Estimating indoor airflow characteristics of natural ventilation systems is very significant in the early design stage. It’s clear that for the early steps of design, ex-isting numerical and experimental analysis methods are very time consuming and they require in depth knowledge of Fluid Dynamics. These methods are not effi-cient especially in the case that the building form changes dynamically. Besides, both wind tunnel testing and Computational Fluid Dynamics simulations are not efficient when it comes to taking output in real-time. Due to all of these reasons, a need for a fast and robust method occurs. Particle-based algorithms are efficient methods for this type of analyses however they have not been used in architec-tural aerodynamics. At this point, a very powerful method which doesn’t require mesh (control volume) is developed. In this study, the details of the developed algorithm and the output of it are given. The algorithm was assessed in three case studies of natural ventilation systems. As a result, it is seen that the developed al-gorithm can be a guide in building-wind interaction analysis for architects in the early design stage. However, in our paper, we do not only present case studies, but also an analysis methodology from architectural and engineering perspectives. This is significant because the methodology and the results of this paper consti-tute a guide for further researches on natural ventilation with a new method and consequently contribute to improved wind quality of indoor spaces.