Modeling the effects of air leakage flows on VOC emissions and transport in building systems

This study is part of the effort of CHAMP (Combined Heat, Air, Moisture and Pollutant transport simulation) model development. The objective of this study is to characterize the air leakage flows through building systems and to quantify and asses their effects on emission and transport of volatile organic compounds (VOCs). Full-scale laboratory experiments on a residential wood frame wall were conducted. The experiments include 1) emission of VOCs (formaldehyde and others) from the wall assembly with airflow through the wall, 2) VOCs (formaldehyde and toluene) and tracer gas injection into the wall cavity with and without airflow through the wall assembly, 3) VOCs and tracer gas transport with airflow from one side of the wall to the other side. Tests were conducted under controlled temperature, RH and pressure condition for both winter and summer cases with VOC injections. Pressure drops across major flow paths were measured and used with pre-determined pressure/flow rate relationship to calculate the airflow through each flow path. A numerical model (CHAMP) was developed and used to analyze air leakage flows and their effects on VOC emission and transport through building systems. Comparison of measured data and simulation results were done to validate the model simulation and identify causes for any discrepancies. The methodologies of laboratory measurements and simulation may be used for analyzing the performance of other building envelops.