A Methodology for Deriving Conversion Coefficients of Natural Infiltration Using Airtightness Data

초록

The commonly used conversion coefficient for natural infiltration rates (N) is derived from single-zone or low-rise building assumptions and therefore fails to account for the substantial pressure differences driven by building height and seasonal temperature variations. These induced pressure differences significantly impact on the variations in infiltration rates within high-rise buildings, particularly during heating and cooling seasons. Therefore, this study develops a floor-resolved methodology for deriving N in high-rise buildings under various seasonal conditions, through extending the effective leakage area (ELA) model and incorporating normalization procedures that reflect seasonal and environmental conditions. Application of this method to high-rise buildings in South Korea shows that both infiltration rates and N values at upper and lower floors exceed those near the neutral pressure level (NPL) by more than a factor of two under winter conditions. Moreover, the derived N values deviate substantially from the commonly assumed reference value of 20 and vary systematically with floor height and season. These findings indicate that using a uniform N value can lead to considerable errors in estimating infiltration and associated energy loads, underscoring the necessity of height- and climate-specific conversion coefficients for accurate energy performance assessment.

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