The increase in the number of applications using hydrogen in the marketplace will require a better understanding of the dispersion and accumulation associated with accidental leaks in a structure. Predict the evolution of the hydrogen concentration over time in a structure, with different flow rates and positions of leak is challenging. CFD modeling was employed extensively in a study designed to characterize possible modifications and costs associated with parking hydrogen-fueled automobiles in buildings. We describe our CFD approach in sufficient detail to justify the choice of model using the commercial software FLUENT, and we explored the relationship between leak positions, release rates, leak duration and hydrogen concentration. When the leak position is approaching to the center of the garage, there is encouragement of stable stratification. Hydrogen concentration is higher and leak scenarios are more dangerous when the leakage time is important and the flow rate is low. Copyright (C) 2015, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.