Impact of Airflow Modelling Approaches on Residential Building Energy Demand Under Different Climatic Conditions

In building energy calculations, outdoor airflow can be represented using fixed assumptions prescribed by regulations or weather-dependent empirical and pressure-network approaches, and the selected approach can affect the resulting energy demand. This study compares five approaches in a four-storey residential reference building: a prescribed floor-area-based outdoor airflow assumption used in a national thermal-insulation standard (M1), two empirical infiltration models (M2–M3), and two AirflowNetwork models using analytical–tabulated or wind-tunnel-derived pressure coefficients (M4–M5). Six representative cities were simulated with typical meteorological year (TMYx) files based on 2009–2023 data and regional envelope configurations. Relative to M1, M5 produced higher annual outdoor airflow in two climate conditions and lower airflow in four, while increasing cooling demand by 0.97–14.48% in all conditions. With an identical leakage network and 15° wind-direction intervals, M5 produced annual air-change rates and heating demands 3.40–4.17% and 2.26–10.98% higher than M4, respectively. The effects of airflow-model selection therefore depend on climatic conditions and the heating or cooling component considered. These findings highlight the importance of interpreting differences between simplified standard outdoor-air assumptions and detailed airflow models in relation to the scope and underlying assumptions of each approach.