 5% building considering the building’s energy-efficiency rating, which was certified through a quantitative building energy analysis. A self-sufficiency rate was also proposed to strengthen the passive standard of the buildings as well as to encourage new and renewable energy production. Accordingly, zero-energy buildings (ZEBs) in Korea are defined as having 60 kWh/(m²·yr) of non-renewable primary energy (NRPE) consumption in residential buildings and 80 kWh/(m²·yr) in non-residential buildings, and the self-reliance rate should be more than 20% of the renewable energy consumption as compared to the total energy consumption of the buildings. In addition, the mandatory installation of building energy management systems (BEMS) was promoted to investigate the energy behavior in buildings to be certified as zero-energy in the future. This study also investigated the number of ZEB certificates during the demonstration period from 2017 to 2019 to analyze the energy demand, non-renewable primary energy, renewable primary energy, and self-sufficiency rate as compared to those under the previous standards. For ZEB Grade 1 as compared to the existing building energy-efficiency rating, the sum of the NRPE decreased more than 50%, and renewable energy consumption increased more than four times.

Accurate standard meteorological data sets for each city are essential elements to assess and analyze high-performance buildings quantitatively in order to ensure that they comply with energy saving policies of the nation. ECO2, which is an assessment program of building energy in Korea, has employed meteorological data of the closest city to the target location from 13 urban meteorological data references; the employment of this program has demonstrated the ability to reflect climatic differences between cities. The present study expanded urban meteorological data to ISO TRY (International Organization for Standard Test Reference Year), an international standard methodology that can calculate the data in a relatively simple manner using observed data in Korea, as much as possible in order to reflect meteorological data, including the air temperature relevant for heating and cooling energy as well as solar radiation (cooling/heating energy) for each city, that affected the assessment of building energy the most. In the present study, existing data is expanded to a show the standard meteorological data of 66 cities that can be put into the Korean assessment program (ECO2). This data considered valid meteorological data (minimum statistical period, air temperature, relative humidity, wind, and solar radiation, etc.) among manned and unmanned observational data obtained from 479 locations from 2001 to 2010. For cities other than the 66 aforementioned cities, zoning was conducted to separate cities that had and did not have the standard meteorological data using a cumulative temperature density graph. In this way, meteorological data can be available in all cities, which will enable more accurate simulation assessments on building energy.

This study presented a methodology and process to establish a passive level for policy making of building energy in South Korea. A passive level in Korea specified in the 2017 Roadmap for non-residential buildings, which was 15 kWh/m²·year, was defined as the heating energy requirement to strengthen the building energy saving design standards, which were typical building energy regulations in Korea. This study also presented insulation standards of roofs, floors, outer walls, and windows in Pyeongchang, Seoul, Gwangju, and Jeju, which were represented cities of four zones in Korea (Middle 1, Middle 2, Southern, and Jeju). Furthermore, the study results were extended to 66 cities around the nation to calculate the heating energy requirements and a severely cold region was added to existing three regions (Middle, Southern, and Jeju) to extend this to four regions (Middle 1, Middle 2, Southern, and Jeju). Afterwards, insulation standards for four represented regions were presented to derive a measure that minimized an energy loss through outer walls or windows in buildings. Finally, this study derived that a return of investment can be achieved in 10 years, which was determined through the comprehensive economic feasibility analysis due to strengthening insulation performances, proving the rationalization of the legal strengthening.

In this study, a comparative economic analysis was conducted for typical greenhouses, plant factories with natural and artificial light, and those with only artificial light, based on the insulation, artificial light, and photovoltaic (PV) installation costs. In addition, the results of research on primary energy consumption and greenhouse gas (GHG) emissions from the use of fossil fuels were presented. By comparing the case-wise annual energy consumption, when all energy sources were converted into primary energy consumption based on the applied coefficients for collection, transport, and processing, to unify calculations for different fossil fuel energy sources, the case of the installed PV systems exhibited large reductions, of 424% and 340%, in terms of primary energy consumption and GHG emissions, respectively. Furthermore, electric heating resulted in higher primary energy consumption and GHG emissions than oil. When the economic analysis included the plant factory installation cost used to maintain the temperature required for plant growth in winter, the PV installation exhibited the highest cost; additionally, all plant factories showed an investment payback period of seven to nine years, which is comparable to typical greenhouses. Based on these results, we aim to reduce the use of fossil fuels for sustainable energy by combining architectural technology for improved energy performance in the agricultural environment.

This study aims to institutionalize an evaluation methodology to assess water-source heat pumps (WSHPs) when designing a zero-energy building. Thus, regions where zero-energy buildings were designed were subdivided into 66 sub-regions, thereby standardizing the temperatures on the source side of WSHPs using river water and pipeline water. Based on these data, ground-source and water-source heat pump system-based simulation (new and renewable energy self-sufficiency rate compared to building energy consumption) values were derived for cases whose condition (region or heat source) was different among the buildings certified as zero-energy buildings. The application of the standard meteorological data and reference hydrothermal data to the ECO2 program and outcome evaluation led to the following findings: in all cases (reference: Seoul), ground-source heat pumps (GSHPs) showed a higher self-sufficiency rate than WSHPs (ground source > pipeline water > river water). The self-sufficiency rate of GSHPs was 11–33% higher than that of WSHPs. In a regional comparison among the cold (Jeongseon), central (Seoul), and southern (Jeju Island) regions, WSHPs exhibited higher energy self-sufficiency rates than GSHPs under the conditions of higher water temperatures in winter and lower water temperatures in summer, as in the southern region.

This study presents an integrated ex-post evaluation of a municipal window-retrofit program in Goyang, Republic of Korea (heating-dominated, Dwa). Using field surveys and pre- and post-utility bills for 36 dwellings, mainly pre-2000 low-rise reinforced-concrete buildings, we normalize climate with HDD and CDD and prices with CPI-deflated tariffs to isolate the intrinsic effect of window replacement. Area-normalized indicators ($∆e$, $\eta$, DPB, NPV, AC) were computed. Average annual savings were 30.2 kWh per m² per year ($\eta$ ≈ 16 percent), consisting of 10.6 kWh per m² per year of gas and 19.6 kWh per m² per year of electricity (n = 36). The median discounted payback was 7.0 years. Under a 50 percent subsidy, about 80 percent of projects recovered private investment within 15 years and showed positive NPV with a median of about USD 4944. The electricity-tariff multiplier had the largest influence on cash flows and payback. The median abatement cost was about USD 352 per tCO₂-eq. A portfolio view indicates that prioritizing low-cost cases maximizes total abatement, and that higher-cost cases merit design or cost review. Using the first post-retrofit year 2023, portfolio abatement is about 623 tCO₂-eq per year. The framework jointly normalizes climate and price effects and yields policy-relevant estimates for heating-dominated contexts.