TDC-based horizontal leakage area estimation in multiunit residential buildings: Three correction factors

Abstract

Infiltration and interzonal airflow driven by wind and stack interactions in a multi-unit residential building (MURB) are crucial factors affecting indoor air and environmental qualities. To analyze the weather-driven airflow in MURBs, it is essential to define accurately the horizontal leakage areas for serial airflow paths on typical and basement floors in the multizone airflow modeling. Considering the challenges in measuring numerous leakage areas, a horizontal leakage estimation method based on the thermal draft coefficient (TDC) is proposed, in which the leakage areas are calculated by the stack-driven pressure differences relatively easy to measure. Moreover, three correction coefficients are theoretically suggested to minimize the TDC uncertainties from (1) different household envelope areas, (2) horizontal temperature distributions on each floor, and (3) multiple shafts in real MURBs. Two validation studies were conducted in a real MURB. First, the TDC-based models were validated by CONTAMW, and the effectiveness of the three correction factors was shown in the simulation-based case. The envelope area ratio correction factor was most effective for leakage areas in dwelling units. The shaft ratio correction factor was necessary for elevator doors on typical floors and all leakage areas on basement floors. The air density correction factor could improve all leakage areas under the horizontal temperature distributions on each floor. Then, based on field measurements, the proposed method was applied to leakage estimation in the building. Compared with the existing method, the field-measurement-based validation case demonstrated a significant improvement in the leakage estimation under measurement uncertainties.