Measurements and computations of contaminantʹs distribution in an office environment

This paper investigates the dispersion of contaminants in an office environment using empirical and modeling techniques. The experiment was conducted in an environmental test facility with the mock-up of two typical office layouts. Layout 1 has two workstations located in the middle of the room and separated by a low-level partition, while Layout 2 has a low level-partition which separates the room into two halves with one workstation at each corner. The test facility, 6.6 m (L)×3.7 m (W)×2.6 m (H), is served by an air-conditioning and mechanical ventilation (ACMV) system which is capable of controlling the air temperature and airflow rates at the supply diffuser and extract grille. The contaminantʹs emission was generated by a constant injection of tracer gas, sulfur hexafluoride (SF6), via a 280 mm×200 mm surface to represent the plane source. The concentration of contaminant in the chamber for both the layouts was measured and simulated using a gas analyzer and a computational fluid dynamic (CFD) program with the Re-Normalization Group k– model, respectively. In general, the predicted concentration of contaminant was in good correlation with the measured concentration. However, the predicted results were always marginally lower than the measured results. The contaminantʹs dispersion pattern was observed to be highly dependent on the velocity flow field. The layout of furniture influenced the airflow pattern and contaminantʹs distribution in the office. On the whole, Layout 1 was better than Layout 2 with a lower level of contaminant at the occupantʹs breathing zones.