https://doi.org/10.6110/KJACR.2025.37.2.55

Ahmin Jang ; Minho Kim ; Chanuk Lee ; Ki-Hyung Yu ; Sung Lok Do

To address the climate crisis, South Korea has set ambitious targets to reduce greenhouse gas emissions by 32.8% by 2030 and 88.1% by 2050, compared to 2018 levels. With approximately 70% of Seoul’s carbon dioxide emissions coming from buildings, it is crucial to reduce emissions in this sector. In support of these efforts, the Ministry of Land, Infrastructure, and Transport (MOLIT) introduced building certification systems. However, these systems mainly relied on design-based evaluations and provided limited assessments for existing buildings. This study applied the ENERGY STAR certification method, which is based on actual energy consumption, to an office building in Korea and compared the results with those from design-based assessments. The findings indicated that while the design-based Energy Use Intensity (EUI) rated the building as Grade 1+++, the actual energy use assessment resulted in a lower rating of Grade 3. This significant discrepancy highlights the need for building certification systems to incorporate actual energy usage data to more effectively support carbon reduction goals.

https://doi.org/10.6110/KJACR.2025.37.2.63

Sae Byul Kang ; Jae Joon Choi ; Hyun Hee Lee

Carbon emissions are inevitable from fossil fuel-based technologies such as LNG and heavy oil. In this context, we present hydrogen combustion technology as a fundamental thermal solution for achieving carbon neutrality. The feasibility of hydrogen combustion was confirmed through a simple nozzle hole combustion test. Following this initial test, a 20 kW domestic boiler was modified to evaluate H2-LNG combustion, conduct pure LNG combustion experiments, and carry out H2-LNG co-firing and pure hydrogen combustion tests. During the pure LNG combustion test, boiler thermal efficiencies and NOx emissions were compared across various boiler thermal loads and combustion air ratios. The results indicated that a lower O2 concentration in the exhaust gas corresponded to relatively higher boiler efficiency. The H2-LNG co-firing tests were conducted at co-firing rates ranging from 21% to 71%. The thermal efficiency during co-firing was found to be reduced by approximately 1-2% compared to the pure LNG combustion test. In the pure hydrogen combustion experiments, NOx emissions were found to be about 4 to 5 times higher than those of LNG combustion.

https://doi.org/10.6110/KJACR.2025.37.2.72

Wonjun Choi ; Sangwon Lee ; Max Langtry ; Ruchi Choudhary

Representation Vector-Based Time Series Similarity Analysis Using Unsupervised Contrastive Learning Time Series Encoder

https://doi.org/10.6110/KJACR.2025.37.2.82

Yeontae Jeong ; Soyeon Kim ; Minkyu Jung ; Donik Ku ; Kijeong Seo ; Minsung Kim

This study involved two research projects aimed at predicting and analyzing the impact of increasing the adoption of heat pump water heaters as an alternative for household heating. First, we assessed the effects of replacing existing household boilers with heat pump water heaters for space heating and hot water supply during winter, focusing on electricity demand and greenhouse gas reductions. The results showed that winter average power demand increased by approximately 20%, while greenhouse gas emissions decreased by about 15% compared to previous levels. Next, we analyzed the effect of heat pump water heater adoption on peak electricity demand. To simplify the evaluation, we assumed the use of thermal energy storage and established two operational scenarios for the heat pump water heaters. We examined hourly changes in power demand for each scenario on the day of maximum electricity demand. In the real-time load-following operation scenario, peak power demand increased by 11.7%, while the storage-based load-following operation maintained the peak power level.

https://doi.org/10.6110/KJACR.2025.37.2.92

Jinkyun Cho

The rapid growth of generative AI and cloud services has significantly increased the demand for data centers and their energy consumption, highlighting the urgent need for sustainable energy management and efficiency improvements. This study explores both technical and institutional strategies aimed at optimizing energy use in data centers. It identifies distributed generation systems as a crucial solution for addressing transmission losses and enhancing the reliability and stability of energy supply, moving away from the inefficiencies of centralized grids. Furthermore, the study emphasizes the importance of optimizing cooling and power supply systems as a vital step in effectively reducing energy consumption while ensuring operational reliability. It also underscores the need for supportive policy frameworks, such as the Decentralized Energy Activation Special Act, to promote the use of renewable energy and foster environmentally sustainable growth within the data center industry. To assess and improve energy and carbon efficiency in data center operations, the study incorporates quantitative metrics like Power Usage Effectiveness (PUE) and Carbon Usage Effectiveness (CUE).