Urban-Scale Building Air Change Rate Estimation Using Corrected Wind Speeds and Three-Zone Building Modeling

This study presents a scalable, time-efficient methodology for estimating building-specific air change rates by incorporating local urban morphology and wind conditions. The presented methodology is used to develop a QGIS-based plugin (Quantum Geographic Information System) to automate the integration of aerodynamic parameters derived from the Urban Multi-scale Environmental Predictor, with a simplified three-zone lumpedparameter model and multizone airflow simulations using CONTAM. The plugin calculates façade-specific wind-speed modifiers across 30° directional intervals. These modifiers are then used in a three-zone CONTAM model to calculate hourly building air change rates. The results were incorporated into an hourly energy consumption model for space heating and validated against measured energy-use from residential buildings in Turin, Italy. Results show that replacing constant air change rates with site-specific estimates reduced the Mean Absolute Percentage Error by 11% to 20%. In particular, the error was reduced from 49% -+ 9% to 32% -+ 6.5% in January, corresponding to a relative error reduction of approximately 34%. The proposed method demonstrates improved accuracy in simulating building energy consumption considering the influence of an accurate shape of the urban environment on air change rates; moreover, it offers an automated framework for urban-scale assessments of ventilation, infiltration, and energy performance.