As building design and operation changes to meet the goals of sustainability, it is critical to address indoor air quality issues such that indoor environmental conditions are maintained. Among the indoor air contaminants of concern in this context are ultrafine particles, which have been shown to have significant health effects. Transport and fate of ultrafine particles in a building is a function of building ventilation and system operation conditions. The objective of this study is to investigate the use of a multi-zone airflow/contaminant transport model (CONTAM 3.1) for prediction of particle transport to support sustainable building design. Simulations were performed to predict outdoor particle entry into a building with different window positions, which were then compared with experimental measurements. The results indicate that indoor particle concentration varies with ventilation rate, particle penetration, and deposition loss. The results also suggest that the CONTAM model can be used in building design for prediction of particle entry into a building to investigate the impacts of various building design decisions and operating strategies.