Research on air infiltration predictive models for residential building at different pressure

The pressure difference in buildings under natural state is usually below 10 Pa, and the air change rate at 50 Pa (ACH 50 ) is often used to evaluate building airtightness. There is a dearth of research on air infiltration predictive model at different pressures in China. Moreover, the airflow coefficient ( C ), a key parameter for air infiltration, is necessary to determine ACH 50 . Based on prior experimental data, several methods including ordinary least squares (OLS), stepwise regression, partial least squares (PLS) and nonlinear fitting with independent variable screening methods, were employed to establish an airflow coefficient model. The determination coefficient ( R 2 ) and the variation coefficient of the root-mean-square error (CV(RMSE)) of these models were compared. The simulation results show that R 2 of the airflow coefficient models for apartments and villas increased by a maximum of 25.9% and 2.3%, respectively, using PLS method. The improvement with nonlinear fitting was weaker. Based on K-P model, a conversion model between ACH 50 and ACH 4 was developed as an air infiltration predictive model under natural state. Blower door and tracer gas tests were conducted to verify the conversion model. The expected error was approximately 10%, which may be caused by measurement errors and shielding from surrounding obstructions. Further studies need to focus on obtaining more experimental data for building airtightness and developing a conversion model for high-rise residential buildings.