In a previous study, a whole room IAQ model consisting of multi-phase emission/sorption model for wall materials and room volume mass balance model catering for practical ventilation schemes was developed. The interactions between volatile organic compounds (VOCs) and building materials composing different building components can thus be modeled based on fundamental mass transfer theories. In the present study, the effects of various ventilation strategies and outdoor source on the indoor gas phase VOC concentration are investigated by simulating different building scenarios. Results show that lead time provision of ventilation can significantly lower the peak indoor VOC concentration at the beginning of the occupancy and also the gas phase VOC concentration during the whole working day. Prolonging the provision of ventilation after the occupants have left seems not to improve the indoor air quality the next working day. The outdoor VOCs sources seem to have substantial effects on indoor VOCs concentration.