Indoor air quality comparison of two air-conditioned zones served by the same air-handling unit

Most indoor air quality (IAQ) investigations take an air handling unit (AHU) - based zone as the basic unit for investigation from the logical viewpoint that the AHU constitutes the mechanism for mixing and (cross-) transportation of pollutants within the zone. If there is very good air-mixing, as indicated by a high air exchange effectiveness, the single zone approach may be sufficient. However, when there is large discrepancy in pollutant generation between spaces within the spaces served by the AHU, or when the ventilation is impeded due to inappropriate partitioning, the zonal characteristics are likely to differ from space to space. This paper reports a comparison of the zonal characterisation of an office space whose ventilation and thermal comfort parameters are different. In this study an integrated approach to IAQ auditing which includes measurements of chemical, biological, particulate, thermal comfort and ventilation parameters was adopted. Significant differences in the values and time profiles of the various pollutant dimensions have been observed between the two zones. These differences are attributable to the dominant influences of interior layout and partitioning, degree of exposure to the exterior, occupant activities, occupant intervention of the ventilation system by operating the operable windows, and the materials deployed for interior partitions.