Airtightness is a critical determinant of energy efficiency and hygrothermal performance in ultra-low-energy buildings, yet empirical data regarding lightweight timber construction under local practices in China’s cold climates remain limited. To bridge this gap, this study investigated 18 lightweight timber buildings in cold regions through comprehensive field measurements, aiming to quantify airtightness levels, identify leakage pathways, and develop a rapid prediction model. Blower door tests revealed that the air change rate at 50 Pa ranged from 3.43–7.89 h−1 (mean: 4.83 h−1), with an average air leakage rate per unit envelope area of 6.102 m3/(m2·h). Leakage detection identified openable (20.0%) and fixed (18.4%) fenestration frames, alongside service penetrations (9.9%), as the primary leakage pathways, while unaccounted airflow was traced to diffuse infiltration at structural junctions. Furthermore, Spearman correlation analysis showed significant associations between leakage rates and geometric determinants like building volume and envelope area, which enabled the development of a highly accurate rapid prediction model via backward elimination regression (R2 = 0.932). These findings establish a vital empirical reference for designing and simulating lightweight timber buildings while providing a practical optimization tool for enhancing energy efficiency in cold climates.
苗展堂 et al. (Mon,) studied this question.