Analysis of the Effects of Climate Change and Aging Factor on Heating and Cooling Loads in Korean and Chinese Cities

Purpose: This study examines the combined effects of building component aging and climate change on heating and cooling loads in residential buildings in Korea and China. Unlike most prior research that addresses these factors separately, this study provides a cross-country comparison across diverse climate zones to identify key sensitivities and inform retrofit priorities. Method: Standardized residential models were developed according to national energy design codes, ensuring comparable geometry and envelope specifications. Four city pairs representing cold, temperate, and warm-humid climates were simulated under RCP 2.6 (2020) and RCP 4.5 (2030~2050) scenarios. Aging effects were modeled by progressive increases in U-values for walls, roofs, and windows, along with reduced airtightness, and regression-based sensitivity analyses quantified their impact on annual heating and cooling loads. Result: Findings indicate that in cold climates, heating loads are highly sensitive to infiltration deterioration, while in warm-humid climates, window degradation dominates heating demand. Cooling loads show a consistent linear increase, whereas heating loads display mixed patterns depending on the balance between warming and aging effects. Overall, cooling was more sensitive than heating, with some cases exceeding 200%, highlighting the importance of airtightness and window durability. These results suggest that retrofit strategies should be climate-specific and can guide energy policy and long-term building performance management in Korea and China.