The objective of this study was to evaluate the effectiveness of using VOC emission signatures of building materials and office equipment for major emission source identification in a workplace. Both the emission signatures and onsite measurements were collected by a PTR-MS. The VOC emission signature of a laser printer as well as selected building materials were first established in a laboratory using middle-scale and small-scale emission test chambers, respectively. The printer and materials were then used in an office building which had a dedicated HVAC system, regular occupancy and associated activities. The PTR-MS equipped with an auto switching valve system was then used to monitor online VOC concentrations at multiple locations simultaneously including outdoor, indoor in occupied space and HVAC supply duct. Different event scenarios were constructed for testing to determine any dynamic correlation among different air samples and the usability of a source identification method developed previously to successfully pinpoint emission sources.